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2010 |
Matthew O. Kimble; Kevin Fleming; Carole Bandy; Julia Kim; Andrea Zambetti Eye tracking and visual attention to threating stimuli in veterans of the Iraq war Journal Article In: Journal of Anxiety Disorders, vol. 24, no. 3, pp. 293–299, 2010. @article{Kimble2010, Theoretical and clinical characterizations of attention in PTSD acknowledge the possibility for both hypervigilance and avoidance of trauma-relevant stimuli. This study used eye tracking technology to investigate visual orientation and attention to traumatic and neutral stimuli in nineteen veterans of the Iraq war. Veterans saw slides in which half the screen had a negatively valenced image and half had a neutral image. Negatively valenced stimuli were further divided into stimuli that varied in trauma relevance (either Iraq war or civilian motor vehicle accidents). Veterans reporting relatively higher levels of PSTD symptoms had larger pupils to all negatively valenced pictures and spent more time looking at them than did veterans lower in PTSD symptoms. Veterans higher in PTSD symptoms also showed a trend towards looking first at Iraq images. The findings suggest that post-traumatic pathology is associated with vigilance rather than avoidance when visually processing negatively valenced and trauma-relevant stimuli. |
Yosuke Kita; Atsuko Gunji; Kotoe Sakihara; Masumi Inagaki; Makiko Kaga; Eiji Nakagawa; Toru Hosokawa Scanning strategies do not modulate face identification: Eye-tracking and near-infrared spectroscopy study Journal Article In: PLoS ONE, vol. 5, no. 6, pp. e11050, 2010. @article{Kita2010, BACKGROUND: During face identification in humans, facial information is sampled (seeing) and handled (processing) in ways that are influenced by the kind of facial image type, such as a self-image or an image of another face. However, the relationship between seeing and information processing is seldom considered. In this study, we aimed to reveal this relationship using simultaneous eye-tracking measurements and near-infrared spectroscopy (NIRS) in face identification tasks. METHODOLOGY/PRINCIPAL FINDINGS: 22 healthy adult subjects (8 males and 14 females) were shown facial morphing movies in which an initial facial image gradually changed into another facial image (that is, the subject's own face was changed to a familiar face). The fixation patterns on facial features were recorded, along with changes in oxyhemoglobin (oxyHb) levels in the frontal lobe, while the subjects identified several faces. In the self-face condition (self-face as the initial image), hemodynamic activity around the right inferior frontal gyrus (IFG) was significantly greater than in the familiar-face condition. On the other hand, the scanning strategy was similar in almost all conditions with more fixations on the eyes and nose than on other areas. Fixation time on the eye area did not correlate with changes in oxyHb levels, and none of the scanning strategy indices could estimate the hemodynamic changes. CONCLUSIONS/SIGNIFICANCE: We conclude that hemodynamic activity, i.e., the means of processing facial information, is not always modulated by the face-scanning strategy, i.e., the way of seeing, and that the right IFG plays important roles in both self-other facial discrimination and self-evaluation. |
Albrecht W. Inhoff; Bradley A. Seymour; Daniel J. Schad; Seth N. Greenberg The size and direction of saccadic curvatures during reading Journal Article In: Vision Research, vol. 50, no. 12, pp. 1117–1130, 2010. @article{Inhoff2010, Eye movements during the reading of multi-line pages of texts were analyzed to determine the trajectory of reading saccades. The results of two experiments showed that the trajectory of the majority of forward-directed saccades was negatively biased, i.e., the trajectory fell below the start and end location of the saccadic movement. This is attributed to a global top-to-bottom orienting of attention. The curvature size and the proportion of negative trajectories were diminished when linguistic processing demands were high and when the beginning lines of a page were read. Longer pre-saccadic fixations also yielded smaller saccadic curvatures, and they resulted in fewer negatively curved forward-directed saccades in Experiment 1 although not in Experiment 2. These findings indicate that the top-to-bottom pull of saccadic trajectories is modulated by processing demands and processing opportunities. The results are in general agreement with a time-locked attraction–inhibition hypothesis, according to which the horizontal movement component of a saccade is initially subject to an automatic top-to-bottom orienting of attention that is subsequently inhibited. |
Lucica Iordanescu; Marcia Grabowecky; Steven L. Franconeri; Jan Theeuwes; Satoru Suzuki Characteristic sounds make you look at target objects more quickly Journal Article In: Attention, Perception, and Psychophysics, vol. 72, no. 7, pp. 1736–1741, 2010. @article{Iordanescu2010, When you are looking for an object, does hearing its characteristic sound make you find it more quickly? Our recent results supported this possibility by demonstrating that when a cat target, for example, was presented among other objects, a simultaneously presented “meow” sound (containing no spatial information) reduced the manual response time for visual localization of the target. To extend these results, we determined how rapidly an object-specific auditory signal can facilitate target detection in visual search. On each trial, participants fixated a spec ified target object as quickly as possible. The target's characteristic sound speeded the saccadic search time within 215–220 msec and also guided the initial saccade toward the target, compared with presentation of a distractor's sound or with no sound. These results suggest that object-based auditory–visual interactions rapidly increase the target object's salience in visual search. |
Angela M. Isaacs; Duane G. Watson Accent detection is a slippery slope: Direction and rate of F0 change drives listeners' comprehension Journal Article In: Language and Cognitive Processes, vol. 25, no. 7-9, pp. 1178–1200, 2010. @article{Isaacs2010, The present study tests whether listeners use F0, duration, or some combination of the two to identify the presence of an accented word in a short discourse. Participants' eye movements to previously mentioned and new objects were monitored as participants listened to instructions to move objects in a display. The name of the target object on critical trials was resynthesized from naturally-produced utterances so that it had either high or low F0 and either long or short duration. Fixations to the new object were highest when there was a steep rise in F0. Fixations to the previously mentioned object were highest when there was a steep drop in F0. These results suggest that listeners use F0 slope to make decisions about the presence of an accent, and that F0 and duration by themselves do not solely determine accent interpretation. |
Osman Iyilikci; Cordula Becker; Onur Güntürkün; Sonia Amado Visual processing asymmetries in change detection Journal Article In: Perception, vol. 39, no. 6, pp. 761–769, 2010. @article{Iyilikci2010, Change detection is critically dependent on attentional mechanisms. However, the relation between an asymmetrical distribution of visuo-spatial attention and the detection of changes in visual scenes is not clear. Spatial tasks are known to induce a stronger activation of the right hemisphere. The effects of such visual processing asymmetries induced by a spatial task on change detection were investigated. When required to detect changes in the left and in the right visual fields, participants were significantly faster in detecting changes on the left than on the right. Importantly, this left-side superiority in change detection is not influenced by inspection time, suggesting a critical role of visual processing benefit for the left visual field. |
Michal Jacob; Shaul Hochstein Graded recognition as a function of the number of target fixations Journal Article In: Vision Research, vol. 50, no. 1, pp. 107–117, 2010. @article{Jacob2010, Target recognition stages were studied by exposing observers to varying controlled numbers of target fixations. The target, present in half the displays, consisted of two identical cards (Identity Search Task; Jacob & Hochstein, 2009). Following more fixations, targets are better recognized, indicated by increased Hit-rate and detectability (according to Unequal Variance Signal Detection Theory), decreased Response Time and growing confidence, reflecting current stage in recognition process. Thus, gathering information over a specific scene region results from a growing number of fixations on that particular region. We conclude that several fixations on a scene location are necessary for achieving recognition. |
Jonathan B. Jacobs; Louis F. Dell'Osso Extending the eXpanded Nystagmus Acuity Function for vertical and multiplanar data Journal Article In: Vision Research, vol. 50, no. 3, pp. 271–278, 2010. @article{Jacobs2010, We updated and extended the functionality of the eXpanded Nystagmus Acuity Function (NAFX), for application under more diverse circumstances, improving its clinical predictive value. The original NAFX "τ-surface" of minimum-necessary-foveation times had been individually calculated for each combination of position and velocity limits. We have replaced it with an idealized mathematical function that repairs the irregularities in its surface due to idiosyncrasies in the subject data used for the initial calculations. To extend applicability to multiplanar data, we combine horizontal and vertical eye-movement data into a single waveform using vector summation. Torsional eye movements have little effect on visual acuity and are ignored. Age-related visual acuity relationships, derived from population data, more accurately relate the NAFX value to acuity for individual patients. Using the same patient fixation data that established the original NAF and NAFX functions, we verified that the updated NAFX yielded equivalent results for uniplanar data. For biplanar data, the results were also comparable to those of uniplanar data of the same magnitude. The updated NAFX yields greater accuracy in prediction of potential visual acuity for subjects of all ages, for uniplanar and multiplanar nystagmus, extending the objective, direct measure of post-therapy waveform improvement, allowing selection of the best therapy for a wider range of nystagmus patients. |
Richard H. A. H. Jacobs; Remco Renken; Stefan Thumfart; Frans W. Cornelissen Different judgments about visual textures invoke different eye movement patterns Journal Article In: Journal of Eye Movement Research, vol. 3, no. 4, pp. 1–13, 2010. @article{Jacobs2010a, Top-down influences on the guidance of the eyes are generally modeled as modulating influences on bottom-up salience maps. Interested in task-driven influences on how, rather than where, the eyes are guided, we expected differences in eye movement parameters accompanying beauty and roughness judgments about visual textures. Participants judged textures for beauty and roughness, while their gaze-behavior was recorded. Eye movement parameters differed between the judgments, showing task effects on how people look at images. Similarity in the spatial distribution of attention suggests that differences in the guidance of attention are non-spatial, possibly feature-based. During the beauty judgment, participants fixated on patches that were richer in color information, further supporting the idea that differences in the guidance of attention are feature-based. A finding of shorter fixation durations during beauty judgments may indicate that extraction of the relevant features is easier during this judgment. This finding is consistent with a more ambient scanning mode during this judgment. The differences in eye movement parameters during different judgments about highly repetitive stimuli highlight the need for models of eye guidance to go beyond salience maps, to include the temporal dynamics of eye guidance. |
Anshul Jain; Stuart Fuller; Benjamin T. Backus In: PLoS ONE, vol. 5, no. 10, pp. e13295, 2010. @article{Jain2010, The visual system can learn to use information in new ways to construct appearance. Thus, signals such as the location or translation direction of an ambiguously rotating wire frame cube, which are normally uninformative, can be learned as cues to determine the rotation direction. This perceptual learning occurs when the formerly uninformative signal is statistically associated with long-trusted visual cues (such as binocular disparity) that disambiguate appearance during training. In previous demonstrations, the newly learned cue was intrinsic to the perceived object, in that the signal was conveyed by the same image elements as the object itself. Here we used extrinsic new signals and observed no learning. We correlated three new signals with long-trusted cues in the rotating cube paradigm: one crossmodal (an auditory signal) and two within modality (visual). Cue recruitment did not occur in any of these conditions, either in single sessions or in ten sessions across as many days. These results suggest that the intrinsic/extrinsic distinction is important for the perceptual system in determining whether it can learn and use new information from the environment to construct appearance. Extrinsic cues do have perceptual effects (e.g. the "bounce-pass" illusion and McGurk effect), so we speculate that extrinsic signals must be recruited for perception, but only if certain conditions are met. These conditions might specify the age of the observer, the strength of the long-trusted cues, or the amount of exposure to the correlation. |
Stephanie Jainta; Jörg Hoormann; Wilhelm Bernhard Kloke; Wolfgang Jaschinski Binocularity during reading fixations: Properties of the minimum fixation disparity Journal Article In: Vision Research, vol. 50, no. 18, pp. 1775–1785, 2010. @article{Jainta2010b, The present study was based on the physiologically reasonable assumption that the binocular system aims for a reduction of fixation disparity during fixation and that the minimum amount of fixation disparity reflects the optimal binocular status. We measured eye movements (EyeLink II) of 18 participants, while they read 60 sentences from the Potsdam-Sentence-Corpus (PSC) at a viewing distance of 60. cm. The minimum fixation disparity was frequently reached directly after the post-saccadic drift, sometimes at the end of fixation and sometimes somewhere in between. Minimum fixation disparity was strongly influenced only by fixation position (within the sentence) while the amplitude of incoming saccade had a negligible effect. Moreover, the effect of fixation position on minimum fixation disparity was correlated with the individual ability to compensate for binocular disconjugacy (due to saccades) while fixating during reading. Generally, we found fixation disparity to be correlated between conditions of reading and fixating single targets, while the reading fixation disparity tended to be more crossed (eso). |
Stephanie Jainta; Jaschin; Arnold J. Wilkins Periodic letter strokes within a word affect fixation disparity during reading Journal Article In: Journal of Vision, vol. 10, no. 13, pp. 1–11, 2010. @article{Jainta2010, We investigated the way in which binocular coordination in reading is affected by the spatial structure of text. Vergence eye movements were measured (EyeLink II) in 32 observers while they read 120 single German sentences (Potsdam Sentence Corpus) silently for comprehension. The similarity in shape between the neighboring strokes of component letters, as measured by the first peak in the horizontal auto-correlation of the images of the words, was found to be associated with (i) a smaller minimum fixation disparity (i.e. vergence error) during fixation; (ii) a longer time to reach this minimum disparity and (iii) a longer overall fixation duration. The results were obtained only for binocular reading: no effects of auto-correlation could be observed for monocular reading. The findings help to explain the longer reading times reported for words and fonts with high auto-correlation and may also begin to provide a causal link between poor binocular control and reading difficulties. |
Stephanie Jainta; Wolfgang Jaschinski “Trait” and “state” aspects of fixation disparity during reading Journal Article In: Journal of Eye Movement Research, vol. 3, no. 3, pp. 1–13, 2010. @article{Jainta2010a, In our study, 14 subjects read 60 sentences from the Potsdam Sentence Corpus twice (viewing distance: 60 cm), while eye movements were measured with the EyeLink II. We analyzed fixation disparities for complete sentence replications (N=388). After subtracting the average fixation disparity of each sentence from each observation (which gave the “state” fixation disparity), 99% of all remaining fixation disparities were aligned, i.e. smaller than one character width (20 min arc) – depending mostly on incoming saccade amplitude and fixation position. Additionally, we measured the heterophoria for each subject during calibration and found a qualitative relationship between average, individual measures of fixation disparity (“trait” fixation disparity) and heterophoria, after dividing the sample in 3 groups of esophore, exophore and orthophore subjects. We showed that the magnitude of “trait” fixation disparity was biased by the direction of heterophoria: the more eso the heterophoria, the more eso the average sentence fixation disparity. In sum, despite a large “trait” fixation disparity (in the range of -6.6 to +33.6 min arc), “state” fixation disparities within a sentence were on average -0.9 (± 8.7) min arc and, thus, as precise as needed, i.e. within the expected extent of Panum's area. |
