All EyeLink Publications
All 8000+ peer-reviewed EyeLink research publications up until 2019 (with some early 2020s) are listed below by year. You can search the publications library using key words such as Visual Search, Smooth Pursuit, Parkinsons, etc. You can also search for individual author names. Eye tracking studies grouped by research area can be found on the solutions pages. If we missed any EyeLink eye tracking paper, please email us!
All EyeLink publications are also available for download / import into reference management software as a single Bibtex (.bib) file.
2008 |
Joshua M Susskind; Daniel H Lee; Andrée Cusi; Roman Feiman; Wojtek Grabski; Adam K Anderson Expressing fear enhances sensory acquisition Journal Article Nature Neuroscience, 11 (7), pp. 843–850, 2008. @article{Susskind2008, title = {Expressing fear enhances sensory acquisition}, author = {Joshua M Susskind and Daniel H Lee and Andrée Cusi and Roman Feiman and Wojtek Grabski and Adam K Anderson}, doi = {10.1038/nn.2138}, year = {2008}, date = {2008-01-01}, journal = {Nature Neuroscience}, volume = {11}, number = {7}, pages = {843--850}, abstract = {It has been proposed that facial expression production originates in sensory regulation. Here we demonstrate that facial expressions of fear are configured to enhance sensory acquisition. A statistical model of expression appearance revealed that fear and disgust expressions have opposite shape and surface reflectance features. We hypothesized that this reflects a fundamental antagonism serving to augment versus diminish sensory exposure. In keeping with this hypothesis, when subjects posed expressions of fear, they had a subjectively larger visual field, faster eye movements during target localization and an increase in nasal volume and air velocity during inspiration. The opposite pattern was found for disgust. Fear may therefore work to enhance perception, whereas disgust dampens it. These convergent results provide support for the Darwinian hypothesis that facial expressions are not arbitrary configurations for social communication, but rather, expressions may have originated in altering the sensory interface with the physical world.}, keywords = {}, pubstate = {published}, tppubtype = {article} } It has been proposed that facial expression production originates in sensory regulation. Here we demonstrate that facial expressions of fear are configured to enhance sensory acquisition. A statistical model of expression appearance revealed that fear and disgust expressions have opposite shape and surface reflectance features. We hypothesized that this reflects a fundamental antagonism serving to augment versus diminish sensory exposure. In keeping with this hypothesis, when subjects posed expressions of fear, they had a subjectively larger visual field, faster eye movements during target localization and an increase in nasal volume and air velocity during inspiration. The opposite pattern was found for disgust. Fear may therefore work to enhance perception, whereas disgust dampens it. These convergent results provide support for the Darwinian hypothesis that facial expressions are not arbitrary configurations for social communication, but rather, expressions may have originated in altering the sensory interface with the physical world. |
Tom Foulsham; Geoffrey Underwood What can saliency models predict about eye movements? Spatial and sequential aspects of fixations during encoding and recognition Journal Article Journal of Vision, 8 (2), pp. 1–17, 2008. @article{Foulsham2008a, title = {What can saliency models predict about eye movements? Spatial and sequential aspects of fixations during encoding and recognition}, author = {Tom Foulsham and Geoffrey Underwood}, doi = {10.1167/8.2.6}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {2}, pages = {1--17}, abstract = {Saliency map models account for a small but significant amount of the variance in where people fixate, but evaluating these models with natural stimuli has led to mixed results. In the present study, the eye movements of participants were recorded while they viewed color photographs of natural scenes in preparation for a memory test (encoding) and when recognizing them later. These eye movements were then compared to the predictions of a well defined saliency map model (L. Itti & C. Koch, 2000), in terms of both individual fixation locations and fixation sequences (scanpaths). The saliency model is a significantly better predictor of fixation location than random models that take into account bias toward central fixations, and this is the case at both encoding and recognition. However, similarity between scanpaths made at multiple viewings of the same stimulus suggests that repetitive scanpaths also contribute to where people look. Top-down recapitulation of scanpaths is a key prediction of scanpath theory (D. Noton & L. Stark, 1971), but it might also be explained by bottom-up guidance. The present data suggest that saliency cannot account for scanpaths and that incorporating these sequences could improve model predictions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saliency map models account for a small but significant amount of the variance in where people fixate, but evaluating these models with natural stimuli has led to mixed results. In the present study, the eye movements of participants were recorded while they viewed color photographs of natural scenes in preparation for a memory test (encoding) and when recognizing them later. These eye movements were then compared to the predictions of a well defined saliency map model (L. Itti & C. Koch, 2000), in terms of both individual fixation locations and fixation sequences (scanpaths). The saliency model is a significantly better predictor of fixation location than random models that take into account bias toward central fixations, and this is the case at both encoding and recognition. However, similarity between scanpaths made at multiple viewings of the same stimulus suggests that repetitive scanpaths also contribute to where people look. Top-down recapitulation of scanpaths is a key prediction of scanpath theory (D. Noton & L. Stark, 1971), but it might also be explained by bottom-up guidance. The present data suggest that saliency cannot account for scanpaths and that incorporating these sequences could improve model predictions. |
Roger Kalla; Neil G Muggleton; Chi-Hung Juan; Alan Cowey; Vincent Walsh The timing of the involvement of the frontal eye fields and posterior parietal cortex in visual search Journal Article NeuroReport, 19 (10), pp. 1069–1073, 2008. @article{Kalla2008, title = {The timing of the involvement of the frontal eye fields and posterior parietal cortex in visual search}, author = {Roger Kalla and Neil G Muggleton and Chi-Hung Juan and Alan Cowey and Vincent Walsh}, doi = {10.1097/WNR.0b013e328304d9c4}, year = {2008}, date = {2008-01-01}, journal = {NeuroReport}, volume = {19}, number = {10}, pages = {1069--1073}, abstract = {The frontal eye fields (FEFs) and posterior parietal cortex (PPC) are important for target detection in conjunction visual search but the relative timings of their contribution have not been compared directly. We addressed this using temporally specific double pulse transcranial magnetic stimulation delivered at different times over FEFs and PPC during performance of a visual search task. Disruption of performance was earlier (0/40 ms) with FEF stimulation than with PPC stimulation (120/160 ms), revealing a clear and substantial temporal dissociation of the involvement of these two areas in conjunction visual search. We discuss these timings with reference to the respective roles of FEF and PPC in the modulation of extrastriate visual areas and selection of responses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The frontal eye fields (FEFs) and posterior parietal cortex (PPC) are important for target detection in conjunction visual search but the relative timings of their contribution have not been compared directly. We addressed this using temporally specific double pulse transcranial magnetic stimulation delivered at different times over FEFs and PPC during performance of a visual search task. Disruption of performance was earlier (0/40 ms) with FEF stimulation than with PPC stimulation (120/160 ms), revealing a clear and substantial temporal dissociation of the involvement of these two areas in conjunction visual search. We discuss these timings with reference to the respective roles of FEF and PPC in the modulation of extrastriate visual areas and selection of responses. |
Christopher M Knapp; Irene Gottlob; Rebecca J McLean; Frank A Proudlock Horizontal and vertical look and stare optokinetic nystagmus symmetry in healthy adult volunteers Journal Article Investigative Ophthalmology & Visual Science, 49 (2), pp. 581–588, 2008. @article{Knapp2008, title = {Horizontal and vertical look and stare optokinetic nystagmus symmetry in healthy adult volunteers}, author = {Christopher M Knapp and Irene Gottlob and Rebecca J McLean and Frank A Proudlock}, doi = {10.1167/iovs.07-0773}, year = {2008}, date = {2008-01-01}, journal = {Investigative Ophthalmology & Visual Science}, volume = {49}, number = {2}, pages = {581--588}, abstract = {PURPOSE: Look optokinetic nystagmus (OKN) consists of voluntary tracking of details in a moving visual field, whereas stare OKN is reflexive and consists of shorter slow phases of lower gain. Horizontal OKN is symmetrical in healthy adults, whereas symmetry of vertical OKN is controversial. Horizontal and vertical look and stare OKN symmetry was measured, and the consistency of individual asymmetries and the effect of varying stimulus conditions were investigated.METHODS: Horizontal and vertical look and stare OKN gains were recorded in 15 healthy volunteers (40 degrees /s) using new methods to delineate look and stare OKN. Responses with right and left eye viewing were compared to investigate consistency of individual OKN asymmetry. In a second experiment, the symmetry of stare OKN was measured in nine volunteers varying velocity (20 degrees /s and 40 degrees /s), contrast (50% and 100%), grating contrast profile (square or sine wave), and stimulus shape (full screen or circular vignetted).RESULTS: There was no horizontal or vertical asymmetry in look or stare OKN gain for all volunteers grouped together. However, individual vertical asymmetries were strongly correlated for left and right eye viewing (look: r = 0.77}, keywords = {}, pubstate = {published}, tppubtype = {article} } PURPOSE: Look optokinetic nystagmus (OKN) consists of voluntary tracking of details in a moving visual field, whereas stare OKN is reflexive and consists of shorter slow phases of lower gain. Horizontal OKN is symmetrical in healthy adults, whereas symmetry of vertical OKN is controversial. Horizontal and vertical look and stare OKN symmetry was measured, and the consistency of individual asymmetries and the effect of varying stimulus conditions were investigated.METHODS: Horizontal and vertical look and stare OKN gains were recorded in 15 healthy volunteers (40 degrees /s) using new methods to delineate look and stare OKN. Responses with right and left eye viewing were compared to investigate consistency of individual OKN asymmetry. In a second experiment, the symmetry of stare OKN was measured in nine volunteers varying velocity (20 degrees /s and 40 degrees /s), contrast (50% and 100%), grating contrast profile (square or sine wave), and stimulus shape (full screen or circular vignetted).RESULTS: There was no horizontal or vertical asymmetry in look or stare OKN gain for all volunteers grouped together. However, individual vertical asymmetries were strongly correlated for left and right eye viewing (look: r = 0.77 |
Andrea E Martin; Brian McElree A content-addressable pointer mechanism underlies comprehension of verb-phrase ellipsis Journal Article Journal of Memory and Language, 58 (3), pp. 879–906, 2008. @article{Martin2008, title = {A content-addressable pointer mechanism underlies comprehension of verb-phrase ellipsis}, author = {Andrea E Martin and Brian McElree}, doi = {10.1016/j.jml.2007.06.010}, year = {2008}, date = {2008-01-01}, journal = {Journal of Memory and Language}, volume = {58}, number = {3}, pages = {879--906}, abstract = {Interpreting a verb-phrase ellipsis (VP ellipsis) requires accessing an antecedent in memory, and then integrating a representation of this antecedent into the local context. We investigated the online interpretation of VP ellipsis in an eye-tracking experiment and four speed-accuracy tradeoff experiments. To investigate whether the antecedent for a VP ellipsis is accessed with a search or direct-access retrieval process, Experiments 1 and 2 measured the effect of the distance between an ellipsis and its antecedent on the speed and accuracy of comprehension. Accuracy was lower with longer distances, indicating that interpolated material reduced the quality of retrieved information about the antecedent. However, contra a search process, distance did not affect the speed of interpreting ellipsis. This pattern suggests that antecedent representations are content-addressable and retrieved with a direct-access process. To determine whether interpreting ellipsis involves copying antecedent information into the ellipsis site, Experiments 3-5 manipulated the length and complexity of the antecedent. Some types of antecedent complexity lowered accuracy, notably, the number of discourse entities in the antecedent. However, neither antecedent length nor complexity affected the speed of interpreting the ellipsis. This pattern is inconsistent with a copy operation, and it suggests that ellipsis interpretation may involve a pointer to extant structures in memory.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Interpreting a verb-phrase ellipsis (VP ellipsis) requires accessing an antecedent in memory, and then integrating a representation of this antecedent into the local context. We investigated the online interpretation of VP ellipsis in an eye-tracking experiment and four speed-accuracy tradeoff experiments. To investigate whether the antecedent for a VP ellipsis is accessed with a search or direct-access retrieval process, Experiments 1 and 2 measured the effect of the distance between an ellipsis and its antecedent on the speed and accuracy of comprehension. Accuracy was lower with longer distances, indicating that interpolated material reduced the quality of retrieved information about the antecedent. However, contra a search process, distance did not affect the speed of interpreting ellipsis. This pattern suggests that antecedent representations are content-addressable and retrieved with a direct-access process. To determine whether interpreting ellipsis involves copying antecedent information into the ellipsis site, Experiments 3-5 manipulated the length and complexity of the antecedent. Some types of antecedent complexity lowered accuracy, notably, the number of discourse entities in the antecedent. However, neither antecedent length nor complexity affected the speed of interpreting the ellipsis. This pattern is inconsistent with a copy operation, and it suggests that ellipsis interpretation may involve a pointer to extant structures in memory. |
Chie Nakatani; Cees Van Leeuwen A pragmatic approach to multi-modality and non-normality in fixation duration studies of cognitive processes Journal Article Journal of Eye Movement Research, 1 (2), pp. 1–12, 2008. @article{Nakatani2008, title = {A pragmatic approach to multi-modality and non-normality in fixation duration studies of cognitive processes}, author = {Chie Nakatani and Cees Van Leeuwen}, doi = {10.1016/0022-3468(90)90802-G}, year = {2008}, date = {2008-01-01}, journal = {Journal of Eye Movement Research}, volume = {1}, number = {2}, pages = {1--12}, abstract = {Interpreting eye-fixation durations in terms of cognitive processing load is complicated by the multimodality of their distribution. An important source of multimodality is the distinction between single and multiple fixations to the same object. Based on the distinction, we separated a log-transformed distribution made to an object in non-reading task. We could reasonably conclude that the separated distributions belong to the same, general logistic distribution, which has a finite population mean and variance. This allowed us to use the sample means as dependent variables in a parametric analysis. Six tasks were compared, which required different levels of post-perceptual processing. A no-task control condition was added to test for perceptual processing. Fixation durations differentiated task-specific perceptual, but not post-perceptual processing demands.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Interpreting eye-fixation durations in terms of cognitive processing load is complicated by the multimodality of their distribution. An important source of multimodality is the distinction between single and multiple fixations to the same object. Based on the distinction, we separated a log-transformed distribution made to an object in non-reading task. We could reasonably conclude that the separated distributions belong to the same, general logistic distribution, which has a finite population mean and variance. This allowed us to use the sample means as dependent variables in a parametric analysis. Six tasks were compared, which required different levels of post-perceptual processing. A no-task control condition was added to test for perceptual processing. Fixation durations differentiated task-specific perceptual, but not post-perceptual processing demands. |
Tim J Smith; John M Henderson Edit Blindness: The relationship between attention and global change blindness in dynamic scenes Journal Article Journal of Eye Movement Research, 2 (2), pp. 1–17, 2008. @article{Smith2008, title = {Edit Blindness: The relationship between attention and global change blindness in dynamic scenes}, author = {Tim J Smith and John M Henderson}, year = {2008}, date = {2008-01-01}, journal = {Journal of Eye Movement Research}, volume = {2}, number = {2}, pages = {1--17}, abstract = {Although we experience the visual world as a continuous, richly detailed space we often fail to notice large and significant changes. Such change blindness has been demonstrated for local object changes and changes to the visual form of whole images, however it is assumed that total changes from one image to another would be easily detected. Film editing presents such total changes several times a minute yet we rarely seem to be aware of them, a phenomenon we refer to here as edit blindness. This phenomenon has never been empirically demonstrated even though film editors believe they have at their disposal techniques that induce edit blindness, the Continuity Editing Rules. In the present study we tested the relationship between Continuity Editing Rules and edit blindness by instructing participants to detect edits while watching excerpts from feature films. Eye movements were recorded during the task. The results indicate that edits constructed according to the Continuity Editing Rules result in greater edit blindness than edits not adhering to the rules. A quarter of edits joining two viewpoints of the same scene were undetected and this increased to a third when the edit coincided with a sudden onset of motion. Some cuts may be missed due to suppression of the cut transients by coinciding with eyeblinks or saccadic eye movements but the majority seem to be due to inattentional blindness as viewers attend to the depicted narrative. In conclusion, this study presents the first empirical evidence of edit blindness and its relationship to natural attentional behaviour during dynamic scene viewing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although we experience the visual world as a continuous, richly detailed space we often fail to notice large and significant changes. Such change blindness has been demonstrated for local object changes and changes to the visual form of whole images, however it is assumed that total changes from one image to another would be easily detected. Film editing presents such total changes several times a minute yet we rarely seem to be aware of them, a phenomenon we refer to here as edit blindness. This phenomenon has never been empirically demonstrated even though film editors believe they have at their disposal techniques that induce edit blindness, the Continuity Editing Rules. In the present study we tested the relationship between Continuity Editing Rules and edit blindness by instructing participants to detect edits while watching excerpts from feature films. Eye movements were recorded during the task. The results indicate that edits constructed according to the Continuity Editing Rules result in greater edit blindness than edits not adhering to the rules. A quarter of edits joining two viewpoints of the same scene were undetected and this increased to a third when the edit coincided with a sudden onset of motion. Some cuts may be missed due to suppression of the cut transients by coinciding with eyeblinks or saccadic eye movements but the majority seem to be due to inattentional blindness as viewers attend to the depicted narrative. In conclusion, this study presents the first empirical evidence of edit blindness and its relationship to natural attentional behaviour during dynamic scene viewing. |
Xuejun Bai; Guoli Yan; Simon P Liversedge; Chuanli Zang; Keith Rayner Reading spaced and unspaced Chinese text: Evidence from eye movements Journal Article Journal of Experimental Psychology: Human Perception and Performance, 34 (5), pp. 1277–1287, 2008. @article{Bai2008, title = {Reading spaced and unspaced Chinese text: Evidence from eye movements}, author = {Xuejun Bai and Guoli Yan and Simon P Liversedge and Chuanli Zang and Keith Rayner}, doi = {10.1037/0096-1523.34.5.1277}, year = {2008}, date = {2008-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {34}, number = {5}, pages = {1277--1287}, abstract = {Native Chinese readers' eye movements were monitored as they read text that did or did not demark word boundary information. In Experiment 1, sentences had 4 types of spacing: normal unspaced text, text with spaces between words, text with spaces between characters that yielded nonwords, and finally text with spaces between every character. The authors investigated whether the introduction of spaces into unspaced Chinese text facilitates reading and whether the word or, alternatively, the character is a unit of information that is of primary importance in Chinese reading. Global and local measures indicated that sentences with unfamiliar word spaced format were as easy to read as visually familiar unspaced text. Nonword spacing and a space between every character produced longer reading times. In Experiment 2, highlighting was used to create analogous conditions: normal Chinese text, highlighting that marked words, highlighting that yielded nonwords, and highlighting that marked each character. The data from both experiments clearly indicated that words, and not individual characters, are the unit of primary importance in Chinese reading.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Native Chinese readers' eye movements were monitored as they read text that did or did not demark word boundary information. In Experiment 1, sentences had 4 types of spacing: normal unspaced text, text with spaces between words, text with spaces between characters that yielded nonwords, and finally text with spaces between every character. The authors investigated whether the introduction of spaces into unspaced Chinese text facilitates reading and whether the word or, alternatively, the character is a unit of information that is of primary importance in Chinese reading. Global and local measures indicated that sentences with unfamiliar word spaced format were as easy to read as visually familiar unspaced text. Nonword spacing and a space between every character produced longer reading times. In Experiment 2, highlighting was used to create analogous conditions: normal Chinese text, highlighting that marked words, highlighting that yielded nonwords, and highlighting that marked each character. The data from both experiments clearly indicated that words, and not individual characters, are the unit of primary importance in Chinese reading. |
Sarah Brown-Schmidt; Christine Gunlogson; Michael K Tanenhaus Addressees distinguish shared from private information when interpreting questions during interactive conversation Journal Article Cognition, 107 (3), pp. 1122–1134, 2008. @article{Brown-Schmidt2008, title = {Addressees distinguish shared from private information when interpreting questions during interactive conversation}, author = {Sarah Brown-Schmidt and Christine Gunlogson and Michael K Tanenhaus}, doi = {10.1016/j.cognition.2007.11.005}, year = {2008}, date = {2008-01-01}, journal = {Cognition}, volume = {107}, number = {3}, pages = {1122--1134}, abstract = {Two experiments examined the role of common ground in the production and on-line interpretation of wh-questions such as What's above the cow with shoes? Experiment 1 examined unscripted conversation, and found that speakers consistently use wh-questions to inquire about information known only to the addressee. Addressees were sensitive to this tendency, and quickly directed attention toward private entities when interpreting these questions. A second experiment replicated the interpretation findings in a more constrained setting. These results add to previous evidence that the common ground influences initial language processes, and suggests that the strength and polarity of common ground effects may depend on contributions of sentence type as well as the interactivity of the situation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two experiments examined the role of common ground in the production and on-line interpretation of wh-questions such as What's above the cow with shoes? Experiment 1 examined unscripted conversation, and found that speakers consistently use wh-questions to inquire about information known only to the addressee. Addressees were sensitive to this tendency, and quickly directed attention toward private entities when interpreting these questions. A second experiment replicated the interpretation findings in a more constrained setting. These results add to previous evidence that the common ground influences initial language processes, and suggests that the strength and polarity of common ground effects may depend on contributions of sentence type as well as the interactivity of the situation. |
Areh Mikulić; Michael C Dorris Temporal and spatial allocation of motor preparation during a mixed-strategy game Journal Article Journal of Neurophysiology, 100 (4), pp. 2101–2108, 2008. @article{Mikulic2008, title = {Temporal and spatial allocation of motor preparation during a mixed-strategy game}, author = {Areh Mikuli{ć} and Michael C Dorris}, doi = {10.1152/jn.90703.2008}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {100}, number = {4}, pages = {2101--2108}, abstract = {Adopting a mixed response strategy in competitive situations can prevent opponents from exploiting predictable play. What drives stochastic action selection is unclear given that choice patterns suggest that, on average, players are indifferent to available options during mixed-strategy equilibria. To gain insight into this stochastic selection process, we examined how motor preparation was allocated during a mixed-strategy game. If selection processes on each trial reflect a global indifference between options, then there should be no bias in motor preparation (unbiased preparation hypothesis). If, however, differences exist in the desirability of options on each trial then motor preparation should be biased toward the preferred option (biased preparation hypothesis). We tested between these alternatives by examining how saccade preparation was allocated as human subjects competed against an adaptive computer opponent in an oculomotor version of the game "matching pennies." Subjects were free to choose between two visual targets using a saccadic eye movement. Saccade preparation was probed by occasionally flashing a visual distractor at a range of times preceding target presentation. The probability that a distractor would evoke a saccade error, and when it failed to do so, the probability of choosing each of the subsequent targets quantified the temporal and spatial evolution of saccade preparation, respectively. Our results show that saccade preparation became increasingly biased as the time of target presentation approached. Specifically, the spatial locus to which saccade preparation was directed varied from trial to trial, and its time course depended on task timing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Adopting a mixed response strategy in competitive situations can prevent opponents from exploiting predictable play. What drives stochastic action selection is unclear given that choice patterns suggest that, on average, players are indifferent to available options during mixed-strategy equilibria. To gain insight into this stochastic selection process, we examined how motor preparation was allocated during a mixed-strategy game. If selection processes on each trial reflect a global indifference between options, then there should be no bias in motor preparation (unbiased preparation hypothesis). If, however, differences exist in the desirability of options on each trial then motor preparation should be biased toward the preferred option (biased preparation hypothesis). We tested between these alternatives by examining how saccade preparation was allocated as human subjects competed against an adaptive computer opponent in an oculomotor version of the game "matching pennies." Subjects were free to choose between two visual targets using a saccadic eye movement. Saccade preparation was probed by occasionally flashing a visual distractor at a range of times preceding target presentation. The probability that a distractor would evoke a saccade error, and when it failed to do so, the probability of choosing each of the subsequent targets quantified the temporal and spatial evolution of saccade preparation, respectively. Our results show that saccade preparation became increasingly biased as the time of target presentation approached. Specifically, the spatial locus to which saccade preparation was directed varied from trial to trial, and its time course depended on task timing. |
Jorge Otero-Millan; Xoana G Troncoso; Stephen L Macknik; Ignacio Serrano-Pedraza; Susana Martinez-Conde Saccades and microsaccades during visual fixation, exploration, and search: Foundations for a common saccadic generator Journal Article Journal of Vision, 8 (14), pp. 1–18, 2008. @article{Otero-Millan2008, title = {Saccades and microsaccades during visual fixation, exploration, and search: Foundations for a common saccadic generator}, author = {Jorge Otero-Millan and Xoana G Troncoso and Stephen L Macknik and Ignacio Serrano-Pedraza and Susana Martinez-Conde}, doi = {10.1167/9.8.447}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {1--18}, abstract = {Microsaccades are known to occur during prolonged visual fixation, but it is a matter of controversy whether they also happen during free-viewing. Here we set out to determine: 1) whether microsaccades occur during free visual exploration and visual search, 2) whether microsaccade dynamics vary as a function of visual stimulation and viewing task, and 3) whether saccades and microsaccades share characteristics that might argue in favor of a common saccade-microsaccade oculomotor generator. Human subjects viewed naturalistic stimuli while performing various viewing tasks, including visual exploration, visual search, and prolonged visual fixation. Their eye movements were simultaneously recorded with high precision. Our results show that microsaccades are produced during the fixation periods that occur during visual exploration and visual search. Microsaccade dynamics during free-viewing moreover varied as a function of visual stimulation and viewing task, with increasingly demanding tasks resulting in increased microsaccade production. Moreover, saccades and microsaccades had comparable spatiotemporal characteristics, including the presence of equivalent refractory periods between all pair-wise combinations of saccades and microsaccades. Thus our results indicate a microsaccade-saccade continuum and support the hypothesis of a common oculomotor generator for saccades and microsaccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microsaccades are known to occur during prolonged visual fixation, but it is a matter of controversy whether they also happen during free-viewing. Here we set out to determine: 1) whether microsaccades occur during free visual exploration and visual search, 2) whether microsaccade dynamics vary as a function of visual stimulation and viewing task, and 3) whether saccades and microsaccades share characteristics that might argue in favor of a common saccade-microsaccade oculomotor generator. Human subjects viewed naturalistic stimuli while performing various viewing tasks, including visual exploration, visual search, and prolonged visual fixation. Their eye movements were simultaneously recorded with high precision. Our results show that microsaccades are produced during the fixation periods that occur during visual exploration and visual search. Microsaccade dynamics during free-viewing moreover varied as a function of visual stimulation and viewing task, with increasingly demanding tasks resulting in increased microsaccade production. Moreover, saccades and microsaccades had comparable spatiotemporal characteristics, including the presence of equivalent refractory periods between all pair-wise combinations of saccades and microsaccades. Thus our results indicate a microsaccade-saccade continuum and support the hypothesis of a common oculomotor generator for saccades and microsaccades. |
Matthew T Crawford; John J Skowronski; Chris Stiff; Ute Leonards Seeing, but not thinking: Limiting the spread of spontaneous trait transference II Journal Article Journal of Experimental Social Psychology, 44 (3), pp. 840–847, 2008. @article{Crawford2008, title = {Seeing, but not thinking: Limiting the spread of spontaneous trait transference II}, author = {Matthew T Crawford and John J Skowronski and Chris Stiff and Ute Leonards}, doi = {10.1016/j.jesp.2007.08.001}, year = {2008}, date = {2008-01-01}, journal = {Journal of Experimental Social Psychology}, volume = {44}, number = {3}, pages = {840--847}, abstract = {When an informant describes trait-implicative behavior of a target, the informant is often associated with the trait implied by the behavior and can be assigned heightened ratings on that trait (STT effects). Presentation of a target photo along with the description seemingly eliminates these effects. Using three different measures of visual attention, the results of two studies show the elimination of STT effects by target photo presentation cannot be attributed to associative mechanisms linked to enhanced visual attention to targets. Instead, presentation of a target's photo likely prompts perceivers to spontaneously make target inferences in much the same way they make spontaneous inferences about self-describers. As argued by Todorov and Uleman [Todorov, A., & Uleman, J. S. (2004). The person reference process in spontaneous trait inferences. Journal of Personality & Social Psychology, 87, 482-493], such attributional processing can preclude the formation of trait associations to informants.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When an informant describes trait-implicative behavior of a target, the informant is often associated with the trait implied by the behavior and can be assigned heightened ratings on that trait (STT effects). Presentation of a target photo along with the description seemingly eliminates these effects. Using three different measures of visual attention, the results of two studies show the elimination of STT effects by target photo presentation cannot be attributed to associative mechanisms linked to enhanced visual attention to targets. Instead, presentation of a target's photo likely prompts perceivers to spontaneously make target inferences in much the same way they make spontaneous inferences about self-describers. As argued by Todorov and Uleman [Todorov, A., & Uleman, J. S. (2004). The person reference process in spontaneous trait inferences. Journal of Personality & Social Psychology, 87, 482-493], such attributional processing can preclude the formation of trait associations to informants. |
