All EyeLink Publications
All 12,000+ peer-reviewed EyeLink research publications up until 2023 (with some early 2024s) are listed below by year. You can search the publications library using keywords such as Visual Search, Smooth Pursuit, Parkinson’s, etc. You can also search for individual author names. Eye-tracking studies grouped by research area can be found on the solutions pages. If we missed any EyeLink eye-tracking papers, please email us!
2015 |
Andreas Gartus; Nicolas Klemer; Helmut Leder The effects of visual context and individual differences on perception and evaluation of modern art and graffiti art Journal Article In: Acta Psychologica, vol. 156, pp. 64–76, 2015. @article{Gartus2015, Traditionally, artworks are seen as autonomous objects that stand (or should stand) on their own. However, at least since the emergence of Conceptual Art in the 1920s and Pop Art in the 1960s, art lacks any distinctive perceptual features that define it as such. Art, therefore, cannot be defined without reference to its context. Some studies have shown that context affects the evaluation of artworks, and that specific contexts (street for graffiti art, museum for modern art) elicit specific effects (Gartus & Leder, 2014). However, it is yet unclear how context changes perception and appreciation processes. In our study we measured eye-movements while participants (64 psychology undergraduates, 48% women) perceived and evaluated beauty, interest, emotional valence, as well as perceived style for modern art and graffiti art embedded into either museum or street contexts. For modern art, beauty and interest ratings were higher in a museum than in a street context, but context made no difference for the ratings of graffiti art. Importantly, we also found an interaction of context and individual interest in graffiti for beauty and interest ratings, as well as for number of fixations. Analyses of eye-movements also revealed that viewing times were in general significantly longer in museum than in street contexts. We conclude that context can have an important influence on aesthetic appreciation. However, some effects depend also on the style of the artworks and the individual art interests of the viewers. |
B. P. Geelen; Alexander H. Wertheim The prevalence effect in lateral masking and its relevance for visual search Journal Article In: Experimental Brain Research, vol. 233, no. 4, pp. 1119–1124, 2015. @article{Geelen2015, In stimulus displays with or without a single target amid 1,644 identical distractors, target prevalence was varied between 20, 50 and 80 %. Maximum gaze deviation was measured to determine the strength of lateral masking in these arrays. The results show that lateral masking was strongest in the 20 % prevalence condition, which differed significantly from both the 50 and 80 % prevalence conditions. No difference was observed between the latter two. This pattern of results corresponds to that found in the literature on the prevalence effect in visual search (stronger lateral masking corresponding to longer search times). The data add to similar findings reported earlier (Wertheim et al. in Exp Brain Res, 170:387-402, 2006), according to which the effects of many well-known factors in visual search correspond to those on lateral masking. These were the effects of set size, disjunctions versus conjunctions, display area, distractor density, the asymmetry effect (Q vs. O's) and viewing distance. The present data, taken together with those earlier findings, may lend credit to a causal hypothesis that lateral masking could be a more important mechanism in visual search than usually assumed. |
Joy J. Geng; Zachary Blumenfeld; Terence L. Tyson; Michael J. Minzenberg Pupil diameter reflects uncertainty in attentional selection during visual search Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 453, 2015. @article{Geng2015, Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. |
Peggy Gerardin; Judith Nicolas; Alessandro Farnè; Denis Pélisson Increasing attentional load boosts saccadic adaptation Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 11, pp. 6304–6312, 2015. @article{Gerardin2015, PURPOSE: Visual exploration relies on saccadic eye movements and attention processes. Saccadic adaptation mechanisms, which calibrate the oculomotor commands to continuously maintain the accuracy of saccades, have been suggested to act at downstream (motor) and upstream (visuoattentional) levels of visuomotor transformation. Conversely, whether attention can directly affect saccadic adaptation remains unknown. To answer this question, we manipulated the level of attention engaged in a visual discrimination task performed during saccadic adaptation. METHODS: Participants performed low or high attention demanding orientation discrimination tasks on largely or faintly oriented Gabor patches, respectively, which served as targets for reactive saccades. Gabor patches systematically jumped backward during eye motion to elicit an adaptive shortening of saccades, and replaced 50 msec later (100 msec in two subjects) by a mask. Subjects judged whether Gabors' orientation was "nearly horizontal" versus "nearly vertical" (low attention demanding) or "slightly left" versus "slightly right" (high attention demanding), or made no discrimination (control task). RESULTS: We found that the build-up and the retention of adaptation of reactive saccades were larger in the "high attention demanding" condition than in the "low attention demanding" and the no-discrimination control conditions. CONCLUSIONS: These results indicate that increasing the level of attention to the perceptual processing of otherwise identical targets boosts saccadic adaptation, and suggest that saccadic adaptation mechanisms and attentional load effects may functionally share common neural substrates. |