Wolfgang Jaschinski; Stephanie Jainta; Wilhelm Bernhard Kloke Objective vs subjective measures of fixation disparity for short and long fixation periods Journal Article In: Ophthalmic and Physiological Optics, vol. 30, no. 4, pp. 379–390, 2010. @article{Jaschinski2010, Purpose: Fixation disparity, i.e. the vergence error for stationary fusion stimuli, can be measured objectively with eye trackers and subjectively with nonius lines. Between these two measures, previous studies found differences that tended to be proportional to the amount of forced vergence, i.e. the discrepancy between vergence and accommodative stimulus. We investigate whether objective and subjective fixation disparity might be similar without forced vergence. Method: We simultaneously measured fixation disparity with the EyeLink II system and with flashed dichoptic nonius lines in 17 subjects who observed targets at a vergence stimulus of 6 deg in an haploscope with 60 cm viewing distance. Results: We found individual differences in objective fixation disparity in a range of about 20 (eso) to )60 (exo) min arc which was considerably larger than the range of subjective fixation disparity. Results were similar for long fixation periods (about 15 s) and short fixation periods (about 1.5 s) between 5 deg saccadic gaze shifts. Further, objective fixation disparity was correlated with objective heterophoria, i.e. the vergence state without a fusion stimulus (r = 0.8, p < 0.001). Conclusion: Subjective fixation disparity explained only about 25% of the inter-individual variability in objective fixation disparity. The discrepancy between these two measures might be explained by sensory shifts in retinal correspondence, also in the present condition without forced vergence. |
Aaron P. Johnson; Rick Gurnsey Size scaling compensates for sensitivity loss produced by a simulated central scotoma in a shape-from-texture task Journal Article In: Journal of Vision, vol. 10, no. 12, pp. 1–16, 2010. @article{Johnson2010, Studies of eccentricity-dependent sensitivity loss typically require participants to maintain fixation while making judgments about stimuli presented at a range of sizes and eccentricities. However, training participants to fixate can prove difficult, and as stimulus size increases, they become poorly localized and may even encroach on the fovea. In the present experiment, we controlled eccentricity of stimulus presentation using a simulated central scotoma of variable size. Participants were asked to perform a 27-alternative forced-choice shape-from-texture task in the presence of a simulated scotoma, with stimulus size and scotoma radius as the independent variables. The resulting psychometric functions for each simulated scotoma were shifted versions of each other on a log size axis. Therefore, stimulus magnification was sufficient to equate sensitivity to shape from texture for all scotoma radii. Increasing scotoma radius also disrupts eye movements, producing increases in fixation frequency and duration, as well as saccade length. |
Manon W. Jones; Holly P. Branigan; Anna Hatzidaki; Mateo Obregón Is the 'naming' deficit in dyslexia a misnomer? Journal Article In: Cognition, vol. 116, no. 1, pp. 56–70, 2010. @article{Jones2010a, We report a study that investigated the widely held belief that naming-speed deficits in developmental dyslexia reflect impaired access to lexical-phonological codes. To investigate this issue, we compared adult dyslexic and adult non-dyslexic readers' performance when naming and semantically categorizing arrays of objects. Dyslexic readers yielded slower response latencies than non-dyslexic readers when naming objects, but a subsequent comparison of object-naming and object-categorization tasks showed that the apparent 'naming' deficit could be attributed to a more general difficulty in retrieving information - either phonological or semantic - from the visual stimulus. Our findings suggest that although visual-phonological connections may be crucial in explaining naming-speed performance they do not fully characterise dyslexic readers' naming-speed impairments. |
Zoï Kapoula; Q. Yang; M. Vernet; P. Bonfils; Alain Londero Eye movement abnormalities in somatic tinnitus: Fixation, smooth pursuit and optokinetic nystagmus Journal Article In: Auris Nasus Larynx, vol. 37, no. 3, pp. 314–321, 2010. @article{Kapoula2010a, Objective: Smooth pursuit (SP), optokinetic nystagmus (OKN) and fixation were investigated in five subjects with somatic tinnitus modulated by eye movements, jaw or neck. Methods: Eye movements were recorded with the EyeLink II video system. Results: (1) Fixation was characterized by high frequency and amplitude of saccade intrusions; (2) SP had low gain particularly in the vertical direction, and it was characterized by high frequency of catch-up saccades with high amplitude, including predictive saccades; (3) OKN also had low gain particularly in the vertical direction. Each subject showed abnormality for more than one type of eye movement, and for specific directions. Conclusions and significance: The results suggest mild dysfunction of cortical-subcortical and cerebellar structures involved in the control of these eye movements. Particularly deficits for vertical pursuit eye movements and fixation instability in line with cerebellar signs. Further studies of more patients with or without modulated tinnitus are in progress. |
Zoï Kapoula; Qing Yang; Audrey Bonnet; Pauline Bourtoire; Jean Sandretto EMDR effects on pursuit eye movements Journal Article In: PLoS ONE, vol. 5, no. 5, pp. e10762, 2010. @article{Kapoula2010b, This study aimed to objectivize the quality of smooth pursuit eye movements in a standard laboratory task before and after an Eye Movement Desensitization and Reprocessing (EMDR) session run on seven healthy volunteers. EMDR was applied on autobiographic worries causing moderate distress. The EMDR session was complete in 5 out of the 7 cases; distress measured by SUDS (Subjective Units of Discomfort Scale) decreased to a near zero value. Smooth pursuit eye movements were recorded by an Eyelink II video system before and after EMDR. For the five complete sessions, pursuit eye movement improved after their EMDR session. Notably, the number of saccade intrusions-catch-up saccades (CUS)-decreased and, reciprocally, there was an increase in the smooth components of the pursuit. Such an increase in the smoothness of the pursuit presumably reflects an improvement in the use of visual attention needed to follow the target accurately. Perhaps EMDR reduces distress thereby activating a cholinergic effect known to improve ocular pursuit. |
Zoï Kapoula; Qing Yang; Marine Vernet; Benedicte Dieudonné; Sandrine Greffard; Marc Verny Spread deficits in initiation, speed and accuracy of horizontal and vertical automatic saccades in dementia with Lewy bodies Journal Article In: Frontiers in Neurology, vol. 1, pp. 138, 2010. @article{Kapoula2010, BACKGROUND: Mosimann et al. (2005) reported prolongation of saccade latency of prosaccades in dementia with Lewy body (DLB). The goal of this study is to go further examining all parameters, such as rates of express latency, but also accuracy and velocity of saccades, and their variability. METHODS: We examined horizontal and vertical saccades in 10 healthy elderly subjects and 10 patients with DLB. Two tasks were used: the gap (fixation target extinguishes prior to target onset) and the overlap (fixation stays on after target onset). Eye movements were recorded with the Eyelink II eye tracker. RESULTS: The main findings were: (1) as for healthy, latencies were shorter in the gap than in the overlap task (a gap effect); (2) for both tasks latency of saccades was longer for DLB patients and for all directions; (3) express latency in the gap task was absent for large majority of DLB patients while such saccades occurred frequency for controls; (4) accuracy and peak velocity were lower in DLB patients; (5) variability of all parameters was abnormally high in DLB patients.$backslash$ CONCLUSIONS: Abnormalities of all parameters, latency, accuracy and peak velocity reflect spread deficits in cortical-subcortical circuits involved in the triggering and execution of saccades. |
Mortier Karen; Wieske Zoest; Martijn Meeter; Jan Theeuwes Word cues affect detection but not localization responses Journal Article In: Attention, Perception, and Psychophysics, vol. 72, no. 1, pp. 65–75, 2010. @article{Karen2010, Many theories assume that pre-knowledge of an upcoming target helps visual selection. In those theories, a top-down set can alter the salience of the target, such that attention can be deployed to the target more efficiently and responses are faster. Evidence for this account stems from visual search studies in which the identity of the upcoming target is cued in advance. In five experiments, we show that top-down knowledge affects the speed with which a singleton target can be detected but not the speed with which it can be localized. Furthermore, we show that these results are independent of the mode of responding (manual or saccadic) and are not due to a ceiling effect. Our results suggest that in singleton search, top-down information does not affect visual selection but most likely does affect response selection. We argue that such an effect is found only when information from different dimensions needs to be integrated to generate a response and that this is the case in singleton detection tasks but not in other singleton search tasks. |
David J. Kelly; Sébastien Miellet; Roberto Caldara Culture shapes eye movements for visually homogeneous objects Journal Article In: Frontiers in Psychology, vol. 1, pp. 6, 2010. @article{Kelly2010, Culture affects the way people move their eyes to extract information in their visual world. Adults from Eastern societies (e.g., China) display a disposition to process information holistically, whereas individuals from Western societies (e.g., Britain) process information analytically. In terms of face processing, adults from Western cultures typically fixate the eyes and mouth, while adults from Eastern cultures fixate centrally on the nose region, yet face recognition accuracy is comparable across populations. A potential explanation for the observed differences relates to social norms concerning eye gaze avoidance/engagement when interacting with conspecifics. Furthermore, it has been argued that faces represent a 'special' stimulus category and are processed holistically, with the whole face processed as a single unit. The extent to which the holistic eye movement strategy deployed by East Asian observers is related to holistic processing for faces is undetermined. To investigate these hypotheses, we recorded eye movements of adults from Western and Eastern cultural backgrounds while learning and recognizing visually homogeneous objects: human faces, sheep faces and greebles. Both group of observers recognized faces better than any other visual category, as predicted by the specificity of faces. However, East Asian participants deployed central fixations across all the visual categories. This cultural perceptual strategy was not specific to faces, discarding any parallel between the eye movements of Easterners with the holistic processing specific to faces. Cultural diversity in the eye movements used to extract information from visual homogenous objects is rooted in more general and fundamental mechanisms. |
Simon P. Kelly; John J. Foxe; Geoffrey Newman; Jay A. Edelman Prepare for conflict: EEG correlates of the anticipation of target competition during overt and covert shifts of visual attention Journal Article In: European Journal of Neuroscience, vol. 31, no. 9, pp. 1690–1700, 2010. @article{Kelly2010a, When preparing to make a saccadic eye movement in a cued direction, perception of stimuli at the target location is enhanced, just as it is when attention is covertly deployed there. Accordingly, the timing and anatomical sources of preparatory brain activity accompanying shifts of covert attention and saccade preparation tend to exhibit a large degree of overlap. However, there is evidence that preparatory processes are modulated by the foreknowledge of visual distractor competition during covert attention, and it is unknown whether eye movement preparation undergoes equivalent modulation. Here we examine preparatory processes in the electroencephalogram of human participants during four blocked versions of a spatial cueing task, requiring either covert detection or saccade execution, and either containing a distractor or not. As in previous work, a typical pattern of spatially selective occipital, parietal and frontal activity was seen in all task versions. However, whereas distractor presence called on an enhancement of spatially selective visual cortical modulation during covert attention, it instead called on increased activity over frontomedial oculomotor areas in the case of overt saccade preparation. We conclude that, although advance orienting signals may be similar in character during overt and covert conditions, the pattern by which these signals are modulated to ameliorate the behavioral costs of distractor competition is highly distinct, pointing to a degree of separability between the overt and covert systems. |
Alon S. Keren; Shlomit Yuval-Greenberg; Leon Y. Deouell Saccadic spike potentials in gamma-band EEG : Characterization , detection and suppression Journal Article In: NeuroImage, vol. 49, no. 3, pp. 2248–2263, 2010. @article{Keren2010, Analysis of high-frequency (gamma-band) neural activity by means of non-invasive EEG is gaining increasing interest. However, we have recently shown that a saccade-related spike potential (SP) seriously confounds the analysis of EEG induced gamma-band responses (iGBR), as the SP eludes traditional EEG artifact rejection methods. Here we provide a comprehensive profile of the SP and evaluate methods for its detection and suppression, aiming to unveil true cerebral gamma-band activity. The SP appears consistently as a sharp biphasic deflection of about 22 ms starting at the saccade onset, with a frequency band of ∼ 20-90 Hz. On the average, larger saccades elicit higher SP amplitudes. The SP amplitude gradually changes from the extra-ocular channels towards posterior sites with the steepest gradients around the eyes, indicating its ocular source. Although the amplitude and the sign of the SP depend on the choice of reference channel, the potential gradients remain the same and non-zero for all references. The scalp topography is modulated almost exclusively by the direction of saccades, with steeper gradients ipsilateral to the saccade target. We discuss how the above characteristics impede attempts to remove these SPs from the EEG by common temporal filtering, choice of different references, or rejection of contaminated trials. We examine the extent to which SPs can be reliably detected without an eye tracker, assess the degree to which scalp current density derivation attenuates the effect of the SP, and propose a tailored ICA procedure for minimizing the effect of the SP. |
Dirk Kerzel; Sabine Born; David Souto Inhibition of steady-state smooth pursuit and catch-up saccades by abrupt visual and auditory Onsets Journal Article In: Journal of Neurophysiology, vol. 104, no. 5, pp. 2573–2585, 2010. @article{Kerzel2010, It is known that visual transients prolong saccadic latency and reduce saccadic frequency. The latter effect was attributed to subcortical structures because it occurred only 60-70 ms after stimulus onset. We examined the effects of large task-irrelevant transients on steady-state pursuit and the generation of catch-up saccades. Two screen-wide stripes of equal contrast (4, 20, or 100%) were briefly flashed at equal eccentricities (3, 6, or 12 degrees ) from the pursuit target. About 100 ms after flash onset, we observed that pursuit gain dropped by 6-12% and catch-up saccades were entirely suppressed. The relatively long latency of the inhibition suggests that it results from cortical mechanisms that may act by promoting fixation or the deployment of attention over the visual field. In addition, we show that a loud irrelevant sound is able to generate the same inhibition of saccades as visual transients, whereas it only induces a weak modulation of pursuit gain, indicating a privileged access of acoustic information to the saccadic system. Finally, irrelevant changes in motion direction orthogonal to pursuit had a smaller and later inhibitory effect. |
Stephanie A. H. Jones; Denise Y. P. Henriques Memory for proprioceptive and multisensory targets is partially coded relative to gaze Journal Article In: Neuropsychologia, vol. 48, no. 13, pp. 3782–3792, 2010. @article{Jones2010, We examined the effect of gaze direction relative to target location on reach endpoint errors made to proprioceptive and multisensory targets. We also explored if and how visual and proprioceptive information about target location are integrated to guide reaches. Participants reached to their unseen left hand in one of three target locations (left of body midline, body midline, or right or body midline), while it remained at a target site (online), or after it was removed from this location (remembered), and also after the target hand had been briefly lit before reaching (multisensory target). The target hand was guided to a target location using a robot-generated path. Reaches were made with the right hand in complete darkness, while gaze was varied in one of four eccentric directions. Horizontal reach errors systematically varied relative to gaze for all target modalities; not only for visually remembered and online proprioceptive targets as has been found in previous studies, but for the first time, also for remembered proprioceptive targets and proprioceptive targets that were briefly visible. These results suggest that the brain represents the locations of online and remembered proprioceptive reach targets, as well as visual-proprioceptive reach targets relative to gaze, along with other motor-related representations. Our results, however, do not suggest that visual and proprioceptive information are optimally integrated when coding the location of multisensory reach targets in this paradigm. |
Donatas Jonikaitis; Torsten Schubert; Heiner Deubel Preparing coordinated eye and hand movements: Dual-task costs are not attentional Journal Article In: Journal of Vision, vol. 10, no. 14, pp. 1–17, 2010. @article{Jonikaitis2010, Dual-task costs are observed when people perform two tasks at the same time. It has been suggested that these costs arise from limitations of movement goal selection when multiple goal-directed movements are made simultaneously. To investigate this, we asked participants to reach and look at different locations while we varied the time between the cues to start the eye and the hand movement between 150 ms and 900 ms. In Experiment 1, participants executed the reach first, and the saccade second, in Experiment 2 the order of the movements was reversed. We observed dual-task costs-participants were slower to start the eye or hand movement if they were planning another movement at that time. In Experiment 3, we investigated whether these dual-task costs were due to limited attentional resources needed to select saccade and reach goal locations. We found that the discrimination of a probe improved at both saccade and reach locations, indicating that attention shifted to both movement goals. Importantly, while we again observed the expected dual-task costs as reflected in movement latencies, there was no apparent delay of the associated attention shifts. Our results rule out attentional goal selection as the causal factor leading to the dual-task costs occurring in eye-hand movements. |