Ava Elahipanah; Bruce K Christensen; Eyal M Reingold Visual selective attention among persons with schizophrenia: The distractor ratio effect Journal Article Schizophrenia Research, 105 , pp. 61–67, 2008. @article{Elahipanah2008, title = {Visual selective attention among persons with schizophrenia: The distractor ratio effect}, author = {Ava Elahipanah and Bruce K Christensen and Eyal M Reingold}, year = {2008}, date = {2008-01-01}, journal = {Schizophrenia Research}, volume = {105}, pages = {61--67}, abstract = {The current study investigated whether impaired visual attention among patients with schizophrenia can be accounted for by poor perceptual organization and impaired search selectivity. Twenty-three patients with schizophrenia and 22 healthy control participants completed a conjunctive visual search task where the relative frequency of the two types of distractors was manipulated. It has been shown that, when the total number of items in a display is fixed, search performance depends on the relative frequency of the types of distractors (i.e., as the ratio becomes more discrepant search time decreases). This modulation of search efficiency reflects participants' ability to group items by their perceptual similarity and then search only the smaller group of items that share a feature with the target. Results show that patients modulate their response time normally as a function of the distractor ratio – that is, they benefit from the presence of a smaller distractor subset in the display. This suggests that patients with schizophrenia, group items according to their perceptual similarity and flexibly deploy their attention to the smaller subset of distractors on each trial. These results demonstrate that search selectivity as a function of the relative frequency of distractors is unimpaired among patients with schizophrenia.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current study investigated whether impaired visual attention among patients with schizophrenia can be accounted for by poor perceptual organization and impaired search selectivity. Twenty-three patients with schizophrenia and 22 healthy control participants completed a conjunctive visual search task where the relative frequency of the two types of distractors was manipulated. It has been shown that, when the total number of items in a display is fixed, search performance depends on the relative frequency of the types of distractors (i.e., as the ratio becomes more discrepant search time decreases). This modulation of search efficiency reflects participants' ability to group items by their perceptual similarity and then search only the smaller group of items that share a feature with the target. Results show that patients modulate their response time normally as a function of the distractor ratio – that is, they benefit from the presence of a smaller distractor subset in the display. This suggests that patients with schizophrenia, group items according to their perceptual similarity and flexibly deploy their attention to the smaller subset of distractors on each trial. These results demonstrate that search selectivity as a function of the relative frequency of distractors is unimpaired among patients with schizophrenia. |
Matthew H Phillips; Jay A Edelman The dependence of visual scanning performance on search direction and difficulty Journal Article Vision Research, 48 (21), pp. 2184–2192, 2008. @article{Phillips2008, title = {The dependence of visual scanning performance on search direction and difficulty}, author = {Matthew H Phillips and Jay A Edelman}, doi = {10.1016/j.visres.2008.06.025}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {21}, pages = {2184--2192}, abstract = {Phillips and Edelman [Phillips, M. H., & Edelman, J. A. (2008). The dependence of visual scanning performance on saccade, fixation, and perceptual metrics. Vision Research, 48(7), 926-936] presented evidence that performance variability in a visual scanning task depends on oculomotor variables related to saccade amplitude rather than fixation duration, and that saccade-related metrics reflects perceptual span. Here, we extend these results by showing that even for extremely difficult searches trial-to-trial performance variability still depends on saccade-related metrics and not fixation duration. We also show that scanning speed is faster for horizontal than for vertical searches, and that these differences derive again from differences in saccade-based metrics and not from differences in fixation duration. We find perceptual span to be larger for horizontal than vertical searches, and approximately symmetric about the line of gaze.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phillips and Edelman [Phillips, M. H., & Edelman, J. A. (2008). The dependence of visual scanning performance on saccade, fixation, and perceptual metrics. Vision Research, 48(7), 926-936] presented evidence that performance variability in a visual scanning task depends on oculomotor variables related to saccade amplitude rather than fixation duration, and that saccade-related metrics reflects perceptual span. Here, we extend these results by showing that even for extremely difficult searches trial-to-trial performance variability still depends on saccade-related metrics and not fixation duration. We also show that scanning speed is faster for horizontal than for vertical searches, and that these differences derive again from differences in saccade-based metrics and not from differences in fixation duration. We find perceptual span to be larger for horizontal than vertical searches, and approximately symmetric about the line of gaze. |
Lillian Chen; Julie E Boland Dominance and context effects on activation of alternative homophone meanings Journal Article Memory and Cognition, 36 (7), pp. 1306–1323, 2008. @article{Chen2008, title = {Dominance and context effects on activation of alternative homophone meanings}, author = {Lillian Chen and Julie E Boland}, doi = {10.3758/MC.36.7.1306}, year = {2008}, date = {2008-01-01}, journal = {Memory and Cognition}, volume = {36}, number = {7}, pages = {1306--1323}, abstract = {Two eyetracking-during-listening experiments showed frequency and context effects on fixation probability for pictures representing multiple meanings of homophones. Participants heard either an imperative sentence instructing them to look at a homophone referent (Experiment 1) or a declarative sentence that was either neutral or biased toward the homophone's subordinate meaning (Experiment 2). At homophone onset in both experiments, the participants viewed four pictures: (1) a referent of one homophone meaning, (2) a shape competitor for a nonpictured homophone meaning, and (3) two unrelated filler objects. In Experiment 1, meaning dominance affected looks to both the homophone referent and the shape competitor. In Experiment 2, as compared with neutral contexts, subordinatebiased contexts lowered the fixation probability for shape competitors of dominant meanings, but shape competitors still attracted more looks than would be expected by chance. We discuss the consistencies and discrepancies of these findings with the selective access and reordered access theories of lexical ambiguity resolution.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two eyetracking-during-listening experiments showed frequency and context effects on fixation probability for pictures representing multiple meanings of homophones. Participants heard either an imperative sentence instructing them to look at a homophone referent (Experiment 1) or a declarative sentence that was either neutral or biased toward the homophone's subordinate meaning (Experiment 2). At homophone onset in both experiments, the participants viewed four pictures: (1) a referent of one homophone meaning, (2) a shape competitor for a nonpictured homophone meaning, and (3) two unrelated filler objects. In Experiment 1, meaning dominance affected looks to both the homophone referent and the shape competitor. In Experiment 2, as compared with neutral contexts, subordinatebiased contexts lowered the fixation probability for shape competitors of dominant meanings, but shape competitors still attracted more looks than would be expected by chance. We discuss the consistencies and discrepancies of these findings with the selective access and reordered access theories of lexical ambiguity resolution. |
Alexander C Schütz; Doris I Braun; Dirk Kerzel; Karl R Gegenfurtner Improved visual sensitivity during smooth pursuit eye movements Journal Article Nature Neuroscience, 11 (10), pp. 1211–1216, 2008. @article{Schuetz2008, title = {Improved visual sensitivity during smooth pursuit eye movements}, author = {Alexander C Schütz and Doris I Braun and Dirk Kerzel and Karl R Gegenfurtner}, doi = {10.1038/nn.2194}, year = {2008}, date = {2008-01-01}, journal = {Nature Neuroscience}, volume = {11}, number = {10}, pages = {1211--1216}, abstract = {When we view the world around us, we constantly move our eyes. This brings objects of interest into the fovea and keeps them there, but visual sensitivity has been shown to deteriorate while the eyes are moving. Here we show that human sensitivity for some visual stimuli is improved during smooth pursuit eye movements. Detection thresholds for briefly flashed, colored stimuli were 16% lower during pursuit than during fixation. Similarly, detection thresholds for luminance-defined stimuli of high spatial frequency were lowered. These findings suggest that the pursuit-induced sensitivity increase may have its neuronal origin in the parvocellular retino-thalamic system. This implies that the visual system not only uses feedback connections to improve processing for locations and objects being attended to, but that a whole processing subsystem can be boosted. During pursuit, facilitation of the parvocellular system may reduce motion blur for stationary objects and increase sensitivity to speed changes of the tracked object.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When we view the world around us, we constantly move our eyes. This brings objects of interest into the fovea and keeps them there, but visual sensitivity has been shown to deteriorate while the eyes are moving. Here we show that human sensitivity for some visual stimuli is improved during smooth pursuit eye movements. Detection thresholds for briefly flashed, colored stimuli were 16% lower during pursuit than during fixation. Similarly, detection thresholds for luminance-defined stimuli of high spatial frequency were lowered. These findings suggest that the pursuit-induced sensitivity increase may have its neuronal origin in the parvocellular retino-thalamic system. This implies that the visual system not only uses feedback connections to improve processing for locations and objects being attended to, but that a whole processing subsystem can be boosted. During pursuit, facilitation of the parvocellular system may reduce motion blur for stationary objects and increase sensitivity to speed changes of the tracked object. |
Tessa Warren; Kerry McConnell; Keith Rayner Effects of context on eye movements when reading about possible and impossible events Journal Article Journal of Experimental Psychology: Learning, Memory, and Cognition, 34 (4), pp. 1001–1010, 2008. @article{Warren2008, title = {Effects of context on eye movements when reading about possible and impossible events}, author = {Tessa Warren and Kerry McConnell and Keith Rayner}, doi = {10.1037/0278-7393.34.4.1001}, year = {2008}, date = {2008-01-01}, journal = {Journal of Experimental Psychology: Learning, Memory, and Cognition}, volume = {34}, number = {4}, pages = {1001--1010}, abstract = {Plausibility violations resulting in impossible scenarios lead to earlier and longer lasting eye movement disruption than violations resulting in highly unlikely scenarios (K. Rayner, T. Warren, B. J. Juhasz, & S. P. Liversedge, 2004; T. Warren & K. McConnell, 2007). This could reflect either differences in the timing of availability of different kinds of information (e.g., selectional restrictions, world knowledge, and context) or differences in their relative power to guide semantic interpretation. The authors investigated eye movements to possible and impossible events in real-world and fantasy contexts to determine when contextual information influences detection of impossibility cued by a semantic mismatch between a verb and an argument. Gaze durations on a target word were longer to impossible events independent of context. However, a measure of the time elapsed from first fixating the target word to moving past it showed disruption only in the real-world context. These results suggest that contextual information did not eliminate initial disruption but moderated it quickly thereafter.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Plausibility violations resulting in impossible scenarios lead to earlier and longer lasting eye movement disruption than violations resulting in highly unlikely scenarios (K. Rayner, T. Warren, B. J. Juhasz, & S. P. Liversedge, 2004; T. Warren & K. McConnell, 2007). This could reflect either differences in the timing of availability of different kinds of information (e.g., selectional restrictions, world knowledge, and context) or differences in their relative power to guide semantic interpretation. The authors investigated eye movements to possible and impossible events in real-world and fantasy contexts to determine when contextual information influences detection of impossibility cued by a semantic mismatch between a verb and an argument. Gaze durations on a target word were longer to impossible events independent of context. However, a measure of the time elapsed from first fixating the target word to moving past it showed disruption only in the real-world context. These results suggest that contextual information did not eliminate initial disruption but moderated it quickly thereafter. |
Albrecht W Inhoff; Matthew S Solomon; Bradley A Seymour; Ralph Radach Eye position changes during reading fixations are spatially selective Journal Article Vision Research, 48 (8), pp. 1027–1039, 2008. @article{Inhoff2008, title = {Eye position changes during reading fixations are spatially selective}, author = {Albrecht W Inhoff and Matthew S Solomon and Bradley A Seymour and Ralph Radach}, doi = {10.1016/j.visres.2008.01.012}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {8}, pages = {1027--1039}, abstract = {Intra-fixation location changes were measured when one-line sentences written in lower or aLtErNaTiNg case were read. Intra-fixation location changes were common and their size was normally distributed except for a relatively high proportion of fixations without a discernible location change. Location changes that did occur were systematically biased toward the right when alternating case was read. Irrespective of case type, changes of the right eye were biased toward the right at the onset of sentence reading, and this spatial bias decreased as sentence reading progressed from left to right. The left eye showed a relatively stable right-directed bias. These results show that processing demands can pull the two fixated eyes in the same direction and that the response to this pull can differ for the right and left eye.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Intra-fixation location changes were measured when one-line sentences written in lower or aLtErNaTiNg case were read. Intra-fixation location changes were common and their size was normally distributed except for a relatively high proportion of fixations without a discernible location change. Location changes that did occur were systematically biased toward the right when alternating case was read. Irrespective of case type, changes of the right eye were biased toward the right at the onset of sentence reading, and this spatial bias decreased as sentence reading progressed from left to right. The left eye showed a relatively stable right-directed bias. These results show that processing demands can pull the two fixated eyes in the same direction and that the response to this pull can differ for the right and left eye. |
Albrecht W Inhoff; Matthew S Starr; Matthew Solomon; Lars Placke Eye movements during the reading of compound words and the influence of lexeme meaning Journal Article Memory and Cognition, 36 (3), pp. 675–687, 2008. @article{Inhoff2008a, title = {Eye movements during the reading of compound words and the influence of lexeme meaning}, author = {Albrecht W Inhoff and Matthew S Starr and Matthew Solomon and Lars Placke}, doi = {10.3758/MC.36.3.675}, year = {2008}, date = {2008-01-01}, journal = {Memory and Cognition}, volume = {36}, number = {3}, pages = {675--687}, abstract = {We examined the use of lexeme meaning during the processing of spatially unified bilexemic compound words by manipulating both the location and the word frequency of the lexeme that primarily defined the meaning of a compound (i.e., the dominant lexeme). The semantically dominant and nondominant lexemes occupied either the beginning or the ending compound word location, and the beginning and ending lexemes could be either high- or low-frequency words. Three tasks were used--lexical decision, naming, and sentence reading--all of which focused on the effects of lexeme frequency as a function of lexeme dominance. The results revealed a larger word frequency effect for the dominant lexeme in all three tasks. Eye movements during sentence reading further revealed larger word frequency effects for the dominant lexeme via several oculomotor motor measures, including the duration of the first fixation on a compound word. These findings favor theoretical conceptions in which the use of lexeme meaning is an integral part of the compound recognition process.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We examined the use of lexeme meaning during the processing of spatially unified bilexemic compound words by manipulating both the location and the word frequency of the lexeme that primarily defined the meaning of a compound (i.e., the dominant lexeme). The semantically dominant and nondominant lexemes occupied either the beginning or the ending compound word location, and the beginning and ending lexemes could be either high- or low-frequency words. Three tasks were used--lexical decision, naming, and sentence reading--all of which focused on the effects of lexeme frequency as a function of lexeme dominance. The results revealed a larger word frequency effect for the dominant lexeme in all three tasks. Eye movements during sentence reading further revealed larger word frequency effects for the dominant lexeme via several oculomotor motor measures, including the duration of the first fixation on a compound word. These findings favor theoretical conceptions in which the use of lexeme meaning is an integral part of the compound recognition process. |
Yuan-Chi Tseng; Chiang-Shan Ray Li The effects of response readiness and error monitoring on saccade countermanding Journal Article The Open Psychology Journal, 1 (1), pp. 18–25, 2008. @article{Tseng2008, title = {The effects of response readiness and error monitoring on saccade countermanding}, author = {Yuan-Chi Tseng and Chiang-Shan Ray Li}, doi = {10.2174/1874350100801010018}, year = {2008}, date = {2008-01-01}, journal = {The Open Psychology Journal}, volume = {1}, number = {1}, pages = {18--25}, abstract = {The stop-signal task (SST) and anti-saccade tasks are both widely used to explore cognitive inhibitory control. Our previous work on a manual SST showed that subjects' readiness to respond to the go signal and the extent to which subjects monitor their errors need to be considered in order to attribute impaired performance to deficits in response inhi- bition. Here we examine whether these same task-related variables similarly influence oculomotor SST and anti-saccade performance. Thirty-six and sixty healthy, adult subjects participated in an oculomotor SST and anti-saccade task, respec- tively, in which the fore-period (FP) of imperative stimulus varied randomly from trial to trial. We computed a FP effect to index response readiness to the imperative stimulus and a post-error slowing (PES) effect to index error monitoring. Contrary to what we had anticipated, other than a weak but negative association between the FP effect and anti-saccade errors, these behavioral variables did not correlate with SST or anti-saccade performance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The stop-signal task (SST) and anti-saccade tasks are both widely used to explore cognitive inhibitory control. Our previous work on a manual SST showed that subjects' readiness to respond to the go signal and the extent to which subjects monitor their errors need to be considered in order to attribute impaired performance to deficits in response inhi- bition. Here we examine whether these same task-related variables similarly influence oculomotor SST and anti-saccade performance. Thirty-six and sixty healthy, adult subjects participated in an oculomotor SST and anti-saccade task, respec- tively, in which the fore-period (FP) of imperative stimulus varied randomly from trial to trial. We computed a FP effect to index response readiness to the imperative stimulus and a post-error slowing (PES) effect to index error monitoring. Contrary to what we had anticipated, other than a weak but negative association between the FP effect and anti-saccade errors, these behavioral variables did not correlate with SST or anti-saccade performance. |
Keith Rayner; Brett Miller; Caren M Rotello Eye movements when looking at print advertisements: The goal of the viewer matters Journal Article Applied Cognitive Psychology, 22 (5), pp. 697–707, 2008. @article{Rayner2008, title = {Eye movements when looking at print advertisements: The goal of the viewer matters}, author = {Keith Rayner and Brett Miller and Caren M Rotello}, doi = {10.1002/acp.1389}, year = {2008}, date = {2008-01-01}, journal = {Applied Cognitive Psychology}, volume = {22}, number = {5}, pages = {697--707}, abstract = {Viewers looked at print advertisements as their eye movements were recorded. Half of them were asked to rate how much they liked each ad (for convenience, we will generally use the term 'ad' from this point on), while the other half were asked to rate the effectiveness of each ad. Previous research indicated that viewers who were asked to consider purchasing products in the ads looked at the text earlier and more often than the picture part of the ad. In contrast, viewers in the present experiment looked at the picture part of the ad earlier and longer than the text. The results indicate quite clearly that the goal of the viewer very much influences where (and for how long) viewers look at different parts of ads, but also indicate that the nature of the ad per se matters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Viewers looked at print advertisements as their eye movements were recorded. Half of them were asked to rate how much they liked each ad (for convenience, we will generally use the term 'ad' from this point on), while the other half were asked to rate the effectiveness of each ad. Previous research indicated that viewers who were asked to consider purchasing products in the ads looked at the text earlier and more often than the picture part of the ad. In contrast, viewers in the present experiment looked at the picture part of the ad earlier and longer than the text. The results indicate quite clearly that the goal of the viewer very much influences where (and for how long) viewers look at different parts of ads, but also indicate that the nature of the ad per se matters. |
Sarah C Creel; Richard N Aslin; Michael K Tanenhaus Heeding the voice of experience: The role of talker variation in lexical access Journal Article Cognition, 106 (2), pp. 633–664, 2008. @article{Creel2008, title = {Heeding the voice of experience: The role of talker variation in lexical access}, author = {Sarah C Creel and Richard N Aslin and Michael K Tanenhaus}, doi = {10.1016/j.cognition.2007.03.013}, year = {2008}, date = {2008-01-01}, journal = {Cognition}, volume = {106}, number = {2}, pages = {633--664}, abstract = {Two experiments used the head-mounted eye-tracking methodology to examine the time course of lexical activation in the face of a non-phonemic cue, talker variation. We found that lexical competition was attenuated by consistent talker differences between words that would otherwise be lexical competitors. In Experiment 1, some English cohort word-pairs were consistently spoken by a single talker (male couch, male cows), while other word-pairs were spoken by different talkers (male sheep, female sheet). After repeated instances of talker-word pairings, words from different-talker pairs showed smaller proportions of competitor fixations than words from same-talker pairs. In Experiment 2, participants learned to identify black-and-white shapes from novel labels spoken by one of two talkers. All of the 16 novel labels were VCVCV word-forms atypical of, but not phonologically illegal in, English. Again, a word was consistently spoken by one talker, and its cohort or rhyme competitor was consistently spoken either by that same talker (same-talker competitor) or the other talker (different-talker competitor). Targets with different-talker cohorts received greater fixation proportions than targets with same-talker cohorts, while the reverse was true for fixations to cohort competitors; there were fewer erroneous selections of competitor referents for different-talker competitors than same-talker competitors. Overall, these results support a view of the lexicon in which entries contain extra-phonemic information. Extensions of the artificial lexicon paradigm and developmental implications are discussed. textcopyright 2007 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two experiments used the head-mounted eye-tracking methodology to examine the time course of lexical activation in the face of a non-phonemic cue, talker variation. We found that lexical competition was attenuated by consistent talker differences between words that would otherwise be lexical competitors. In Experiment 1, some English cohort word-pairs were consistently spoken by a single talker (male couch, male cows), while other word-pairs were spoken by different talkers (male sheep, female sheet). After repeated instances of talker-word pairings, words from different-talker pairs showed smaller proportions of competitor fixations than words from same-talker pairs. In Experiment 2, participants learned to identify black-and-white shapes from novel labels spoken by one of two talkers. All of the 16 novel labels were VCVCV word-forms atypical of, but not phonologically illegal in, English. Again, a word was consistently spoken by one talker, and its cohort or rhyme competitor was consistently spoken either by that same talker (same-talker competitor) or the other talker (different-talker competitor). Targets with different-talker cohorts received greater fixation proportions than targets with same-talker cohorts, while the reverse was true for fixations to cohort competitors; there were fewer erroneous selections of competitor referents for different-talker competitors than same-talker competitors. Overall, these results support a view of the lexicon in which entries contain extra-phonemic information. Extensions of the artificial lexicon paradigm and developmental implications are discussed. textcopyright 2007 Elsevier B.V. All rights reserved. |
Daniel Baldauf; Heiner Deubel Visual attention during the preparation of bimanual movements Journal Article Vision Research, 48 (4), pp. 549–563, 2008. @article{Baldauf2008, title = {Visual attention during the preparation of bimanual movements}, author = {Daniel Baldauf and Heiner Deubel}, doi = {10.1016/j.visres.2007.11.023}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {4}, pages = {549--563}, abstract = {We investigated the deployment of visual attention during the preparation of bimanually coordinated actions. In a dual-task paradigm participants had to execute bimanual pointing movements to different peripheral locations, and to identify target letters that had been briefly presented at various peripheral locations during the latency period before movement initialisation. The discrimination targets appeared either at the movement goal of the left or the right hand, or at other locations that were not movement-relevant in the particular trial. Performance in the letter discrimination task served as a measure for the distribution of visual attention during the action preparation. The results showed that the goal positions of both hands are selected before movement onset, revealing a superior discrimination performance at the action-relevant locations (Experiment 1). Selection-for-action in the preparation of bimanual movements involved attention being spread to both goal locations in parallel, independently of whether the targets had been cued by colour or semantically (Experiment 2). A comparison with perceptual performance in unimanual reaching suggested that the total amount of attentional resources that are distributed over the visual field depended on the demands of the primary motor task, with more attentional resources being deployed for the selection of multiple goal positions than for the selection of a single goal (Experiment 3).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the deployment of visual attention during the preparation of bimanually coordinated actions. In a dual-task paradigm participants had to execute bimanual pointing movements to different peripheral locations, and to identify target letters that had been briefly presented at various peripheral locations during the latency period before movement initialisation. The discrimination targets appeared either at the movement goal of the left or the right hand, or at other locations that were not movement-relevant in the particular trial. Performance in the letter discrimination task served as a measure for the distribution of visual attention during the action preparation. The results showed that the goal positions of both hands are selected before movement onset, revealing a superior discrimination performance at the action-relevant locations (Experiment 1). Selection-for-action in the preparation of bimanual movements involved attention being spread to both goal locations in parallel, independently of whether the targets had been cued by colour or semantically (Experiment 2). A comparison with perceptual performance in unimanual reaching suggested that the total amount of attentional resources that are distributed over the visual field depended on the demands of the primary motor task, with more attentional resources being deployed for the selection of multiple goal positions than for the selection of a single goal (Experiment 3). |
William L Miller; Vincenzo Maffei; Gianfranco Bosco; Marco Iosa; Myrka Zago; Emiliano Macaluso; Francesco Lacquaniti Vestibular nuclei and cerebellum put visual gravitational motion in context Journal Article Journal of Neurophysiology, 99 (4), pp. 1969–1982, 2008. @article{Miller2008, title = {Vestibular nuclei and cerebellum put visual gravitational motion in context}, author = {William L Miller and Vincenzo Maffei and Gianfranco Bosco and Marco Iosa and Myrka Zago and Emiliano Macaluso and Francesco Lacquaniti}, doi = {10.1152/jn.00889.2007}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {99}, number = {4}, pages = {1969--1982}, abstract = {Animal survival in the forest, and human success on the sports field, often depend on the ability to seize a target on the fly. All bodies fall at the same rate in the gravitational field, but the corresponding retinal motion varies with apparent viewing distance. How then does the brain predict time-to-collision under gravity? A perspective context from natural or pictorial settings might afford accurate predictions of gravity's effects via the recovery of an environmental reference from the scene structure. We report that embedding motion in a pictorial scene facilitates interception of gravitational acceleration over unnatural acceleration, whereas a blank scene eliminates such bias. Functional magnetic resonance imaging (fMRI) revealed blood-oxygen-level-dependent correlates of these visual context effects on gravitational motion processing in the vestibular nuclei and posterior cerebellar vermis. Our results suggest an early stage of integration of high-level visual analysis with gravity-related motion information, which may represent the substrate for perceptual constancy of ubiquitous gravitational motion.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Animal survival in the forest, and human success on the sports field, often depend on the ability to seize a target on the fly. All bodies fall at the same rate in the gravitational field, but the corresponding retinal motion varies with apparent viewing distance. How then does the brain predict time-to-collision under gravity? A perspective context from natural or pictorial settings might afford accurate predictions of gravity's effects via the recovery of an environmental reference from the scene structure. We report that embedding motion in a pictorial scene facilitates interception of gravitational acceleration over unnatural acceleration, whereas a blank scene eliminates such bias. Functional magnetic resonance imaging (fMRI) revealed blood-oxygen-level-dependent correlates of these visual context effects on gravitational motion processing in the vestibular nuclei and posterior cerebellar vermis. Our results suggest an early stage of integration of high-level visual analysis with gravity-related motion information, which may represent the substrate for perceptual constancy of ubiquitous gravitational motion. |
Julie N Buchan; Martin Paré; Kevin G Munhall The effect of varying talker identity and listening conditions on gaze behavior during audiovisual speech perception Journal Article Brain Research, 1242 , pp. 162–171, 2008. @article{Buchan2008, title = {The effect of varying talker identity and listening conditions on gaze behavior during audiovisual speech perception}, author = {Julie N Buchan and Martin Paré and Kevin G Munhall}, doi = {10.1016/j.brainres.2008.06.083}, year = {2008}, date = {2008-01-01}, journal = {Brain Research}, volume = {1242}, pages = {162--171}, abstract = {During face-to-face conversation the face provides auditory and visual linguistic information, and also conveys information about the identity of the speaker. This study investigated behavioral strategies involved in gathering visual information while watching talking faces. The effects of varying talker identity and varying the intelligibility of speech (by adding acoustic noise) on gaze behavior were measured with an eyetracker. Varying the intelligibility of the speech by adding noise had a noticeable effect on the location and duration of fixations. When noise was present subjects adopted a vantage point that was more centralized on the face by reducing the frequency of the fixations on the eyes and mouth and lengthening the duration of their gaze fixations on the nose and mouth. Varying talker identity resulted in a more modest change in gaze behavior that was modulated by the intelligibility of the speech. Although subjects generally used similar strategies to extract visual information in both talker variability conditions, when noise was absent there were more fixations on the mouth when viewing a different talker every trial as opposed to the same talker every trial. These findings provide a useful baseline for studies examining gaze behavior during audiovisual speech perception and perception of dynamic faces.}, keywords = {}, pubstate = {published}, tppubtype = {article} } During face-to-face conversation the face provides auditory and visual linguistic information, and also conveys information about the identity of the speaker. This study investigated behavioral strategies involved in gathering visual information while watching talking faces. The effects of varying talker identity and varying the intelligibility of speech (by adding acoustic noise) on gaze behavior were measured with an eyetracker. Varying the intelligibility of the speech by adding noise had a noticeable effect on the location and duration of fixations. When noise was present subjects adopted a vantage point that was more centralized on the face by reducing the frequency of the fixations on the eyes and mouth and lengthening the duration of their gaze fixations on the nose and mouth. Varying talker identity resulted in a more modest change in gaze behavior that was modulated by the intelligibility of the speech. Although subjects generally used similar strategies to extract visual information in both talker variability conditions, when noise was absent there were more fixations on the mouth when viewing a different talker every trial as opposed to the same talker every trial. These findings provide a useful baseline for studies examining gaze behavior during audiovisual speech perception and perception of dynamic faces. |
André Andre Kaminiarz; Bart Krekelberg; Frank Bremmer Expansion of visual space during optokinetic afternystagmus (OKAN) Journal Article Journal of Neurophysiology, 99 (5), pp. 2470–2478, 2008. @article{Kaminiarz2008, title = {Expansion of visual space during optokinetic afternystagmus (OKAN)}, author = {André Andre Kaminiarz and Bart Krekelberg and Frank Bremmer}, doi = {10.1152/jn.00017.2008}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {99}, number = {5}, pages = {2470--2478}, abstract = {The mechanisms underlying visual perceptual stability are usually investigated using voluntary eye movements. In such studies, errors in perceptual stability during saccades and pursuit are commonly interpreted as mismatches between actual eye position and eye-position signals in the brain. The generality of this interpretation could in principle be tested by investigating spatial localization during reflexive eye movements whose kinematics are very similar to those of voluntary eye movements. Accordingly, in this study, we determined mislocalization of flashed visual targets during optokinetic afternystagmus (OKAN). These eye movements are quite unique in that they occur in complete darkness and are generated by subcortical control mechanisms. We found that during horizontal OKAN slow phases, subjects mislocalize targets away from the fovea in the horizontal direction. This corresponds to a perceived expansion of visual space and is unlike mislocalization found for any other voluntary or reflexive eye movement. Around the OKAN fast phases, we found a bias in the direction of the fast phase prior to its onset and opposite to the fast-phase direction thereafter. Such a biphasic modulation has also been reported in the temporal vicinity of saccades and during optokinetic nystagmus (OKN). A direct comparison, however, showed that the modulation during OKAN was much larger and occurred earlier relative to fast-phase onset than during OKN. A simple mismatch between the current eye position and the eye-position signal in the brain is unlikely to explain such disparate results across similar eye movements. Instead, these data support the view that mislocalization arises from errors in eye-centered position information.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The mechanisms underlying visual perceptual stability are usually investigated using voluntary eye movements. In such studies, errors in perceptual stability during saccades and pursuit are commonly interpreted as mismatches between actual eye position and eye-position signals in the brain. The generality of this interpretation could in principle be tested by investigating spatial localization during reflexive eye movements whose kinematics are very similar to those of voluntary eye movements. Accordingly, in this study, we determined mislocalization of flashed visual targets during optokinetic afternystagmus (OKAN). These eye movements are quite unique in that they occur in complete darkness and are generated by subcortical control mechanisms. We found that during horizontal OKAN slow phases, subjects mislocalize targets away from the fovea in the horizontal direction. This corresponds to a perceived expansion of visual space and is unlike mislocalization found for any other voluntary or reflexive eye movement. Around the OKAN fast phases, we found a bias in the direction of the fast phase prior to its onset and opposite to the fast-phase direction thereafter. Such a biphasic modulation has also been reported in the temporal vicinity of saccades and during optokinetic nystagmus (OKN). A direct comparison, however, showed that the modulation during OKAN was much larger and occurred earlier relative to fast-phase onset than during OKN. A simple mismatch between the current eye position and the eye-position signal in the brain is unlikely to explain such disparate results across similar eye movements. Instead, these data support the view that mislocalization arises from errors in eye-centered position information. |
Denise H Wu; Anne Morganti; Anjan Chatterjee Neural substrates of processing path and manner information of a moving event Journal Article Neuropsychologia, 46 (2), pp. 704–713, 2008. @article{Wu2008, title = {Neural substrates of processing path and manner information of a moving event}, author = {Denise H Wu and Anne Morganti and Anjan Chatterjee}, doi = {10.1016/j.neuropsychologia.2007.09.016}, year = {2008}, date = {2008-01-01}, journal = {Neuropsychologia}, volume = {46}, number = {2}, pages = {704--713}, abstract = {Languages consistently distinguish the path and the manner of a moving event in different constituents, even if the specific constituents themselves vary across languages. Children also learn to categorize moving events according to their path and manner at different ages. Motivated by these linguistic and developmental observations, we employed fMRI to test the hypothesis that perception of and attention to path and manner of motion is segregated neurally. Moreover, we hypothesize that such segregation respects the "dorsal-where and ventral-what" organizational principle of vision. Consistent with this proposal, we found that attention to the path of a moving event was associated with greater activity within bilateral inferior/superior parietal lobules and the frontal eye-field, while attention to manner was associated with greater activity within bilateral postero-lateral inferior/middle temporal regions. Our data provide evidence that motion perception, traditionally considered as a dorsal "where" visual attribute, further segregates into dorsal path and ventral manner attributes. This neural segregation of the components of motion, which are linguistically tagged, points to a perceptual counterpart of the functional organization of concepts and language.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Languages consistently distinguish the path and the manner of a moving event in different constituents, even if the specific constituents themselves vary across languages. Children also learn to categorize moving events according to their path and manner at different ages. Motivated by these linguistic and developmental observations, we employed fMRI to test the hypothesis that perception of and attention to path and manner of motion is segregated neurally. Moreover, we hypothesize that such segregation respects the "dorsal-where and ventral-what" organizational principle of vision. Consistent with this proposal, we found that attention to the path of a moving event was associated with greater activity within bilateral inferior/superior parietal lobules and the frontal eye-field, while attention to manner was associated with greater activity within bilateral postero-lateral inferior/middle temporal regions. Our data provide evidence that motion perception, traditionally considered as a dorsal "where" visual attribute, further segregates into dorsal path and ventral manner attributes. This neural segregation of the components of motion, which are linguistically tagged, points to a perceptual counterpart of the functional organization of concepts and language. |
Helene Intraub; Christopher A Dickinson False memory 1/20th of a second later: What the early onset of boundary extension reveals about perception Journal Article Psychological Science, 19 (10), pp. 1007–1014, 2008. @article{Intraub2008, title = {False memory 1/20th of a second later: What the early onset of boundary extension reveals about perception}, author = {Helene Intraub and Christopher A Dickinson}, doi = {10.1111/j.1467-9280.2008.02192.x}, year = {2008}, date = {2008-01-01}, journal = {Psychological Science}, volume = {19}, number = {10}, pages = {1007--1014}, abstract = {Errors of commission are thought to be caused by heavy memory loads, confusing information, lengthy retention intervals, or some combination of these factors. We report false memory beyond the boundaries of a view, boundary extension, after less than 1/20th of a second. Photographs of scenes were interrupted by a 42-ms or 250-ms mask, 250 ms into viewing, before reappearing or being replaced with a different view (Experiment 1). Postinterruption photographs that were unchanged were rated as closer up than the original views; when the photographs were changed, the same pair of closer-up and wider-angle views was rated as more similar when the closer view was first, rather than second. Thus, observers remembered preinterruption views with extended boundaries. Results were replicated when the interruption included a saccade (Experiment 2). The brevity of these interruptions has implications for visual scanning; it also challenges the traditional distinction between perception and memory. We offer an alternative conceptualization that shows how source monitoring can explain false memory after an interruption briefer than an eyeblink.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Errors of commission are thought to be caused by heavy memory loads, confusing information, lengthy retention intervals, or some combination of these factors. We report false memory beyond the boundaries of a view, boundary extension, after less than 1/20th of a second. Photographs of scenes were interrupted by a 42-ms or 250-ms mask, 250 ms into viewing, before reappearing or being replaced with a different view (Experiment 1). Postinterruption photographs that were unchanged were rated as closer up than the original views; when the photographs were changed, the same pair of closer-up and wider-angle views was rated as more similar when the closer view was first, rather than second. Thus, observers remembered preinterruption views with extended boundaries. Results were replicated when the interruption included a saccade (Experiment 2). The brevity of these interruptions has implications for visual scanning; it also challenges the traditional distinction between perception and memory. We offer an alternative conceptualization that shows how source monitoring can explain false memory after an interruption briefer than an eyeblink. |
D A Mills; T C Frohman; S L Davis; A R Salter; S McClure; I Beatty; A Shah; S Galetta; E Eggenberger; D S Zee; Elliot M Frohman Break in binocular fusion during head turning in MS patients with INO Journal Article Neurology, 71 , pp. 457–460, 2008. @article{Mills2008, title = {Break in binocular fusion during head turning in MS patients with INO}, author = {D A Mills and T C Frohman and S L Davis and A R Salter and S McClure and I Beatty and A Shah and S Galetta and E Eggenberger and D S Zee and Elliot M Frohman}, doi = {10.1212/NXI.0000000000000061}, year = {2008}, date = {2008-01-01}, journal = {Neurology}, volume = {71}, pages = {457--460}, abstract = {Internuclear ophthalmoparesis (INO) is the most common eye movement abnormality observed in pa- tients with multiple sclerosis (MS).1 While most MS patients with INO have no or little misalignment in the straight ahead position, significant disconjugacy occurs during horizontal saccades or with horizontal (yaw axis) head turning.2 A break in binocular fusion can produce a loss of stereopsis and depth percep- tion, transient diplopia (perceived as a double image or visual blur), oscillopsia, and disorientation.2 The purpose of this investigation was to confirm the hy- pothesis that a break in binocular fusion occurs in MS patients with INO during head or body turning, and that the magnitude of disconjugacy will be di- rectly correlated with the severity of this eye move- ment syndrome.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Internuclear ophthalmoparesis (INO) is the most common eye movement abnormality observed in pa- tients with multiple sclerosis (MS).1 While most MS patients with INO have no or little misalignment in the straight ahead position, significant disconjugacy occurs during horizontal saccades or with horizontal (yaw axis) head turning.2 A break in binocular fusion can produce a loss of stereopsis and depth percep- tion, transient diplopia (perceived as a double image or visual blur), oscillopsia, and disorientation.2 The purpose of this investigation was to confirm the hy- pothesis that a break in binocular fusion occurs in MS patients with INO during head or body turning, and that the magnitude of disconjugacy will be di- rectly correlated with the severity of this eye move- ment syndrome. |
Elina Birmingham; Walter F Bischof; Alan Kingstone Social attention and real-world scenes: The roles of action, competition and social content Journal Article Quarterly Journal of Experimental Psychology, 61 (7), pp. 986–998, 2008. @article{Birmingham2008, title = {Social attention and real-world scenes: The roles of action, competition and social content}, author = {Elina Birmingham and Walter F Bischof and Alan Kingstone}, doi = {10.1080/17470210701410375}, year = {2008}, date = {2008-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {61}, number = {7}, pages = {986--998}, abstract = {The present study examined how social attention is influenced by social content and the presence of items that are available for attention. We monitored observers' eye movements while they freely viewed real-world social scenes containing either 1 or 3 people situated among a variety of objects. Building from the work of Yarbus (1965/1967) we hypothesized that observers would demonstrate a preferential bias to fixate the eyes of the people in the scene, although other items would also receive attention. In addition, we hypothesized that fixations to the eyes would increase as the social content (i.e., number of people) increased. Both hypotheses were supported by the data, and we also found that the level of activity in the scene influenced attention to eyes when social content was high. The present results provide support for the notion that the eyes are selected by others in order to extract social information. Our study also suggests a simple and surreptitious methodology for studying social attention to real-world stimuli in a range of populations, such as those with autism spectrum disorders.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The present study examined how social attention is influenced by social content and the presence of items that are available for attention. We monitored observers' eye movements while they freely viewed real-world social scenes containing either 1 or 3 people situated among a variety of objects. Building from the work of Yarbus (1965/1967) we hypothesized that observers would demonstrate a preferential bias to fixate the eyes of the people in the scene, although other items would also receive attention. In addition, we hypothesized that fixations to the eyes would increase as the social content (i.e., number of people) increased. Both hypotheses were supported by the data, and we also found that the level of activity in the scene influenced attention to eyes when social content was high. The present results provide support for the notion that the eyes are selected by others in order to extract social information. Our study also suggests a simple and surreptitious methodology for studying social attention to real-world stimuli in a range of populations, such as those with autism spectrum disorders. |
Elina Birmingham; Walter Bischof; Alan Kingstone Gaze selection in complex social scenes Journal Article Visual Cognition, 16 (2-3), pp. 341–355, 2008. @article{Birmingham2008a, title = {Gaze selection in complex social scenes}, author = {Elina Birmingham and Walter Bischof and Alan Kingstone}, doi = {10.1080/13506280701434532}, year = {2008}, date = {2008-01-01}, journal = {Visual Cognition}, volume = {16}, number = {2-3}, pages = {341--355}, abstract = {A great deal of recent research has sought to understand the factors and neural systems that mediate the orienting of spatial attention to a gazed-at location. What have rarely been examined, however, are the factors that are critical to the initial selection of gaze information from complex visual scenes. For instance, is gaze prioritized relative to other possible body parts and objects within a scene? The present study springboards from the seminal work of Yarbus (1965/1967), who had originally examined participants? scan paths while they viewed visual scenes containing one or more people. His work suggested to us that the selection of gaze information may depend on the task that is assigned to participants, the social content of the scene, and/or the activity level depicted within the scene. Our results show clearly that all of these factors can significantly modulate the selection of gaze information. Specifically, the selection of gaze was enhanced when the task was to describe the social attention within a scene, and when the social content and activity level in a scene were high. Nevertheless, it is also the case that participants always selected gaze information more than any other stimulus. Our study has broad implications for future investigations of social attention as well as resolving a number of longstanding issues that had undermined the classic original work of Yarbus. A great deal of recent research has sought to understand the factors and neural systems that mediate the orienting of spatial attention to a gazed-at location. What have rarely been examined, however, are the factors that are critical to the initial selection of gaze information from complex visual scenes. For instance, is gaze prioritized relative to other possible body parts and objects within a scene? The present study springboards from the seminal work of Yarbus (1965/1967), who had originally examined participants? scan paths while they viewed visual scenes containing one or more people. His work suggested to us that the selection of gaze information may depend on the task that is assigned to participants, the social content of the scene, and/or the activity level depicted within the scene. Our results show clearly that all of these factors can significantly modulate the selection of gaze information. Specifically, the selection of gaze was enhanced when the task was to describe the social attention within a scene, and when the social content and activity level in a scene were high. Nevertheless, it is also the case that participants always selected gaze information more than any other stimulus. Our study has broad implications for future investigations of social attention as well as resolving a number of longstanding issues that had undermined the classic original work of Yarbus.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A great deal of recent research has sought to understand the factors and neural systems that mediate the orienting of spatial attention to a gazed-at location. What have rarely been examined, however, are the factors that are critical to the initial selection of gaze information from complex visual scenes. For instance, is gaze prioritized relative to other possible body parts and objects within a scene? The present study springboards from the seminal work of Yarbus (1965/1967), who had originally examined participants? scan paths while they viewed visual scenes containing one or more people. His work suggested to us that the selection of gaze information may depend on the task that is assigned to participants, the social content of the scene, and/or the activity level depicted within the scene. Our results show clearly that all of these factors can significantly modulate the selection of gaze information. Specifically, the selection of gaze was enhanced when the task was to describe the social attention within a scene, and when the social content and activity level in a scene were high. Nevertheless, it is also the case that participants always selected gaze information more than any other stimulus. Our study has broad implications for future investigations of social attention as well as resolving a number of longstanding issues that had undermined the classic original work of Yarbus. A great deal of recent research has sought to understand the factors and neural systems that mediate the orienting of spatial attention to a gazed-at location. What have rarely been examined, however, are the factors that are critical to the initial selection of gaze information from complex visual scenes. For instance, is gaze prioritized relative to other possible body parts and objects within a scene? The present study springboards from the seminal work of Yarbus (1965/1967), who had originally examined participants? scan paths while they viewed visual scenes containing one or more people. His work suggested to us that the selection of gaze information may depend on the task that is assigned to participants, the social content of the scene, and/or the activity level depicted within the scene. Our results show clearly that all of these factors can significantly modulate the selection of gaze information. Specifically, the selection of gaze was enhanced when the task was to describe the social attention within a scene, and when the social content and activity level in a scene were high. Nevertheless, it is also the case that participants always selected gaze information more than any other stimulus. Our study has broad implications for future investigations of social attention as well as resolving a number of longstanding issues that had undermined the classic original work of Yarbus. |
John D Koehn; Elizabeth Roy; Jason J S Barton The "diagonal effect": A systematic error in oblique antisaccades Journal Article Journal of Neurophysiology, 100 (2), pp. 587–597, 2008. @article{Koehn2008, title = {The "diagonal effect": A systematic error in oblique antisaccades}, author = {John D Koehn and Elizabeth Roy and Jason J S Barton}, doi = {10.1152/jn.90268.2008}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {100}, number = {2}, pages = {587--597}, abstract = {Antisaccades are known to show greater variable error and also a systematic hypometria in their amplitude compared with visually guided prosaccades. In this study, we examined whether their accuracy in direction (as opposed to amplitude) also showed a systematic error. We had human subjects perform prosaccades and antisaccades to goals located at a variety of polar angles. In the first experiment, subjects made prosaccades or antisaccades to one of eight equidistant locations in each block, whereas in the second, they made saccades to one of two equidistant locations per block. In the third, they made antisaccades to one of two locations at different distances but with the same polar angle in each block. Regardless of block design, the results consistently showed a saccadic systematic error, in that oblique antisaccades (but not prosaccades) requiring unequal vertical and horizontal vector components were deviated toward the 45 degrees diagonal meridians. This finding could not be attributed to range effects in either Cartesian or polar coordinates. A perceptual origin of the diagonal effect is suggested by similar systematic errors in other studies of memory-guided manual reaching or perceptual estimation of direction, and may indicate a common spatial bias when there is uncertain information about spatial location.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Antisaccades are known to show greater variable error and also a systematic hypometria in their amplitude compared with visually guided prosaccades. In this study, we examined whether their accuracy in direction (as opposed to amplitude) also showed a systematic error. We had human subjects perform prosaccades and antisaccades to goals located at a variety of polar angles. In the first experiment, subjects made prosaccades or antisaccades to one of eight equidistant locations in each block, whereas in the second, they made saccades to one of two equidistant locations per block. In the third, they made antisaccades to one of two locations at different distances but with the same polar angle in each block. Regardless of block design, the results consistently showed a saccadic systematic error, in that oblique antisaccades (but not prosaccades) requiring unequal vertical and horizontal vector components were deviated toward the 45 degrees diagonal meridians. This finding could not be attributed to range effects in either Cartesian or polar coordinates. A perceptual origin of the diagonal effect is suggested by similar systematic errors in other studies of memory-guided manual reaching or perceptual estimation of direction, and may indicate a common spatial bias when there is uncertain information about spatial location. |
J F Soechting; M Flanders Extrapolation of visual motion for manual interception Journal Article Journal of Neurophysiology, 99 (6), pp. 2956–2967, 2008. @article{Soechting2008, title = {Extrapolation of visual motion for manual interception}, author = {J F Soechting and M Flanders}, doi = {10.1152/jn.90308.2008}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {99}, number = {6}, pages = {2956--2967}, abstract = {A frequent goal of hand movement is to touch a moving target or to make contact with a stationary object that is in motion relative to the moving head and body. This process requires a prediction of the target's motion, since the initial direction of the hand movement anticipates target motion. This experiment was designed to define the visual motion parameters that are incorporated in this prediction of target motion. On seeing a go signal (a change in target color), human subjects slid the right index finger along a touch-sensitive computer monitor to intercept a target moving along an unseen circular or oval path. The analysis focused on the initial direction of the interception movement, which was found to be influenced by the time required to intercept the target and the target's distance from the finger's starting location. Initial direction also depended on the curvature of the target's trajectory in a manner that suggested that this parameter was underestimated during the process of extrapolation. The pattern of smooth pursuit eye movements suggests that the extrapolation of visual target motion was based on local motion cues around the time of the onset of hand movement, rather than on a cognitive synthesis of the target's pattern of motion.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A frequent goal of hand movement is to touch a moving target or to make contact with a stationary object that is in motion relative to the moving head and body. This process requires a prediction of the target's motion, since the initial direction of the hand movement anticipates target motion. This experiment was designed to define the visual motion parameters that are incorporated in this prediction of target motion. On seeing a go signal (a change in target color), human subjects slid the right index finger along a touch-sensitive computer monitor to intercept a target moving along an unseen circular or oval path. The analysis focused on the initial direction of the interception movement, which was found to be influenced by the time required to intercept the target and the target's distance from the finger's starting location. Initial direction also depended on the curvature of the target's trajectory in a manner that suggested that this parameter was underestimated during the process of extrapolation. The pattern of smooth pursuit eye movements suggests that the extrapolation of visual target motion was based on local motion cues around the time of the onset of hand movement, rather than on a cognitive synthesis of the target's pattern of motion. |
Katsumi Watanabe; Kenji Yokoi Dynamic distortion of visual position representation around moving objects Journal Article Journal of Vision, 8 (3), pp. 1–11, 2008. @article{Watanabe2008, title = {Dynamic distortion of visual position representation around moving objects}, author = {Katsumi Watanabe and Kenji Yokoi}, doi = {10.1109/ISDEA.2012.47}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {3}, pages = {1--11}, abstract = {The relative visual positions of briefly flashed stimuli are systematically modified in the presence of motion signals (R. Nijhawan, 2002; D. Whitney, 2002). Previously, we investigated the two-dimensional distortion of relative-position representations between moving and flashed stimuli. The results showed that the perceived position of a flash is not uniformly displaced but shifted toward a single convergent point back along the trajectory of a moving object (K. Watanabe & K. Yokoi, 2006, 2007). In the present study, we examined the temporal dynamics of the anisotropic distortion of visual position representation. While observers fixated on a stationary cross, a black disk appeared, moved along a horizontal trajectory, and disappeared. A white dot was briefly flashed at various positions relative to the moving disk and at various timings relative to the motion onset/offset. The temporal emerging-waning pattern of anisotropic mislocalization indicated that position representation in the space ahead of a moving object differs qualitatively from that in the space behind it. Thus, anisotropic mislocalization cannot be explained by either a spatially or a temporally homogeneous process. Instead, visual position representation is anisotropically influenced by moving objects in both space and time.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The relative visual positions of briefly flashed stimuli are systematically modified in the presence of motion signals (R. Nijhawan, 2002; D. Whitney, 2002). Previously, we investigated the two-dimensional distortion of relative-position representations between moving and flashed stimuli. The results showed that the perceived position of a flash is not uniformly displaced but shifted toward a single convergent point back along the trajectory of a moving object (K. Watanabe & K. Yokoi, 2006, 2007). In the present study, we examined the temporal dynamics of the anisotropic distortion of visual position representation. While observers fixated on a stationary cross, a black disk appeared, moved along a horizontal trajectory, and disappeared. A white dot was briefly flashed at various positions relative to the moving disk and at various timings relative to the motion onset/offset. The temporal emerging-waning pattern of anisotropic mislocalization indicated that position representation in the space ahead of a moving object differs qualitatively from that in the space behind it. Thus, anisotropic mislocalization cannot be explained by either a spatially or a temporally homogeneous process. Instead, visual position representation is anisotropically influenced by moving objects in both space and time. |
Stephen M Emrich; Justin D N Ruppel; Naseem Al-Aidroos; Jay Pratt; Susanne Ferber Out with the old: Inhibition of old items in a preview search is limited Journal Article Perception and Psychophysics, 70 (8), pp. 1552–1557, 2008. @article{Emrich2008, title = {Out with the old: Inhibition of old items in a preview search is limited}, author = {Stephen M Emrich and Justin D N Ruppel and Naseem Al-Aidroos and Jay Pratt and Susanne Ferber}, doi = {10.3758/PP.70.8.1552}, year = {2008}, date = {2008-01-01}, journal = {Perception and Psychophysics}, volume = {70}, number = {8}, pages = {1552--1557}, abstract = {If some of the distractors in a visual search task are previewed prior to the presentation of the remaining distractors and the target, search time is reduced relative to when all of the items are displayed simultaneously. Here, we tested whether the ability to preferentially search new items during such a preview search is limited. We confirmed previous studies: The proportion of fixations on old items was significantly less than chance. However, the probability of fixating old locations was negatively affected by increasing the number of previewed distractors, suggesting that inhibition is limited to a small number of old items. Furthermore, the ability to inhibit old locations was limited to the first four fixations, indicating that by the fifth fixation, the resources required to sustain inhibition had been depleted. Together, these findings suggest that inhibition of old items in a preview search is a top-down mediated process dependent on capacity-limited cognitive resources.}, keywords = {}, pubstate = {published}, tppubtype = {article} } If some of the distractors in a visual search task are previewed prior to the presentation of the remaining distractors and the target, search time is reduced relative to when all of the items are displayed simultaneously. Here, we tested whether the ability to preferentially search new items during such a preview search is limited. We confirmed previous studies: The proportion of fixations on old items was significantly less than chance. However, the probability of fixating old locations was negatively affected by increasing the number of previewed distractors, suggesting that inhibition is limited to a small number of old items. Furthermore, the ability to inhibit old locations was limited to the first four fixations, indicating that by the fifth fixation, the resources required to sustain inhibition had been depleted. Together, these findings suggest that inhibition of old items in a preview search is a top-down mediated process dependent on capacity-limited cognitive resources. |
H T Nefs; J M Harris Induced motion in depth and the effects of vergence eye movements Journal Article Journal of Vision, 8 (3), pp. 1–16, 2008. @article{Nefs2008, title = {Induced motion in depth and the effects of vergence eye movements}, author = {H T Nefs and J M Harris}, doi = {10.1167/8.3.8}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {3}, pages = {1--16}, abstract = {Induced motion is the false impression that physically stationary objects move when in the presence of other objects that really move. In this study, we investigated this motion illusion in the depth dimension. We raised three related questions, as follows: (1) What cues in the stimulus are responsible for this motion illusion in depth? (2) Is the size of this illusion affected by vergence eye movements? And (3) are the effects of eye movements different for motion in depth and for motion in the frontoparallel plane? To answer these questions, we measured the point of subjective stationarity. Observers viewed an inducer target that oscillated in depth and a test target that was located directly above it. The test target moved in phase or out of phase with the inducer, but with a smaller amplitude. Observers had to indicate whether the test target and the inducer target moved in phase or out of phase with one another. They were asked to keep their eyes either on the test target or on the inducer. For motion in depth, created by binocular disparity and retinal size change or by binocular disparity alone, we found that when the eyes followed the inducer, subjective stationarity occurred at approximately 40-45% of the inducer's amplitude. When the eyes were kept fixated on the test target, the bias decreased tenfold to around 4%. When size change was the only cue to motion in depth, there was no illusory motion. When the eyes were kept on an inducer moving in the frontoparallel plane, induced motion was of the same order as for induced motion in depth, namely, approximately 44%. When the induced motion was in the frontoparallel plane, we found that perceived stationarity occurred at approximately 23% of inducer's amplitude when the eyes were kept on the test target.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Induced motion is the false impression that physically stationary objects move when in the presence of other objects that really move. In this study, we investigated this motion illusion in the depth dimension. We raised three related questions, as follows: (1) What cues in the stimulus are responsible for this motion illusion in depth? (2) Is the size of this illusion affected by vergence eye movements? And (3) are the effects of eye movements different for motion in depth and for motion in the frontoparallel plane? To answer these questions, we measured the point of subjective stationarity. Observers viewed an inducer target that oscillated in depth and a test target that was located directly above it. The test target moved in phase or out of phase with the inducer, but with a smaller amplitude. Observers had to indicate whether the test target and the inducer target moved in phase or out of phase with one another. They were asked to keep their eyes either on the test target or on the inducer. For motion in depth, created by binocular disparity and retinal size change or by binocular disparity alone, we found that when the eyes followed the inducer, subjective stationarity occurred at approximately 40-45% of the inducer's amplitude. When the eyes were kept fixated on the test target, the bias decreased tenfold to around 4%. When size change was the only cue to motion in depth, there was no illusory motion. When the eyes were kept on an inducer moving in the frontoparallel plane, induced motion was of the same order as for induced motion in depth, namely, approximately 44%. When the induced motion was in the frontoparallel plane, we found that perceived stationarity occurred at approximately 23% of inducer's amplitude when the eyes were kept on the test target. |
Lee Hogarth; Anthony Dickinson; Alison Austin; Craig Brown; Theodora Duka Attention and expectation in human predictive learning: The role of uncertainty Journal Article Quarterly Journal of Experimental Psychology, 61 (11), pp. 1658–1668, 2008. @article{Hogarth2008, title = {Attention and expectation in human predictive learning: The role of uncertainty}, author = {Lee Hogarth and Anthony Dickinson and Alison Austin and Craig Brown and Theodora Duka}, doi = {10.1080/17470210701643439}, year = {2008}, date = {2008-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {61}, number = {11}, pages = {1658--1668}, abstract = {Three localized, visual pattern stimuli were trained as predictive signals of auditory outcomes. One signal partially predicted an aversive noise in Experiment 1 and a neutral tone in Experiment 2, whereas the other signals consistently predicted either the occurrence or absence of the noise. The expectation of the noise was measured during each signal presentation, and only participants for whom this expectation demonstrated contingency knowledge showed differential attention to the signals. Importantly, when attention was measured by visual fixations, the contingency-aware group attended more to the partially predictive signal than to the consistent predictors in both experiments. This profile of visual attention supports the Pearce and Hall (1980) theory of the role of attention in associative learning.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Three localized, visual pattern stimuli were trained as predictive signals of auditory outcomes. One signal partially predicted an aversive noise in Experiment 1 and a neutral tone in Experiment 2, whereas the other signals consistently predicted either the occurrence or absence of the noise. The expectation of the noise was measured during each signal presentation, and only participants for whom this expectation demonstrated contingency knowledge showed differential attention to the signals. Importantly, when attention was measured by visual fixations, the contingency-aware group attended more to the partially predictive signal than to the consistent predictors in both experiments. This profile of visual attention supports the Pearce and Hall (1980) theory of the role of attention in associative learning. |