Johanna K. Kaakinen; Jukka Hyönä Task effects on eye movements during reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 36, no. 6, pp. 1561–1566, 2010. @article{Kaakinen2010, The present study examined how proofreading and reading-for-comprehension instructions influence eye movements during reading. Thirty-seven participants silently read sentences containing compound words as target words while their eye movements were being recorded. We manipulated word length and frequency to examine how task instructions influence orthographic versus lexical-semantic processing during reading. Task instructions influenced both temporal and spatial aspects of eye movements: The initial landing position in words was shifted leftward, the saccade length was shorter, first fixation and gaze duration were longer, and refixation probability was higher during proofreading than during reading for comprehension. Moreover, in comparison to instructions for reading for comprehension, proofreading instructions increased both orthographic and lexical-semantic processing. This became apparent in a greater word length and word frequency effect in gaze duration during proofreading than during reading for comprehension. The present study suggests that the allocation of attentional resources during reading is significantly modulated by task demands. |
Evgenia Kanonidou; Frank A. Proudlock; Irene Gottlob Reading strategies in mild to moderate strabismic amblyopia: An eye movement investigation Journal Article In: Investigative Ophthalmology & Visual Science, vol. 51, no. 7, pp. 3502–3508, 2010. @article{Kanonidou2010, PURPOSE. To investigate oculomotor strategies in strabismic amblyopia and evaluate abnormalities during monocular and binocular reading. METHODS. Eye movements were recorded with a head-mounted infrared video eye-tracker (250 Hz, <0.01 degrees resolution) in 20 strabismic amblyopes (mean age, 44.9 +/- 10.7 years) and 20 normal control subjects (mean age, 42.8 +/- 10.9 years) while they silently read paragraphs of text. Monocular reading comparisons were made between the amblyopic eye and the nondominant eye of control subjects and the nonamblyopic eye and the dominant eye of the control subjects. Binocular reading between the amblyopic and control subjects was also compared. RESULTS. Mean reading speed, number of progressive and regressive saccades per line, saccadic amplitude (of progressive saccades), and fixation duration were estimated. Inter- and intrasubject statistical comparisons were made. Reading speed was significantly slower in amblyopes than in control subjects during monocular reading with amblyopic (13.094 characters/s vs. 22.188 characters/s; P < 0.0001) and nonamblyopic eyes (16.241 characters/s vs. 22.349 characters/s, P < 0.0001), and binocularly (15.698 characters/s vs. 23.425 characters/s, P < 0.0001). In amblyopes, reading was significantly slower with the amblyopic eye than with the nonamblyopic eye in binocular viewing (P < 0.05). These differences were associated with significantly more regressive saccades and longer fixation durations, but not with changes in saccadic amplitudes. CONCLUSIONS. In strabismic amblyopia, reading is impaired, not only during monocular viewing with the amblyopic eye, but also with the nonamblyopic eye and binocularly, even though normal visual acuity pertains to the latter two conditions. The impaired reading performance is associated with differences in both the saccadic and fixational patterns, most likely as adaptation strategies to abnormal sensory experiences such as crowding and suppression. |
Yoni Pertzov; Ehud Zohary; Galia Avidan Rapid formation of spatiotopic representations as revealed by inhibition of return Journal Article In: Journal of Neuroscience, vol. 30, no. 26, pp. 8882–8887, 2010. @article{Pertzov2010, Inhibition of return (IOR), a performance decrement for stimuli appearing at recently cued locations, occurs when the target and cue share the same screen position. This is in contrast to cue-based attention facilitation effects that were recently suggested to be mapped in a retinotopic reference frame, the prevailing representation throughout early visual processing stages. Here, we investigate the dynamics of IOR in both reference frames, using a modified cued-location saccadic reaction time task with an intervening saccade between cue and target presentation. Thus, on different trials, the target was present either at the same retinotopic location as the cue, or at the same screen position (e.g., spatiotopic location). IOR was primarily found for targets appearing at the same spatiotopic position as the initial cue, when the cue and target were presented at the same hemifield. This suggests that there is restricted information transfer of cue position across the two hemispheres. Moreover, the effect was maximal when the target was presented 10 ms after the intervening saccade ended and was attenuated in longer delays. In our case, therefore, the representation of previously attended locations (as revealed by IOR) is not remapped slowly after the execution of a saccade. Rather, either a retinotopic representation is remapped rapidly, adjacent to the end of the saccade (using a prospective motor command), or the positions of the cue and target are encoded in a spatiotopic reference frame, regardless of eye position. Spatial attention can therefore be allocated to target positions defined in extraretinal coordinates. |
Martin J. Pickering; Brian Mcelree; Steven Frisson; Lillian Chen; Matthew J. Traxler Underspecification and aspectual coercion Journal Article In: Discourse Processes, vol. 42, no. 2, pp. 131–155, 2010. @article{Pickering2010, In principle, comprehenders might always make immediate commitments to the interpretation of expressions (full commitment) or wait until such decisions are necessary (minimal commitment; Frazier & Rayner, 1990). One interesting case involves decisions about telicity: whether expressions refer to events that are determinate versus indeterminate with respect to an endpoint. Thus, the insect hopped is apparently determinate, but continuing with a clause beginning with until, in which case hopped must be interpreted as an ongoing activity, is possible. Studies using secondary lexical decision and "stop-making-sense" tasks found that comprehenders experienced difficulty with these continuations, compatible with full commitment (Pinango, Zurif, & Jackendoff, 1999; Todorova, Straub, Badecker, & Frank, 2000a, 2000b). However, we report 2 self-paced reading and 2 eye-tracking experiments that indicate readers do not experience any difficulty with these types of mismatches in telicity. We argue that during normal reading, comprehenders do not immediately need to commit fully to the telicity of events and that full commitment may only occur when processing demands induce immediate decisions. We contrast these results with evidence for full commitment in complement coercions, for example, began the book (McElree, Traxler, Pickering, Seely, & Jackendoff, 2001) and other forms of semantic interpretation. |
Alexander Pollatsek; Denis Drieghe; Linnaea Stockall; Roberto G. Almeida The interpretation of ambiguous trimorphemic words in sentence context Journal Article In: Psychonomic Bulletin & Review, vol. 17, no. 1, pp. 88–94, 2010. @article{Pollatsek2010, Many trimorphemic words are structurally and semantically ambiguous. For example, unlockable can either be un-lockable (cannot be locked) or unlock-able (can be unlocked). Which interpretation is preferred and whether the preceding sentence context affects the initial interpretation is not clear from prior research. The present experiment embedded ambiguous trimorphemic words in sentence contexts, manipulated whether or not preceding context disambiguated the meaning, and examined the pattern of fixation durations on the ambiguous word and the remainder of the text. The results indicated that the unlock-able interpretation was preferred; moreover, preceding context did not exert a significant effect until the eyes had initially exited from the target word. |
B. Machner; C. Klein; Andreas Sprenger; P. Baumbach; P. P. Pramstaller; Christoph Helmchen; Wolfgang Heide Eye movement disorders are different in Parkin-linked and idiopathic early-onset PD Journal Article In: Neurology, vol. 75, pp. 125–128, 2010. @article{Machner2010, OBJECTIVES Parkin gene mutations are the most common cause of early-onset parkinsonism. Patients with Parkin mutations may be clinically indistinguishable from patients with idiopathic early-onset Parkinson disease (EOPD) without Parkin mutations. Eye movement disorders have been shown to differentiate parkinsonian syndromes, but have never been systematically studied in Parkin mutation carriers. METHODS Eye movements were recorded in symptomatic (n = 9) and asymptomatic Parkin mutation carriers (n = 13), patients with idiopathic EOPD (n = 14), and age-matched control subjects (n = 27) during established oculomotor tasks. RESULTS Both patients with EOPD and symptomatic Parkin mutation carriers showed hypometric prosaccades toward visual stimuli, as well as deficits in suppressing reflexive saccades toward unintended targets (antisaccade task). When directing gaze toward memorized target positions, patients with EOPD exhibited hypometric saccades, whereas symptomatic Parkin mutation carriers showed normal saccades. In contrast to patients with EOPD, the symptomatic Parkin mutation carriers showed impaired tracking of a moving target (reduced smooth pursuit gain). The asymptomatic Parkin mutation carriers did not differ from healthy control subjects in any of the tasks. CONCLUSIONS Although clinically similarly affected, symptomatic Parkin mutation carriers and patients with idiopathic EOPD differed in several oculomotor tasks. This finding may point to distinct anatomic structures underlying either condition: dysfunctions of cortical areas involved in smooth pursuit (V5, frontal eye field) in Parkin-linked parkinsonism vs greater impairment of basal ganglia circuits in idiopathic Parkinson disease. |
Kevin J. MacKenzie; David M. Hoffman; Simon J. Watt Accommodation to multiple-focal-plane displays: Implications for improving stereoscopic displays and for accommodation control Journal Article In: Journal of Vision, vol. 10, no. 8, pp. 1–22, 2010. @article{MacKenzie2010, Most stereoscopic displays present images at a single focal plane, resulting in "conflicts" between the stimuli to vergence and accommodation. Minimizing these conflicts is beneficial because they can cause distorted depth percepts, visual fatigue, and reduced stereoscopic performance. One proposed solution is to present a sum of images at multiple focal planes and to vary focal depth continuously by distributing image intensity across planes-a technique referred to as depth filtering. We evaluated this digital approximation to real-world variations in focal depth by measuring accommodation responses to depth-filtered stimuli at various simulated distances. Specifically, we determined the maximum image-plane separation that supported accurate and reliable accommodation. We used an analysis of retinal-image formation to predict when responses might be inaccurate. Accommodation to depth-filtered images was accurate and precise for image-plane separations up to ∼1 diopter, suggesting that depth filtering can be used to precisely match accommodation and vergence demands in a practical display. At larger plane separations, responses broke down in a manner consistent with our analysis. We develop this approach to consider how different spatial frequencies contribute to accommodation control. The results suggest that higher spatial frequencies contribute less to the accommodation response than has previously been thought. |
Vincenzo Maffei; Emiliano Macaluso; Iole Indovina; Guy A. Orban; Francesco Lacquaniti Processing of targets in smooth or apparent motion along the vertical in the human brain: An fMRI study Journal Article In: Journal of Neurophysiology, vol. 103, no. 1, pp. 360–370, 2010. @article{Maffei2010, Neural substrates for processing constant speed visual motion have been extensively studied. Less is known about the brain activity patterns when the target speed changes continuously, for instance under the influence of gravity. Using functional MRI (fMRI), here we compared brain responses to accelerating/decelerating targets with the responses to constant speed targets. The target could move along the vertical under gravity (1g), under reversed gravity (-1g), or at constant speed (0g). In the first experiment, subjects observed targets moving in smooth motion and responded to a GO signal delivered at a random time after target arrival. As expected, we found that the timing of the motor responses did not depend significantly on the specific motion law. Therefore brain activity in the contrast between different motion laws was not related to motor timing responses. Average BOLD signals were significantly greater for 1g targets than either 0g or -1g targets in a distributed network including bilateral insulae, left lingual gyrus, and brain stem. Moreover, in these regions, the mean activity decreased monotonically from 1g to 0g and to -1g. In the second experiment, subjects intercepted 1g, 0g, and -1g targets either in smooth motion (RM) or in long-range apparent motion (LAM). We found that the sites in the right insula and left lingual gyrus, which were selectively engaged by 1g targets in the first experiment, were also significantly more active during 1g trials than during -1g trials both in RM and LAM. The activity in 0g trials was again intermediate between that in 1g trials and that in -1g trials. Therefore in these regions the global activity modulation with the law of vertical motion appears to hold for both RM and LAM. Instead, a region in the inferior parietal lobule showed a preference for visual gravitational motion only in LAM but not RM. |
Alexander Maier; Geoffrey K. Adams; Christopher Aura; David A. Leopold Distinct superficial and deep laminar domains of activity in the visual cortex during rest and stimulation Journal Article In: Frontiers in Systems Neuroscience, vol. 4, pp. 1–11, 2010. @article{Maier2010, Spatial patterns of spontaneous neural activity at rest have previously been associated with specific networks in the brain, including those pertaining to the functional architecture of the primary visual cortex (V1). However, despite the prominent anatomical differences between cortical layers, little is known about the laminar pattern of spontaneous activity in V1. We address this topic by investigating the amplitude and coherence of ongoing local field potential (LFP) signals measured from different layers in V1 of macaque monkeys during rest and upon presentation of a visual stimulus. We used a linear microelectrode array to measure LFP signals at multiple, evenly spaced positions throughout the cortical thickness. Analyzing both the mean LFP amplitudes and between-contact LFP coherences, we identified two distinct zones of activity, roughly corresponding to superficial and deep layers, divided by a sharp transition near the bottom of layer 4. The LFP signals within each laminar zone were highly coherent, whereas those between zones were not. This functional compartmentalization was found not only during rest, but also when the receptive field was stimulated during a visual task. These results demonstrate the existence of distinct superficial and deep functional domains of coherent LFP activity in V1 that may reflect the intrinsic interplay of V1 microcircuitry with cortical and subcortical targets, respectively. |
Femke Maij; Eli Brenner; Hyung-Chul O. Li; Frans W. Cornelissen; Jeroen B. J. Smeets The use of the saccade target as a visual reference when localizing flashes during saccades Journal Article In: Journal of Vision, vol. 10, no. 4, pp. 1–9, 2010. @article{Maij2010, Flashes presented around the time of a saccade are often mislocalized. Such mislocalization is influenced by various factors. Here, we evaluate the role of the saccade target as a landmark when localizing flashes. The experiment was performed in a normally illuminated room to provide ample other visual references. Subjects were instructed to follow a randomly jumping target with their eyes. We flashed a black dot on the screen around the time of saccade onset. The subjects were asked to localize the black dot by touching the appropriate location on the screen. In a first experiment, the saccade target was displaced during the saccade. In a second experiment, it disappeared at different moments. Both manipulations affected the mislocalization. We conclude that our subjects' judgments are partly based on the flashed dot's position relative to the saccade target. |
George L. Malcolm; John M. Henderson Combining top-down processes to guide eye movements during real-world scene search Journal Article In: Journal of Vision, vol. 10, no. 2, pp. 1–11, 2010. @article{Malcolm2010, Eye movements can be guided by various types of information in real-world scenes. Here we investigated how the visual system combines multiple types of top-down information to facilitate search. We manipulated independently the specificity of the search target template and the usefulness of contextual constraint in an object search task. An eye tracker was used to segment search time into three behaviorally defined epochs so that influences on specific search processes could be identified. The results support previous studies indicating that the availability of either a specific target template or scene context facilitates search. The results also show that target template and contextual constraints combine additively in facilitating search. The results extend recent eye guidance models by suggesting the manner in which our visual system utilizes multiple types of top-down information. |