Antimo Buonocore; Robert D McIntosh Saccadic inhibition underlies the remote distractor effect Journal Article Experimental Brain Research, 191 (1), pp. 117–122, 2008. @article{Buonocore2008, title = {Saccadic inhibition underlies the remote distractor effect}, author = {Antimo Buonocore and Robert D McIntosh}, doi = {10.1007/s00221-008-1558-7}, year = {2008}, date = {2008-01-01}, journal = {Experimental Brain Research}, volume = {191}, number = {1}, pages = {117--122}, abstract = {The remote distractor effect is a robust finding whereby a saccade to a lateralised visual target is delayed by the simultaneous, or near simultaneous, onset of a distractor in the opposite hemifield. Saccadic inhibition is a more recently discovered phenomenon whereby a transient change to the scene during a visual task induces a depression in saccadic frequency beginning within 70 ms, and maximal around 90-100 ms. We assessed whether saccadic inhibition is responsible for the increase in saccadic latency induced by remote distractors. Participants performed a simple saccadic task in which the delay between target and distractor was varied between 0, 25, 50, 100 and 150 ms. Examination of the distributions of saccadic latencies showed that each distractor produced a discrete dip in saccadic frequency, time-locked to distractor onset, conforming closely to the character of saccadic inhibition. We conclude that saccadic inhibition underlies the remote distractor effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The remote distractor effect is a robust finding whereby a saccade to a lateralised visual target is delayed by the simultaneous, or near simultaneous, onset of a distractor in the opposite hemifield. Saccadic inhibition is a more recently discovered phenomenon whereby a transient change to the scene during a visual task induces a depression in saccadic frequency beginning within 70 ms, and maximal around 90-100 ms. We assessed whether saccadic inhibition is responsible for the increase in saccadic latency induced by remote distractors. Participants performed a simple saccadic task in which the delay between target and distractor was varied between 0, 25, 50, 100 and 150 ms. Examination of the distributions of saccadic latencies showed that each distractor produced a discrete dip in saccadic frequency, time-locked to distractor onset, conforming closely to the character of saccadic inhibition. We conclude that saccadic inhibition underlies the remote distractor effect. |
K -M Lee; E L Keller Neural activity in the frontal eye fields modulated by the number of alternatives in target choice Journal Article The Journal of Neuroscience, 28 (9), pp. 2242–2251, 2008. @article{Lee2008, title = {Neural activity in the frontal eye fields modulated by the number of alternatives in target choice}, author = {K -M Lee and E L Keller}, doi = {10.1523/JNEUROSCI.3596-07.2008}, year = {2008}, date = {2008-01-01}, journal = {The Journal of Neuroscience}, volume = {28}, number = {9}, pages = {2242--2251}, abstract = {Selection of identical responses may not use the same neural mechanisms when the number of alternatives (NA) for the selection changes, as suggested by Hick's law. For elucidating the choice mechanisms, frontal eye field (FEF) neurons were monitored during a color-to-location choice saccade task as the number of potential targets was varied. Visual responses to alternative targets decreased as NA increased, whereas perisaccade activities increased with NA. These modulations of FEF activities seem closely related to the choice process because the activity enhancements coincided with the timing of target selection, and the neural modulation was greater as NA increased, features expected of neural correlates for a choice process from the perspective of Hick's law. Our current observations suggest two novel notions of FEF neuronal behavior that have not been reported previously: (1) cells called "phasic visual" that do not discharge in the perisaccade interval in a delayed-saccade paradigm show such activity in a choice response task at the time of the saccade; and (2) the activity in FEF visuomotor cells display an inverse relationship between perisaccadic activity and the time of saccade triggering with higher levels of activity leading to longer saccade reaction times. These findings support the area's involvement in sensory-motor translation for target selection through coactivation and competitive interaction of neural populations that code for alternative action sets.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Selection of identical responses may not use the same neural mechanisms when the number of alternatives (NA) for the selection changes, as suggested by Hick's law. For elucidating the choice mechanisms, frontal eye field (FEF) neurons were monitored during a color-to-location choice saccade task as the number of potential targets was varied. Visual responses to alternative targets decreased as NA increased, whereas perisaccade activities increased with NA. These modulations of FEF activities seem closely related to the choice process because the activity enhancements coincided with the timing of target selection, and the neural modulation was greater as NA increased, features expected of neural correlates for a choice process from the perspective of Hick's law. Our current observations suggest two novel notions of FEF neuronal behavior that have not been reported previously: (1) cells called "phasic visual" that do not discharge in the perisaccade interval in a delayed-saccade paradigm show such activity in a choice response task at the time of the saccade; and (2) the activity in FEF visuomotor cells display an inverse relationship between perisaccadic activity and the time of saccade triggering with higher levels of activity leading to longer saccade reaction times. These findings support the area's involvement in sensory-motor translation for target selection through coactivation and competitive interaction of neural populations that code for alternative action sets. |
N Alahyane; V Fonteille; C Urquizar; R Salemme; N Nighoghossian; D Pelisson; C Tilikete Separate neural substrates in the human cerebellum for sensory-motor adaptation of reactive and of scanning voluntary saccades Journal Article Cerebellum, 7 (4), pp. 595–601, 2008. @article{Alahyane2008, title = {Separate neural substrates in the human cerebellum for sensory-motor adaptation of reactive and of scanning voluntary saccades}, author = {N Alahyane and V Fonteille and C Urquizar and R Salemme and N Nighoghossian and D Pelisson and C Tilikete}, doi = {10.1007/s12311-008-0065-5}, year = {2008}, date = {2008-01-01}, journal = {Cerebellum}, volume = {7}, number = {4}, pages = {595--601}, abstract = {Sensory-motor adaptation processes are critically involved in maintaining accurate motor behavior throughout life. Yet their underlying neural substrates and task-dependency bases are still poorly understood. We address these issues here by studying adaptation of saccadic eye movements, a well-established model of sensory-motor plasticity. The cerebellum plays a major role in saccadic adaptation but it has not yet been investigated whether this role can account for the known specificity of adaptation to the saccade type (e.g., reactive versus voluntary). Two patients with focal lesions in different parts of the cerebellum were tested using the double-step target paradigm. Each patient was submitted to two separate sessions: one for reactive saccades (RS) triggered by the sudden appearance of a visual target and the second for scanning voluntary saccades (SVS) performed when exploring a more complex scene. We found that a medial cerebellar lesion impaired adaptation of reactive-but not of voluntary-saccades, whereas a lateral lesion affected adaptation of scanning voluntary saccades, but not of reactive saccades. These findings provide the first evidence of an involvement of the lateral cerebellum in saccadic adaptation, and extend the demonstrated role of the cerebellum in RS adaptation to adaptation of SVS. The double dissociation of adaptive abilities is also consistent with our previous hypothesis of the involvement in saccadic adaptation of partially separated cerebellar areas specific to the reactive or voluntary task (Alahyane et al. Brain Res 1135:107-121 (2007)).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sensory-motor adaptation processes are critically involved in maintaining accurate motor behavior throughout life. Yet their underlying neural substrates and task-dependency bases are still poorly understood. We address these issues here by studying adaptation of saccadic eye movements, a well-established model of sensory-motor plasticity. The cerebellum plays a major role in saccadic adaptation but it has not yet been investigated whether this role can account for the known specificity of adaptation to the saccade type (e.g., reactive versus voluntary). Two patients with focal lesions in different parts of the cerebellum were tested using the double-step target paradigm. Each patient was submitted to two separate sessions: one for reactive saccades (RS) triggered by the sudden appearance of a visual target and the second for scanning voluntary saccades (SVS) performed when exploring a more complex scene. We found that a medial cerebellar lesion impaired adaptation of reactive-but not of voluntary-saccades, whereas a lateral lesion affected adaptation of scanning voluntary saccades, but not of reactive saccades. These findings provide the first evidence of an involvement of the lateral cerebellum in saccadic adaptation, and extend the demonstrated role of the cerebellum in RS adaptation to adaptation of SVS. The double dissociation of adaptive abilities is also consistent with our previous hypothesis of the involvement in saccadic adaptation of partially separated cerebellar areas specific to the reactive or voluntary task (Alahyane et al. Brain Res 1135:107-121 (2007)). |
Nadia Alahyane; Anne-Dominique Devauchelle; Roméo Salemme; Denis Pélisson Spatial transfer of adaptation of scanning voluntary saccades in humans Journal Article Neuroreport, 19 (1), pp. 37–41, 2008. @article{Alahyane2008a, title = {Spatial transfer of adaptation of scanning voluntary saccades in humans}, author = {Nadia Alahyane and Anne-Dominique Devauchelle and Roméo Salemme and Denis Pélisson}, doi = {10.1097/WNR.0b013e3282f2a5f2}, year = {2008}, date = {2008-01-01}, journal = {Neuroreport}, volume = {19}, number = {1}, pages = {37--41}, abstract = {The properties and neural substrates of the adaptive mechanisms that maintain over time the accuracy of voluntary, internally triggered saccades are still poorly understood. Here, we used transfer tests to evaluate the spatial properties of adaptation of scanning voluntary saccades. We found that an adaptive reduction of the size of a horizontal rightward 7 degrees saccade transferred to other saccades of a wide range of amplitudes and directions. This transfer decreased as tested saccades increasingly differed in amplitude or direction from the trained saccade, being null for vertical and leftward saccades. Voluntary saccade adaptation thus presents bounded, but large adaptation fields, suggesting that at least part of the underlying neural substrate encodes saccades as vectors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The properties and neural substrates of the adaptive mechanisms that maintain over time the accuracy of voluntary, internally triggered saccades are still poorly understood. Here, we used transfer tests to evaluate the spatial properties of adaptation of scanning voluntary saccades. We found that an adaptive reduction of the size of a horizontal rightward 7 degrees saccade transferred to other saccades of a wide range of amplitudes and directions. This transfer decreased as tested saccades increasingly differed in amplitude or direction from the trained saccade, being null for vertical and leftward saccades. Voluntary saccade adaptation thus presents bounded, but large adaptation fields, suggesting that at least part of the underlying neural substrate encodes saccades as vectors. |
Hans Peter Frey; Christian Honey; P König; Peter Konig What's color got to do with it? The influence of color on visual attention in different categories Journal Article Journal of Vision, 8 (14), pp. 1–17, 2008. @article{Frey2008, title = {What's color got to do with it? The influence of color on visual attention in different categories}, author = {Hans Peter Frey and Christian Honey and P König and Peter Konig}, doi = {10.1167/8.14.6.Introduction}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {1--17}, abstract = {Certain locations attract human gaze in natural visual scenes. Are there measurable features, which distinguish these locations from others? While there has been extensive research on luminance-defined features, only few studies have examined the influence of color on overt attention. In this study, we addressed this question by presenting color-calibrated stimuli and analyzing color features that are known to be relevant for the responses of LGN neurons. We recorded eye movements of 15 human subjects freely viewing colored and grayscale images of seven different categories. All images were also analyzed by the saliency map model (L. Itti, C. Koch, & E. Niebur, 1998). We find that human fixation locations differ between colored and grayscale versions of the same image much more than predicted by the saliency map. Examining the influence of various color features on overt attention, we find two extreme categories: while in rainforest images all color features are salient, none is salient in fractals. In all other categories, color features are selectively salient. This shows that the influence of color on overt attention depends on the type of image. Also, it is crucial to analyze neurophysiologically relevant color features for quantifying the influence of color on attention.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Certain locations attract human gaze in natural visual scenes. Are there measurable features, which distinguish these locations from others? While there has been extensive research on luminance-defined features, only few studies have examined the influence of color on overt attention. In this study, we addressed this question by presenting color-calibrated stimuli and analyzing color features that are known to be relevant for the responses of LGN neurons. We recorded eye movements of 15 human subjects freely viewing colored and grayscale images of seven different categories. All images were also analyzed by the saliency map model (L. Itti, C. Koch, & E. Niebur, 1998). We find that human fixation locations differ between colored and grayscale versions of the same image much more than predicted by the saliency map. Examining the influence of various color features on overt attention, we find two extreme categories: while in rainforest images all color features are salient, none is salient in fractals. In all other categories, color features are selectively salient. This shows that the influence of color on overt attention depends on the type of image. Also, it is crucial to analyze neurophysiologically relevant color features for quantifying the influence of color on attention. |
M S Baptista; C Bohn; R Kliegl; R Engbert; J Kurths Reconstruction of eye movements during blinks Journal Article Chaos, 18 (1), pp. 1–15, 2008. @article{Baptista2008, title = {Reconstruction of eye movements during blinks}, author = {M S Baptista and C Bohn and R Kliegl and R Engbert and J Kurths}, doi = {10.1063/1.2890843}, year = {2008}, date = {2008-01-01}, journal = {Chaos}, volume = {18}, number = {1}, pages = {1--15}, abstract = {In eye movement research in reading, the amount of data plays a crucial role for the validation of results. A methodological problem for the analysis of the eye movement in reading are blinks, when readers close their eyes. Blinking rate increases with increasing reading time, resulting in high data losses, especially for older adults or reading impaired subjects. We present a method, based on the symbolic sequence dynamics of the eye movements, that reconstructs the horizontal position of the eyes while the reader blinks. The method makes use of an observed fact that the movements of the eyes before closing or after opening contain information about the eyes movements during blinks. Test results indicate that our reconstruction method is superior to methods that use simpler interpolation approaches. In addition, analyses of the reconstructed data show no significant deviation from the usual behavior observed in readers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In eye movement research in reading, the amount of data plays a crucial role for the validation of results. A methodological problem for the analysis of the eye movement in reading are blinks, when readers close their eyes. Blinking rate increases with increasing reading time, resulting in high data losses, especially for older adults or reading impaired subjects. We present a method, based on the symbolic sequence dynamics of the eye movements, that reconstructs the horizontal position of the eyes while the reader blinks. The method makes use of an observed fact that the movements of the eyes before closing or after opening contain information about the eyes movements during blinks. Test results indicate that our reconstruction method is superior to methods that use simpler interpolation approaches. In addition, analyses of the reconstructed data show no significant deviation from the usual behavior observed in readers. |
Michael D Crossland; Antony B Morland; Mary P Feely; Elisabeth von dem Hagen; Gary S Rubin The effect of age and fixation instability on retinotopic mapping of primary visual cortex Journal Article Investigative Ophthalmology & Visual Science, 49 (8), pp. 3734–3739, 2008. @article{Crossland2008, title = {The effect of age and fixation instability on retinotopic mapping of primary visual cortex}, author = {Michael D Crossland and Antony B Morland and Mary P Feely and Elisabeth von dem Hagen and Gary S Rubin}, doi = {10.1167/iovs.07-1621}, year = {2008}, date = {2008-01-01}, journal = {Investigative Ophthalmology & Visual Science}, volume = {49}, number = {8}, pages = {3734--3739}, abstract = {PURPOSE: Functional magnetic resonance imaging (fMRI) experiments determining the retinotopic structure of visual cortex have commonly been performed on young adults, who are assumed to be able to maintain steady fixation throughout the trial duration. The authors quantified the effects of age and fixation stability on the quality of retinotopic maps of primary visual cortex. METHODS: With the use of a 3T fMRI scanner, the authors measured cortical activity in six older and six younger normally sighted participants observing an expanding flickering checkerboard stimulus of 30 degrees diameter. The area of flattened primary visual cortex (V1) showing any blood oxygen level-dependent (BOLD) activity to the visual stimulus and the area responding to the central 3.75 degrees of the stimulus (relating to the central ring of our target) were recorded. Fixation stability was measured while participants observed the same stimuli outside the scanner using an infrared gazetracker. RESULTS: There were no age-related changes in the area of V1. However, the proportion of V1 active to our visual stimulus was lower for the older observers than for the younger observers (overall activity: 89.8% of V1 area for older observers, 98.6% for younger observers; P textless0.05). This effect was more pronounced for the central 3.75 degrees of the target (older subjects, 26.4%; younger subjects, 40.7%; P textless0.02). No significant relationship existed between fixation stability and age or the magnitude of activity in the primary visual cortex. CONCLUSIONS: Although the cortical area remains unchanged, healthy older persons show less BOLD activity in V1 than do younger persons. Normal variations in fixation stability do not have a significant effect on the accuracy of experiments to determine the retinotopic structure of the visual cortex.}, keywords = {}, pubstate = {published}, tppubtype = {article} } PURPOSE: Functional magnetic resonance imaging (fMRI) experiments determining the retinotopic structure of visual cortex have commonly been performed on young adults, who are assumed to be able to maintain steady fixation throughout the trial duration. The authors quantified the effects of age and fixation stability on the quality of retinotopic maps of primary visual cortex. METHODS: With the use of a 3T fMRI scanner, the authors measured cortical activity in six older and six younger normally sighted participants observing an expanding flickering checkerboard stimulus of 30 degrees diameter. The area of flattened primary visual cortex (V1) showing any blood oxygen level-dependent (BOLD) activity to the visual stimulus and the area responding to the central 3.75 degrees of the stimulus (relating to the central ring of our target) were recorded. Fixation stability was measured while participants observed the same stimuli outside the scanner using an infrared gazetracker. RESULTS: There were no age-related changes in the area of V1. However, the proportion of V1 active to our visual stimulus was lower for the older observers than for the younger observers (overall activity: 89.8% of V1 area for older observers, 98.6% for younger observers; P textless0.05). This effect was more pronounced for the central 3.75 degrees of the target (older subjects, 26.4%; younger subjects, 40.7%; P textless0.02). No significant relationship existed between fixation stability and age or the magnitude of activity in the primary visual cortex. CONCLUSIONS: Although the cortical area remains unchanged, healthy older persons show less BOLD activity in V1 than do younger persons. Normal variations in fixation stability do not have a significant effect on the accuracy of experiments to determine the retinotopic structure of the visual cortex. |
Lee Hogarth; Anthony Dickinson; Molly Janowski; Aleksandra Nikitina; Theodora Duka The role of attentional bias in mediating human drug-seeking behaviour Journal Article Psychopharmacology, 201 (1), pp. 29–41, 2008. @article{Hogarth2008a, title = {The role of attentional bias in mediating human drug-seeking behaviour}, author = {Lee Hogarth and Anthony Dickinson and Molly Janowski and Aleksandra Nikitina and Theodora Duka}, doi = {10.1007/s00213-008-1244-2}, year = {2008}, date = {2008-01-01}, journal = {Psychopharmacology}, volume = {201}, number = {1}, pages = {29--41}, abstract = {RATIONALE: The attentional bias for drug cues is believed to be a causal cognitive process mediating human drug seeking and relapse. OBJECTIVES, METHODS AND RESULTS: To test this claim, we trained smokers on a tobacco conditioning procedure in which the conditioned stimulus (or S+) acquired parallel control of an attentional bias (measured with an eye tracker), tobacco expectancy and instrumental tobacco-seeking behaviour. Although this correlation between measures may be regarded as consistent with the claim that the attentional bias for the S+ mediated tobacco seeking, when a secondary task was added in the test phase, the attentional bias for the S+ was abolished, yet the control of tobacco expectancy and tobacco seeking remained intact. CONCLUSIONS: This dissociation suggests that the attentional bias for drug cues is not necessary for the control that drug cues exert over drug-seeking behaviour. The question raised by these data is what function does the attentional bias serve if it does not mediate drug seeking?}, keywords = {}, pubstate = {published}, tppubtype = {article} } RATIONALE: The attentional bias for drug cues is believed to be a causal cognitive process mediating human drug seeking and relapse. OBJECTIVES, METHODS AND RESULTS: To test this claim, we trained smokers on a tobacco conditioning procedure in which the conditioned stimulus (or S+) acquired parallel control of an attentional bias (measured with an eye tracker), tobacco expectancy and instrumental tobacco-seeking behaviour. Although this correlation between measures may be regarded as consistent with the claim that the attentional bias for the S+ mediated tobacco seeking, when a secondary task was added in the test phase, the attentional bias for the S+ was abolished, yet the control of tobacco expectancy and tobacco seeking remained intact. CONCLUSIONS: This dissociation suggests that the attentional bias for drug cues is not necessary for the control that drug cues exert over drug-seeking behaviour. The question raised by these data is what function does the attentional bias serve if it does not mediate drug seeking? |
Elmar H Pinkhardt; Reinhart Jürgens; Wolfgang Becker; Federica Valdarno; Albert C Ludolph; Jan Kassubek Differential diagnostic value of eye movement recording in PSP-parkinsonism, Richardson's syndrome, and idiopathic Parkinson's disease Journal Article Journal of Neurology, 255 (12), pp. 1916–1925, 2008. @article{Pinkhardt2008, title = {Differential diagnostic value of eye movement recording in PSP-parkinsonism, Richardson's syndrome, and idiopathic Parkinson's disease}, author = {Elmar H Pinkhardt and Reinhart Jürgens and Wolfgang Becker and Federica Valdarno and Albert C Ludolph and Jan Kassubek}, doi = {10.1007/s00415-009-0027-y}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurology}, volume = {255}, number = {12}, pages = {1916--1925}, abstract = {Vertical gaze palsy is a highly relevant clinical sign in parkinsonian syndromes. As the eponymous sign of progressive supranuclear palsy (PSP), it is one of the core features in the diagnosis of this disease. Recent studies have suggested a further differentiation of PSP in Richardson's syndrome (RS) and PSP-parkinsonism (PSPP). The aim of this study was to search for oculomotor abnormalities in the PSP-P subset of a sample of PSP patients and to compare these findings with those of (i) RS patients, (ii) patients with idiopathic Parkinson's disease (IPD), and (iii) a control group. Twelve cases of RS, 5 cases of PSP-P, and 27 cases of IPD were examined by use of video-oculography (VOG) and compared to 23 healthy normal controls. Both groups of PSP patients (RS, PSP-P) had significantly slower saccades than either IPD patients or controls, whereas no differences in saccadic eye peak velocity were found between the two PSP groups or in the comparison of IPD with controls. RS and PSP-P were also similar to each other with regard to smooth pursuit eye movements (SPEM), with both groups having significantly lower gain than controls (except for downward pursuit); however, SPEM gain exhibited no consistent difference between PSP and IPD. A correlation between eye movement data and clinical data (Hoehn & Yahr scale or disease duration) could not be observed. As PSP-P patients were still in an early stage of the disease when a differentiation from IPD is difficult on clinical grounds, the clear-cut separation between PSP-P and IPD obtained by measuring saccade velocity suggests that VOG could contribute to the early differentiation between these patient groups.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vertical gaze palsy is a highly relevant clinical sign in parkinsonian syndromes. As the eponymous sign of progressive supranuclear palsy (PSP), it is one of the core features in the diagnosis of this disease. Recent studies have suggested a further differentiation of PSP in Richardson's syndrome (RS) and PSP-parkinsonism (PSPP). The aim of this study was to search for oculomotor abnormalities in the PSP-P subset of a sample of PSP patients and to compare these findings with those of (i) RS patients, (ii) patients with idiopathic Parkinson's disease (IPD), and (iii) a control group. Twelve cases of RS, 5 cases of PSP-P, and 27 cases of IPD were examined by use of video-oculography (VOG) and compared to 23 healthy normal controls. Both groups of PSP patients (RS, PSP-P) had significantly slower saccades than either IPD patients or controls, whereas no differences in saccadic eye peak velocity were found between the two PSP groups or in the comparison of IPD with controls. RS and PSP-P were also similar to each other with regard to smooth pursuit eye movements (SPEM), with both groups having significantly lower gain than controls (except for downward pursuit); however, SPEM gain exhibited no consistent difference between PSP and IPD. A correlation between eye movement data and clinical data (Hoehn & Yahr scale or disease duration) could not be observed. As PSP-P patients were still in an early stage of the disease when a differentiation from IPD is difficult on clinical grounds, the clear-cut separation between PSP-P and IPD obtained by measuring saccade velocity suggests that VOG could contribute to the early differentiation between these patient groups. |
Paul Reeve; James J Clark; Kevin J O'Regan Convergent flash localization near saccades without equivalent "compression" of perceived separation Journal Article Journal of Vision, 8 (13), pp. 1–19, 2008. @article{Reeve2008, title = {Convergent flash localization near saccades without equivalent "compression" of perceived separation}, author = {Paul Reeve and James J Clark and Kevin J O'Regan}, doi = {10.1167/8.13.5}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {13}, pages = {1--19}, abstract = {Visual space is sometimes said to be "compressed" before saccadic eye movements. The most central evidence for this hypothesis is a converging pattern of localization errors on single flashes presented close to saccade time under certain conditions. An intuitive version of the compression hypothesis predicts that the reported distance between simultaneous, spatially separated presaccadic flashes should contract in the same way as their individual locations. In our experiment we tested this prediction by having subjects perform one of two tasks on stimuli made up of two bars simultaneously flashed near saccade time: either localizing one of the bars or judging the separation between the two. Localization judgments showed the previously observed converging pattern over the 50-100 ms before saccades. Contractions in perceived separation between the two bars were not accurately predicted by this pattern: they occurred mainly during saccades and were much weaker than convergence in localization. Different forms of spatial information about flashed stimuli can be differentially modulated before, during, and after saccades. Structural alterations in the perceptual field around saccades may explain these different effects, but alternative hypotheses based on decision making under uncertainty and on the influence of other perisaccadic mechanisms are also consistent with this and other evidence.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual space is sometimes said to be "compressed" before saccadic eye movements. The most central evidence for this hypothesis is a converging pattern of localization errors on single flashes presented close to saccade time under certain conditions. An intuitive version of the compression hypothesis predicts that the reported distance between simultaneous, spatially separated presaccadic flashes should contract in the same way as their individual locations. In our experiment we tested this prediction by having subjects perform one of two tasks on stimuli made up of two bars simultaneously flashed near saccade time: either localizing one of the bars or judging the separation between the two. Localization judgments showed the previously observed converging pattern over the 50-100 ms before saccades. Contractions in perceived separation between the two bars were not accurately predicted by this pattern: they occurred mainly during saccades and were much weaker than convergence in localization. Different forms of spatial information about flashed stimuli can be differentially modulated before, during, and after saccades. Structural alterations in the perceptual field around saccades may explain these different effects, but alternative hypotheses based on decision making under uncertainty and on the influence of other perisaccadic mechanisms are also consistent with this and other evidence. |
Caroline Blais; Rachael E Jack; Christoph Scheepers; Daniel Fiset; Roberto Caldara Culture shapes how we look at faces Journal Article PLoS ONE, 3 (8), pp. 1–8, 2008. @article{Blais2008, title = {Culture shapes how we look at faces}, author = {Caroline Blais and Rachael E Jack and Christoph Scheepers and Daniel Fiset and Roberto Caldara}, year = {2008}, date = {2008-01-01}, journal = {PLoS ONE}, volume = {3}, number = {8}, pages = {1--8}, abstract = {Background: Face processing, amongst many basic visual skills, is thought to be invariant across all humans. From as early as 1965, studies of eye movements have consistently revealed a systematic triangular sequence of fixations over the eyes and the mouth, suggesting that faces elicit a universal, biologically-determined information extraction pattern. Methodology/Principal Findings: Here we monitored the eye movements of Western Caucasian and East Asian observers while they learned, recognized, and categorized by race Western Caucasian and East Asian faces. Western Caucasian observers reproduced a scattered triangular pattern of fixations for faces of both races and across tasks. Contrary to intuition, East Asian observers focused more on the central region of the face. Conclusions/Significance: These results demonstrate that face processing can no longer be considered as arising from a universal series of perceptual events. The strategy employed to extract visual information from faces differs across cultures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Face processing, amongst many basic visual skills, is thought to be invariant across all humans. From as early as 1965, studies of eye movements have consistently revealed a systematic triangular sequence of fixations over the eyes and the mouth, suggesting that faces elicit a universal, biologically-determined information extraction pattern. Methodology/Principal Findings: Here we monitored the eye movements of Western Caucasian and East Asian observers while they learned, recognized, and categorized by race Western Caucasian and East Asian faces. Western Caucasian observers reproduced a scattered triangular pattern of fixations for faces of both races and across tasks. Contrary to intuition, East Asian observers focused more on the central region of the face. Conclusions/Significance: These results demonstrate that face processing can no longer be considered as arising from a universal series of perceptual events. The strategy employed to extract visual information from faces differs across cultures. |
Ralf Engbert; Antje Nuthmann Self-consistent estimation of mislocated fixations during reading Journal Article PLoS ONE, 3 (2), pp. 1–6, 2008. @article{Engbert2008, title = {Self-consistent estimation of mislocated fixations during reading}, author = {Ralf Engbert and Antje Nuthmann}, doi = {10.1371/journal.pone.0001534}, year = {2008}, date = {2008-01-01}, journal = {PLoS ONE}, volume = {3}, number = {2}, pages = {1--6}, abstract = {During reading, we generate saccadic eye movements to move words into the center of the visual field for word processing. However, due to systematic and random errors in the oculomotor system, distributions of within-word landing positions are rather broad and show overlapping tails, which suggests that a fraction of fixations is mislocated and falls on words to the left or right of the selected target word. Here we propose a new procedure for the self-consistent estimation of the likelihood of mislocated fixations in normal reading. Our approach is based on iterative computation of the proportions of several types of oculomotor errors, the underlying probabilities for word-targeting, and corrected distributions of landing positions. We found that the average fraction of mislocated fixations ranges from about 10% to more than 30% depending on word length. These results show that fixation probabilities are strongly affected by oculomotor errors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } During reading, we generate saccadic eye movements to move words into the center of the visual field for word processing. However, due to systematic and random errors in the oculomotor system, distributions of within-word landing positions are rather broad and show overlapping tails, which suggests that a fraction of fixations is mislocated and falls on words to the left or right of the selected target word. Here we propose a new procedure for the self-consistent estimation of the likelihood of mislocated fixations in normal reading. Our approach is based on iterative computation of the proportions of several types of oculomotor errors, the underlying probabilities for word-targeting, and corrected distributions of landing positions. We found that the average fraction of mislocated fixations ranges from about 10% to more than 30% depending on word length. These results show that fixation probabilities are strongly affected by oculomotor errors. |
Eric Matheron; Qing Yang; Thanh Thuan Lê; Zoï Kapoula Effects of ocular dominance on the vertical vergence induced by a 2-diopter vertical prism during standing Journal Article Neuroscience Letters, 444 (2), pp. 176–180, 2008. @article{Matheron2008, title = {Effects of ocular dominance on the vertical vergence induced by a 2-diopter vertical prism during standing}, author = {Eric Matheron and Qing Yang and Thanh Thuan L{ê} and Zo{ï} Kapoula}, doi = {10.1016/j.neulet.2008.08.025}, year = {2008}, date = {2008-01-01}, journal = {Neuroscience Letters}, volume = {444}, number = {2}, pages = {176--180}, abstract = {This study examined the eye movement responses to vertical disparity induced by a 2-diopter vertical prism base down while in standing position. Vertical vergence movements are known to be small requiring accurate measurement with the head stabilized, and was done with the EyeLink 2. The 2-diopter vertical prism, base down, was inserted in front of either the non-dominant eye (NDE) or dominant eye (DE) at 40 and 200 cm. The results showed that vertical vergence was stronger and excessive relative to the required value (i.e. 1.14°) when the prism was on the NDE for both distances, but more appropriate when the prism was on the DE. The results suggest that sensory disparity process and vertical vergence responses are modulated by eye dominance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study examined the eye movement responses to vertical disparity induced by a 2-diopter vertical prism base down while in standing position. Vertical vergence movements are known to be small requiring accurate measurement with the head stabilized, and was done with the EyeLink 2. The 2-diopter vertical prism, base down, was inserted in front of either the non-dominant eye (NDE) or dominant eye (DE) at 40 and 200 cm. The results showed that vertical vergence was stronger and excessive relative to the required value (i.e. 1.14°) when the prism was on the NDE for both distances, but more appropriate when the prism was on the DE. The results suggest that sensory disparity process and vertical vergence responses are modulated by eye dominance. |
Tamara A Russell; Melissa J Green; Ian Simpson; Max Coltheart Remediation of facial emotion perception in schizophrenia: Concomitant changes in visual attention Journal Article Schizophrenia Research, 103 (1-3), pp. 248–256, 2008. @article{Russell2008, title = {Remediation of facial emotion perception in schizophrenia: Concomitant changes in visual attention}, author = {Tamara A Russell and Melissa J Green and Ian Simpson and Max Coltheart}, doi = {10.1016/j.schres.2008.04.033}, year = {2008}, date = {2008-01-01}, journal = {Schizophrenia Research}, volume = {103}, number = {1-3}, pages = {248--256}, abstract = {The study examined changes in visual attention in schizophrenia following training with a social-cognitive remediation package designed to improve facial emotion recognition (the Micro-Expression Training Tool; METT). Forty out-patients with schizophrenia were randomly allocated to active training (METT; n = 26), or repeated exposure (RE; n = 14); all completed an emotion recognition task with concurrent eye movement recording. Emotion recognition accuracy was significantly improved in the METT group, and this effect was maintained after one week. Immediately following training, the METT group directed more eye movements within feature areas of faces (i.e., eyes, nose, mouth) compared to the RE group. The number of fixations directed to feature areas of faces was positively associated with emotion recognition accuracy prior to training. After one week, the differences between METT and RE groups in viewing feature areas of faces were reduced to trends. However, within group analyses of the METT group revealed significantly increased number of fixations to, and dwell time within, feature areas following training which were maintained after one week. These results provide the first evidence that improvements in emotion recognition following METT training are associated with changes in visual attention to the feature areas of emotional faces. These findings support the contribution of visual attention abnormalities to emotion recognition impairment in schizophrenia, and suggest that one mechanism for improving emotion recognition involves re-directing visual attention to relevant features of emotional faces.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The study examined changes in visual attention in schizophrenia following training with a social-cognitive remediation package designed to improve facial emotion recognition (the Micro-Expression Training Tool; METT). Forty out-patients with schizophrenia were randomly allocated to active training (METT; n = 26), or repeated exposure (RE; n = 14); all completed an emotion recognition task with concurrent eye movement recording. Emotion recognition accuracy was significantly improved in the METT group, and this effect was maintained after one week. Immediately following training, the METT group directed more eye movements within feature areas of faces (i.e., eyes, nose, mouth) compared to the RE group. The number of fixations directed to feature areas of faces was positively associated with emotion recognition accuracy prior to training. After one week, the differences between METT and RE groups in viewing feature areas of faces were reduced to trends. However, within group analyses of the METT group revealed significantly increased number of fixations to, and dwell time within, feature areas following training which were maintained after one week. These results provide the first evidence that improvements in emotion recognition following METT training are associated with changes in visual attention to the feature areas of emotional faces. These findings support the contribution of visual attention abnormalities to emotion recognition impairment in schizophrenia, and suggest that one mechanism for improving emotion recognition involves re-directing visual attention to relevant features of emotional faces. |
Giovanni Taibbi; Zhong I Wang; Louis F Dell'Osso Infantile nystagmus syndrome : Broadening the high-foveation-quality fi eld with contact lenses Journal Article Ophthalmology, 2 (3), pp. 585–589, 2008. @article{Taibbi2008, title = {Infantile nystagmus syndrome : Broadening the high-foveation-quality fi eld with contact lenses}, author = {Giovanni Taibbi and Zhong I Wang and Louis F Dell'Osso}, year = {2008}, date = {2008-01-01}, journal = {Ophthalmology}, volume = {2}, number = {3}, pages = {585--589}, abstract = {We investigated the effects of contact lenses in broadening and improving the high-foveation-quality fi eld in a subject with infantile nystagmus syndrome (INS). A high-speed, digitized video system was used for the eye-movement recording. The subject was asked to fi xate a far target at different horizontal gaze angles with contact lenses inserted. Data from the subject while fi xating at far without refractive correction and at near (at a convergence angle of 60 PD), were used for comparison. The eXpanded Nystagmus Acuity Function (NAFX) was used to evaluate the foveation quality at each gaze angle. Contact lenses broadened the high- foveation-quality range of gaze angles in this subject. The broadening was comparable to that achieved during 60 PD of convergence although the NAFX values were lower. Contact lenses allowed the subject to see “more” (he had a wider range of high-foveation-quality gaze angles) and “better” (he had improved foveation at each gaze angle). Instead of being contraindicated by INS, contact lenses emerge as a potentially important therapeutic option. Contact lenses employ afferent feedback via the ophthalmic division of the V cranial nerve to damp INS slow phases over a broadened range of gaze angles. This supports the proprioceptive hypothesis of INS improvement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the effects of contact lenses in broadening and improving the high-foveation-quality fi eld in a subject with infantile nystagmus syndrome (INS). A high-speed, digitized video system was used for the eye-movement recording. The subject was asked to fi xate a far target at different horizontal gaze angles with contact lenses inserted. Data from the subject while fi xating at far without refractive correction and at near (at a convergence angle of 60 PD), were used for comparison. The eXpanded Nystagmus Acuity Function (NAFX) was used to evaluate the foveation quality at each gaze angle. Contact lenses broadened the high- foveation-quality range of gaze angles in this subject. The broadening was comparable to that achieved during 60 PD of convergence although the NAFX values were lower. Contact lenses allowed the subject to see “more” (he had a wider range of high-foveation-quality gaze angles) and “better” (he had improved foveation at each gaze angle). Instead of being contraindicated by INS, contact lenses emerge as a potentially important therapeutic option. Contact lenses employ afferent feedback via the ophthalmic division of the V cranial nerve to damp INS slow phases over a broadened range of gaze angles. This supports the proprioceptive hypothesis of INS improvement. |
Alexandra Soliman; Gillian A O'Driscoll; Jens Pruessner; Anne Lise V Holahan; Isabelle Boileau; Danny Gagnon; Alain Dagher Stress-induced dopamine release in humans at risk of psychosis: A [ "C] raclopride PET study Journal Article Neuropsychopharmacology, 33 (8), pp. 2033–2041, 2008. @article{Soliman2008, title = {Stress-induced dopamine release in humans at risk of psychosis: A [ "C] raclopride PET study}, author = {Alexandra Soliman and Gillian A O'Driscoll and Jens Pruessner and Anne Lise V Holahan and Isabelle Boileau and Danny Gagnon and Alain Dagher}, doi = {10.1038/sj.npp.1301597}, year = {2008}, date = {2008-01-01}, journal = {Neuropsychopharmacology}, volume = {33}, number = {8}, pages = {2033--2041}, abstract = {Drugs that increase dopamine levels in the brain can cause psychotic symptoms in healthy individuals and worsen them in schizophrenic patients. Psychological stress also increases dopamine release and is thought to play a role in susceptibility to psychotic illness. We hypothesized that healthy individuals at elevated risk of developing psychosis would show greater striatal dopamine release than controls in response to stress. Using positron emission tomography and [(11)C]raclopride, we measured changes in synaptic dopamine concentrations in 10 controls and 16 psychometric schizotypes; 9 with perceptual aberrations (PerAb, ie positive schizotypy) and 7 with physical anhedonia (PhysAn, ie negative schizotypy). [(11)C]Raclopride binding potential was measured during a psychological stress task and a sensory-motor control. All three groups showed significant increases in self-reported stress and cortisol levels between the stress and control conditions. However, only the PhysAn group showed significant stress-induced dopamine release. Dopamine release in the entire sample was significantly negatively correlated with smooth pursuit gain, an endophenotype linked to frontal lobe function. Our findings suggest the presence of abnormalities in the dopamine response to stress in negative symptom schizotypy, and provide indirect evidence of a link to frontal function.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Drugs that increase dopamine levels in the brain can cause psychotic symptoms in healthy individuals and worsen them in schizophrenic patients. Psychological stress also increases dopamine release and is thought to play a role in susceptibility to psychotic illness. We hypothesized that healthy individuals at elevated risk of developing psychosis would show greater striatal dopamine release than controls in response to stress. Using positron emission tomography and [(11)C]raclopride, we measured changes in synaptic dopamine concentrations in 10 controls and 16 psychometric schizotypes; 9 with perceptual aberrations (PerAb, ie positive schizotypy) and 7 with physical anhedonia (PhysAn, ie negative schizotypy). [(11)C]Raclopride binding potential was measured during a psychological stress task and a sensory-motor control. All three groups showed significant increases in self-reported stress and cortisol levels between the stress and control conditions. However, only the PhysAn group showed significant stress-induced dopamine release. Dopamine release in the entire sample was significantly negatively correlated with smooth pursuit gain, an endophenotype linked to frontal lobe function. Our findings suggest the presence of abnormalities in the dopamine response to stress in negative symptom schizotypy, and provide indirect evidence of a link to frontal function. |
Robert D Gordon; Sarah D Vollmer; Megan L Frankl Object continuity and the transsaccadic representation of form Journal Article Perception and Psychophysics, 70 (4), pp. 667–679, 2008. @article{Gordon2008, title = {Object continuity and the transsaccadic representation of form}, author = {Robert D Gordon and Sarah D Vollmer and Megan L Frankl}, doi = {10.3758/PP}, year = {2008}, date = {2008-01-01}, journal = {Perception and Psychophysics}, volume = {70}, number = {4}, pages = {667--679}, abstract = {Transsaccadic object file representations were investigated in three experiments. Subjects moved their eyes from a central fixation cross to a location between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials on which the target identity matched one of the preview objects, its orientation either matched or did not match the previewed orientation. The results of Experiments 1 and 2 revealed that orientation changes disrupt perceptual continuity for objects located near fixation, but not for objects located further from fixation. The results of Experiment 3 confirmed that orientation changes do not disrupt continuity for distant objects, while showing that subjects nevertheless maintain an object-specific representation of the orientation of such objects. Together, the results suggest that object files represent orientation but that whether or not orientation plays a role in the processes that determine continuity depends on the quality of the perceptual representation. While}, keywords = {}, pubstate = {published}, tppubtype = {article} } Transsaccadic object file representations were investigated in three experiments. Subjects moved their eyes from a central fixation cross to a location between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials on which the target identity matched one of the preview objects, its orientation either matched or did not match the previewed orientation. The results of Experiments 1 and 2 revealed that orientation changes disrupt perceptual continuity for objects located near fixation, but not for objects located further from fixation. The results of Experiment 3 confirmed that orientation changes do not disrupt continuity for distant objects, while showing that subjects nevertheless maintain an object-specific representation of the orientation of such objects. Together, the results suggest that object files represent orientation but that whether or not orientation plays a role in the processes that determine continuity depends on the quality of the perceptual representation. While |
Kohske Takahashi; Katsumi Watanabe Persisting effect of prior experience of change blindness Journal Article Perception, 37 (2), pp. 324–327, 2008. @article{Takahashi2008, title = {Persisting effect of prior experience of change blindness}, author = {Kohske Takahashi and Katsumi Watanabe}, doi = {10.1068/p5906}, year = {2008}, date = {2008-01-01}, journal = {Perception}, volume = {37}, number = {2}, pages = {324--327}, abstract = {Most cognitive scientists know that an airplane tends to lose its engine when the display is flickering. How does such prior experience influence visual search? We recorded eye movements made by vision researchers while they were actively performing a change-detection task. In selected trials, we presented Rensink's familiar 'airplane' display, but with changes occurring at locations other than the jet engine. The observers immediately noticed that there was no change in the location where the engine had changed in the previous change-blindness demonstration. Nevertheless, eye-movement analyses indicated that the observers were compelled to look at the location of the unchanged engine. These results demonstrate the powerful effect of prior experience on eye movements, even when the observers are aware of the futility of doing so.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Most cognitive scientists know that an airplane tends to lose its engine when the display is flickering. How does such prior experience influence visual search? We recorded eye movements made by vision researchers while they were actively performing a change-detection task. In selected trials, we presented Rensink's familiar 'airplane' display, but with changes occurring at locations other than the jet engine. The observers immediately noticed that there was no change in the location where the engine had changed in the previous change-blindness demonstration. Nevertheless, eye-movement analyses indicated that the observers were compelled to look at the location of the unchanged engine. These results demonstrate the powerful effect of prior experience on eye movements, even when the observers are aware of the futility of doing so. |
Zhi-Lei Zhang; Christopher R L Cantor; Clifton M Schor Effects of luminance and saccadic suppression on perisaccadic spatial distortions Journal Article Journal of vision, 8 (14), pp. 22 1–18, 2008. @article{Zhang2008, title = {Effects of luminance and saccadic suppression on perisaccadic spatial distortions}, author = {Zhi-Lei Zhang and Christopher R L Cantor and Clifton M Schor}, doi = {10.1167/8.14.22r/8/14/22/ [pii]}, year = {2008}, date = {2008-01-01}, journal = {Journal of vision}, volume = {8}, number = {14}, pages = {22 1--18}, abstract = {Visual directions of foveal targets flashed just prior to the onset of a saccade are misperceived as shifted in the direction of the eye movement. We examined the effects of luminance level and temporal interactions on the amplitude of these perisaccadic spatial distortions (PSDs). PSDs were larger for both single and sequentially double-flashed stimuli with low than high luminance levels, and there was a reduction of PSDs for low luminance targets flashed immediately before the saccade. Significant temporal interactions were suggested by PSDs for a pair of sequentially presented flashes (ISI = 50 ms) that could not be predicted from the single-flash distortions: PSD increased for the first flash and decreased for the second compared to the single-flash distortions. We also found that when the flash pair was presented near saccade onset, the perceived distortion of the earlier flash overtook that of the later flash, even though the late flash occurred closer in time to the saccade. To explain these effects, we propose that stimulus-dependent nonlinearities (contrast gain control and saccadic suppression) influence the duration of the temporal impulse response of both single- and double-flashed stimuli.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual directions of foveal targets flashed just prior to the onset of a saccade are misperceived as shifted in the direction of the eye movement. We examined the effects of luminance level and temporal interactions on the amplitude of these perisaccadic spatial distortions (PSDs). PSDs were larger for both single and sequentially double-flashed stimuli with low than high luminance levels, and there was a reduction of PSDs for low luminance targets flashed immediately before the saccade. Significant temporal interactions were suggested by PSDs for a pair of sequentially presented flashes (ISI = 50 ms) that could not be predicted from the single-flash distortions: PSD increased for the first flash and decreased for the second compared to the single-flash distortions. We also found that when the flash pair was presented near saccade onset, the perceived distortion of the earlier flash overtook that of the later flash, even though the late flash occurred closer in time to the saccade. To explain these effects, we propose that stimulus-dependent nonlinearities (contrast gain control and saccadic suppression) influence the duration of the temporal impulse response of both single- and double-flashed stimuli. |
Naseem Al-aidroos; Jos J Adam; Martin H Fischer; Jay Pratt Structured perceptual arrays and the modulation of Fitts's Law: Examining saccadic eye movements Journal Article Journal of Motor Behavior, 40 (2), pp. 155–164, 2008. @article{Al-aidroos2008, title = {Structured perceptual arrays and the modulation of Fitts's Law: Examining saccadic eye movements}, author = {Naseem Al-aidroos and Jos J Adam and Martin H Fischer and Jay Pratt}, year = {2008}, date = {2008-01-01}, journal = {Journal of Motor Behavior}, volume = {40}, number = {2}, pages = {155--164}, abstract = {On the basis of recent observations of a modulation of Fitts's law for manual pointing movements in structured visual arrays (J. J. Adam, R. Mol, J. Pratt, & M. H. Fischer, 2006; J. Pratt, J. J. Adam, & M. H. Fischer, 2007), the authors examined whether a similar modulation occurs for saccadic eye move- ments. Healthy participants (N = 19) made horizontal saccades to targets that appeared randomly in 1 of 4 positions, either on an empty background or within 1 of 4 placeholder boxes. Whereas in previous studies, placeholders caused a decrease in movement time (MT) without the normal decrease in movement accuracy predicted by Fitts's law, placeholders in the present experiment increased saccadic accuracy (decreased endpoint variability) with- out an increase in MT. The present results extend the findings of J. J. Adam et al. of a modulation of Fitts's law from the temporal domain to the spatial domain and from manual movements to eye movements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } On the basis of recent observations of a modulation of Fitts's law for manual pointing movements in structured visual arrays (J. J. Adam, R. Mol, J. Pratt, & M. H. Fischer, 2006; J. Pratt, J. J. Adam, & M. H. Fischer, 2007), the authors examined whether a similar modulation occurs for saccadic eye move- ments. Healthy participants (N = 19) made horizontal saccades to targets that appeared randomly in 1 of 4 positions, either on an empty background or within 1 of 4 placeholder boxes. Whereas in previous studies, placeholders caused a decrease in movement time (MT) without the normal decrease in movement accuracy predicted by Fitts's law, placeholders in the present experiment increased saccadic accuracy (decreased endpoint variability) with- out an increase in MT. The present results extend the findings of J. J. Adam et al. of a modulation of Fitts's law from the temporal domain to the spatial domain and from manual movements to eye movements. |
Lu Qi Xiao; Jun Yun Zhang; Rui Wang; Stanley A Klein; Dennis M Levi; Cong Yu Complete transfer of perceptual learning across retinal locations enabled by double training Journal Article Current Biology, 18 (24), pp. 1922–1926, 2008. @article{Xiao2008, title = {Complete transfer of perceptual learning across retinal locations enabled by double training}, author = {Lu Qi Xiao and Jun Yun Zhang and Rui Wang and Stanley A Klein and Dennis M Levi and Cong Yu}, doi = {10.1016/j.cub.2008.10.030}, year = {2008}, date = {2008-01-01}, journal = {Current Biology}, volume = {18}, number = {24}, pages = {1922--1926}, publisher = {Elsevier Ltd}, abstract = {Practice improves discrimination of many basic visual features, such as contrast, orientation, and positional offset [1-7]. Perceptual learning of many of these tasks is found to be retinal location specific, in that learning transfers little to an untrained retinal location [1, 6-8]. In most perceptual learning models, this location specificity is interpreted as a pointer to a retinotopic early visual cortical locus of learning [1, 6-11]. Alternatively, an untested hypothesis is that learning could occur in a central site, but it consists of two separate aspects: learning to discriminate a specific stimulus feature ("feature learning"), and learning to deal with stimulus-nonspecific factors like local noise at the stimulus location ("location learning") [12]. Therefore, learning is not transferable to a new location that has never been location trained. To test this hypothesis, we developed a novel double-training paradigm that employed conventional feature training (e.g., contrast) at one location, and additional training with an irrelevant feature/task (e.g., orientation) at a second location, either simultaneously or at a different time. Our results showed that this additional location training enabled a complete transfer of feature learning (e.g., contrast) to the second location. This finding challenges location specificity and its inferred cortical retinotopy as central concepts to many perceptual-learning models and suggests that perceptual learning involves higher nonretinotopic brain areas that enable location transfer.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Practice improves discrimination of many basic visual features, such as contrast, orientation, and positional offset [1-7]. Perceptual learning of many of these tasks is found to be retinal location specific, in that learning transfers little to an untrained retinal location [1, 6-8]. In most perceptual learning models, this location specificity is interpreted as a pointer to a retinotopic early visual cortical locus of learning [1, 6-11]. Alternatively, an untested hypothesis is that learning could occur in a central site, but it consists of two separate aspects: learning to discriminate a specific stimulus feature ("feature learning"), and learning to deal with stimulus-nonspecific factors like local noise at the stimulus location ("location learning") [12]. Therefore, learning is not transferable to a new location that has never been location trained. To test this hypothesis, we developed a novel double-training paradigm that employed conventional feature training (e.g., contrast) at one location, and additional training with an irrelevant feature/task (e.g., orientation) at a second location, either simultaneously or at a different time. Our results showed that this additional location training enabled a complete transfer of feature learning (e.g., contrast) to the second location. This finding challenges location specificity and its inferred cortical retinotopy as central concepts to many perceptual-learning models and suggests that perceptual learning involves higher nonretinotopic brain areas that enable location transfer. |
Erik D Reichle; Polina M Vanyukov; Patryk A Laurent; Tessa Warren Serial or parallel? Using depth-of-processing to examine attention allocation during reading Journal Article Vision Research, 48 (17), pp. 1831–1836, 2008, ISSN: 00426989. @article{Reichle2008, title = {Serial or parallel? Using depth-of-processing to examine attention allocation during reading}, author = {Erik D Reichle and Polina M Vanyukov and Patryk A Laurent and Tessa Warren}, doi = {10.1016/j.visres.2008.05.007}, issn = {00426989}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {17}, pages = {1831--1836}, abstract = {This paper presents an experiment investigating attention allocation in four tasks requiring varied degrees of lexical processing of 1-4 simultaneously displayed words. Response times and eye movements were only modestly affected by the number of words in an asterisk-detection task but increased markedly with the number of words in letter-detection, rhyme-judgment, and semantic-judgment tasks, suggesting that attention may not be serial for tasks that do not require significant lexical processing (e.g., detecting visual features), but is approximately serial for tasks that do (e.g., retrieving word meanings). The implications of these results for models of readers' eye movements are discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper presents an experiment investigating attention allocation in four tasks requiring varied degrees of lexical processing of 1-4 simultaneously displayed words. Response times and eye movements were only modestly affected by the number of words in an asterisk-detection task but increased markedly with the number of words in letter-detection, rhyme-judgment, and semantic-judgment tasks, suggesting that attention may not be serial for tasks that do not require significant lexical processing (e.g., detecting visual features), but is approximately serial for tasks that do (e.g., retrieving word meanings). The implications of these results for models of readers' eye movements are discussed. |
Marine Vernet; Qing Yang; Gintautas Daunys; Christophe Orssaud; Thomas Eggert; Zoï Kapoula How the brain obeys Hering's law: A TMS study of the posterior parietal cortex Journal Article Investigative Ophthalmology & Visual Science, 49 (1), pp. 230–237, 2008. @article{Vernet2008, title = {How the brain obeys Hering's law: A TMS study of the posterior parietal cortex}, author = {Marine Vernet and Qing Yang and Gintautas Daunys and Christophe Orssaud and Thomas Eggert and Zo{ï} Kapoula}, doi = {10.1167/iovs.07-0854}, year = {2008}, date = {2008-01-01}, journal = {Investigative Ophthalmology & Visual Science}, volume = {49}, number = {1}, pages = {230--237}, abstract = {PURPOSE: Human ocular saccades are not perfectly yoked; the origin of this disconjugacy (muscular versus central) remains controversial. The purpose of this study was to test a cortical influence on the binocular coordination of saccades. METHODS: The authors used a gap paradigm to elicit vertical or horizontal saccades of 10 degrees , randomly interleaved; transcranial magnetic stimulation (TMS) was applied on the posterior parietal cortex (PPC) 100 ms after the target onset. RESULTS: TMS of the left or right PPC increased (i) the misalignment of the eyes during the presaccadic fixation period; (ii) the size difference between the saccades of the eyes, called disconjugacy; the increase of disconjugacy was significant for rightward and downward saccades after TMS of the right PPC and for downward saccades after TMS of the left PPC. CONCLUSIONS: The authors conclude that the PPC is actively involved in maintaining eye alignment during fixation and in the control of binocular coordination of saccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } PURPOSE: Human ocular saccades are not perfectly yoked; the origin of this disconjugacy (muscular versus central) remains controversial. The purpose of this study was to test a cortical influence on the binocular coordination of saccades. METHODS: The authors used a gap paradigm to elicit vertical or horizontal saccades of 10 degrees , randomly interleaved; transcranial magnetic stimulation (TMS) was applied on the posterior parietal cortex (PPC) 100 ms after the target onset. RESULTS: TMS of the left or right PPC increased (i) the misalignment of the eyes during the presaccadic fixation period; (ii) the size difference between the saccades of the eyes, called disconjugacy; the increase of disconjugacy was significant for rightward and downward saccades after TMS of the right PPC and for downward saccades after TMS of the left PPC. CONCLUSIONS: The authors conclude that the PPC is actively involved in maintaining eye alignment during fixation and in the control of binocular coordination of saccades. |
Mark B Neider; Gregory J Zelinsky Exploring set size effects in scenes: Identifying the objects of search Journal Article Visual Cognition, 16 (1), pp. 1–10, 2008. @article{Neider2008, title = {Exploring set size effects in scenes: Identifying the objects of search}, author = {Mark B Neider and Gregory J Zelinsky}, doi = {10.1080/13506280701381691}, year = {2008}, date = {2008-01-01}, journal = {Visual Cognition}, volume = {16}, number = {1}, pages = {1--10}, abstract = {Traditional search paradigms utilize simple displays, allowing a precise determination of set size. However, objects in realistic scenes are largely uncountable, and typically visually and semantically complex. Can traditional conceptions of set size be applied to search in realistic scenes? Observers searched quasirealistic scenes for a tank target hidden among tree distractors varying in number and density. Search efficiency improved as trees were added to the display, a reverse set size effect. Eye movement analyses revealed that observers fixated individual trees when the set size was small, and the open regions between trees when the set size was large. Rather than a set size consisting of objectively countable objects, we interpret these data as evidence for a restricted functional set size consisting of idiosyncratically defined objects of search. Observers exploit low-level perceptual grouping processes and high-level semantic scene constraints to dynamically create objects that are appropriate to a given search task.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Traditional search paradigms utilize simple displays, allowing a precise determination of set size. However, objects in realistic scenes are largely uncountable, and typically visually and semantically complex. Can traditional conceptions of set size be applied to search in realistic scenes? Observers searched quasirealistic scenes for a tank target hidden among tree distractors varying in number and density. Search efficiency improved as trees were added to the display, a reverse set size effect. Eye movement analyses revealed that observers fixated individual trees when the set size was small, and the open regions between trees when the set size was large. Rather than a set size consisting of objectively countable objects, we interpret these data as evidence for a restricted functional set size consisting of idiosyncratically defined objects of search. Observers exploit low-level perceptual grouping processes and high-level semantic scene constraints to dynamically create objects that are appropriate to a given search task. |
Marine Vernet; Qing Yang; Gintautas Daunys; Christophe Orssaud; Zoï Kapoula TMS of the posterior parietal cortex delays the latency of unpredictable saccades but not when they are combined with predictable divergence Journal Article Brain Research Bulletin, 76 (1-2), pp. 50–56, 2008. @article{Vernet2008a, title = {TMS of the posterior parietal cortex delays the latency of unpredictable saccades but not when they are combined with predictable divergence}, author = {Marine Vernet and Qing Yang and Gintautas Daunys and Christophe Orssaud and Zo{ï} Kapoula}, doi = {10.1016/j.brainresbull.2007.11.007}, year = {2008}, date = {2008-01-01}, journal = {Brain Research Bulletin}, volume = {76}, number = {1-2}, pages = {50--56}, abstract = {This study tests the influence of transcranial magnetic stimulation (TMS) of the posterior parietal cortex (PPC) on the initiation of horizontal and vertical saccades, alone or combined with a predictable divergence. A gap paradigm was used; TMS was applied 100 ms after target onset. TMS of the left PPC increased the latency of unpredictable rightward saccades, while TMS of the right PPC increased the latency of unpredictable downward saccades. Yet, when unpredictable saccades were combined with predictable divergence, neither component was affected. We suggest that in the latter case, the initiation of both components was taken in charge by another area, e.g. frontal. Thus, even when one component was predictable, a common mechanism controls the initiation of both components. The results confirm that TMS only modifies the latency when the cortical area stimulated is involved in the triggering of the eye movement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study tests the influence of transcranial magnetic stimulation (TMS) of the posterior parietal cortex (PPC) on the initiation of horizontal and vertical saccades, alone or combined with a predictable divergence. A gap paradigm was used; TMS was applied 100 ms after target onset. TMS of the left PPC increased the latency of unpredictable rightward saccades, while TMS of the right PPC increased the latency of unpredictable downward saccades. Yet, when unpredictable saccades were combined with predictable divergence, neither component was affected. We suggest that in the latter case, the initiation of both components was taken in charge by another area, e.g. frontal. Thus, even when one component was predictable, a common mechanism controls the initiation of both components. The results confirm that TMS only modifies the latency when the cortical area stimulated is involved in the triggering of the eye movement. |
Marine Vernet; Qing Yang; Gintautas Daunys; Christophe Orssaud; Zoï Kapoula Divergence influences triggering of both vertical and horizontal saccades Journal Article Optometry and Vision Science, 85 (3), pp. 187–195, 2008. @article{Vernet2008b, title = {Divergence influences triggering of both vertical and horizontal saccades}, author = {Marine Vernet and Qing Yang and Gintautas Daunys and Christophe Orssaud and Zo{ï} Kapoula}, doi = {10.1097/OPX.0b013e3181647196}, year = {2008}, date = {2008-01-01}, journal = {Optometry and Vision Science}, volume = {85}, number = {3}, pages = {187--195}, abstract = {Purpose. In real life, divergence is frequently combined with vertical saccades. The purpose of this study was to examine the initiation of vertical and horizontal saccades, pure or combined with divergence. Methods. We used a gap paradigm to elicit vertical or horizontal saccades (10 degrees), pure or combined with a predictable divergence (10 degrees). Eye movements from 12 subjects were recorded with EyeLink II. Results. The major results were (i) when combined with divergence, the latency of horizontal saccades increased but not the latency of vertical saccades; (ii) for both vertical and horizontal saccades, a tight correlation between the latency of saccade and divergence was found; (iii) when the divergence was anticipated, the saccade was delayed. Conclusion. We conclude that the initiation of both components of combined movements is interdependent.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose. In real life, divergence is frequently combined with vertical saccades. The purpose of this study was to examine the initiation of vertical and horizontal saccades, pure or combined with divergence. Methods. We used a gap paradigm to elicit vertical or horizontal saccades (10 degrees), pure or combined with a predictable divergence (10 degrees). Eye movements from 12 subjects were recorded with EyeLink II. Results. The major results were (i) when combined with divergence, the latency of horizontal saccades increased but not the latency of vertical saccades; (ii) for both vertical and horizontal saccades, a tight correlation between the latency of saccade and divergence was found; (iii) when the divergence was anticipated, the saccade was delayed. Conclusion. We conclude that the initiation of both components of combined movements is interdependent. |