Debra Malpass; Antje S. Meyer The time course of name retrieval during multiple-object naming: Evidence from extrafoveal-on-foveal effects Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 36, no. 2, pp. 523–537, 2010. @article{Malpass2010, The goal of the study was to examine whether speakers naming pairs of objects would retrieve the names of the objects in parallel or in sequence. To this end, we recorded the speakers' eye movements and determined whether the difficulty of retrieving the name of the 2nd object affected the duration of the gazes to the 1st object. Two experiments, which differed in the spatial arrangement of the objects, showed that the speakers looked longer at the 1st object when the name of the 2nd object was easy than when it was more difficult to retrieve. Thus, the easy 2nd-object names interfered more with the processing of the 1st object than the more difficult 2nd-object names. In the 3rd experiment, the processing of the 1st object was rendered more difficult by presenting it upside down. No effect of 2nd-object difficulty on the gaze duration for the 1st object was found. These results suggest that speakers can retrieve the names of a foveated and an extrafoveal object in parallel, provided that the processing of the foveated object is not too demanding. |
Sabira K. Mannan; Christopher Kennard; Daniela Potter; Yi Pan; David Soto Early oculomotor capture by new onsets driven by the contents of working memory Journal Article In: Vision Research, vol. 50, no. 16, pp. 1590–1597, 2010. @article{Mannan2010, Oculomotor capture can occur automatically in a bottom-up way through the sudden appearance of a new object or in a top-down fashion when a stimulus in the array matches the contents of working memory. However, it is not clear whether or not working memory processing can influence the early stages of oculomotor capture by abrupt onsets. Here we present clear evidence for an early modulation driven by stimulus matches to the contents of working memory in the colour dimension. Interestingly, verbal as well as visual information in working memory influenced the direction of the fastest saccades made in search, saccadic latencies and the curvature of the scan paths made to the search target. This pattern of results arose even though the contents of working memory were detrimental for search, demonstrating an early, automatic top-down mediation of oculomotor onset capture by the contents of working memory. |
Jun Maruta; Minah Suh; Sumit N. Niogi; Pratik Mukherjee; Jamshid Ghajar Visual tracking synchronization as a metric for concussion screening Journal Article In: Journal of Head Trauma Rehabilitation, vol. 25, no. 4, pp. 293–305, 2010. @article{Maruta2010, Our goal was to determine whether performance variability during predictive visual tracking can provide a screening measure for mild traumatic brain injury (mTBI). Seventeen subjects with chronic postconcussive syndrome and 9 healthy control subjects were included in this study. Eye movements were recorded with video-oculography as the subject visually tracked a target that moved through a circular trajectory. We compared the variability of gaze positional errors relative to the target with the microstructural integrity of white matter tracts as measured by the fractional anisotropy (FA) parameter of diffusion tensor imaging. Gaze error variability was significantly correlated with the mean FA values of the right anterior corona radiata (ACR) and the left superior cerebellar peduncle, tracts that support spatial processing and sustenance of attention, and the genu of the corpus callosum. Because the ACR and the genu are among the most frequently damaged white matter tracts in mTBI, the correlations imply that gaze error variability during visual tracking may provide a useful screening tool for mTBI. Gaze error variability was also significantly correlated with attention and working memory measures in neurocognitive testing; thus, measurement of visual tracking performance is promising as a fast and practical screening tool for mTBI. |
Sebastiaan Mathôt; Jan Theeuwes Evidence for the predictive remapping of visual attention Journal Article In: Experimental Brain Research, vol. 200, no. 1, pp. 117–122, 2010. @article{Mathot2010, When attending an object in visual space, perception of the object remains stable despite frequent eye movements. It is assumed that visual stability is due to the process of remapping, in which retinotopically organized maps are updated to compensate for the retinal shifts caused by eye movements. Remapping is predictive when it starts before the actual eye movement. Until now, most evidence for predictive remapping has been obtained in single cell studies involving monkeys. Here, we report that predictive remapping affects visual attention prior to an eye movement. Immediately following a saccade, we show that attention has partly shifted with the saccade (Experiment 1). Importantly, we show that remapping is predictive and affects the locus of attention prior to saccade execution (Experiments 2 and 3): before the saccade was executed, there was attentional facilitation at the location which, after the saccade, would retinotopically match the attended location. |
Sebastiaan Mathôt; Jan Theeuwes Gradual remapping results in early retinotopic and late spatiotopic inhibition of return Journal Article In: Psychological Science, vol. 21, no. 12, pp. 1793–1798, 2010. @article{Mathot2010a, Here we report that immediately following the execution of an eye movement, oculomotor inhibition of return resides in retinotopic (eye-centered) coordinates. At longer postsaccadic intervals, inhibition resides in spatiotopic (world-centered) coordinates. These results are explained in terms of perisaccadic remapping. In the interval surrounding an eye movement, information is remapped within retinotopic maps to compensate for the retinal displacement. Because remapping is not an instantaneous process, a fast, but gradual, transfer of inhibition of return from retinotopic to spatiotopic coordinates can be observed in the postsaccadic interval. The observation that visual stability is preserved in inhibition of return is consistent with its function as a "foraging facilitator," which requires locations to be inhibited across multiple eye movements. The current results support the idea that the visual system is retinotopically organized and that the appearance of a spatiotopic organization is due to remapping of visual information to compensate for eye movements. |
Ellen Matthias; Peter Bublak; Hermann J. Muller; Werner X. Schneider; Joseph Krummenacher; Kathrin Finke The influence of alertness on spatial and nonspatial components of visual attention Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 36, pp. 38–56, 2010. @article{Matthias2010, Three experiments investigated whether spatial and nonspatial components of visual attention would be influenced by changes in (healthy, young) subjects' level of alertness and whether such effects on separable components would occur independently of each other. The experiments used a no-cue/alerting-cue design with varying cue-target stimulus onset asynchronies in two different whole-report paradigms based on Bundesen's (1990) theory of visual attention, which permits spatial and nonspatial components of selective attention to be assessed independently. The results revealed the level of alertness to affect both the spatial distribution of attentional weighting and processing speed, but not visual short-term memory capacity, with the effect on processing speed preceding that on the spatial distribution of attentional weighting. This pattern indicates that the level of alertness influences both spatial and nonspatial component mechanisms of visual attention and that these two effects develop independently of each other; moreover, it suggests that intrinsic and phasic alertness effects involve the same processing route, on which spatial and nonspatial mechanisms are mediated by independent processing systems that are activated, due to increased alertness, in temporal succession. |
Anna Ma-Wyatt; Martin Stritzke; Julia Trommershäuser Eye-hand coordination while pointing rapidly under risk Journal Article In: Experimental Brain Research, vol. 203, no. 1, pp. 131–145, 2010. @article{MaWyatt2010, Humans make rapid, goal-directed movements to interact with their environment. Saccadic eye movements usually accompany rapid hand movements, suggesting neural coupling, although it remains unclear what determines the strength of the coupling. Here, we present evidence that humans can alter eye-hand coordination in response to risk associated with endpoint variability. We used a paradigm in which human participants were forced to point rapidly under risk and were penalized or rewarded depending on the hand movement outcome. A separate reward schedule was employed for relative saccadic endpoint position. Participants received a monetary reward proportional to points won. We present a model that defines optimality of eye-hand coordination for this task depending on where the hand lands relative to the eye. A comparison of the results and model predictions showed that participants could optimize performance to maximize gain in some conditions, but not others. Participants produced near-optimal results when no feedback was given about relative saccade location and when negative feedback was provided for large distances between the saccade and hand. Participants were sub-optimal when given negative feedback for saccades very close to the hand endpoint. Our results suggest that eye-hand coordination is flexible when pointing rapidly under risk, but final eye position remains correlated with finger location. |
Bob Mcmurray; Vicki M. Samelson; Sung H. Lee; J. Bruce Tomblin Individual differences in spoken word recognition: A processing approach with implications for SLI Journal Article In: Cognitive Psychology, vol. 60, no. 1, pp. 1–39, 2010. @article{Mcmurray2010, Thirty years of research has uncovered the broad principles that characterize spoken word processing across listeners. However, there have been few systematic investigations of individual differences. Such an investigation could help refine models of word recognition by indicating which processing parameters are likely to vary, and could also have important implications for work on language impairment. The present study begins to fill this gap by relating individual differences in overall language ability to variation in online word recognition processes. Using the visual world paradigm, we evaluated online spoken word recognition in adolescents who varied in both basic language abilities and non-verbal cognitive abilities. Eye movements to target, cohort and rhyme objects were monitored during spoken word recognition, as an index of lexical activation. Adolescents with poor language skills showed fewer looks to the target and more fixations to the cohort and rhyme competitors. These results were compared to a number of variants of the TRACE model (McClelland & Elman, 1986) that were constructed to test a range of theoretical approaches to language impairment: impairments at sensory and phonological levels; vocabulary size, and generalized slowing. None of the existing approaches were strongly supported, and variation in lexical decay offered the best fit. Thus, basic word recognition processes like lexical decay may offer a new way to characterize processing differences in language impairment. |
Bob McMurray; Vicki M. Samelson; Sung Hee Lee; J. Bruce Tomblin Individual differences in online spoken word recognition: Implications for SLI Journal Article In: Cognitive Psychology, vol. 60, no. 1, pp. 1–39, 2010. @article{McMurray2010b, Thirty years of research has uncovered the broad principles that characterize spoken word processing across listeners. However, there have been few systematic investigations of individual differences. Such an investigation could help refine models of word recognition by indicating which processing parameters are likely to vary, and could also have important implications for work on language impairment. The present study begins to fill this gap by relating individual differences in overall language ability to variation in online word recognition processes. Using the visual world paradigm, we evaluated online spoken word recognition in adolescents who varied in both basic language abilities and non-verbal cognitive abilities. Eye movements to target, cohort and rhyme objects were monitored during spoken word recognition, as an index of lexical activation. Adolescents with poor language skills showed fewer looks to the target and more fixations to the cohort and rhyme competitors. These results were compared to a number of variants of the TRACE model (McClelland & Elman, 1986) that were constructed to test a range of theoretical approaches to language impairment: impairments at sensory and phonological levels; vocabulary size, and generalized slowing. None of the existing approaches were strongly supported, and variation in lexical decay offered the best fit. Thus, basic word recognition processes like lexical decay may offer a new way to characterize processing differences in language impairment. |
Eugene McSorley; Alice G. Cruickshank Evidence that indirect inhibition of saccade initiation improves saccade accuracy Journal Article In: i-Perception, vol. 1, no. 2, pp. 73–82, 2010. @article{McSorley2010, Saccadic eye-movements to a visual target are less accurate if there are distracters close to its location (local distracters). The addition of more distracters, remote from the target location (remote distracters), invokes an involuntary increase in the response latency of the saccade and attenuates the effect of local distracters on accuracy. This may be due to the target and distracters directly competing (direct route) or to the remote distracters acting to impair the ability to disengage from fixation (indirect route). To distinguish between these we examined the development of saccade competition by recording saccade latency and accuracy responses made to a target and local distracter compared with those made with an addition of a remote distracter. The direct route would predict that the remote distracter impacts on the developing competition between target and local distracter, while the indirect route would predict no change as the accuracy benefit here derives from accessing the same competitive process but at a later stage. We found that the presence of the remote distracter did not change the pattern of accuracy improvement. This suggests that the remote distracter was acting along an indirect route that inhibits disengagement from fixation, slows saccade initiation, and enables more accurate saccades to be made. |
Alexander Pastukhov; Jochen Braun Rare but precious: Microsaccades are highly informative about attentional allocation Journal Article In: Vision Research, vol. 50, no. 12, pp. 1173–1184, 2010. @article{Pastukhov2010, To clarify the relation between attention and microsaccades, we monitored microsaccades while observers performed tasks with different attentional demand. In four high-demand conditions, observers shifted attention covertly to a peripheral location, or focused attention at fixation. Three corresponding low-demand conditions on physically identical displays provided a basis for comparison. Our results revealed two distinct effects of attentional load: higher loads were associated consistently with lower microsaccade rates, but also with increased directional selectivity (up to 98% congruent). In short, when microsaccades were most rare, the direction of microsaccades proved most informative about the location of the attention focus. The detailed time-courses of the two effects differed, however, suggesting that they may reflect independent processes. |
Andrea L. Patalano; Barbara J. Juhasz; Joanna Dicke The relationship between indecisiveness and eye movement patterns in a decision making informational search task Journal Article In: Journal of Behavioral Decision Making, vol. 23, pp. 353–368, 2010. @article{Patalano2010, Indecisiveness is a trait-related general tendency to experience decision difficulties across a variety of situations, leading to decision delay, worry, and regret. Indecisive- ness is proposed (Rassin, 2007) to be associated with an increase in desire for information acquisition and reliance on compensatory strategies—as evidenced by alternative-based information search—during decision making. However existing studies provide conflicting findings. We conducted an information board study of indecisiveness, using eye tracking methodology, to test the hypotheses that the relationship between indecisiveness and choice strategy depends on being in the early stage of the decision making process, and that it depends on being in the presence of an opportunity to delay choice. We found strong evidence for the first hypothesis in that indecisive individuals changed shift behavior from the first to the second half of the task, consistent with a move from greater to lesser compensatory processing, while the shift behavior of decisive individuals suggested lesser compensatory processing over the whole task. Indecisiveness was also related to time spent viewing attributes of the selected course, and to time spent looking away from decision information. These findings resolve past discrepancies, suggest an interesting account of how the decision process unfolds for indecisive versus decisive individuals, and contribute to a better understanding of this tendency. |
Elena G. Patsenko; Erik M. Altmann How planful is routine behavior? A selective-attention model of performance in the Tower of Hanoi Journal Article In: Journal of Experimental Psychology: General, vol. 139, no. 1, pp. 95–116, 2010. @article{Patsenko2010, Routine human behavior has often been attributed to plans-mental representations of sequences goals and actions-but can also be attributed to more opportunistic interactions of mind and a structured environment. This study asks whether performance on a task traditionally analyzed in terms of plans can be better understood from a "situated" (or "embodied") perspective. A saccade-contingent display-updating paradigm is used to change the environment by adding, deleting, and moving task-relevant objects without participants' direct awareness. Response latencies, action patterns, and eye movements all indicate that performance is guided not by plans stored in memory but by a control routine bound to objects as needed by perception and selective attention. The results have implications for interpreting everyday task performance and particular neuropsychological deficits. |