Julius Verrel; Harold Bekkering; Bert Steenbergen Eye-hand coordination during manual object transport with the affected and less affected hand in adolescents with hemiparetic cerebral palsy Journal Article Experimental Brain Research, 187 (1), pp. 107–116, 2008. @article{Verrel2008, title = {Eye-hand coordination during manual object transport with the affected and less affected hand in adolescents with hemiparetic cerebral palsy}, author = {Julius Verrel and Harold Bekkering and Bert Steenbergen}, doi = {10.1007/s00221-008-1287-y}, year = {2008}, date = {2008-01-01}, journal = {Experimental Brain Research}, volume = {187}, number = {1}, pages = {107--116}, abstract = {In the present study we investigated eye-hand coordination in adolescents with hemiparetic cerebral palsy (CP) and neurologically healthy controls. Using an object prehension and transport task, we addressed two hypotheses, motivated by the question whether early brain damage and the ensuing limitations of motor activity lead to general and/or effector-specific effects in visuomotor control of manual actions. We hypothesized that individuals with hemiparetic CP would more closely visually monitor actions with their affected hand, compared to both their less affected hand and to control participants without a sensorimotor impairment. A second, more speculative hypothesis was that, in relation to previously established deficits in prospective action control in individuals with hemiparetic CP, gaze patterns might be less anticipatory in general, also during actions performed with the less affected hand. Analysis of the gaze and hand movement data revealed the increased visual monitoring of participants with CP when using their affected hand at the beginning as well as during object transport. In contrast, no general deficit in anticipatory gaze control in the participants with hemiparetic CP could be observed. Collectively, these findings are the first to directly show that individuals with hemiparetic CP adapt eye-hand coordination to the specific constraints of the moving limb, presumably to compensate for sensorimotor deficits.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the present study we investigated eye-hand coordination in adolescents with hemiparetic cerebral palsy (CP) and neurologically healthy controls. Using an object prehension and transport task, we addressed two hypotheses, motivated by the question whether early brain damage and the ensuing limitations of motor activity lead to general and/or effector-specific effects in visuomotor control of manual actions. We hypothesized that individuals with hemiparetic CP would more closely visually monitor actions with their affected hand, compared to both their less affected hand and to control participants without a sensorimotor impairment. A second, more speculative hypothesis was that, in relation to previously established deficits in prospective action control in individuals with hemiparetic CP, gaze patterns might be less anticipatory in general, also during actions performed with the less affected hand. Analysis of the gaze and hand movement data revealed the increased visual monitoring of participants with CP when using their affected hand at the beginning as well as during object transport. In contrast, no general deficit in anticipatory gaze control in the participants with hemiparetic CP could be observed. Collectively, these findings are the first to directly show that individuals with hemiparetic CP adapt eye-hand coordination to the specific constraints of the moving limb, presumably to compensate for sensorimotor deficits. |
Christopher A Dickinson; Helene Intraub Transsaccadic representation of layout: What is the time course of boundary extension? Journal Article Journal of Experimental Psychology: Human Perception and Performance, 34 (3), pp. 543–555, 2008. @article{Dickinson2008, title = {Transsaccadic representation of layout: What is the time course of boundary extension?}, author = {Christopher A Dickinson and Helene Intraub}, doi = {10.1037/0096-1523.34.3.543}, year = {2008}, date = {2008-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {34}, number = {3}, pages = {543--555}, abstract = {How rapidly does boundary extension occur? Across experiments, trials included a 3-scene sequence (325 ms/picture), masked interval, and repetition of 1 scene. The repetition was the same view or differed (more close-up or wide angle). Observers rated the repetition as same as, closer than, or more wide angle than the original view on a 5-point scale. Masked intervals were 100, 250, 625, or 1,000 ms in Experiment 1 and 42, 100, or 250 ms in Experiments 2 and 3. Boundary extension occurred in all cases: Identical views were rated as too "close-up," and distractor views elicited the rating asymmetry typical of boundary extension (wider angle distractors were rated as being more similar to the original than were closer up distractors). Most important, boundary extension was evident when only a 42-ms mask separated the original and test views. Experiments 1 and 3 included conditions eliciting a gaze shift prior to the rating test; this did not eliminate boundary extension. Results show that boundary extension is available soon enough and is robust enough to play an on-line role in view integration, perhaps supporting incorporation of views within a larger spatial framework.}, keywords = {}, pubstate = {published}, tppubtype = {article} } How rapidly does boundary extension occur? Across experiments, trials included a 3-scene sequence (325 ms/picture), masked interval, and repetition of 1 scene. The repetition was the same view or differed (more close-up or wide angle). Observers rated the repetition as same as, closer than, or more wide angle than the original view on a 5-point scale. Masked intervals were 100, 250, 625, or 1,000 ms in Experiment 1 and 42, 100, or 250 ms in Experiments 2 and 3. Boundary extension occurred in all cases: Identical views were rated as too "close-up," and distractor views elicited the rating asymmetry typical of boundary extension (wider angle distractors were rated as being more similar to the original than were closer up distractors). Most important, boundary extension was evident when only a 42-ms mask separated the original and test views. Experiments 1 and 3 included conditions eliciting a gaze shift prior to the rating test; this did not eliminate boundary extension. Results show that boundary extension is available soon enough and is robust enough to play an on-line role in view integration, perhaps supporting incorporation of views within a larger spatial framework. |
Paola Escudero; Rachel Hayes-Harb; Holger Mitterer Novel second-language words and asymmetric lexical access Journal Article Journal of Phonetics, 36 (2), pp. 345–360, 2008. @article{Escudero2008, title = {Novel second-language words and asymmetric lexical access}, author = {Paola Escudero and Rachel Hayes-Harb and Holger Mitterer}, doi = {10.1016/j.wocn.2007.11.002}, year = {2008}, date = {2008-01-01}, journal = {Journal of Phonetics}, volume = {36}, number = {2}, pages = {345--360}, abstract = {The lexical and phonetic mapping of auditorily confusable L2 nonwords was examined by teaching L2 learners novel words and by later examining their word recognition using an eye-tracking paradigm. During word learning, two groups of highly proficient Dutch learners of English learned 20 English nonwords, of which 10 contained the English contrast /$epsilon$/-æ/ (a confusable contrast for native Dutch speakers). One group of subjects learned the words by matching their auditory forms to pictured meanings, while a second group additionally saw the spelled forms of the words. We found that the group who received only auditory forms confused words containing /æ/ and /$epsilon$/ symmetrically, i.e., both /æ/ and /$epsilon$/ auditory tokens triggered looks to pictures containing both /æ/ and /$epsilon$/. In contrast, the group who also had access to spelled forms showed the same asymmetric word recognition pattern found by previous studies, i.e., they only looked at pictures of words containing /$epsilon$/ when presented with /$epsilon$/ target tokens, but looked at pictures of words containing both /æ/ and /$epsilon$/ when presented with /æ/ target tokens. The results demonstrate that L2 learners can form lexical contrasts for auditorily confusable novel L2 words. However, and most importantly, this study suggests that explicit information over the contrastive nature of two new sounds may be needed to build separate lexical representations for similar-sounding L2 words.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lexical and phonetic mapping of auditorily confusable L2 nonwords was examined by teaching L2 learners novel words and by later examining their word recognition using an eye-tracking paradigm. During word learning, two groups of highly proficient Dutch learners of English learned 20 English nonwords, of which 10 contained the English contrast /$epsilon$/-æ/ (a confusable contrast for native Dutch speakers). One group of subjects learned the words by matching their auditory forms to pictured meanings, while a second group additionally saw the spelled forms of the words. We found that the group who received only auditory forms confused words containing /æ/ and /$epsilon$/ symmetrically, i.e., both /æ/ and /$epsilon$/ auditory tokens triggered looks to pictures containing both /æ/ and /$epsilon$/. In contrast, the group who also had access to spelled forms showed the same asymmetric word recognition pattern found by previous studies, i.e., they only looked at pictures of words containing /$epsilon$/ when presented with /$epsilon$/ target tokens, but looked at pictures of words containing both /æ/ and /$epsilon$/ when presented with /æ/ target tokens. The results demonstrate that L2 learners can form lexical contrasts for auditorily confusable novel L2 words. However, and most importantly, this study suggests that explicit information over the contrastive nature of two new sounds may be needed to build separate lexical representations for similar-sounding L2 words. |
Dale J Barr Pragmatic expectations and linguistic evidence: Listeners anticipate but do not integrate common ground Journal Article Cognition, 109 (1), pp. 18–40, 2008. @article{Barr2008, title = {Pragmatic expectations and linguistic evidence: Listeners anticipate but do not integrate common ground}, author = {Dale J Barr}, doi = {10.1016/j.cognition.2008.07.005}, year = {2008}, date = {2008-01-01}, journal = {Cognition}, volume = {109}, number = {1}, pages = {18--40}, publisher = {Elsevier B.V.}, abstract = {When listeners search for the referent of a speaker's expression, they experience interference from privileged knowledge, knowledge outside of their 'common ground' with the speaker. Evidence is presented that this interference reflects limitations in lexical processing. In three experiments, listeners' eye movements were monitored as they searched for the target of a speaker's referring expression in a display that also contained a phonological competitor (e.g., bucket/buckle). Listeners anticipated that the speaker would refer to something in common ground, but they did not experience less interference from a competitor in privileged ground than from a matched competitor in common ground. In contrast, interference from the competitor was eliminated when it was ruled out by a semantic constraint. These findings support a view of comprehension as relying on multiple systems with distinct access to information and present a challenge for constraint-based views of common ground.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When listeners search for the referent of a speaker's expression, they experience interference from privileged knowledge, knowledge outside of their 'common ground' with the speaker. Evidence is presented that this interference reflects limitations in lexical processing. In three experiments, listeners' eye movements were monitored as they searched for the target of a speaker's referring expression in a display that also contained a phonological competitor (e.g., bucket/buckle). Listeners anticipated that the speaker would refer to something in common ground, but they did not experience less interference from a competitor in privileged ground than from a matched competitor in common ground. In contrast, interference from the competitor was eliminated when it was ruled out by a semantic constraint. These findings support a view of comprehension as relying on multiple systems with distinct access to information and present a challenge for constraint-based views of common ground. |
Don C Mitchell; Xingjia Shen; Matthew J Green; Timothy L Hodgson Accounting for regressive eye-movements in models of sentence processing: A reappraisal of the Selective Reanalysis hypothesis Journal Article Journal of Memory and Language, 59 (3), pp. 266–293, 2008. @article{Mitchell2008, title = {Accounting for regressive eye-movements in models of sentence processing: A reappraisal of the Selective Reanalysis hypothesis}, author = {Don C Mitchell and Xingjia Shen and Matthew J Green and Timothy L Hodgson}, doi = {10.1016/j.jml.2008.06.002}, year = {2008}, date = {2008-01-01}, journal = {Journal of Memory and Language}, volume = {59}, number = {3}, pages = {266--293}, abstract = {When people read temporarily ambiguous sentences, there is often an increased prevalence of regressive eye-movements launched from the word that resolves the ambiguity. Traditionally, such regressions have been interpreted at least in part as reflecting readers' efforts to re-read and reconfigure earlier material, as exemplified by the Selective Reanalysis hypothesis [Frazier, L., & Rayner, K. (1982). Making and correcting errors during sentence comprehension: Eye movements in the analysis of structurally ambiguous sentences. Cognitive Psychology, 14, 178-210]. Within such frameworks it is assumed that the selection of saccadic landing-sites is linguistically supervised. As an alternative to this proposal, we consider the possibility (dubbed the Time Out hypothesis) that regression control is partly decoupled from linguistic operations and that landing-sites are instead selected on the basis of low-level spatial properties such as their proximity to the point from which the regressive saccade was launched. Two eye-tracking experiments were conducted to compare the explanatory potential of these two accounts. Experiment 1 manipulated the formatting of linguistically identical sentences and showed, contrary to purely linguistic supervision, that the landing site of the first regression from a critical word was reliably influenced by the physical layout of the text. Experiment 2 used a fixed physical format but manipulated the position in the display at which reanalysis-relevant material was located. Here the results showed a highly reliable linguistic influence on the overall distribution of regression landing sites (though with few effects being apparent on the very first regression). These results are interpreted as reflecting mutually exclusive forms of regression control with fixation sequences being influenced both by spatially constrained, partially decoupled supervision systems as well as by some kind of linguistic guidance. The findings are discussed in relation to existing computational models of eye-movements in reading.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When people read temporarily ambiguous sentences, there is often an increased prevalence of regressive eye-movements launched from the word that resolves the ambiguity. Traditionally, such regressions have been interpreted at least in part as reflecting readers' efforts to re-read and reconfigure earlier material, as exemplified by the Selective Reanalysis hypothesis [Frazier, L., & Rayner, K. (1982). Making and correcting errors during sentence comprehension: Eye movements in the analysis of structurally ambiguous sentences. Cognitive Psychology, 14, 178-210]. Within such frameworks it is assumed that the selection of saccadic landing-sites is linguistically supervised. As an alternative to this proposal, we consider the possibility (dubbed the Time Out hypothesis) that regression control is partly decoupled from linguistic operations and that landing-sites are instead selected on the basis of low-level spatial properties such as their proximity to the point from which the regressive saccade was launched. Two eye-tracking experiments were conducted to compare the explanatory potential of these two accounts. Experiment 1 manipulated the formatting of linguistically identical sentences and showed, contrary to purely linguistic supervision, that the landing site of the first regression from a critical word was reliably influenced by the physical layout of the text. Experiment 2 used a fixed physical format but manipulated the position in the display at which reanalysis-relevant material was located. Here the results showed a highly reliable linguistic influence on the overall distribution of regression landing sites (though with few effects being apparent on the very first regression). These results are interpreted as reflecting mutually exclusive forms of regression control with fixation sequences being influenced both by spatially constrained, partially decoupled supervision systems as well as by some kind of linguistic guidance. The findings are discussed in relation to existing computational models of eye-movements in reading. |
Steven Frisson; Brian McElree Complement coercion is not modulated by competition: Evidence from eye movements Journal Article Journal of Experimental Psychology: Learning, Memory, and Cognition, 34 (1), pp. 1–11, 2008. @article{Frisson2008a, title = {Complement coercion is not modulated by competition: Evidence from eye movements}, author = {Steven Frisson and Brian McElree}, doi = {10.1037/0278-7393.34.1.1}, year = {2008}, date = {2008-01-01}, journal = {Journal of Experimental Psychology: Learning, Memory, and Cognition}, volume = {34}, number = {1}, pages = {1--11}, abstract = {An eye-movement study examined the processing of expressions requiring complement coercion (J. Pustejovsky, 1995), in which a noun phrase that does not denote an event (e.g., the book) appears as the complement of an event-selecting verb (e.g., began the book). Previous studies demonstrated that these expressions are more costly to process than are control expressions that can be processed with basic compositional operations (L. Pylkka ̈nen & B. McElree, 2006). Complement coercion is thought to be costly because comprehenders need to construct an event sense of the complement to satisfy the semantic restrictions of the verb (e.g., began writing the book). The reported experiment tests the alternative hypotheses that the cost arises from the need to select 1 interpretation from several or from competition between alternative interpretations. Expressions with weakly constrained interpretations (no dominant interpretation and several alternative interpretations) were not more costly to process than expressions with a strongly constrained interpretation (1 dominant interpretation and few alternative interpretations). These results are consistent with the hypothesis that the cost reflects the on-line construction of an event sense for the complement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } An eye-movement study examined the processing of expressions requiring complement coercion (J. Pustejovsky, 1995), in which a noun phrase that does not denote an event (e.g., the book) appears as the complement of an event-selecting verb (e.g., began the book). Previous studies demonstrated that these expressions are more costly to process than are control expressions that can be processed with basic compositional operations (L. Pylkka ̈nen & B. McElree, 2006). Complement coercion is thought to be costly because comprehenders need to construct an event sense of the complement to satisfy the semantic restrictions of the verb (e.g., began writing the book). The reported experiment tests the alternative hypotheses that the cost arises from the need to select 1 interpretation from several or from competition between alternative interpretations. Expressions with weakly constrained interpretations (no dominant interpretation and several alternative interpretations) were not more costly to process than expressions with a strongly constrained interpretation (1 dominant interpretation and few alternative interpretations). These results are consistent with the hypothesis that the cost reflects the on-line construction of an event sense for the complement. |
Linus Holm; Johan Eriksson; Linus Andersson Looking as if you know: Systematic object inspection precedes object recognition Journal Article Journal of Vision, 8 (4), pp. 1–7, 2008. @article{Holm2008, title = {Looking as if you know: Systematic object inspection precedes object recognition}, author = {Linus Holm and Johan Eriksson and Linus Andersson}, doi = {10.1167/8.4.14}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {4}, pages = {1--7}, abstract = {Sometimes we seem to look at the very object we are searching for, without consciously seeing it. How do we select object relevant information before we become aware of the object? We addressed this question in two recognition experiments involving pictures of fragmented objects. In Experiment 1, participants preferred to look at the target object rather than a control region 25 fixations prior to explicit recognition. Furthermore, participants inspected the target as if they had identified it around 9 fixations prior to explicit recognition. In Experiment 2, we investigated the influence of semantic knowledge in guiding object inspection prior to explicit recognition. Consistently, more specific knowledge about target identity made participants scan the fragmented stimulus more efficiently. For instance, non-target regions were rejected faster when participants knew the target object's name. Both experiments showed that participants were looking at the objects as if they knew them before they became aware of their identity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sometimes we seem to look at the very object we are searching for, without consciously seeing it. How do we select object relevant information before we become aware of the object? We addressed this question in two recognition experiments involving pictures of fragmented objects. In Experiment 1, participants preferred to look at the target object rather than a control region 25 fixations prior to explicit recognition. Furthermore, participants inspected the target as if they had identified it around 9 fixations prior to explicit recognition. In Experiment 2, we investigated the influence of semantic knowledge in guiding object inspection prior to explicit recognition. Consistently, more specific knowledge about target identity made participants scan the fragmented stimulus more efficiently. For instance, non-target regions were rejected faster when participants knew the target object's name. Both experiments showed that participants were looking at the objects as if they knew them before they became aware of their identity. |
Xiaochuan Pan; Kosuke Sawa; Ichiro Tsuda; Minoru Tsukada; Masamichi Sakagami Reward prediction based on stimulus categorization in primate lateral prefrontal cortex Journal Article Nature Neuroscience, 11 (6), pp. 703–712, 2008. @article{Pan2008, title = {Reward prediction based on stimulus categorization in primate lateral prefrontal cortex}, author = {Xiaochuan Pan and Kosuke Sawa and Ichiro Tsuda and Minoru Tsukada and Masamichi Sakagami}, doi = {10.1038/nn.2128}, year = {2008}, date = {2008-01-01}, journal = {Nature Neuroscience}, volume = {11}, number = {6}, pages = {703--712}, abstract = {To adapt to changeable or unfamiliar environments, it is important that animals develop strategies for goal-directed behaviors that meet the new challenges. We used a sequential paired-association task with asymmetric reward schedule to investigate how prefrontal neurons integrate multiple already-acquired associations to predict reward. Two types of reward-related neurons were observed in the lateral prefrontal cortex: one type predicted reward independent of physical properties of visual stimuli and the other encoded the reward value specific to a category of stimuli defined by the task requirements. Neurons of the latter type were able to predict reward on the basis of stimuli that had not yet been associated with reward, provided that another stimulus from the same category was paired with reward. The results suggest that prefrontal neurons can represent reward information on the basis of category and propagate this information to category members that have not been linked directly with any experience of reward.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To adapt to changeable or unfamiliar environments, it is important that animals develop strategies for goal-directed behaviors that meet the new challenges. We used a sequential paired-association task with asymmetric reward schedule to investigate how prefrontal neurons integrate multiple already-acquired associations to predict reward. Two types of reward-related neurons were observed in the lateral prefrontal cortex: one type predicted reward independent of physical properties of visual stimuli and the other encoded the reward value specific to a category of stimuli defined by the task requirements. Neurons of the latter type were able to predict reward on the basis of stimuli that had not yet been associated with reward, provided that another stimulus from the same category was paired with reward. The results suggest that prefrontal neurons can represent reward information on the basis of category and propagate this information to category members that have not been linked directly with any experience of reward. |
Steven Frisson; Elizabeth Niswander-Klement; Alexander Pollatsek The role of semantic transparency in the processing of English compound words Journal Article British Journal of Psychology, 99 (1), pp. 87–107, 2008. @article{Frisson2008b, title = {The role of semantic transparency in the processing of English compound words}, author = {Steven Frisson and Elizabeth Niswander-Klement and Alexander Pollatsek}, doi = {10.1348/000712607X181304}, year = {2008}, date = {2008-01-01}, journal = {British Journal of Psychology}, volume = {99}, number = {1}, pages = {87--107}, abstract = {Experiment 1 examined whether the semantic transparency of an English unspaced compound word affected how long it took to process it in reading. Three types of opaque words were each compared with a matched set of transparent words (i.e. matched on the length and frequency of the constituents and the frequency of the word as a whole). Two sets of the opaque words were partially opaque: either the first constituent was not related to the meaning of the compound (opaque-transparent) or the second constituent was not related to the meaning of the compound (transparent-opaque). In the third set (opaque-opaque), neither constituent was related to the meaning of the compound. For all three sets, there was no significant difference between the opaque and the transparent words on any eye-movement measure. This replicates an earlier finding with Finnish compound words (Pollatsek & Hyönä, 2005) and indicates that, although there is now abundant evidence that the component constituents play a role in the encoding of compound words, the meaning of the compound word is not constructed from the parts, at least for compound words for which a lexical entry exists. Experiment 2 used the same compounds but with a space between the constituents. This presentation resulted in a transparency effect, indicating that when an assembly route is 'forced', transparency does play a role.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Experiment 1 examined whether the semantic transparency of an English unspaced compound word affected how long it took to process it in reading. Three types of opaque words were each compared with a matched set of transparent words (i.e. matched on the length and frequency of the constituents and the frequency of the word as a whole). Two sets of the opaque words were partially opaque: either the first constituent was not related to the meaning of the compound (opaque-transparent) or the second constituent was not related to the meaning of the compound (transparent-opaque). In the third set (opaque-opaque), neither constituent was related to the meaning of the compound. For all three sets, there was no significant difference between the opaque and the transparent words on any eye-movement measure. This replicates an earlier finding with Finnish compound words (Pollatsek & Hyönä, 2005) and indicates that, although there is now abundant evidence that the component constituents play a role in the encoding of compound words, the meaning of the compound word is not constructed from the parts, at least for compound words for which a lexical entry exists. Experiment 2 used the same compounds but with a space between the constituents. This presentation resulted in a transparency effect, indicating that when an assembly route is 'forced', transparency does play a role. |
Adele Diederich; Hans Colonius Crossmodal interaction in saccadic reaction time: Separating multisensory from warning effects in the time window of integration model Journal Article Experimental Brain Research, 186 (1), pp. 1–22, 2008. @article{Diederich2008, title = {Crossmodal interaction in saccadic reaction time: Separating multisensory from warning effects in the time window of integration model}, author = {Adele Diederich and Hans Colonius}, doi = {10.1007/s00221-007-1197-4}, year = {2008}, date = {2008-01-01}, journal = {Experimental Brain Research}, volume = {186}, number = {1}, pages = {1--22}, abstract = {In a focused attention task saccadic reaction time (SRT) to a visual target stimulus (LED) was measured with an auditory (white noise burst) or tactile (vibration applied to palm) non-target presented in ipsi- or contralateral position to the target. Crossmodal facilitation of SRT was observed under all configurations and stimulus onset asynchrony (SOA) values ranging from -500 (non-target prior to target) to 0 ms, but the effect was larger for ipsi- than for contralateral presentation within an SOA range from -200 ms to 0. The time-window-of-integration (TWIN) model (Colonius and Diederich in J Cogn Neurosci 16:1000, 2004) is extended here to separate the effect of a spatially unspecific warning effect of the non-target from a spatially specific and genuine multisensory integration effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In a focused attention task saccadic reaction time (SRT) to a visual target stimulus (LED) was measured with an auditory (white noise burst) or tactile (vibration applied to palm) non-target presented in ipsi- or contralateral position to the target. Crossmodal facilitation of SRT was observed under all configurations and stimulus onset asynchrony (SOA) values ranging from -500 (non-target prior to target) to 0 ms, but the effect was larger for ipsi- than for contralateral presentation within an SOA range from -200 ms to 0. The time-window-of-integration (TWIN) model (Colonius and Diederich in J Cogn Neurosci 16:1000, 2004) is extended here to separate the effect of a spatially unspecific warning effect of the non-target from a spatially specific and genuine multisensory integration effect. |
Ian Cunnings; Harald Clahsen The time-course of morphological constraints: A study of plurals inside derived words Journal Article The Mental Lexicon, 3 (2), pp. 149–175, 2008. @article{Cunnings2008, title = {The time-course of morphological constraints: A study of plurals inside derived words}, author = {Ian Cunnings and Harald Clahsen}, doi = {10.1075/ml.3.2.01cun}, year = {2008}, date = {2008-01-01}, journal = {The Mental Lexicon}, volume = {3}, number = {2}, pages = {149--175}, abstract = {The avoidance of regular but not irregular plurals inside compounds (e.g., *rats eater vs. mice eater) has been one of the most widely studied morphological phenomena in the psycholinguistics literature. To examine whether the constraints that are responsible for this contrast have any general significance beyond compounding, we investigated derived word forms containing regular and irregular plurals in two experiments. Experiment 1 was an offline acceptability judgment task, and Experiment 2 measured eye movements during reading derived words containing regular and irregular plurals and uninflected base nouns. The results from both experiments show that the constraint against regular plurals inside compounds generalizes to derived words. We argue that this constraint cannot be reduced to phonological properties, but is instead morphological in nature. The eye-movement data provide detailed information on the time-course of processing derived word forms indicating that early stages of processing are affected by a general constraint that disallows inflected words from feeding derivational processes, and that the more specific constraint against regular plurals comes in at a subsequent later stage of processing. We argue that these results are consistent with stage-based models of language processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The avoidance of regular but not irregular plurals inside compounds (e.g., *rats eater vs. mice eater) has been one of the most widely studied morphological phenomena in the psycholinguistics literature. To examine whether the constraints that are responsible for this contrast have any general significance beyond compounding, we investigated derived word forms containing regular and irregular plurals in two experiments. Experiment 1 was an offline acceptability judgment task, and Experiment 2 measured eye movements during reading derived words containing regular and irregular plurals and uninflected base nouns. The results from both experiments show that the constraint against regular plurals inside compounds generalizes to derived words. We argue that this constraint cannot be reduced to phonological properties, but is instead morphological in nature. The eye-movement data provide detailed information on the time-course of processing derived word forms indicating that early stages of processing are affected by a general constraint that disallows inflected words from feeding derivational processes, and that the more specific constraint against regular plurals comes in at a subsequent later stage of processing. We argue that these results are consistent with stage-based models of language processing. |
Lizzy Bleumers; Peter De Graef; Karl Verfaillie; Johan Wagemans Eccentric grouping by proximity in multistable dot lattices Journal Article Vision Research, 48 (2), pp. 179–192, 2008. @article{Bleumers2008, title = {Eccentric grouping by proximity in multistable dot lattices}, author = {Lizzy Bleumers and Peter {De Graef} and Karl Verfaillie and Johan Wagemans}, doi = {10.1016/j.visres.2007.10.024}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {2}, pages = {179--192}, abstract = {The Pure Distance Law predicts grouping by proximity in dot lattices that can be organised in four ways by grouping dots along parallel lines. It specifies a quantitative relationship between the relative probability of perceiving an organisation and the relative distance between the grouped dots. The current study was set up to investigate whether this principle holds both for centrally and for eccentrically displayed dot lattices. To this end, dot lattices were displayed either in central vision, or to the right of fixation with their closest border at 3° or 15°. We found that the Pure Distance Law adequately predicted grouping of centrally displayed dot lattices but did not capture the eccentric data well, even when the eccentric dot lattices were scaled. Specifically, a better fit was obtained when we included the possibility in the model that in some trials participants could not report an organisation and consequently responded randomly. A plausible interpretation for the occurrence of random responses in the eccentric conditions is that under these circumstances an attention shift is required from the locus of fixation towards the dot lattice, which occasionally fails to take place. When grouping could be reported, scale and eccentricity appeared to interact. The effect of the relative interdot distances on the perceptual organisation of the dot lattices was estimated to be stronger in peripheral vision than in central vision at the two largest scales, but this difference disappeared when the smallest scale was applied.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Pure Distance Law predicts grouping by proximity in dot lattices that can be organised in four ways by grouping dots along parallel lines. It specifies a quantitative relationship between the relative probability of perceiving an organisation and the relative distance between the grouped dots. The current study was set up to investigate whether this principle holds both for centrally and for eccentrically displayed dot lattices. To this end, dot lattices were displayed either in central vision, or to the right of fixation with their closest border at 3° or 15°. We found that the Pure Distance Law adequately predicted grouping of centrally displayed dot lattices but did not capture the eccentric data well, even when the eccentric dot lattices were scaled. Specifically, a better fit was obtained when we included the possibility in the model that in some trials participants could not report an organisation and consequently responded randomly. A plausible interpretation for the occurrence of random responses in the eccentric conditions is that under these circumstances an attention shift is required from the locus of fixation towards the dot lattice, which occasionally fails to take place. When grouping could be reported, scale and eccentricity appeared to interact. The effect of the relative interdot distances on the perceptual organisation of the dot lattices was estimated to be stronger in peripheral vision than in central vision at the two largest scales, but this difference disappeared when the smallest scale was applied. |