Nikole D. Patson; Tessa Warren Eye movements when reading implausible sentences: Investigating potential structural influences on semantic integration Journal Article In: Quarterly Journal of Experimental Psychology, vol. 63, no. 8, pp. 1516–1532, 2010. @article{Patson2010, The disruption that occurs in response to reading about implausible events in unambiguous sentences can be informative about the time course of semantic interpretation (e.g. Hagoort, Hald, Bastiaansen, & Petersson, 2004; Nieuwland & Van Berkum, 2006; Warren & McConnell, 2007). Two eye-tracking studies used implausible sentences to investigate whether local factors like the structural relationships and the distance between words cueing a plausibility violation influence how quickly those words are integrated into a global semantic interpretation. Experiment 1 suggested that eye-movement disruption was unaffected by the number of words intervening between the words cueing the implausibility. Experiment 2 demonstrated that eye-movement disruption to implausibility occurred along the same time course regardless of whether the words cueing the implausibility were in a theta-assigning relation or not. These results suggest that these local structural factors do not influence how quickly new words are integrated into a semantic representation, but rather the global event representation determines the time course over which implausibility is detected. |
John M. Pearson; Benjamin Y. Hayden; Michael L. Platt Explicit information reduces discounting behavior in monkeys Journal Article In: Frontiers in Psychology, vol. 1, pp. 237, 2010. @article{Pearson2010, Animals are notoriously impulsive in common laboratory experiments, preferring smaller, sooner rewards to larger, delayed rewards even when this reduces average reward rates. By contrast, the same animals often engage in natural behaviors that require extreme patience, such as food caching, stalking prey, and traveling long distances to high-quality food sites. One possible explanation for this discrepancy is that standard laboratory delay discounting tasks artificially inflate impulsivity by subverting animals' common learning strategies. To test this idea, we examined choices made by rhesus macaques in two variants of a standard delay discounting task. In the conventional variant, post-reward delays were uncued and adjusted to render total trial length constant; in the second, all delays were cued explicitly. We found that measured discounting was significantly reduced in the cued task, with discount parameters well below those reported in studies using the standard uncued design. When monkeys had complete information, their decisions were more consistent with a strategy of reward rate maximization. These results indicate that monkeys, and perhaps other animals, are more patient than is normally assumed, and that laboratory measures of delay discounting may overstate impulsivity. |
Erik D. Reichle; Andrew E. Reineberg; Jonathan W. Schooler Eye movements during mindless reading Journal Article In: Psychological Science, vol. 21, no. 9, pp. 1300–1310, 2010. @article{Reichle2010, Mindless reading occurs when the eyes continue moving across the page even though the mind is thinking about something unrelated to the text. Despite how commonly it occurs, very little is known about mindless reading. The present experiment examined eye movements during mindless reading. Comparisons of fixation-duration measures collected during intervals of normal reading and intervals of mindless reading indicate that fixations during the latter were longer and less affected by lexical and linguistic variables than fixations during the former. Also, eye movements immediately preceding self-caught mind wandering were especially erratic. These results suggest that the cognitive processes that guide eye movements during normal reading are not engaged during mindless reading. We discuss the implications of these findings for theories of eye movement control in reading, for the distinction between experiential awareness and meta-awareness, and for reading comprehension. |
Eyal M. Reingold; Jinmian Yang; Keith Rayner The time course of word frequency and case alternation effects on fixation times in reading: Evidence for lexical control of eye movements Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 36, no. 6, pp. 1677–1683, 2010. @article{Reingold2010, Participants' eye movements were monitored while they read sentences in which high-frequency and low-frequency target words were presented either in normal font (e.g., account) or case alternated (e.g., aCcOuNt). The influence of the word frequency and case alternation manipulations on fixation times was examined. Although both manipulations had comparable effects on standard first-pass fixation measures, word frequency, but not case alternation was found to influence the duration of the first fixation in trials with multiple first-pass fixations. Assuming that lexical processing is more often incomplete at the termination of the first in multiple first-pass fixations than at the end of single first-pass fixations, the present findings provide strong evidence for an influence of word frequency on early lexical processing. Importantly, such a demonstration of a fast acting influence of a lexical variable on fixation times satisfies a critical prerequisite for establishing lexical control of eye movements in reading. |
Eva Reinisch; Alexandra Jesse; James M. McQueen Early use of phonetic information in spoken word recognition: Lexical stress drives eye movements immediately Journal Article In: Quarterly Journal of Experimental Psychology, vol. 63, no. 4, pp. 772–783, 2010. @article{Reinisch2010, For optimal word recognition listeners should use all relevant acoustic information as soon as it comes available. Using printed-word eye tracking we investigated when during word processing Dutch listeners use suprasegmental lexical stress information to recognize words. Fixations on targets such as "OCtopus" (capitals indicate stress) were more frequent than fixations on segmentally overlapping but differently stressed competitors ("okTOber") before segmental information could disambiguate the words. Furthermore, prior to segmental disambiguation, initially stressed words were stronger lexical competitors than noninitially stressed words. Listeners recognize words by immediately using all relevant information in the speech signal. |
Gui Qin Ren; Yufang Yang Syntactic boundaries and comma placement during silent reading of Chinese text: Evidence from eye movements Journal Article In: Journal of Research in Reading, vol. 33, no. 2, pp. 168–177, 2010. @article{Ren2010, In an eye-tracking experiment, we investigated whether and how a comma influences the reading of Chinese sentences comprised of different types of syntactic constituent such as word, phrase and clause. Participants read Chinese sentences that did or did not insert a comma at the end of a syntactic constituent. The results showed that the fixation times were shorter for the target word followed by a comma than for that followed by no comma, which suggests that a comma facilitated word identification during the reading of Chinese sentences. Furthermore, the insertion of commas shortened the total fixation times in the post-target region only for the clause condition. The data are consistent with previous findings concerning the role of segmentation cues in reading, and compatible with the implicit prosody hypothesis. |
Brian A. Richardson; Ramesh Balasubramaniam The effect of entrainment on the timing of periodic eye movements Journal Article In: Neuroscience Letters, vol. 469, no. 1, pp. 117–121, 2010. @article{Richardson2010, We performed an experiment in which eight healthy individuals made periodic eye movements at five pacing interval conditions (500 ms, 750 ms, 1000 ms, 1250 ms, and 1500 ms). Three methods of entrainment were used in the synchronization phase: saccade, continuous pursuit and discontinuous pursuit. The stimulus train was extinguished and in the continuation phase, subjects made saccadic eye movements at the entrained movement frequencies between two static targets. Using the Wing-Kristofferson model, clock and motor variance were extracted from the time series of continuation trials for all three entrainment conditions. Our results revealed a main effect of time interval on total variance clock variance (as predicted by Weber's law) and on motor variance. We also report that the pursuit entrainment conditions resulted in and mean duration and variance to the saccade entrainment. These results suggest that the neural networks recruited to support a periodic motor timing task depend on the method used to establish the temporal reference. |
Lee Richstone; Michael J. Schwartz; Casey Seideman; Jeffrey Cadeddu; Sandra P. Marshall; Louis R. Kavoussi Eye metrics as an objective assessment of surgical skill Journal Article In: Annals of Surgery, vol. 252, no. 1, pp. 177–182, 2010. @article{Richstone2010, OBJECTIVE: Currently, surgical skills assessment relies almost exclusively on subjective measures, which are susceptible to multiple biases. We investigate the use of eye metrics as an objective tool for assessment of surgical skill. SUMMARY BACKGROUND DATA: Eye tracking has helped elucidate relationships between eye movements, visual attention, and insight, all of which are employed during complex task performance (Kowler and Martins, Science. 1982;215:997-999; Tanenhaus et al, Science. 1995;268:1632-1634; Thomas and Lleras, Psychon Bull Rev. 2007;14:663-668; Thomas and Lleras, Cognition. 2009;111:168-174; Schriver et al, Hum Factors. 2008;50:864-878; Kahneman, Attention and Effort. 1973). Discovery of associations between characteristic eye movements and degree of cognitive effort have also enhanced our appreciation of the learning process. METHODS: Using linear discriminate analysis (LDA) and nonlinear neural network analyses (NNA) to classify surgeons into expert and nonexpert cohorts, we examine the relationship between complex eye and pupillary movements, collectively referred to as eye metrics, and surgical skill level. RESULTS: Twenty-one surgeons participated in the simulated and live surgical environments. In the simulated surgical setting, LDA and NNA were able to correctly classify surgeons as expert or nonexpert with 91.9% and 92.9% accuracy, respectively. In the live operating room setting, LDA and NNA were able to correctly classify surgeons as expert or nonexpert with 81.0% and 90.7% accuracy, respectively. CONCLUSIONS: We demonstrate, in simulated and live-operating environments, that eye metrics can reliably distinguish nonexpert from expert surgeons. As current medical educators rely on subjective measures of surgical skill, eye metrics may serve as the basis for objective assessment in surgical education and credentialing in the future. Further development of this potential educational tool is warranted to assess its ability to both reliably classify larger groups of surgeons and follow progression of surgical skill during postgraduate training. |
Fabian Schnier; Eckart Zimmermann; Markus Lappe Adaptation and mislocalization fields for saccadic outward adaptation in humans Journal Article In: Journal of Eye Movement Research, vol. 3, no. 3, pp. 1–18, 2010. @article{Schnier2010, Adaptive shortening of a saccade influences the metrics of other saccades within a spatial window around the adapted target. Within this adaptation field visual stimuli presented before an adapted saccade are mislocalized in proportion to the change of the saccade metric. We investigated the saccadic adaptation field and associated localization changes for saccade lengthening, or outward adaptation. We measured the adaptation field for two different saccade adaptations (14 deg to 20 deg and 20 deg to 26 deg) by testing transfer to 34 different target positions. We measured localization judgements by asking subjects to localize a probe flashed before saccade onset. The amount of adaptation transfer differed for different target locations. It increased with increases of the horizontal component of the saccade and remained largely constant with deviation of the vertical component of the saccade. Mislocalization of probes inside the adaptation field was correlated with the amount of adaptation of saccades to the probe location. These findings are consistent with the assumption that oculomotor space and perceptual space are linked to each other. |
Elizabeth R. Schotter; Raymond W. Berry; Craig R. M. McKenzie; Keith Rayner Gaze bias: Selective encoding and liking effects Journal Article In: Visual Cognition, vol. 18, no. 8, pp. 1113–1132, 2010. @article{Schotter2010, People look longer at things that they choose than things they do not choose. How much of this tendency—the gaze bias effect—is due to a liking effect compared to the information encoding aspect of the decision-making process? Do these processes compete under certain conditions? We monitored eye movements during a visual decision-making task with four decision prompts: Like, dislike, older, and newer. The gaze bias effect was present during the first dwell in all conditions except the dislike condition, when the preference to look at the liked item and the goal to identify the disliked item compete. Colour content (whether a photograph was colour or black-and-white), not decision type, influenced the gaze bias effect in the older/newer decisions because colour is a relevant feature for such decisions. These interactions appear early in the eye movement record, indicating that gaze bias is influenced during information encoding. |
Alexander C. Schütz; Doris I. Braun; J. Anthony Movshon; Karl R. Gegenfurtner Does the noise matter? Effects of different kinematogram types on smooth pursuit eye movements and perception Journal Article In: Journal of Vision, vol. 10, no. 13, pp. 1–22, 2010. @article{Schuetz2010a, We investigated how the human visual system and the pursuit system react to visual motion noise. We presented three different types of random-dot kinematograms at five different coherence levels. For transparent motion, the signal and noise labels on each dot were preserved throughout each trial, and noise dots moved with the same speed as the signal dots but in fixed random directions. For white noise motion, every 20 ms the signal and noise labels were randomly assigned to each dot and noise dots appeared at random positions. For Brownian motion, signal and noise labels were also randomly assigned, but the noise dots moved at the signal speed in a direction that varied randomly from moment to moment. Neither pursuit latency nor early eye acceleration differed among the different types of kinematograms. Late acceleration, pursuit gain, and perceived speed all depended on kinematogram type, with good agreement between pursuit gain and perceived speed. For transparent motion, pursuit gain and perceived speed were independent of coherence level. For white and Brownian motions, pursuit gain and perceived speed increased with coherence but were higher for white than for Brownian motion. This suggests that under our conditions, the pursuit system integrates across all directions of motion but not across all speeds. |
Alexander C. Schütz; M. Concetta Morrone Compression of time during smooth pursuit eye movements Journal Article In: Vision Research, vol. 50, no. 24, pp. 2702–2713, 2010. @article{Schuetz2010, Humans have a clear sense for the passage of time, but while implicit motor timing is quite accurate, explicit timing is prone to distortions particularly during action (Wenke & Haggard, 2009) and saccadic eye movements (Morrone, Ross, & Burr, 2005). Here, we investigated whether perceived duration is also affected by the execution of smooth pursuit eye movements, showing a compression of apparent duration similar to that observed during saccades. To this end, we presented two brief bars that marked intervals between 100 and 300 ms and asked subjects to judge their duration during fixation and pursuit. We found a compression of perceived duration for bars modulated in luminance contrast of about 32% and for bars modulated in chromatic contrast of 14% during pursuit compared to fixation. Interestingly, Weber ratios were similar for fixation and pursuit, if they are expressed as ratio between JND and perceived duration. This compression was constant for pursuit speeds from 7 to 14 deg/s and did not occur for intervals marked by auditory events. These results argue for a modality-specific component in the processing of temporal information. |
Christopher R. Sears; Charmaine L. Thomas; Jessica M. Lehuquet; Jeremy C. S. Johnson Attentional biases in dysphoria: An eye-tracking study of the allocation and disengagement of attention Journal Article In: Cognition and Emotion, vol. 24, no. 8, pp. 1349–1368, 2010. @article{Sears2010, This study looked for evidence of biases in the allocation and disengagement of attention in dysphoric individuals. Participants studied images for a recognition memory test while their eye fixations were tracked and recorded. Four image types were presented (depression-related, anxiety- related, positive, neutral) in each of two study conditions. For the simultaneous study condition, four images (one of each type) were presented simultaneously for 10 seconds, and the number of fixations and the total fixation time to each image was measured, similar to the procedure used by Eizenman et al. (2003) and Kellough, Beevers, Ellis, and Wells (2008). For the sequential study condition, four images (one of each type) were presented consecutively, each for 4 seconds; to measure disengagement of attention an endogenous cuing procedure was used (Posner, 1980). Dysphoric individuals spent significantly less time attending to positive images than non-dysphoric individuals, but there were no group differences in attention to depression-related images. There was also no evidence of a dysphoria-related bias in initial shifts of attention. With respect to the disengagement of attention, dysphoric individuals were slower to disengage their attention from depression-related images. The recognition memory data showed that dysphoric individuals had poorer memory for emotional images, but there was no evidence of a conventional mood-congruent memory bias. Differences in the attentional and memory biases observed in depressed and dysphoric individuals are discussed. |
Gerardo Cepeda Porras; Yann Gaël Guéhéneuc An empirical study on the efficiency of different design pattern representations in UML class diagrams Journal Article In: Empirical Software Engineering, vol. 15, no. 5, pp. 493–522, 2010. @article{Porras2010, Design patterns are recognized in the software engineering community as useful solutions to recurring design problems that improve the quality of programs. They are more and more used by developers in the design and implementation of their programs. Therefore, the visualization of the design patterns used in a program could be useful to efficiently understand how it works. Currently, a common representation to visualize design patterns is the UML collaboration notation. Previous work noticed some limitations in the UML representation and proposed new representations to tackle these limitations. However, none of these pieces of work conducted empirical studies to compare their new representations with the UML representation. We designed and conducted an empirical study to collect data on the performance of developers on basic tasks related to design pattern comprehension (i.e., identifying composition, role, participation) to evaluate the impact of three visual representations and to compare them with the UML one. We used eye-trackers to measure the developers' effort during the execution of the study. Collected data and their analyses show that stereotype-enhanced UML diagrams are more efficient for identifying composition and role than the UML collaboration notation. The UML representation and the pattern-enhanced class diagrams are more efficient for locating the classes participating in a design pattern (i.e., identifying participation). |
Gillian Porter; Ute Leonards; Gordon Wilcock; Judy Haworth; Tom Troscianko; Andrea Tales New insights into feature and conjunction search: II. Evidence from Alzheimer's disease Journal Article In: Cortex, vol. 46, no. 5, pp. 637–649, 2010. @article{Porter2010, Deficits in inefficient visual search task performance in Alzheimer's disease (AD) have been linked both to a general depletion of attentional resources and to a specific difficulty in performing conjunction discriminations. It has been difficult to examine the latter proposal because the uniqueness of conjunction search as compared to other visual search tasks has remained a matter of debate. We explored both these claims by measuring pupil dilation, as a measure of resource application, while patients with AD performed a conjunction search task and two single-feature search tasks of similar difficulty in healthy individuals. Maximum pupil dilation in the AD group was greater during performance of the conjunction than the feature search tasks, although pupil response was indistinguishable for the three tasks in healthy controls. This, together with patients' false positive errors for the conjunction task, indicates an AD-specific deficit impacting upon the ability to combine information on multiple dimensions. In addition, maximum pupil dilation was no less for patients than the control group during task performance, which tends to oppose the concept of general resource depletion in AD. However, eye movement patterns in the patient group indicated that they were less able than controls to use organised strategies to assist with task performance. The data are therefore in keeping with a loss of access to resource-saving strategies, rather than a loss of resources per se, in AD. Moreover they demonstrate an additional processing mechanism in performing conjunction search compared with inefficient single-feature search. |
Gillian Porter; Andrea Tales; Ute Leonards What makes cast shadows hard to see? Journal Article In: Journal of Vision, vol. 10, no. 3, pp. 1–18, 2010. @article{Porter2010a, Visual search is slowed for cast shadows lit from above, as compared to the same search items inverted and so not interpreted as shadows (R. A. Rensink & P. Cavanagh, 2004). The underlying mechanisms for such impaired shadow processing are still not understood. Here we investigated the processing levels at which this shadow-related slowing might operate, by examining its interaction with a range of different phenomena including eye movements, perceptual learning, and stimulus presentation context. The data demonstrated that the shadow mechanism affects the number of saccades during the search rather than the duration until first saccade onset and can be overridden by prolonged training, which then transfers from one type of shadow stimulus to another. Shadow-related slowing did not differ for peripheral and central search items but was reduced when participants searched unilateral displays as compared to bilateral ones. Together our findings suggest that difficulties with perceiving shadows are due to visual processes linked to object recognition, rather than to shadow-specific identification and suppression mechanisms in low-level sensory visual areas. Findings are discussed in the context of the need for the visual system to distinguish between illumination and material. |
Gillian Porter; Andrea Tales; Tom Troscianko; Gordon Wilcock; Judy Haworth; Ute Leonards New insights into feature and conjunction search: I. Evidence from pupil size, eye movements and ageing Journal Article In: Cortex, vol. 46, no. 5, pp. 621–636, 2010. @article{Porter2010c, Differences in the processing mechanisms underlying visual feature and conjunction search are still under debate, one problem being a common emphasis on performance measures (speed and accuracy) which do not necessarily provide insights to the underlying processing principles. Here, eye movements and pupil dilation were used to investigate sampling strategy and processing load during performance of a conjunction and two feature-search tasks, with younger (18-27 years) and healthy older (61-83 years) age groups compared for evidence of differential age-related changes. The tasks involved equivalent processing time per item, were controlled in terms of target-distractor similarity, and did not allow perceptual grouping. Close matching of the key tasks was confirmed by patterns of fixation duration and an equal number of saccades required to find a target. Moreover, moment-to-moment pupillary dilation was indistinguishable across the tasks for both age groups, suggesting that all required the same total amount of effort or resources.Despite matching, subtle differences in eye movement patterns occurred between tasks: the conjunction task required more saccades to reach a target-absent decision and involved shorter saccade amplitudes than the feature tasks. General age-related changes were manifested in an increased number of saccades and longer fixation durations in older than younger participants. In addition, older people showed disproportionately longer and more variable fixation durations for the conjunction task specifically. These results suggest a fundamental difference between conjunction and feature search: accurate target identification in the conjunction context requires more conservative eye movement patterns, with these further adjusted in healthy ageing. The data also highlight the independence of eye movement and pupillometry measures and stress the importance of saccades and strategy for understanding the processing mechanisms driving different types of visual search. |
Melanie A. Porter; Tracey A. Shaw; Pamela J. Marsh An unusual attraction to the eyes in Williams-Beuren syndrome: A manipulation of facial affect while measuring face scanpaths Journal Article In: Cognitive Neuropsychiatry, vol. 15, no. 6, pp. 505–530, 2010. @article{Porter2010b, INTRODUCTION: This study aimed to investigate face scanpaths and emotion recognition in Williams-Beuren syndrome (WBS) and whether: (1) the eyes capture the attention of WBS individuals faster than typically developing mental age-matched controls; (2) WBS patients spend abnormally prolonged periods of time viewing the eye region; and (3) emotion recognition skills or eye gaze patterns change depending on the emotional valance of the face. METHODS: Visual scanpaths were recorded while 16 WBS patients and 16 controls passively viewed happy, angry, fearful, and neutral faces. Emotion recognition was subsequently measured. RESULTS: The eyes did not capture the attention of WBS patients faster than controls, but once WBS patients attended to the eyes, they spent significantly more time looking at this region. Unexpectedly, WBS patients showed an impaired ability to recognise angry faces, but face scanpaths were similar across the different facial expressions. CONCLUSIONS: Findings suggest that face processing is atypical in WBS and that emotion recognition and eye gaze abnormalities in WBS are likely to be more complex than previously thought. Findings highlight the need to develop remediation programmes to teach WBS patients how to explore all facial features, enhancing their emotion recognition skills and "normalising" their social interactions. |
Steven L. Prime; Michael Vesia; J. Douglas Crawford TMS over human frontal eye fields disrupts trans-saccadic memory of multiple objects Journal Article In: Cerebral Cortex, vol. 20, no. 4, pp. 759–772, 2010. @article{Prime2010, We recently showed that transcranial magnetic stimulation (TMS) over the right parietal eye fields disrupts memory of object features and locations across saccades. We applied TMS over the frontal eye fields (FEF) as subjects compared the feature details of visual targets presented either within a single eye fixation (Fixation Task) or across a saccade (Saccade Task). TMS pulses were randomly delivered at one of 3 time intervals around the time of the saccade, or at equivalent times in the Fixation Task. A No-TMS control confirmed that subjects could normally retain approximately 3 visual features. TMS in the Fixation Task had no effect compared with No-TMS, but differences among TMS times were found during right FEF stimulation. TMS over either the right or left FEF disrupted memory performance in the Saccade Task when stimulation coincided most closely with the saccade. The capacity to compare pre-and postsaccadic features was reduced to 1-2 objects, as expected if the spatial aspect of memory was disrupted. These findings suggest that the FEF plays a role in the spatial processing involved in trans-saccadic memory of visual features. We propose that this process employs saccade-related feedback signals similar to those observed in spatial updating. |
Claudio M. Privitera; Laura W. Renninger; Thom Carney; Stanley A. Klein; Mario Aguilar Pupil dilation during visual target detection Journal Article In: Journal of Vision, vol. 10, no. 10, pp. 1–14, 2010. @article{Privitera2010, It has long been documented that emotional and sensory events elicit a pupillary dilation. Is the pupil response a reliable marker of a visual detection event while viewing complex imagery? In two experiments where viewers were asked to report the presence of a visual target during rapid serial visual presentation (RSVP), pupil dilation was significantly associated with target detection. The amplitude of the dilation depended on the frequency of targets and the time of target presentation relative to the start of the trial. Larger dilations were associated with trials having fewer targets and with targets viewed earlier in the run. We found that dilation was influenced by, but not dependent on, the requirement of a button press. Interestingly, we also found that dilation occurred when viewers fixated a target but did not report seeing it. We will briefly discuss the role of noradrenaline in mediating these pupil behaviors. |
Pirita Pyykkönen; Jukka Hyönä; Roger P. G. Van Gompel Activating gender stereotypes during online spoken language processing: Evidence from visual world eye tracking Journal Article In: Experimental Psychology, vol. 57, no. 2, pp. 126–133, 2010. @article{Pyykkoenen2010a, This study used the visual world eye-tracking method to investigate activation of general world knowledge related to gender-stereotypical role names in online spoken language comprehension in Finnish. The results showed that listeners activated gender stereotypes elaboratively in story contexts where this information was not needed to build coherence. Furthermore, listeners made additional inferences based on gender stereotypes to revise an already established coherence relation. Both results are consistent with mental models theory (e.g., Garnham, 2001). They are harder to explain by the minimalist account (McKoon & Ratcliff, 1992) which suggests that people limit inferences to those needed to establish coherence in discourse. |
Pirita Pyykkönen; Juhani Jarvikivi Activation and persistence of implicit causality information in spoken language comprehension Journal Article In: Experimental Psychology, vol. 57, no. 1, pp. 5–16, 2010. @article{Pyykkoenen2010, A visual world eye-tracking study investigated the activation and persistence of implicit causality information in spoken language comprehension. We showed that people infer the implicit causality of verbs as soon as they encounter such verbs in discourse, as is predicted by proponents of the immediate focusing account (Greene & McKoon, 1995; Koornneef & Van Berkum, 2006; Van Berkum, Koornneef, Otten, & Nieuwland, 2007). Interestingly, we observed activation of implicit causality information even before people encountered the causal conjunction. However, while implicit causality information was persistent as the discourse unfolded, it did not have a privileged role as a focusing cue immediately at the ambiguous pronoun when people were resolving its antecedent. Instead, our study indicated that implicit causality does not affect all referents to the same extent, rather it interacts with other cues in the discourse, especially when one of the referents is already prominently in focus. |
Pia Rämä; Thierry Baccino Eye fixation-related potentials (EFRPs) during object identification Journal Article In: Visual Neuroscience, vol. 27, no. 5-6, pp. 187–192, 2010. @article{Raemae2010, Eye fixation-related potential (EFRP) measures electrical brain activity in response to eye fixations. The aim of the current study was to investigate whether the EFRPs vary during consecutive eye fixations while subjects were performing an object identification task. Eye fixations evoked P1 and N1 components at the occipital and parietal recording sites. The latency of P1 component increased during consecutive fixations. The amplitude of P1 increased and the amplitude of N1 decreased during consecutive fixations. The results indicate that EFRPs are modulated during consecutive fixations, suggesting that the current technique may provide a useful tool to study temporal dynamics of visual perception and processes underlying object identification. |
Christoph Rasche; Karl R. Gegenfurtner Visual orienting in dynamic broadband (1/f) noise sequences Journal Article In: Attention, Perception, and Psychophysics, vol. 72, no. 1, pp. 100–113, 2010. @article{Rasche2010, Visual orienting has typically been characterized using simple displays—for example, displays with a static target placed on a homogeneous background. In the present study, visual orienting was investigated using a dynamic broadband (1/f) noise display that should mimic a more naturalistic setting and that should allow saccadic orienting experiments to be performed with fewer constraints. In Experiment 1, it was shown that the noise movie contains gaze-attracting features that are almost as distinct as the ones measured for (static) real-word scenes. The movie can therefore serve as a strong distractor. In Experiment 2, observers carried out a luminance target search that showed that saccadic amplitude errors were substantially higher (18%) than the ones measured in simple displays. That error is certainly one of the primary factors making gaze-fixation prediction in complex scenes difficult. |
Keith Rayner; Monica S. Castelhano; Jinmian Yang Preview benefit during eye fixations in reading for older and younger readers Journal Article In: Psychology and Aging, vol. 25, no. 3, pp. 714–718, 2010. @article{Rayner2010, Older and younger readers read sentences as their eye movements were recorded, and the boundary paradigm (Rayner, 1975) was used to present either a valid or an invalid parafoveal preview of a target word. During the saccade to the target word, the preview word changed to the target word. For early measures of processing time (first fixation duration and single fixation duration), the standard preview benefit effect (shorter fixation times on the target word with a valid preview than an invalid preview) was obtained for both older and younger readers. However, for gaze duration and go-past time, the preview benefit was somewhat attenuated in the older readers in comparison to the younger readers, suggesting that on some fixations older readers obtain less preview benefit from the word to the right of fixation. |
Keith Rayner; Timothy J. Slattery; Nathalie N. Bélanger Eye movements, the perceptual span, and reading speed Journal Article In: Psychonomic Bulletin & Review, vol. 17, no. 6, pp. 834–839, 2010. @article{Rayner2010a, The perceptual span or region of effective vision during eye fixations in reading was examined as a function of reading speed (fast readers were compared with slow readers), font characteristics (fixed width vs. proportional width), and intraword spacing (normal or reduced). The main findings were that fast readers (reading at about 330 wpm) had a larger perceptual span than did slow readers (reading about 200 wpm) and that the span was not affected by whether or not the text was fixed width or proportional width. In addition, there were interesting font and intraword spacing effects that have important implications for the optimal use of space in a line of text. |
Victor Sander; Brian Soper; Stefan Everling Nonhuman primate event-related potentials associated with pro- and anti-saccades Journal Article In: NeuroImage, vol. 49, no. 2, pp. 1650–1658, 2010. @article{Sander2010, Non-invasive event-related potential (ERP) recordings have become a popular technique to study neural activity associated with saccades in humans. To date, it is not known whether nonhuman primates exhibit similar saccade-related ERPs. Here, we recorded ERPs associated with the performance of randomly interleaved pro- and anti-saccades in macaque monkeys. Stimulus-aligned ERPs showed short-latency visual component with more negative P2 and N2 peak amplitudes on anti- than on pro-saccade trials. Saccade-aligned ERPs showed a larger presaccadic negativity on anti- than pro-saccade trials, and a presaccadic positivity on pro-saccade trials, which was attenuated or absent on anti-saccade trials. This was followed by sharp negative spike potential immediately prior to the movement. Overall, these findings demonstrate that macaque monkeys, like humans, exhibit task-related differences of visual ERPs associated with pro- and anti-saccades and furthermore share presaccadic positivity as well as a spike potential prior to these tasks. We suggest that the presaccadic positivity on pro-saccade trials is generated by a source in the contralateral frontal eye fields and that the more negative voltage on anti-saccade trials is the result of additional sources of opposite polarity in neighboring frontal areas. |