Adele Diederich; Hans Colonius; Adele Diederich Brain Research, 1242 , pp. 219–230, 2008. @article{Diederich2008a, title = {When a high-intensity "distractor" is better then a low-intensity one: Modeling the effect of an auditory or tactile nontarget stimulus on visual saccadic reaction time}, author = {Adele Diederich and Hans Colonius and Adele Diederich}, doi = {10.1016/j.brainres.2008.05.081}, year = {2008}, date = {2008-01-01}, journal = {Brain Research}, volume = {1242}, pages = {219--230}, publisher = {Elsevier B.V.}, abstract = {In a focused attention task saccadic reaction time (SRT) to a visual target stimulus (LED) was measured with an auditory (white noise burst) or tactile (vibration applied to palm) nontarget presented in ipsi- or contralateral position to the target. Crossmodal facilitation of SRT was observed under all configurations and stimulus onset asynchrony (SOA) values ranging from - 250 ms (nontarget prior to target) to 50 ms. This study specifically addressed the effect of varying nontarget intensity. While facilitation effects for auditory nontargets are somewhat more pronounced than for tactile ones, decreasing intensity slightly reduced facilitation for both types of nontargets. The time course of crossmodal mean SRT over SOA and the pattern of facilitation observed here suggest the existence of two distinct underlying mechanisms: (a) a spatially unspecific crossmodal warning triggered by the nontarget being detected early enough before the arrival of the target plus (b) a spatially specific multisensory integration mechanism triggered by the target processing time terminating within the time window of integration. It is shown that the time window of integration (TWIN) model introduced by the authors gives a reasonable quantitative account of the data relating observed SRT to the unobservable probability of integration and crossmodal warning for each SOA value under a high and low intensity level of the nontarget.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In a focused attention task saccadic reaction time (SRT) to a visual target stimulus (LED) was measured with an auditory (white noise burst) or tactile (vibration applied to palm) nontarget presented in ipsi- or contralateral position to the target. Crossmodal facilitation of SRT was observed under all configurations and stimulus onset asynchrony (SOA) values ranging from - 250 ms (nontarget prior to target) to 50 ms. This study specifically addressed the effect of varying nontarget intensity. While facilitation effects for auditory nontargets are somewhat more pronounced than for tactile ones, decreasing intensity slightly reduced facilitation for both types of nontargets. The time course of crossmodal mean SRT over SOA and the pattern of facilitation observed here suggest the existence of two distinct underlying mechanisms: (a) a spatially unspecific crossmodal warning triggered by the nontarget being detected early enough before the arrival of the target plus (b) a spatially specific multisensory integration mechanism triggered by the target processing time terminating within the time window of integration. It is shown that the time window of integration (TWIN) model introduced by the authors gives a reasonable quantitative account of the data relating observed SRT to the unobservable probability of integration and crossmodal warning for each SOA value under a high and low intensity level of the nontarget. |
Luke Barrington; Tim K Marks; Janet Hui-wen Hsiao; Garrison W Cottrell NIMBLE: A kernel density model of saccade-based visual memory Journal Article Journal of Vision, 8 (14), pp. 17–17, 2008. @article{Barrington2008, title = {NIMBLE: A kernel density model of saccade-based visual memory}, author = {Luke Barrington and Tim K Marks and Janet {Hui-wen Hsiao} and Garrison W Cottrell}, doi = {10.1167/8.14.17}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {17--17}, abstract = {We present a Bayesian version of J. Lacroix, J. Murre, and E. Postma's (2006) Natural Input Memory (NIM) model of saccadic visual memory. Our model, which we call NIMBLE (NIM with Bayesian Likelihood Estimation), uses a cognitively plausible image sampling technique that provides a foveated representation of image patches. We conceive of these memorized image fragments as samples from image class distributions and model the memory of these fragments using kernel density estimation. Using these models, we derive class-conditional probabilities of new image fragments and combine individual fragment probabilities to classify images. Our Bayesian formulation of the model extends easily to handle multi-class problems. We validate our model by demonstrating human levels of performance on a face recognition memory task and high accuracy on multi-category face and object identification. We also use NIMBLE to examine the change in beliefs as more fixations are taken from an image. Using fixation data collected from human subjects, we directly compare the performance of NIMBLE's memory component to human performance, demonstrating that using human fixation locations allows NIMBLE to recognize familiar faces with only a single fixation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a Bayesian version of J. Lacroix, J. Murre, and E. Postma's (2006) Natural Input Memory (NIM) model of saccadic visual memory. Our model, which we call NIMBLE (NIM with Bayesian Likelihood Estimation), uses a cognitively plausible image sampling technique that provides a foveated representation of image patches. We conceive of these memorized image fragments as samples from image class distributions and model the memory of these fragments using kernel density estimation. Using these models, we derive class-conditional probabilities of new image fragments and combine individual fragment probabilities to classify images. Our Bayesian formulation of the model extends easily to handle multi-class problems. We validate our model by demonstrating human levels of performance on a face recognition memory task and high accuracy on multi-category face and object identification. We also use NIMBLE to examine the change in beliefs as more fixations are taken from an image. Using fixation data collected from human subjects, we directly compare the performance of NIMBLE's memory component to human performance, demonstrating that using human fixation locations allows NIMBLE to recognize familiar faces with only a single fixation. |
Adele Diederich; Hans Colonius; Annette Schomburg Assessing age-related multisensory enhancement with the time-window-of-integration model Journal Article Neuropsychologia, 46 (10), pp. 2556–2562, 2008. @article{Diederich2008b, title = {Assessing age-related multisensory enhancement with the time-window-of-integration model}, author = {Adele Diederich and Hans Colonius and Annette Schomburg}, doi = {10.1016/j.neuropsychologia.2008.03.026}, year = {2008}, date = {2008-01-01}, journal = {Neuropsychologia}, volume = {46}, number = {10}, pages = {2556--2562}, abstract = {Although from multisensory research a great deal is known about how the different senses interact, there is little knowledge as to the impact of aging on these multisensory processes. In this study, we measured saccadic reaction time (SRT) of aged and young individuals to the onset of a visual target stimulus with and without an accessory auditory stimulus occurring (focused attention task). The response time pattern for both groups was similar: mean SRT to bimodal stimuli was generally shorter than to unimodal stimuli, and mean bimodal SRT was shorter when the auditory accessory was presented ipsilaterally rather than contralaterally to the target. The elderly participants were considerably slower than the younger participants under all conditions but showed a greater multisensory enhancement, that is, they seem to benefit more from bimodal stimulus presentation. In an attempt to weigh the contributions of peripheral sensory processes relative to more central cognitive processes possibly responsible for the difference in the younger and older adults, the time-window-of-integration (TWIN) model for crossmodal interaction in saccadic eye movements developed by the authors was fitted to the data from both groups. The model parameters suggest that (i) there is a slowing of the peripheral sensory processing in the elderly, (ii) as a result of this slowing, the probability of integration is smaller in the elderly even with a wider time-window-of-integration, and (iii) multisensory integration, if it occurs, manifests itself in larger neural enhancement in the elderly; however, because of (ii), on average the integration effect is not large enough to compensate for the peripheral slowing in the elderly.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although from multisensory research a great deal is known about how the different senses interact, there is little knowledge as to the impact of aging on these multisensory processes. In this study, we measured saccadic reaction time (SRT) of aged and young individuals to the onset of a visual target stimulus with and without an accessory auditory stimulus occurring (focused attention task). The response time pattern for both groups was similar: mean SRT to bimodal stimuli was generally shorter than to unimodal stimuli, and mean bimodal SRT was shorter when the auditory accessory was presented ipsilaterally rather than contralaterally to the target. The elderly participants were considerably slower than the younger participants under all conditions but showed a greater multisensory enhancement, that is, they seem to benefit more from bimodal stimulus presentation. In an attempt to weigh the contributions of peripheral sensory processes relative to more central cognitive processes possibly responsible for the difference in the younger and older adults, the time-window-of-integration (TWIN) model for crossmodal interaction in saccadic eye movements developed by the authors was fitted to the data from both groups. The model parameters suggest that (i) there is a slowing of the peripheral sensory processing in the elderly, (ii) as a result of this slowing, the probability of integration is smaller in the elderly even with a wider time-window-of-integration, and (iii) multisensory integration, if it occurs, manifests itself in larger neural enhancement in the elderly; however, because of (ii), on average the integration effect is not large enough to compensate for the peripheral slowing in the elderly. |
Elliot L Hong; Kathleen A Turano; Hugh B O'Neill; Lei Hao; Ikwunga Wonodi; Robert P McMahon; Amie Elliott; Gunvant K Thaker Refining the predictive pursuit endophenotype in schizophrenia. Journal Article Biological Psychiatry, 63 (5), pp. 458–464, 2008. @article{Hong2008, title = {Refining the predictive pursuit endophenotype in schizophrenia.}, author = {Elliot L Hong and Kathleen A Turano and Hugh B O'Neill and Lei Hao and Ikwunga Wonodi and Robert P McMahon and Amie Elliott and Gunvant K Thaker}, doi = {10.1016/j.biopsych.2007.06.004}, year = {2008}, date = {2008-01-01}, journal = {Biological Psychiatry}, volume = {63}, number = {5}, pages = {458--464}, abstract = {Background: To utilize fully a schizophrenia endophenotype in gene search and subsequent neurobiological studies, it is critical that the precise underlying physiologic deficit is identified. Abnormality in smooth pursuit eye movements is one of the endophenotypes of schizophrenia. The precise nature of the abnormality is unknown. Previous work has shown a reduced predictive pursuit response to a briefly masked (i.e., invisible) moving object in schizophrenia. However, the overt awareness of target removal can confound the measurement. Methods: This study employed a novel method that covertly stabilized the moving target image onto the fovea. The foveal stabilization was implemented after the target on a monitor had oscillated at least for one cycle and near the change of direction when the eye velocity momentarily reached zero. Thus, the subsequent pursuit eye movements were completely predictive and internally driven. Eye velocity during this foveally stabilized smooth pursuit was compared among schizophrenia patients (n = 45), their unaffected first-degree relatives (n = 42), and healthy comparison subjects (n = 22). Results: Schizophrenia patients and their unaffected relatives performed similarly and both had substantially reduced predictive pursuit acceleration and velocity under the foveally stabilized condition. Conclusions: These findings show that inability to maintain internal representation of the target motion or integration of such information into a predictive response may be the specific brain deficit indexed by the smooth pursuit endophenotype in schizophrenia. Similar performance between patients and unaffected relatives suggests that the refined predictive pursuit measure may index a less complex genetic origin of the eye-tracking deficits in schizophrenia families.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: To utilize fully a schizophrenia endophenotype in gene search and subsequent neurobiological studies, it is critical that the precise underlying physiologic deficit is identified. Abnormality in smooth pursuit eye movements is one of the endophenotypes of schizophrenia. The precise nature of the abnormality is unknown. Previous work has shown a reduced predictive pursuit response to a briefly masked (i.e., invisible) moving object in schizophrenia. However, the overt awareness of target removal can confound the measurement. Methods: This study employed a novel method that covertly stabilized the moving target image onto the fovea. The foveal stabilization was implemented after the target on a monitor had oscillated at least for one cycle and near the change of direction when the eye velocity momentarily reached zero. Thus, the subsequent pursuit eye movements were completely predictive and internally driven. Eye velocity during this foveally stabilized smooth pursuit was compared among schizophrenia patients (n = 45), their unaffected first-degree relatives (n = 42), and healthy comparison subjects (n = 22). Results: Schizophrenia patients and their unaffected relatives performed similarly and both had substantially reduced predictive pursuit acceleration and velocity under the foveally stabilized condition. Conclusions: These findings show that inability to maintain internal representation of the target motion or integration of such information into a predictive response may be the specific brain deficit indexed by the smooth pursuit endophenotype in schizophrenia. Similar performance between patients and unaffected relatives suggests that the refined predictive pursuit measure may index a less complex genetic origin of the eye-tracking deficits in schizophrenia families. |
Sebastian Pannasch; Jens R Helmert; Katharina Roth; Ann-Katrin Herbold; Henrik Walter Visual fixation durations and saccade amplitudes: Shifting relationship in a variety of conditions Journal Article Journal of Eye Movement Research, 2 (2), pp. 1–19, 2008. @article{Pannasch2008, title = {Visual fixation durations and saccade amplitudes: Shifting relationship in a variety of conditions}, author = {Sebastian Pannasch and Jens R Helmert and Katharina Roth and Ann-Katrin Herbold and Henrik Walter}, doi = {10.16910/jemr.2.2.4}, year = {2008}, date = {2008-01-01}, journal = {Journal of Eye Movement Research}, volume = {2}, number = {2}, pages = {1--19}, abstract = {Is there any relationship between visual fixation durations and saccade amplitudes in free exploration of pictures and scenes? In four experiments with naturalistic stimuli, we compared eye movements during early and late phases of scene perception. Influences of repeated presentation of similar stimuli (Experiment 1), object density (Experiment 2), emotional stimuli (Experiment 3) and mood induction (Experiment 4) were examined. The results demonstrate a systematic increase in the durations of fixations and a decrease for saccadic amplitudes over the time course of scene perception. This relationship was very stable across the variety of studied conditions. It can be interpreted in terms of a shifting balance of the two modes of visual information processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Is there any relationship between visual fixation durations and saccade amplitudes in free exploration of pictures and scenes? In four experiments with naturalistic stimuli, we compared eye movements during early and late phases of scene perception. Influences of repeated presentation of similar stimuli (Experiment 1), object density (Experiment 2), emotional stimuli (Experiment 3) and mood induction (Experiment 4) were examined. The results demonstrate a systematic increase in the durations of fixations and a decrease for saccadic amplitudes over the time course of scene perception. This relationship was very stable across the variety of studied conditions. It can be interpreted in terms of a shifting balance of the two modes of visual information processing. |
Geoffrey Underwood; Emma Templeman; Laura Lamming; Tom Foulsham Is attention necessary for object identification? Evidence from eye movements during the inspection of real-world scenes Journal Article Consciousness and Cognition, 17 (1), pp. 159–170, 2008. @article{Underwood2008, title = {Is attention necessary for object identification? Evidence from eye movements during the inspection of real-world scenes}, author = {Geoffrey Underwood and Emma Templeman and Laura Lamming and Tom Foulsham}, doi = {10.1016/j.concog.2006.11.008}, year = {2008}, date = {2008-01-01}, journal = {Consciousness and Cognition}, volume = {17}, number = {1}, pages = {159--170}, abstract = {Eye movements were recorded during the display of two images of a real-world scene that were inspected to determine whether they were the same or not (a comparative visual search task). In the displays where the pictures were different, one object had been changed, and this object was sometimes taken from another scene and was incongruent with the gist. The experiment established that incongruous objects attract eye fixations earlier than the congruous counterparts, but that this effect is not apparent until the picture has been displayed for several seconds. By controlling the visual saliency of the objects the experiment eliminates the possibility that the incongruency effect is dependent upon the conspicuity of the changed objects. A model of scene perception is suggested whereby attention is unnecessary for the partial recognition of an object that delivers sufficient information about its visual characteristics for the viewer to know that the object is improbable in that particular scene, and in which full identification requires foveal inspection.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Eye movements were recorded during the display of two images of a real-world scene that were inspected to determine whether they were the same or not (a comparative visual search task). In the displays where the pictures were different, one object had been changed, and this object was sometimes taken from another scene and was incongruent with the gist. The experiment established that incongruous objects attract eye fixations earlier than the congruous counterparts, but that this effect is not apparent until the picture has been displayed for several seconds. By controlling the visual saliency of the objects the experiment eliminates the possibility that the incongruency effect is dependent upon the conspicuity of the changed objects. A model of scene perception is suggested whereby attention is unnecessary for the partial recognition of an object that delivers sufficient information about its visual characteristics for the viewer to know that the object is improbable in that particular scene, and in which full identification requires foveal inspection. |
Gianluca U Sorrento; Denise Y P Henriques Reference frame conversions for repeated arm movements Journal Article Journal of Neurophysiology, 99 (6), pp. 2968–2984, 2008. @article{Sorrento2008, title = {Reference frame conversions for repeated arm movements}, author = {Gianluca U Sorrento and Denise Y P Henriques}, doi = {10.1152/jn.90225.2008}, year = {2008}, date = {2008-01-01}, journal = {Journal of Neurophysiology}, volume = {99}, number = {6}, pages = {2968--2984}, abstract = {The aim of this study was to further understand how the brain represents spatial information for shaping aiming movements to targets. Both behavioral and neurophysiological studies have shown that the brain represents spatial memory for reaching targets in an eye-fixed frame. To date, these studies have only shown how the brain stores and updates target locations for generating a single arm movement. But once a target's location has been computed relative to the hand to program a pointing movement, is that information reused for subsequent movements to the same location? Or is the remembered target location reconverted from eye to motor coordinates each time a pointing movement is made? To test between these two possibilities, we had subjects point twice to the remembered location of a previously foveated target after shifting their gaze to the opposite side of the target site before each pointing movement. When we compared the direction of pointing errors for the second movement to those of the first, we found that errors for each movement varied as a function of current gaze so that pointing endpoints fell on opposite sides of the remembered target site in the same trial. Our results suggest that when shaping multiple pointing movements to the same location the brain does not use information from the previous arm movement such as an arm-fixed representation of the target but instead mainly uses the updated eye-fixed representation of the target to recalculate its location into the appropriate motor frame.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The aim of this study was to further understand how the brain represents spatial information for shaping aiming movements to targets. Both behavioral and neurophysiological studies have shown that the brain represents spatial memory for reaching targets in an eye-fixed frame. To date, these studies have only shown how the brain stores and updates target locations for generating a single arm movement. But once a target's location has been computed relative to the hand to program a pointing movement, is that information reused for subsequent movements to the same location? Or is the remembered target location reconverted from eye to motor coordinates each time a pointing movement is made? To test between these two possibilities, we had subjects point twice to the remembered location of a previously foveated target after shifting their gaze to the opposite side of the target site before each pointing movement. When we compared the direction of pointing errors for the second movement to those of the first, we found that errors for each movement varied as a function of current gaze so that pointing endpoints fell on opposite sides of the remembered target site in the same trial. Our results suggest that when shaping multiple pointing movements to the same location the brain does not use information from the previous arm movement such as an arm-fixed representation of the target but instead mainly uses the updated eye-fixed representation of the target to recalculate its location into the appropriate motor frame. |
Benjamin Y Hayden; Sarah R Heilbronner; Amrita C Nair; Michael L Platt Cognitive influences on risk-seeking by rhesus macaques Journal Article Judgement and Decision Making, 3 (5), pp. 389–395, 2008. @article{Hayden2008, title = {Cognitive influences on risk-seeking by rhesus macaques}, author = {Benjamin Y Hayden and Sarah R Heilbronner and Amrita C Nair and Michael L Platt}, doi = {10.1016/j.biotechadv.2011.08.021.Secreted}, year = {2008}, date = {2008-01-01}, journal = {Judgement and Decision Making}, volume = {3}, number = {5}, pages = {389--395}, abstract = {Humans and other animals are idiosyncratically sensitive to risk, either preferring or avoiding options having the same value but differing in uncertainty. Many explanations for risk sensitivity rely on the non-linear shape of a hypothesized utility curve. Because such models do not place any importance on uncertainty per se, utility curve-based accounts predict indifference between risky and riskless options that offer the same distribution of rewards. Here we show that monkeys strongly prefer uncertain gambles to alternating rewards with the same payoffs, demonstrating that uncertainty itself contributes to the appeal of risky options. Based on prior observations, we hypothesized that the appeal of the risky option is enhanced by the salience of the potential jackpot. To test this, we subtly manipulated payoffs in a second gambling task. We found that monkeys are more sensitive to small changes in the size of the large reward than to equivalent changes in the size of the small reward, indicating that they attend preferentially to the jackpots. Together, these results challenge utility curve-based accounts of risk sensitivity, and suggest that psychological factors, such as outcome salience and uncertainty itself, contribute to risky decision-making.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Humans and other animals are idiosyncratically sensitive to risk, either preferring or avoiding options having the same value but differing in uncertainty. Many explanations for risk sensitivity rely on the non-linear shape of a hypothesized utility curve. Because such models do not place any importance on uncertainty per se, utility curve-based accounts predict indifference between risky and riskless options that offer the same distribution of rewards. Here we show that monkeys strongly prefer uncertain gambles to alternating rewards with the same payoffs, demonstrating that uncertainty itself contributes to the appeal of risky options. Based on prior observations, we hypothesized that the appeal of the risky option is enhanced by the salience of the potential jackpot. To test this, we subtly manipulated payoffs in a second gambling task. We found that monkeys are more sensitive to small changes in the size of the large reward than to equivalent changes in the size of the small reward, indicating that they attend preferentially to the jackpots. Together, these results challenge utility curve-based accounts of risk sensitivity, and suggest that psychological factors, such as outcome salience and uncertainty itself, contribute to risky decision-making. |
Jan L Souman; Tom C A Freeman Motion perception during sinusoidal smooth pursuit eye movements: Signal latencies and non-linearities Journal Article Journal of Vision, 8 (14), pp. 1–14, 2008. @article{Souman2008, title = {Motion perception during sinusoidal smooth pursuit eye movements: Signal latencies and non-linearities}, author = {Jan L Souman and Tom C A Freeman}, doi = {10.1167/8.14.10r/8/14/10/ [pii]}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {1--14}, abstract = {Smooth pursuit eye movements add motion to the retinal image. To compensate, the visual system can combine estimates of pursuit velocity and retinal motion to recover motion with respect to the head. Little attention has been paid to the temporal characteristics of this compensation process. Here, we describe how the latency difference between the eye movement signal and the retinal signal can be measured for motion perception during sinusoidal pursuit. In two experiments, observers compared the peak velocity of a motion stimulus presented in pursuit and fixation intervals. Both the pursuit target and the motion stimulus moved with a sinusoidal profile. The phase and amplitude of the motion stimulus were varied systematically in different conditions, along with the amplitude of pursuit. The latency difference between the eye movement signal and the retinal signal was measured by fitting the standard linear model and a non-linear variant to the observed velocity matches. We found that the eye movement signal lagged the retinal signal by a small amount. The non-linear model fitted the velocity matches better than the linear one and this difference increased with pursuit amplitude. The results support previous claims that the visual system estimates eye movement velocity and retinal velocity in a non-linear fashion and that the latency difference between the two signals is small.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Smooth pursuit eye movements add motion to the retinal image. To compensate, the visual system can combine estimates of pursuit velocity and retinal motion to recover motion with respect to the head. Little attention has been paid to the temporal characteristics of this compensation process. Here, we describe how the latency difference between the eye movement signal and the retinal signal can be measured for motion perception during sinusoidal pursuit. In two experiments, observers compared the peak velocity of a motion stimulus presented in pursuit and fixation intervals. Both the pursuit target and the motion stimulus moved with a sinusoidal profile. The phase and amplitude of the motion stimulus were varied systematically in different conditions, along with the amplitude of pursuit. The latency difference between the eye movement signal and the retinal signal was measured by fitting the standard linear model and a non-linear variant to the observed velocity matches. We found that the eye movement signal lagged the retinal signal by a small amount. The non-linear model fitted the velocity matches better than the linear one and this difference increased with pursuit amplitude. The results support previous claims that the visual system estimates eye movement velocity and retinal velocity in a non-linear fashion and that the latency difference between the two signals is small. |
Gregory J Digirolamo; Jason S McCarley; Arthur F Kramer; Harry J Griffin Voluntary and reflexive eye movements to illusory lengths Journal Article Visual Cognition, 16 (1), pp. 68–89, 2008. @article{Digirolamo2008, title = {Voluntary and reflexive eye movements to illusory lengths}, author = {Gregory J Digirolamo and Jason S McCarley and Arthur F Kramer and Harry J Griffin}, doi = {10.1080/13506280701339160}, year = {2008}, date = {2008-01-01}, journal = {Visual Cognition}, volume = {16}, number = {1}, pages = {68--89}, abstract = {Considerable debate surrounds the extent and manner that motor control is, like perception, susceptible to visual illusions. Using the Brentano version of the Mu ¨ller-Lyer illusion, we measured the accuracy of voluntary and reflexive eye movements to the endpoints of equal length line segments that appeared different (Experiment 1) and different length line segments that appeared equal (Experiment 3). Voluntary and reflexive saccades were both influenced by the illusion, but the former were more strongly biased and closer to the subjective percept. Experiment 2 demonstrated that these data were the results of the illusion and not centre-of- gravity effects. The representations underlying perception and action interact and this interaction produces biases for actions, particularly voluntary actions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Considerable debate surrounds the extent and manner that motor control is, like perception, susceptible to visual illusions. Using the Brentano version of the Mu ¨ller-Lyer illusion, we measured the accuracy of voluntary and reflexive eye movements to the endpoints of equal length line segments that appeared different (Experiment 1) and different length line segments that appeared equal (Experiment 3). Voluntary and reflexive saccades were both influenced by the illusion, but the former were more strongly biased and closer to the subjective percept. Experiment 2 demonstrated that these data were the results of the illusion and not centre-of- gravity effects. The representations underlying perception and action interact and this interaction produces biases for actions, particularly voluntary actions. |
Melissa J Green; Jennifer H Waldron; Ian Simpson; Max Coltheart Visual processing of social context during mental state perception in schizophrenia Journal Article Journal of Psychiatry and Neuroscience, 33 (1), pp. 34–42, 2008. @article{Green2008, title = {Visual processing of social context during mental state perception in schizophrenia}, author = {Melissa J Green and Jennifer H Waldron and Ian Simpson and Max Coltheart}, year = {2008}, date = {2008-01-01}, journal = {Journal of Psychiatry and Neuroscience}, volume = {33}, number = {1}, pages = {34--42}, abstract = {OBJECTIVE: To examine schizophrenia patients' visual attention to social contextual information during a novel mental state perception task. METHOD: Groups of healthy participants (n = 26) and schizophrenia patients (n = 24) viewed 7 image pairs depicting target characters presented context-free and context-embedded (i.e., within an emotion-congruent social context). Gaze position was recorded with the EyeLink I Gaze Tracker while participants performed a mental state inference task. Mean eye movement variables were calculated for each image series (context-embedded v. context-free) to examine group differences in social context processing. RESULTS: The schizophrenia patients demonstrated significantly fewer saccadic eye movements when viewing context-free images and significantly longer eye-fixation durations when viewing context-embedded images. Healthy individuals significantly shortened eye-fixation durations when viewing context-embedded images, compared with context-free images, to enable rapid scanning and uptake of social contextual information; however, this pattern of visual attention was not pronounced in schizophrenia patients. In association with limited scanning and reduced visual attention to contextual information, schizophrenia patients' assessment of the mental state of characters embedded in social contexts was less accurate. CONCLUSION: In people with schizophrenia, inefficient integration of social contextual information in real-world situations may negatively affect the ability to infer mental and emotional states from facial expressions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVE: To examine schizophrenia patients' visual attention to social contextual information during a novel mental state perception task. METHOD: Groups of healthy participants (n = 26) and schizophrenia patients (n = 24) viewed 7 image pairs depicting target characters presented context-free and context-embedded (i.e., within an emotion-congruent social context). Gaze position was recorded with the EyeLink I Gaze Tracker while participants performed a mental state inference task. Mean eye movement variables were calculated for each image series (context-embedded v. context-free) to examine group differences in social context processing. RESULTS: The schizophrenia patients demonstrated significantly fewer saccadic eye movements when viewing context-free images and significantly longer eye-fixation durations when viewing context-embedded images. Healthy individuals significantly shortened eye-fixation durations when viewing context-embedded images, compared with context-free images, to enable rapid scanning and uptake of social contextual information; however, this pattern of visual attention was not pronounced in schizophrenia patients. In association with limited scanning and reduced visual attention to contextual information, schizophrenia patients' assessment of the mental state of characters embedded in social contexts was less accurate. CONCLUSION: In people with schizophrenia, inefficient integration of social contextual information in real-world situations may negatively affect the ability to infer mental and emotional states from facial expressions. |
Stuart Jackson; Fred Cummins; Nuala Brady Rapid perceptual switching of a reversible biological figure Journal Article PLoS ONE, 3 (12), pp. 1–15, 2008. @article{Jackson2008, title = {Rapid perceptual switching of a reversible biological figure}, author = {Stuart Jackson and Fred Cummins and Nuala Brady}, doi = {10.1371/journal.pone.0003982}, year = {2008}, date = {2008-01-01}, journal = {PLoS ONE}, volume = {3}, number = {12}, pages = {1--15}, abstract = {Certain visual stimuli can give rise to contradictory perceptions. In this paper we examine the temporal dynamics of perceptual reversals experienced with biological motion, comparing these dynamics to those observed with other ambiguous structure from motion (SFM) stimuli. In our first experiment, naïve observers monitored perceptual alternations with an ambiguous rotating walker, a figure that randomly alternates between walking in clockwise (CW) and counter-clockwise (CCW) directions. While the number of reported reversals varied between observers, the observed dynamics (distribution of dominance durations, CW/CCW proportions) were comparable to those experienced with an ambiguous kinetic depth cylinder. In a second experiment, we compared reversal profiles with rotating and standard point-light walkers (i.e. non-rotating). Over multiple test repetitions, three out of four observers experienced consistently shorter mean percept durations with the rotating walker, suggesting that the added rotational component may speed up reversal rates with biomotion. For both stimuli, the drift in alternation rate across trial and across repetition was minimal. In our final experiment, we investigated whether reversals with the rotating walker and a non-biological object with similar global dimensions (rotating cuboid) occur at random phases of the rotation cycle. We found evidence that some observers experience peaks in the distribution of response locations that are relatively stable across sessions. Using control data, we discuss the role of eye movements in the development of these reversal patterns, and the related role of exogenous stimulus characteristics. In summary, we have demonstrated that the temporal dynamics of reversal with biological motion are similar to other forms of ambiguous SFM. We conclude that perceptual switching with biological motion is a robust bistable phenomenon.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Certain visual stimuli can give rise to contradictory perceptions. In this paper we examine the temporal dynamics of perceptual reversals experienced with biological motion, comparing these dynamics to those observed with other ambiguous structure from motion (SFM) stimuli. In our first experiment, naïve observers monitored perceptual alternations with an ambiguous rotating walker, a figure that randomly alternates between walking in clockwise (CW) and counter-clockwise (CCW) directions. While the number of reported reversals varied between observers, the observed dynamics (distribution of dominance durations, CW/CCW proportions) were comparable to those experienced with an ambiguous kinetic depth cylinder. In a second experiment, we compared reversal profiles with rotating and standard point-light walkers (i.e. non-rotating). Over multiple test repetitions, three out of four observers experienced consistently shorter mean percept durations with the rotating walker, suggesting that the added rotational component may speed up reversal rates with biomotion. For both stimuli, the drift in alternation rate across trial and across repetition was minimal. In our final experiment, we investigated whether reversals with the rotating walker and a non-biological object with similar global dimensions (rotating cuboid) occur at random phases of the rotation cycle. We found evidence that some observers experience peaks in the distribution of response locations that are relatively stable across sessions. Using control data, we discuss the role of eye movements in the development of these reversal patterns, and the related role of exogenous stimulus characteristics. In summary, we have demonstrated that the temporal dynamics of reversal with biological motion are similar to other forms of ambiguous SFM. We conclude that perceptual switching with biological motion is a robust bistable phenomenon. |