Daniel R. Saunders; David K. Williamson; Nikolaus F. Troje Gaze patterns during perception of direction and gender from biological motion Journal Article In: Journal of Vision, vol. 10, no. 11, pp. 1–10, 2010. @article{Saunders2010, Humans can perceive many properties of a creature in motion from the movement of the major joints alone. However it is likely that some regions of the body are more informative than others, dependent on the task. We recorded eye movements while participants performed two tasks with point-light walkers: determining the direction of walking, or determining the walker's gender. To vary task difficulty, walkers were displayed from different view angles and with different degrees of expressed gender. The effects on eye movement were evaluated by generating fixation maps, and by analyzing the number of fixations in regions of interest representing the shoulders, pelvis, and feet. In both tasks participants frequently fixated the pelvis region, but there were relatively more fixations at the shoulders in the gender task, and more fixations at the feet in the direction task. Increasing direction task difficulty increased the focus on the foot region. An individual's task performance could not be predicted by their distribution of fixations. However by showing where observers seek information, the study supports previous findings that the feet play an important part in the perception of walking direction, and that the shoulders and hips are particularly important for the perception of gender. |
Paige E. Scalf; Diane M. Beck Competition in visual cortex impedes attention to multiple items Journal Article In: Journal of Neuroscience, vol. 30, no. 1, pp. 161–169, 2010. @article{Scalf2010, Traditional explanations of our limited attentional capacity focus on our ability to direct attention to multiple items. We ask whether this difficulty in simultaneously attending to multiple items stems from an inability to effectively represent multiple attended items. Although attending to one of a set of neighboring stimuli can isolate it from competitive interactions in visual cortex, no such isolation should occur if multiple competing items are attended. Indeed, we find that attention is ineffective at enhancing blood oxygen level-dependent signal in visual cortical area V4 when it is directed to three stimuli simultaneously, but only when those three stimuli compete in visual cortex. This suggests that competition may prevent attention from acting as effectively on representations of multiple items as it does on representations of a single item. In contrast to traditional explanations that posit limits in the sources of attentional control, we show that mechanisms at the sites of stimulus representation may also impose limits on our ability to attend to multiple items simultaneously. |
Katherine Wilson Scangos; Veit Stuphorn Medial frontal cortex motivates but does not control movement initiation in the countermanding task Journal Article In: Journal of Neuroscience, vol. 30, no. 5, pp. 1968–1982, 2010. @article{Scangos2010, Voluntary control of behavior implies the ability to select what action is performed. The supplementary motor area (SMA) and pre-SMA are widely considered to be of central importance for this ability because of their role in movement initiation and inhibition. To test this hypothesis, we recorded from neurons in SMA and pre-SMA of monkeys performing an arm countermanding task. Temporal analysis of neural activity and behavior in this task allowed us to test whether neural activity is sufficient to control movement initiation or inhibition. Surprisingly, 99% (242 of 243) of movement-related neurons in SMA and pre-SMA failed to exhibit time-locked activity changes predictive of movement initiation in this task. We also found a second group of neurons that was more active during successful response cancelation. Of these putative inhibitory cells, 18% (7 of 40) responded early enough to be able to influence the cancelation of the movement. Thus, when tested with the countermanding task, the SMA/pre-SMA region may play a role in movement inhibition but does not appear to control movement initiation. However, the activity of 76% (202 of 267) of movement-related neurons was contingent on the expectation of reward and 42% of them reflected the amount of expected reward. These findings suggest that the movement-related activity in pre-SMA and SMA might represent the motivation for a specific action but does not determine whether or not that action is performed. This motivational signal in pre-SMA and SMA could provide an essential link between reward expectation and motor execution. |
Daniel J. Schad; Antje Nuthmann; Ralf Engbert Eye movements during reading of randomly shuffled text Journal Article In: Vision Research, vol. 50, no. 23, pp. 2600–2616, 2010. @article{Schad2010, In research on eye-movement control during reading, the importance of cognitive processes related to language comprehension relative to visuomotor aspects of saccade generation is the topic of an ongoing debate. Here we investigate various eye-movement measures during reading of randomly shuffled meaningless text as compared to normal meaningful text. To ensure processing of the material, readers were occasionally probed for words occurring in normal or shuffled text. For reading of shuffled text we observed longer fixation times, less word skippings, and more refixations than in normal reading. Shuffled-text reading further differed from normal reading in that low-frequency words were not overall fixated longer than high-frequency words. However, the frequency effect was present on long words, but was reversed for short words. Also, consistent with our prior research we found distinct experimental effects of spatially distributed processing over several words at a time, indicating how lexical word processing affected eye movements. Based on analyses of statistical linear mixed-effect models we argue that the results are compatible with the hypothesis that the perceptual span is more strongly modulated by foveal load in the shuffled reading task than in normal reading. Results are discussed in the context of computational models of reading. |
Kerstin I. Schattka; Ralph Radach; Walter Huber Eye movement correlates of acquired central dyslexia Journal Article In: Neuropsychologia, vol. 48, no. 10, pp. 2959–2973, 2010. @article{Schattka2010, Based on recent progress in theory and measurement techniques, the analysis of eye movements has become one of the major methodological tools in experimental reading research. Our work uses this approach to advance the understanding of impaired information processing in acquired central dyslexia of stroke patients with aphasia. Up to now there has been no research attempting to analyze both word-based viewing time measures and local fixation patterns in dyslexic readers. The goal of the study was to find out whether specific eye movement parameters reflect pathologically preferred segmental reading in contrast to lexical reading.We compared oral reading of single words of normal controls (n=11) with six aphasic participants (two cases of deep, surface and residual dyslexia each). Participants were asked to read aloud lines of target words differing in length and frequency. Segmental reading was characterized by deviant spatial distribution of saccadic landing positions with initial fixations located mainly at the beginning of the word, while lexical readers showed the normative 'preferred landing positions' left to the center of the words. Contrary to expectation, word length did not distinguish between segmental and lexical readers, while word frequency showed the expected effect for lexical readers only. Their mean fixation duration was already prolonged during first pass reading reflecting their attempts of immediate access to lexical information. After first pass reading, re-reading time was significantly increased in all participants with acquired central dyslexia due to their exceedingly higher monitoring demands for oral reading. |
Michael Scheel; Mathias Abegg; Linda J. Lanyon; Andre Mattman; Jason J. S. Barton Eye movement and diffusion tensor imaging analysis of treatment effects in a Niemann-Pick Type C patient Journal Article In: Molecular Genetics and Metabolism, vol. 99, no. 3, pp. 291–295, 2010. @article{Scheel2010, New treatment options for Niemann-Pick Type C (NPC) have recently become available. To assess the efficiency and efficacy of these new treatment markers for disease status and progression are needed. Both the diagnosis and the monitoring of disease progression are challenging and mostly rely on clinical impression and functional testing of horizontal eye movements. Diffusion tensor imaging (DTI) provides information about the microintegrity especially of white matter. We show here in a case report how DTI and measures derived from this imaging method can serve as adjunct quantitative markers for disease management in Niemann-Pick Type C. Two approaches are taken - first, we compare the fractional anisotropy (FA) in the white matter globally between a 29-year-old NPC patient and 18 healthy age-matched controls and show the remarkable difference in FA relatively early in the course of the disease. Second, a voxelwise comparison of FA values reveals where white matter integrity is compromised locally and demonstrate an individualized analysis of FA changes before and after 1 year of treatment with Miglustat. This method might be useful in future treatment trials for NPC to assess treatment effects. |
Jason Rupp; Tanya Blekher; Jacqueline Gray Jackson; Xabier Beristain; Jeanine Marshall; Siu L. Hui; Joanne Wojcieszek; Tatiana M. Foroud Progression in prediagnostic Huntington disease Journal Article In: Journal of Neurology, Neurosurgery and Psychiatry, vol. 81, no. 4, pp. 379–384, 2010. @article{Rupp2010, OBJECTIVE: To examine rates of decline in individuals at risk for Huntington disease (HD). METHODS: 106 individuals at risk for HD completed a battery of neurocognitive, psychomotor and oculomotor tasks at two visits, approximately 2.5 years apart. Participants were classified as: (1) without the CAG expansion (normal controls, NC; n=68) or (2) with the CAG expansion (CAG+; n=38). The CAG+ group was further subdivided into those near to (near; n=19) or far from (far; n=19) their estimated age of onset. Longitudinal performance in the CAG+ group was evaluated with a repeated measures model with two main effects (time to onset, visit) and their interaction. Analysis of covariance was employed to detect differences in longitudinal performance in the three groups (NC, near and far). RESULTS: In the CAG+, the interaction term was significant (p < or = 0.02) for four measures (movement time, alternate button tapping, variability of latency for a memory guided task and percentage of errors for a more complex memory guided task), suggesting the rate of decline was more rapid as subjects approached onset. Longitudinal progression in the three groups differed for several variables (p<0.05). In most, the near group had significantly faster progression than NC; however, comparisons of the NC and far groups were less consistent. CONCLUSIONS: Different patterns of progression were observed during the prediagnostic period. For some measures, CAG+ subjects closer to estimated onset showed a more rapid decline while for other measures the CAG+ group had a constant rate of decline throughout the prediagnostic period that was more rapid than in NC. |
Jennifer D. Ryan; Lily Riggs; Douglas A. McQuiggan Eye movement monitoring of memory Journal Article In: Journal of Visualized Experiments, vol. 42, pp. 1–5, 2010. @article{Ryan2010, Explicit (often verbal) reports are typically used to investigate memory (e.g. "Tell me what you remember about the person you saw at the bank yesterday."), however such reports can often be unreliable or sensitive to response bias, and may be unobtainable in some participant populations. Furthermore, explicit reports only reveal when information has reached consciousness and cannot comment on when memories were accessed during processing, regardless of whether the information is subsequently accessed in a conscious manner. Eye movement monitoring (eye tracking) provides a tool by which memory can be probed without asking participants to comment on the contents of their memories, and access of such memories can be revealed on-line. Video-based eye trackers (either head-mounted or remote) use a system of cameras and infrared markers to examine the pupil and corneal reflection in each eye as the participant views a display monitor. For head-mounted eye trackers, infrared markers are also used to determine head position to allow for head movement and more precise localization of eye position. Here, we demonstrate the use of a head-mounted eye tracking system to investigate memory performance in neurologically-intact and neurologically-impaired adults. Eye movement monitoring procedures begin with the placement of the eye tracker on the participant, and setup of the head and eye cameras. Calibration and validation procedures are conducted to ensure accuracy of eye position recording. Real-time recordings of X,Y-coordinate positions on the display monitor are then converted and used to describe periods of time in which the eye is static (i.e. fixations) versus in motion (i.e., saccades). Fixations and saccades are time-locked with respect to the onset/offset of a visual display or another external event (e.g. button press). Experimental manipulations are constructed to examine how and when patterns of fixations and saccades are altered through different types of prior experience. The influence of memory is revealed in the extent to which scanning patterns to new images differ from scanning patterns to images that have been previously studied. Memory can also be interrogated for its specificity; for instance, eye movement patterns that differ between an identical and an altered version of a previously studied image reveal the storage of the altered detail in memory. These indices of memory can be compared across participant populations, thereby providing a powerful tool by which to examine the organization of memory in healthy individuals, and the specific changes that occur to memory with neurological insult or decline. |
Jean Saint-Aubin The long range parafoveal processing ofsyntactic information is impossible: A reply to Foucambert (2008) Journal Article In: Psychologie Francaise, vol. 55, no. 3, pp. 211–222, 2010. @article{SaintAubin2010, Based on results with a new method, Foucambert (2008) argued that syntactic processing can occur as far as 27 characters to the right of the fixation point. In this reply, we demonstrate that the method used by Foucambert was not appropriate. In addition, Foucambert's results did not support his conclusion. We replicate Foucambert's study while monitoring eye movements. Results revealed that subjects' eye movements were biased to the right of the fixation point. In addition, subjects were unable to engage in syntactic processing of words far in periphery. Taken together, results fit well with current models of eye movements and of the missing-letter effect. |
Jean Saint-Aubin; Sophie Kenny; Annie Roy-Charland The role of eye movements in the missing-letter effect revisited with the rapid serial visual presentation procedure Journal Article In: Canadian Journal of Experimental Psychology, vol. 64, no. 1, pp. 47–52, 2010. @article{SaintAubin2010a, When participants read a text while searching for a target letter, they are more likely to miss the target letter embedded in frequent function words than in less frequent content words. This effect is usually observed with a text displayed normally, for which it has been found that frequent function words are fixated for a smaller amount of time than less frequent content words. However, similar pattern of omissions have been observed with a rapid serial visual presentation procedure in which words appear one at a time. These parallel results would demonstrate that fixation duration per se is not the proximal cause of the missing-letter effect only if eye movements are not made during the rapid serial visual presentation procedure. Therefore, the authors performed eye monitoring during the rapid serial visual presentation procedure. Results revealed that, with a rapid serial visual presentation procedure, participants fixated function and content words for almost the entire presentation duration. It is concluded that eye movements are not the proximal cause of the missing-letter effect. |
Emilio Salinas; Swetha Shankar; M. Gabriela Costello; Dantong Zhu; Terrence R. Stanford Waiting is the hardest part: Comparison of two computational strategies for performing a compelled-response task Journal Article In: Frontiers in Computational Neuroscience, vol. 4, pp. 153, 2010. @article{Salinas2010, The neural basis of choice behavior is commonly investigated with tasks in which a subject analyzes a stimulus and reports his or her perceptual experience with an appropriate motor action. We recently developed a novel task, the compelled-saccade task, with which the influence of the sensory information on the subject's choice can be tracked through time with millisecond resolution, thus providing a new tool for correlating neuronal activity and behavior. This paradigm has a crucial feature: the signal that instructs the subject to make an eye movement is given before the cue that indicates which of two possible choices is the correct one. Previously, we found that psychophysical performance in this task could be accurately replicated by a model in which two developing oculomotor plans race to a threshold and the incoming perceptual information differentially accelerates their trajectories toward it. However, the task design suggests an alternative mechanism: instead of modifying an ongoing oculomotor plan on the fly as the sensory information becomes available, the subject could try to wait, withholding the oculomotor response until the sensory cue is revealed. Here, we use computer simulations to explore and compare the performance of these two types of model. We find that both reproduce the main features of the psychophysical data in the compelled-saccade task, but they give rise to distinct behavioral and neurophysiological predictions. Although, superficially, the waiting model is intuitively appealing, it is ultimately inconsistent with experimental results from this and other tasks. |
Anne Pier Salverda; Michael K. Tanenhaus Tracking the time course of orthographic information in spoken-word recognition Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 36, no. 5, pp. 1108–1117, 2010. @article{Salverda2010, Two visual-world experiments evaluated the time course and use of orthographic information in spoken-word recognition using printed words as referents. Participants saw 4 words on a computer screen and listened to spoken sentences instructing them to click on one of the words (e.g., Click on the word bead). The printed words appeared 200 ms before the onset of the spoken target word. In Experiment 1, the display included the target word and a competitor with either a lower degree (e.g., bear) or a higher degree (e.g., bean) of phonological overlap with the target. Both competitors had the same degree of orthographic overlap with the target. There were more fixations to the competitors than to unrelated distractors. Crucially, the likelihood of fixating a competitor did not vary as a function of the amount of phonological overlap between target and competitor. In Experiment 2, the display included the target word and a competitor with either a lower degree (e.g., bare) or a higher degree (e.g., bear) of orthographic overlap with the target. Competitors were homophonous and thus had the same degree of phonological overlap with the target. There were more fixations to higher overlap competitors than to lower overlap competitors, beginning during the temporal interval where initial fixations driven by the vowel are expected to occur. The authors conclude that orthographic information is rapidly activated as a spoken word unfolds and is immediately used in mapping spoken words onto potential printed referents. |
A. E. Ritchie; P. G. Griffiths; P. F. Chinnery; A. W. Davidson Eye movement recordings to investigate a supranuclear component in chronic progressive external ophthalmoplegia: A cross-sectional study Journal Article In: British Journal of Ophthalmology, vol. 94, no. 9, pp. 1165–1168, 2010. @article{Ritchie2010, BACKGROUND: It has been postulated that eye movement disorders in chronic progressive external ophthalmoplegia (CPEO) have a neurological as well as a myopathic component to them. AIM: To investigate whether there is a supranuclear component to eye movement disorders in CPEO using eye movement recordings. METHODS: Saccade and smooth pursuit (SP) characteristics together with vestibulo-ocular reflex (VOR) gain and VOR suppression (VORS) gain in 18 patients with CPEO and 34 normal patients were measured using Eyelink II video-oculography. RESULTS: The asymptotic values of the peak velocity main sequence curves were reduced in the CPEO group compared to those of normal patients, with a mean of 161 degrees/s (95% CI 126 degrees/s to 197 degrees/s) compared with 453 degrees/s (95% CI 430 to 475 degrees/s), respectively. Saccadic latency was longer in CPEO (263 ms; 95% CI 250 to 278), compared to controls (185 ms; 95% CI 181 to 189). Smooth pursuit and VOR gains were impaired in CPEO, although this could be explained by non-supranuclear causes. VORS gain was identical in the two groups. CONCLUSIONS: This study does not support a supranuclear component to the ophthalmoplegia of CPEO, although the increased latencies observed may warrant further investigation. |
Helen Rodger; David J. Kelly; Caroline Blais; Roberto Caldara Inverting faces does not abolish cultural diversity in eye movements Journal Article In: Perception, vol. 39, no. 11, pp. 1491–1503, 2010. @article{Rodger2010, Face processing is widely understood to be a basic, universal visual function effortlessly achieved by people from all cultures and races. The remarkable recognition performance for faces is markedly and specifically affected by picture-plane inversion: the so-called face-inversion effect (FIE), a finding often used as evidence for face-specific mechanisms. However, it has recently been shown that culture shapes the way people deploy eye movements to extract information from faces. Interestingly, the comparable lack of experience with inverted faces across cultures offers a unique opportunity to establish the extent to which such cultural perceptual biases in eye movements are robust, but also to assess whether face-specific mechanisms are universally tuned. Here we monitored the eye movements of Western Caucasian (WC) and East Asian (EA) observers while they learned and recognised WC and EA inverted faces. Both groups of observers showed a comparable impairment in recognising inverted faces of both races. WC observers deployed a scattered inverted triangular scanpath with a bias towards the mouth, whereas EA observers uniformly extended the focus of their fixations from the centre towards the eyes. Overall, our data show that cultural perceptual differences in eye movements persist during the FIE, questioning the universality of face-processing mechanisms. |
Pieter R. Roelfsema; Roos Houtkamp; Ilia Korjoukov Further evidence for the spread of attention during contour grouping: A reply to Crundall, Dewhurst, and Underwood (2008) Journal Article In: Attention, Perception, and Psychophysics, vol. 72, no. 3, pp. 849–862, 2010. @article{Roelfsema2010, In a contour-grouping task, subjects decide whether contour elements belong to the same or different curves. Houtkamp, Spekreijse, and Roelfsema (2003) demonstrated that object-based attention spreads gradually over contour elements that have to be grouped in perception. Crundall, Dewhurst, and Underwood (2008) challenged this spreading-attention model and suggested that attention in the contour-grouping task is not object based but rather has the shape of a zoom lens that moves along the relevant curve. To distinguish between object-based and spatial attention, they changed the stimulus and measured the impact on performance. Subjects were not able to correct for changes at the start of the relevant curve toward the end of the trial. They suggested that attention did not stay at the beginning of the curve, in accordance with a moving zoom lens model. Here, we examine the task of Crundall et al. and find that subjects perceive the changes but fail to correct their response. By measuring change detection directly, we find that performance is much better for the start of the relevant curve than for an irrelevant curve, at all times. Our findings do not support the zoom lens model but provide further support for the spreading-attention model. |
Martin Rolfs; Tomas Knapen; Patrick Cavanagh Global saccadic adaptation Journal Article In: Vision Research, vol. 50, no. 18, pp. 1882–1890, 2010. @article{Rolfs2010, Our actions need constant calibration to arrive accurately at locations of their intended goals; errors in execution must drive rapid adjustments. As an example, saccadic eye movements are vital for bringing objects of interest into the high-acuity center of vision and they must be continually tuned to compensate for ongoing changes in body, muscle strength and neural variability. This adaptation of eye movement responses can be induced artificially by systematically displacing the saccade targets by a constant proportion during each saccade. Observers do not notice these shifts and yet the oculomotor system does, rapidly compensating for the landing error until the saccades finally land close to the artificially displaced target. This recalibration has been described as spatially selective, dropping off with distance in direction and amplitude from the adapted saccade vector. However, we now report that this local adaptation property is a consequence of adapting to only one direction at a time, the method generally used in previous studies. When we induced adaptation in all directions, using a quasi-random walk where each target was displaced 25% back toward to the previous fixation, we found strong, spatially generalized adaptation that could not be accounted for by an accumulation of many vector-specific adaptations. This global adaptation is a plausible strategy for calibration given the absence of any obvious growth changes or muscle deficits that would lead to vector specific losses and it provides a robust model for testing motor calibration. |
Stéphanie Rossit; Larissa Szymanek; Stephen H. Butler; Monika Harvey Memory-guided saccade processing in visual form agnosia (patient DF) Journal Article In: Experimental Brain Research, vol. 200, no. 1, pp. 109–116, 2010. @article{Rossit2010, According to Milner and Goodale's model (The visual brain in action, Oxford University Press, Oxford, 2006) areas in the ventral visual stream mediate visual perception and oV-line actions, whilst regions in the dorsal visual stream mediate the on-line visual control of action. Strong evidence for this model comes from a patient (DF), who suffers from visual form agnosia after bilateral damage to the ventro-lateral occipital region, sparing V1. It has been reported that she is normal in immediate reaching and grasping, yet severely impaired when asked to perform delayed actions. Here we investigated whether this dissociation would extend to saccade execution. Neurophysiological studies and TMS work in humans have shown that the posterior parietal cortex (PPC), on the right in particular (supposedly spared in DF), is involved in the control of memory-guided saccades. Surprisingly though, we found that, just as reported for reaching and grasping, DF's saccadic accuracy was much reduced in the memory compared to the stimulus-guided condition. These data support the idea of a tight coupling of eye and hand movements and further suggest that dorsal stream structures may not be sufficient to drive memory-guided saccadic performance. |
Sarah Bate; Catherine Haslam; Timothy L. Hodgson; Ashok Jansari; Nicola J. Gregory; Janice Kay Positive and negative emotion enhances the processing of famous faces in a semantic judgment task Journal Article In: Neuropsychology, vol. 24, no. 1, pp. 84–89, 2010. @article{Bate2010, Previous work has consistently reported a facilitatory influence of positive emotion in face recognition (e.g., D'Argembeau, Van der Linden, Comblain, & Etienne, 2003). However, these reports asked participants to make recognition judgments in response to faces, and it is unknown whether emotional valence may influence other stages of processing, such as at the level of semantics. Furthermore, other evidence suggests that negative rather than positive emotion facilitates higher level judgments when processing nonfacial stimuli (e.g., Mickley & Kensinger, 2008), and it is possible that negative emotion also influences latter stages of face processing. The present study addressed this issue, examining the influence of emotional valence while participants made semantic judgments in response to a set of famous faces. Eye movements were monitored while participants performed this task, and analyses revealed a reduction in information extraction for the faces of liked and disliked celebrities compared with those of emotionally neutral celebrities. Thus, in contrast to work using familiarity judgments, both positive and negative emotion facilitated processing in this semantic-based task. This pattern of findings is discussed in relation to current models of face processing. |
Oliver Baumann; Jason B. Mattingley Scaling of neural responses to visual and auditory motion in the human cerebellum Journal Article In: Journal of Neuroscience, vol. 30, no. 12, pp. 4489–4495, 2010. @article{Baumann2010, The human cerebellum contains approximately half of all the neurons within the cerebrum, yet most experimental work in human neuroscience over the last century has focused exclusively on the structure and functions of the forebrain. The cerebellum has an undisputed role in a range of motor functions (Thach et al., 1992), but its potential contributions to sensory and cognitive processes are widely debated (Stoodley and Schmahmann, 2009). Here we used functional magnetic resonance imaging to test the hypothesis that the human cerebellum is involved in the acquisition of auditory and visual sensory data. We monitored neural activity within the cerebellum while participants engaged in a task that required them to discriminate the direction of a visual or auditory motion signal in noise. We identified a distinct set of cerebellar regions that were differentially activated for visual stimuli (vermal lobule VI and right-hemispheric lobule X) and auditory stimuli (right-hemispheric lobules VIIIA and VIIIB and hemispheric lobule VI bilaterally). In addition, we identified a region in left crus I in which activity correlated significantly with increases in the perceptual demands of the task (i.e., with decreasing signal strength), for both auditory and visual stimuli. Our results support suggestions of a role for the cerebellum in the processing of auditory and visual motion and suggest that parts of cerebellar cortex are concerned with tracking movements of objects around the animal, rather than with controlling movements of the animal itself (Paulin, 1993). |
Paul M. Bays; V. Singh-Curry; N. Gorgoraptis; Jon Driver; Masud Husain Integration of goal- and stimulus-related visual signals revealed by damage to human parietal cortex Journal Article In: Journal of Neuroscience, vol. 30, no. 17, pp. 5968–5978, 2010. @article{Bays2010, Where we look is determined both by our current intentions and by the tendency of visually salient items to "catch our eye." After damage to parietal cortex, the normal process of directing attention is often profoundly impaired. Here, we tracked parietal patients' eye movements during visual search to separately map impairments in goal-directed orienting to targets versus stimulus-driven gaze shifts to salient but task-irrelevant probes. Deficits in these two distinct types of attentional selection are shown to be identical in both magnitude and spatial distribution, consistent with damage to a "priority map" that integrates goal- and stimulus-related signals to select visual targets. When goal-relevant and visually salient items compete for attention, the outcome depends on a biased competition in which the priority of contralesional targets is undervalued. On the basis of these findings, we further demonstrate that parietal patients' spatial bias (neglect) in goal-directed visual exploration can be corrected and even reversed by systematically manipulating the spatial distribution of stimulus salience in the visual array. |
Melissa R. Beck; Maura C. Lohrenz; J. Gregory Trafton Measuring search efficiency in complex visual search tasks: Global and local clutter Journal Article In: Journal of Experimental Psychology: Applied, vol. 16, no. 3, pp. 238–250, 2010. @article{Beck2010, Set size and crowding affect search efficiency by limiting attention for recognition and attention against competition; however, these factors can be difficult to quantify in complex search tasks. The current experiments use a quantitative measure of the amount and variability of visual information (i.e., clutter) in highly complex stimuli (i.e., digital aeronautical charts) to examine limits of attention in visual search. Undergraduates at a large southern university searched for a target among 4, 8, or 16 distractors in charts with high, medium, or low global clutter. The target was in a high or low local-clutter region of the chart. In Experiment 1, reaction time increased as global clutter increased, particularly when the target was in a high local-clutter region. However, there was no effect of distractor set size, supporting the notion that global clutter is a better measure of attention against competition in complex visual search tasks. As a control, Experiment 2 demonstrated that increasing the number of distractors leads to a typical set size effect when there is no additional clutter (i.e., no chart). In Experiment 3, the effects of global and local clutter were minimized when the target was highly salient. When the target was nonsalient, more fixations were observed in high global clutter charts, indicating that the number of elements competing with the target for attention was also high. The results suggest design techniques that could improve pilots' search performance in aeronautical charts. |
Stefanie I. Becker Testing a postselectional account of across-dimension switch costs Journal Article In: Psychonomic Bulletin & Review, vol. 17, no. 6, pp. 853–861, 2010. @article{Becker2010, In visual search for a pop-out target, responses are faster when the target dimension from the previous trial is repeated than when it changes. Currently, it is unclear whether these across-dimension switch costs originate from processes that guide attention to the target or from later processes (e.g., target identification or response selection). The present study tested two critical predictions of a response-selection account of across-dimension switch costs-namely, (1) that switch costs should occur even when visual attention is guided by a completely different feature and (2) that changing the target dimension should affect the speed of responding, but not the speed of eye movements to the target. The results supported both predictions, indicating that changes of the target dimension do not affect early processes that guide attention to the target but, rather, affect later processes, which commence after the target has been selected. |
Stefanie I. Becker The role of target-distractor relationships in guiding attention and the eyes in visual search Journal Article In: Journal of Experimental Psychology: General, vol. 139, no. 2, pp. 247–265, 2010. @article{Becker2010a, Current models of visual search assume that visual attention can be guided by tuning attention toward specific feature values (e.g., particular size, color) or by inhibiting the features of the irrelevant nontargets. The present study demonstrates that attention and eye movements can also be guided by a relational specification of how the target differs from the irrelevant distractors (e.g., larger, redder, darker). Guidance by the relational properties of the target governed intertrial priming effects and capture by irrelevant distractors. First, intertrial switch costs occurred only upon reversals of the coarse relationship between target and nontargets, but they did not occur when the target and nontarget features changed such that the relation remained the same. Second, irrelevant distractors captured most strongly when they differed in the correct direction from all other items–despite the fact that they were less similar to the target. This suggests that priming and contingent capture, which have previously been regarded as prime evidence for feature-based selection, are really due to a relational selection mechanism. Here I propose a new relational vector account of guidance, which holds promise to synthesize a wide range of different findings that have previously been attributed to different mechanisms of visual search. |