Benjamin Y Hayden; Amrita C Nair; Allison N McCoy; Michael L Platt Posterior cingulate cortex mediates outcome-contingent allocation of behavior Journal Article Neuron, 60 (1), pp. 19–25, 2008. @article{Hayden2008a, title = {Posterior cingulate cortex mediates outcome-contingent allocation of behavior}, author = {Benjamin Y Hayden and Amrita C Nair and Allison N McCoy and Michael L Platt}, doi = {10.1016/j.neuron.2008.09.012}, year = {2008}, date = {2008-01-01}, journal = {Neuron}, volume = {60}, number = {1}, pages = {19--25}, abstract = {Adaptive decision making requires selecting an action and then monitoring its consequences to improve future decisions. The neuronal mechanisms supporting action evaluation and subsequent behavioral modification, however, remain poorly understood. To investigate the contribution of posterior cingulate cortex (CGp) to these processes, we recorded activity of single neurons in monkeys performing a gambling task in which the reward outcome of each choice strongly influenced subsequent choices. We found that CGp neurons signaled reward outcomes in a nonlinear fashion and that outcome-contingent modulations in firing rate persisted into subsequent trials. Moreover, firing rate on any one trial predicted switching to the alternative option on the next trial. Finally, microstimulation in CGp following risky choices promoted a preference reversal for the safe option on the following trial. Collectively, these results demonstrate that CGp directly contributes to the evaluative processes that support dynamic changes in decision making in volatile environments.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Adaptive decision making requires selecting an action and then monitoring its consequences to improve future decisions. The neuronal mechanisms supporting action evaluation and subsequent behavioral modification, however, remain poorly understood. To investigate the contribution of posterior cingulate cortex (CGp) to these processes, we recorded activity of single neurons in monkeys performing a gambling task in which the reward outcome of each choice strongly influenced subsequent choices. We found that CGp neurons signaled reward outcomes in a nonlinear fashion and that outcome-contingent modulations in firing rate persisted into subsequent trials. Moreover, firing rate on any one trial predicted switching to the alternative option on the next trial. Finally, microstimulation in CGp following risky choices promoted a preference reversal for the safe option on the following trial. Collectively, these results demonstrate that CGp directly contributes to the evaluative processes that support dynamic changes in decision making in volatile environments. |
Jörg Hoormann; Stephanie Jainta; Wolfgang Jaschinski The effect of calibration errors on the accuracy of the eye movement recordings Journal Article Journal of Eye Movement Research, 1 (2), pp. 1–7, 2008. @article{Hoormann2008, title = {The effect of calibration errors on the accuracy of the eye movement recordings}, author = {Jörg Hoormann and Stephanie Jainta and Wolfgang Jaschinski}, doi = {10.16910/jemr.1.2.3}, year = {2008}, date = {2008-01-01}, journal = {Journal of Eye Movement Research}, volume = {1}, number = {2}, pages = {1--7}, abstract = {For calibrating eye movement recordings, a regression between spatially defined calibration points and corresponding measured raw data is performed. Based on this regression, a confidence interval (CI) of the actually measured eye position can be calculated in order to$backslash$nquantify the measurement error introduced by inaccurate calibration coefficients. For calculating this CI, a standard deviation (SD) - depending on the calibration quality and the$backslash$ndesign of the calibration procedure - is needed.$backslash$nExamples of binocular recordings with separate monocular calibrations illustrate that the SD is almost independent of the number and spatial separation between the calibration points – even though the later was expected from theoretical simulation. Our simulations and recordings demonstrate that the SD depends critically on residuals at certain calibration points, thus robust regressions are suggested.}, keywords = {}, pubstate = {published}, tppubtype = {article} } For calibrating eye movement recordings, a regression between spatially defined calibration points and corresponding measured raw data is performed. Based on this regression, a confidence interval (CI) of the actually measured eye position can be calculated in order to$backslash$nquantify the measurement error introduced by inaccurate calibration coefficients. For calculating this CI, a standard deviation (SD) - depending on the calibration quality and the$backslash$ndesign of the calibration procedure - is needed.$backslash$nExamples of binocular recordings with separate monocular calibrations illustrate that the SD is almost independent of the number and spatial separation between the calibration points – even though the later was expected from theoretical simulation. Our simulations and recordings demonstrate that the SD depends critically on residuals at certain calibration points, thus robust regressions are suggested. |
Benjamin W Tatler; Benjamin T Vincent Systematic tendencies in scene viewing Journal Article Journal of Eye Movement Research, 2 (2), pp. 1–18, 2008. @article{Tatler2008, title = {Systematic tendencies in scene viewing}, author = {Benjamin W Tatler and Benjamin T Vincent}, doi = {http://dx.doi.org/10.16910/jemr.2.2.5}, year = {2008}, date = {2008-01-01}, journal = {Journal of Eye Movement Research}, volume = {2}, number = {2}, pages = {1--18}, abstract = {While many current models of scene perception debate the relative roles of low- and high- level factors in eye guidance, systematic tendencies in how the eyes move may be infor- mative. We consider how each saccade and fixation is influenced by that which preceded or followed it, during free inspection of images of natural scenes. We find evidence to suggest periods of localized scanning separated by ‘global' relocations to new regions of the scene. We also find evidence to support the existence of small amplitude ‘corrective' saccades in natural image viewing. Our data reveal statistical dependencies between suc- cessive eye movements, which may be informative in furthering our understanding of eye guidance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } While many current models of scene perception debate the relative roles of low- and high- level factors in eye guidance, systematic tendencies in how the eyes move may be infor- mative. We consider how each saccade and fixation is influenced by that which preceded or followed it, during free inspection of images of natural scenes. We find evidence to suggest periods of localized scanning separated by ‘global' relocations to new regions of the scene. We also find evidence to support the existence of small amplitude ‘corrective' saccades in natural image viewing. Our data reveal statistical dependencies between suc- cessive eye movements, which may be informative in furthering our understanding of eye guidance. |
Christof Körner; Iain D Gilchrist Memory processes in multiple-target visual search Journal Article Psychological Research, 72 (1), pp. 99–105, 2008. @article{Koerner2008, title = {Memory processes in multiple-target visual search}, author = {Christof Körner and Iain D Gilchrist}, doi = {10.1007/s00426-006-0075-1}, year = {2008}, date = {2008-01-01}, journal = {Psychological Research}, volume = {72}, number = {1}, pages = {99--105}, abstract = {Gibson, Li, Skow, Brown, and Cooke (Psychological Science, 11, 324–327, 2000) had participants carry out a search task in which they were required to detect the presence of one or two targets. In order to successfully perform such a multiple-target visual search task, participants had to remember the location of the Wrst target while searching for the second target. In two experiments we investigated the cost of remembering this target location. In Experiment 1, we compared performance on the Gibson et al. task with performance on a more conventional present–absent search task. The comparison suggests a substantial performance cost as measured by reaction time, number of Wxations and slope of the search functions. In Experment 2, we looked in detail at reWxations of distractors, which are a direct measure of attentional deployment. We demonstrated that the cost in this multiple-target visual search task was due to an increased number of reWxations on previously visited distractors. Such reWxations were present right from the start of the search. This change in search behaviour may be caused by the necessity of having to remember a target-allocating memory for the upcoming target may consume memory capacity that may otherwise be available for the tagging of distractors. These results support the notion of limited capacity memory processes in search. Introduction}, keywords = {}, pubstate = {published}, tppubtype = {article} } Gibson, Li, Skow, Brown, and Cooke (Psychological Science, 11, 324–327, 2000) had participants carry out a search task in which they were required to detect the presence of one or two targets. In order to successfully perform such a multiple-target visual search task, participants had to remember the location of the Wrst target while searching for the second target. In two experiments we investigated the cost of remembering this target location. In Experiment 1, we compared performance on the Gibson et al. task with performance on a more conventional present–absent search task. The comparison suggests a substantial performance cost as measured by reaction time, number of Wxations and slope of the search functions. In Experment 2, we looked in detail at reWxations of distractors, which are a direct measure of attentional deployment. We demonstrated that the cost in this multiple-target visual search task was due to an increased number of reWxations on previously visited distractors. Such reWxations were present right from the start of the search. This change in search behaviour may be caused by the necessity of having to remember a target-allocating memory for the upcoming target may consume memory capacity that may otherwise be available for the tagging of distractors. These results support the notion of limited capacity memory processes in search. Introduction |
Benjamin W Tatler; Nicholas J Wade; Kathrin Kaulard Examining art: Dissociating pattern and perceptual influences on oculomotor behaviour Journal Article Spatial Vision, 21 (1-2), pp. 165–184, 2008. @article{Tatler2008a, title = {Examining art: Dissociating pattern and perceptual influences on oculomotor behaviour}, author = {Benjamin W Tatler and Nicholas J Wade and Kathrin Kaulard}, doi = {10.1163/156856808782713807}, year = {2008}, date = {2008-01-01}, journal = {Spatial Vision}, volume = {21}, number = {1-2}, pages = {165--184}, abstract = {When observing art the viewer's understanding results from the interplay between the marks made on the surface by the artist and the viewer's perception and knowledge of it. Here we use a novel set of stimuli to dissociate the influences of the marks on the surface and the viewer's perceptual experience upon the manner in which the viewer inspects art. Our stimuli provide the opportunity to study situations in which (1) the same visual stimulus can give rise to two different perceptual experiences in the viewer, and (2) the visual stimuli differ but give rise to the same perceptual experience in the viewer. We find that oculomotor behaviour changes when the perceptual experience changes. Oculomotor behaviour also differs when the viewer's perceptual experience is the same but the visual stimulus is different. The methodology used and insights gained from this study offer a first step toward an experimental exploration of the relative influences of the artist's creation and viewer's perception when viewing art and also toward a better understanding of the principles of composition in portraiture.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When observing art the viewer's understanding results from the interplay between the marks made on the surface by the artist and the viewer's perception and knowledge of it. Here we use a novel set of stimuli to dissociate the influences of the marks on the surface and the viewer's perceptual experience upon the manner in which the viewer inspects art. Our stimuli provide the opportunity to study situations in which (1) the same visual stimulus can give rise to two different perceptual experiences in the viewer, and (2) the visual stimuli differ but give rise to the same perceptual experience in the viewer. We find that oculomotor behaviour changes when the perceptual experience changes. Oculomotor behaviour also differs when the viewer's perceptual experience is the same but the visual stimulus is different. The methodology used and insights gained from this study offer a first step toward an experimental exploration of the relative influences of the artist's creation and viewer's perception when viewing art and also toward a better understanding of the principles of composition in portraiture. |
Casimir J H Ludwig; Adam Ranson; Iain D Gilchrist Oculomotor capture by transient events: A comparison of abrupt onsets, offsets, motion, and flicker Journal Article Journal of Vision, 8 (14), pp. 1–16, 2008. @article{Ludwig2008, title = {Oculomotor capture by transient events: A comparison of abrupt onsets, offsets, motion, and flicker}, author = {Casimir J H Ludwig and Adam Ranson and Iain D Gilchrist}, doi = {10.1167/8.14.11}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {1--16}, abstract = {Attentional and oculomotor capture by some salient visual event gives insight into what types of dynamic signals the human orienting system is sensitive to. We examined the sensitivity of the saccadic eye movement system to 4 types of dynamic, but task-irrelevant, visual events: abrupt onset, abrupt offset, motion onset and flicker onset. We varied (1) the primary task (contrast vs. motion discrimination) and (2) the amount of prior knowledge of the location of the dynamic event. Interference from the irrelevant events was quantified using a discrimination threshold metric. When the primary task involved contrast discrimination, all four events disrupted performance approximately equally, including the sudden disappearance of an old object. However, when motion was the task-relevant dimension, abrupt onsets and offsets did not disrupt performance at all, but motion onset had a strong effect. Providing more spatial certainty to observers decreased the amount of direct oculomotor capture but nevertheless impaired performance. We conclude that oculomotor capture is predominantly contingent upon the channel the observer monitors in order to perform the primary visual task.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Attentional and oculomotor capture by some salient visual event gives insight into what types of dynamic signals the human orienting system is sensitive to. We examined the sensitivity of the saccadic eye movement system to 4 types of dynamic, but task-irrelevant, visual events: abrupt onset, abrupt offset, motion onset and flicker onset. We varied (1) the primary task (contrast vs. motion discrimination) and (2) the amount of prior knowledge of the location of the dynamic event. Interference from the irrelevant events was quantified using a discrimination threshold metric. When the primary task involved contrast discrimination, all four events disrupted performance approximately equally, including the sudden disappearance of an old object. However, when motion was the task-relevant dimension, abrupt onsets and offsets did not disrupt performance at all, but motion onset had a strong effect. Providing more spatial certainty to observers decreased the amount of direct oculomotor capture but nevertheless impaired performance. We conclude that oculomotor capture is predominantly contingent upon the channel the observer monitors in order to perform the primary visual task. |
Yasuhiro Seya; Hidetoshi Nakayasu; Patrick Patterson Visual search of trained and untrained drivers in a driving simulator Journal Article Japanese Psychological Research, 50 (4), pp. 242–252, 2008. @article{Seya2008, title = {Visual search of trained and untrained drivers in a driving simulator}, author = {Yasuhiro Seya and Hidetoshi Nakayasu and Patrick Patterson}, doi = {10.1111/j.1468-5884.2008.00380.x}, year = {2008}, date = {2008-01-01}, journal = {Japanese Psychological Research}, volume = {50}, number = {4}, pages = {242--252}, abstract = {To investigate the effects of driving experience on visual search during driving, we measured eye movements during driving tasks using a driving simulator. We evaluated trained and untrained drivers for selected driving road section types (for example, intersections and straight roads). Participants in the trained group had received driving training by the simulator before the experiment, while the others had no driving training by it. In the experiment, the participants were instructed to drive safely in the simulator. The results of scan paths showed that eye positions were less variable in the trained group than in the untrained group. Total eye-movement distances were shorter, and fixation durations were longer in the trained group than in the untrained group. These results suggest that trained drivers may perceive relevant information efficiently with few eye movements by using their anticipation skills and useful field of view, which may have been developed through their driving training in the simulator.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To investigate the effects of driving experience on visual search during driving, we measured eye movements during driving tasks using a driving simulator. We evaluated trained and untrained drivers for selected driving road section types (for example, intersections and straight roads). Participants in the trained group had received driving training by the simulator before the experiment, while the others had no driving training by it. In the experiment, the participants were instructed to drive safely in the simulator. The results of scan paths showed that eye positions were less variable in the trained group than in the untrained group. Total eye-movement distances were shorter, and fixation durations were longer in the trained group than in the untrained group. These results suggest that trained drivers may perceive relevant information efficiently with few eye movements by using their anticipation skills and useful field of view, which may have been developed through their driving training in the simulator. |
Harold H Greene Distance-from-target dynamics during visual search Journal Article Vision Research, 48 (23-24), pp. 2476–2484, 2008. @article{Greene2008, title = {Distance-from-target dynamics during visual search}, author = {Harold H Greene}, doi = {10.1016/j.visres.2008.08.013}, year = {2008}, date = {2008-01-01}, journal = {Vision Research}, volume = {48}, number = {23-24}, pages = {2476--2484}, abstract = {Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 noted that visual search with eye movements may be characterized by a search phase in which fixations do not move towards the target, followed by a phase in which fixations move steadily towards the target. They speculated that the phases are related to memory and recognition processes. Human visual search and Monte Carlo simulations are described towards an explanation. Distance-from-target dynamics were demonstrated to be sensitive to geometric constraints and therefore do not provide a solution to the question of memory in visual search. Finally, it is concluded that the specific distance-from-target dynamics noted by Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 are parsimoniously explained by random walks that were initialized at the centre of their stimulus displays.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 noted that visual search with eye movements may be characterized by a search phase in which fixations do not move towards the target, followed by a phase in which fixations move steadily towards the target. They speculated that the phases are related to memory and recognition processes. Human visual search and Monte Carlo simulations are described towards an explanation. Distance-from-target dynamics were demonstrated to be sensitive to geometric constraints and therefore do not provide a solution to the question of memory in visual search. Finally, it is concluded that the specific distance-from-target dynamics noted by Tseng, Y. C., & Li, C. S. (2004). Oculomotor correlates of context-guided learning in visual search. Perception & Psychophysics, 66, 1368-1378 are parsimoniously explained by random walks that were initialized at the centre of their stimulus displays. |
Ali Ezzati; Ashkan Golzar; Arash S R Afraz Topography of the motion aftereffect with and without eye movements Journal Article Journal of Vision, 8 (14), pp. 1–16, 2008. @article{Ezzati2008, title = {Topography of the motion aftereffect with and without eye movements}, author = {Ali Ezzati and Ashkan Golzar and Arash S R Afraz}, doi = {10.1167/8.14.23}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {1--16}, abstract = {Although a lot is known about various properties of the motion aftereffect (MAE), there is no systematic study of the topographic organization of MAE. In the current study, first we provided a topographic map of the MAE to investigate its spatial properties in detail. To provide a fine topographic map, we measured MAE with small test stimuli presented at different loci after adaptation to motion in a large region within the visual field. We found that strength of MAE is highest on the internal edge of the adapted area. Our results show a sharper aftereffect boundary for the shearing motion compared to compression and expansion boundaries. In the second experiment, using a similar paradigm, we investigated topographic deformation of the MAE area after a single saccadic eye movement. Surprisingly, we found that topographic map of MAE splits into two separate regions after the saccade: one corresponds to the retinal location of the adapted stimulus and the other matches the spatial location of the adapted region on the display screen. The effect was stronger at the retinotopic location. The third experiment is basically replication of the second experiment in a smaller zone that confirms the results of previous experiments in individual subjects. The eccentricity of spatiotopic area is different from retinotopic area in the second experiment; Experiment 3 controls the effect of eccentricity and confirms the major results of the second experiment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although a lot is known about various properties of the motion aftereffect (MAE), there is no systematic study of the topographic organization of MAE. In the current study, first we provided a topographic map of the MAE to investigate its spatial properties in detail. To provide a fine topographic map, we measured MAE with small test stimuli presented at different loci after adaptation to motion in a large region within the visual field. We found that strength of MAE is highest on the internal edge of the adapted area. Our results show a sharper aftereffect boundary for the shearing motion compared to compression and expansion boundaries. In the second experiment, using a similar paradigm, we investigated topographic deformation of the MAE area after a single saccadic eye movement. Surprisingly, we found that topographic map of MAE splits into two separate regions after the saccade: one corresponds to the retinal location of the adapted stimulus and the other matches the spatial location of the adapted region on the display screen. The effect was stronger at the retinotopic location. The third experiment is basically replication of the second experiment in a smaller zone that confirms the results of previous experiments in individual subjects. The eccentricity of spatiotopic area is different from retinotopic area in the second experiment; Experiment 3 controls the effect of eccentricity and confirms the major results of the second experiment. |
David Souto; Dirk Kerzel Dynamics of attention during the initiation of smooth pursuit eye movements Journal Article Journal of Vision, 8 (14), pp. 3–1–16, 2008. @article{Souto2008, title = {Dynamics of attention during the initiation of smooth pursuit eye movements}, author = {David Souto and Dirk Kerzel}, doi = {10.1167/8.14.3}, year = {2008}, date = {2008-01-01}, journal = {Journal of Vision}, volume = {8}, number = {14}, pages = {3--1--16}, abstract = {Many studies indicate that saccades are necessarily preceded by a shift of attention to the target location. There is no direct evidence for the same coupling during smooth pursuit. If smooth pursuit and attention were coupled, pursuit onset should be delayed whenever attention is focused on a stationary, non-target location. To test this hypothesis, observers were instructed to shift their attention to a peripheral location according to a location cue (Experiments 1 and 2) or a symbolic cue (Experiment 3) around the time of smooth pursuit initiation. Attending to static targets had only negligible effects on smooth pursuit latencies and the early open-loop response but lowered pursuit velocity substantially about the onset of closed-loop pursuit. Around this time, eye velocity reflected the competition between the to-be-tracked and to-be-attended object motion, entailing a reduction of eye velocity by 50% compared to the single task condition. The precise time course of attentional modulation of smooth pursuit initiation was at odds with the idea that an attention shift must precede any voluntary eye movement. Finally, the initial catch-up saccades were strongly delayed with attention diverted from the pursuit target. Implications for models of target selection for pursuit and saccades are discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many studies indicate that saccades are necessarily preceded by a shift of attention to the target location. There is no direct evidence for the same coupling during smooth pursuit. If smooth pursuit and attention were coupled, pursuit onset should be delayed whenever attention is focused on a stationary, non-target location. To test this hypothesis, observers were instructed to shift their attention to a peripheral location according to a location cue (Experiments 1 and 2) or a symbolic cue (Experiment 3) around the time of smooth pursuit initiation. Attending to static targets had only negligible effects on smooth pursuit latencies and the early open-loop response but lowered pursuit velocity substantially about the onset of closed-loop pursuit. Around this time, eye velocity reflected the competition between the to-be-tracked and to-be-attended object motion, entailing a reduction of eye velocity by 50% compared to the single task condition. The precise time course of attentional modulation of smooth pursuit initiation was at odds with the idea that an attention shift must precede any voluntary eye movement. Finally, the initial catch-up saccades were strongly delayed with attention diverted from the pursuit target. Implications for models of target selection for pursuit and saccades are discussed. |
Alexander Pollatsek; Timothy J Slattery; Barbara Juhasz The processing of novel and lexicalised prefixed words in reading Journal Article Language and Cognitive Processes, 23 (7-8), pp. 1133–1158, 2008. @article{Pollatsek2008, title = {The processing of novel and lexicalised prefixed words in reading}, author = {Alexander Pollatsek and Timothy J Slattery and Barbara Juhasz}, doi = {10.1080/01690960801945484}, year = {2008}, date = {2008-01-01}, journal = {Language and Cognitive Processes}, volume = {23}, number = {7-8}, pages = {1133--1158}, abstract = {Two experiments compared how relatively long novel prefixed words (e.g., overfarm) and existing prefixed words were processed in reading. The use of novel prefixed words allows one to examine the roles of whole-word access and decompositional processing in the processing of non-novel prefixed words. The two experiments found that, although there was a large cost to novelty (e.g., gaze durations were about 100 ms longer for novel prefixedwords), the effect of the frequency of the root morpheme on fixation measures was about the same for novel and non-novel prefixed words for most measures. This finding rules out a (‘‘horse-race'') dual-route model of processing for existing prefixed words in which the whole-word and decompositional route are parallel and independent, as such a model would predict a substantially larger root frequency effect for novel words (where whole-word processes do not exist). The most likely model to explain the processing of prefixed words is a parallel interactive one.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two experiments compared how relatively long novel prefixed words (e.g., overfarm) and existing prefixed words were processed in reading. The use of novel prefixed words allows one to examine the roles of whole-word access and decompositional processing in the processing of non-novel prefixed words. The two experiments found that, although there was a large cost to novelty (e.g., gaze durations were about 100 ms longer for novel prefixedwords), the effect of the frequency of the root morpheme on fixation measures was about the same for novel and non-novel prefixed words for most measures. This finding rules out a (‘‘horse-race'') dual-route model of processing for existing prefixed words in which the whole-word and decompositional route are parallel and independent, as such a model would predict a substantially larger root frequency effect for novel words (where whole-word processes do not exist). The most likely model to explain the processing of prefixed words is a parallel interactive one. |
Seppo Vainio; Jukka Hyönä; Anneli Pajunen Processing modifier-head agreement in reading: Evidence for a delayed effect of agreement Journal Article Memory and Cognition, 36 (2), pp. 329–340, 2008. @article{Vainio2008, title = {Processing modifier-head agreement in reading: Evidence for a delayed effect of agreement}, author = {Seppo Vainio and Jukka Hyönä and Anneli Pajunen}, doi = {10.3758/MC.36.2.329}, year = {2008}, date = {2008-01-01}, journal = {Memory and Cognition}, volume = {36}, number = {2}, pages = {329--340}, abstract = {The present study examined whether type of inflectional case (semantic or grammatical) and phonological and morphological transparency affect the processing of Finnish modifier-head agreement in reading. Readers' eye movement patterns were registered. In Experiment 1, an agreeing modifier condition (agreement was transparent) was compared with a no-modifier condition, and in Experiment 2, similar constructions with opaque agreement were used. In both experiments, agreement was found to affect the processing of the target noun with some delay. In Experiment 3, unmarked and case-marked modifiers were used. The results again demonstrated a delayed agreement effect, ruling out the possibility that the agreement effects observed in Experiments 1 and 2 reflect a mere modifier-presence effect. We concluded that agreement exerts its effect at the level of syntactic integration but not at the level of lexical access.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The present study examined whether type of inflectional case (semantic or grammatical) and phonological and morphological transparency affect the processing of Finnish modifier-head agreement in reading. Readers' eye movement patterns were registered. In Experiment 1, an agreeing modifier condition (agreement was transparent) was compared with a no-modifier condition, and in Experiment 2, similar constructions with opaque agreement were used. In both experiments, agreement was found to affect the processing of the target noun with some delay. In Experiment 3, unmarked and case-marked modifiers were used. The results again demonstrated a delayed agreement effect, ruling out the possibility that the agreement effects observed in Experiments 1 and 2 reflect a mere modifier-presence effect. We concluded that agreement exerts its effect at the level of syntactic integration but not at the level of lexical access. |
Sarah Bate; Catherine Haslam; Jeremy J Tree; Timothy L Hodgson Evidence of an eye movement-based memory effect in congenital prosopagnosia Journal Article Cortex, 44 (7), pp. 806–819, 2008. @article{Bate2008, title = {Evidence of an eye movement-based memory effect in congenital prosopagnosia}, author = {Sarah Bate and Catherine Haslam and Jeremy J Tree and Timothy L Hodgson}, doi = {10.1016/j.cortex.2007.02.004}, year = {2008}, date = {2008-01-01}, journal = {Cortex}, volume = {44}, number = {7}, pages = {806--819}, abstract = {While extensive work has examined the role of covert recognition in acquired prosopagnosia, little attention has been directed to this process in the congenital form of the disorder. Indeed, evidence of covert recognition has only been demonstrated in one congenital case in which autonomic measures provided evidence of recognition (Jones and Tranel, 2001), whereas two investigations using behavioural indicators failed to demonstrate the effect (de Haan and Campbell, 1991; Bentin et al., 1999). In this paper, we use a behavioural indicator, an "eye movement-based memory effect" (Althoff and Cohen, 1999), to provide evidence of covert recognition in congenital prosopagnosia. In an initial experiment, we examined viewing strategies elicited to famous and novel faces in control participants, and found fewer fixations and reduced regional sampling for famous compared to novel faces. In a second experiment, we examined the same processes in a patient with congenital prosopagnosia (AA), and found some evidence of an eye movement-based memory effect regardless of his recognition accuracy. Finally, we examined whether a difference in scanning strategy was evident for those famous faces AA failed to explicitly recognise, and again found evidence of reduced sampling for famous faces. We use these findings to (a) provide evidence of intact structural representations in a case of congenital prosopagnosia, and (b) to suggest that covert recognition can be demonstrated using behavioural indicators in this disorder.}, keywords = {}, pubstate = {published}, tppubtype = {article} } While extensive work has examined the role of covert recognition in acquired prosopagnosia, little attention has been directed to this process in the congenital form of the disorder. Indeed, evidence of covert recognition has only been demonstrated in one congenital case in which autonomic measures provided evidence of recognition (Jones and Tranel, 2001), whereas two investigations using behavioural indicators failed to demonstrate the effect (de Haan and Campbell, 1991; Bentin et al., 1999). In this paper, we use a behavioural indicator, an "eye movement-based memory effect" (Althoff and Cohen, 1999), to provide evidence of covert recognition in congenital prosopagnosia. In an initial experiment, we examined viewing strategies elicited to famous and novel faces in control participants, and found fewer fixations and reduced regional sampling for famous compared to novel faces. In a second experiment, we examined the same processes in a patient with congenital prosopagnosia (AA), and found some evidence of an eye movement-based memory effect regardless of his recognition accuracy. Finally, we examined whether a difference in scanning strategy was evident for those famous faces AA failed to explicitly recognise, and again found evidence of reduced sampling for famous faces. We use these findings to (a) provide evidence of intact structural representations in a case of congenital prosopagnosia, and (b) to suggest that covert recognition can be demonstrated using behavioural indicators in this disorder. |