Mónika Gergelyfi; Benvenuto Jacob; Etienne Olivier; Alexandre Zénon Dissociation between mental fatigue and motivational state during prolonged mental activity Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 176, 2015. @article{Gergelyfi2015, Mental fatigue (MF) is commonly observed following prolonged cognitive activity and can have major repercussions on the daily life of patients as well as healthy individuals. Despite its important impact, the cognitive processes involved in MF remain largely unknown. An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement. Here, to test this hypothesis, we measured various neural, autonomic, psychometric and behavioral signatures of MF and motivation (EEG, ECG, pupil size, eye blinks, Skin conductance responses (SCRs), questionnaires and performance in a working memory (WM) task) in healthy volunteers, while MF was induced by Sudoku tasks performed for 120 min. Moreover extrinsic motivation was manipulated by using different levels of monetary reward. We found that, during the course of the experiment, the participants' subjective feeling of fatigue increased and their performance worsened while their blink rate and heart rate variability (HRV) increased. Conversely, reward-induced EEG, pupillometric and skin conductance signal changes, regarded as indicators of task engagement, remained constant during the experiment, and failed to correlate with the indices of MF. In addition, MF did not affect a simple reaction time task, despite the strong influence of extrinsic motivation on this task. Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF. These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources. |
Franziska Geringswald; Anne Herbik; Wolfram Hofmüller; Michael B. Hoffmann; Stefan Pollmann Visual memory for objects following foveal vision loss Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1471–1484, 2015. @article{Geringswald2015a, Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual long-term memory for objects in patients suffering from foveal vision loss due to age-related macular degeneration. We measured patients' change detection sensitivity after a period of free scene exploration monocularly with their worse eye when possible, and under binocular vision, comparing sensitivity and eye movements to matched normal-sighted controls. A highly salient cue was used to capture attention to a nontarget location before a target change occurred in half of the trials, ensuring that change detection relied on memory. Patients' monocular and binocular sensitivity to object change was comparable to controls, even after more than 4 intervening fixations, and not significantly correlated with visual impairment. We conclude that extrafoveal vision suffices for efficient encoding into visual long-term memory. |
Franziska Geringswald; Stefan Pollmann Central and peripheral vision loss differentially affects contextual cueing in visual search Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1485–1496, 2015. @article{Geringswald2015, Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental learning of contextual cues or the expression of learning, that is, the guidance of search by learned target-distractor configurations. Visual search with a central scotoma reduced contex-tual cueing both with respect to search times and gaze parameters. However, when the scotoma was subsequently removed, contextual cueing was observed in a comparable magnitude as for controls who had searched without scotoma simulation throughout the experiment. This indicated that search with a central scotoma did not prevent incidental context learning, but interfered with search guidance by learned contexts. We discuss the role of visuospatial working memory load as source of this interference. In contrast to central vision loss, peripheral vision loss was expected to prevent spatial configuration learning itself, because the restricted search window did not allow the integration of invariant local configurations with the global display layout. This expectation was confirmed in that visual search with a simulated peripheral scotoma eliminated contextual cueing not only in the initial learning phase with scotoma, but also in the subsequent test phase without scotoma. |
Saeideh Ghahghaei; Preeti Verghese Efficient saccade planning requires time and clear choices Journal Article In: Vision Research, vol. 113, pp. 125–136, 2015. @article{Ghahghaei2015, We use eye movements constantly to gather information. Saccades are efficient when they maximize the information required for the task, however there is controversy regarding the efficiency of eye movement planning. For example, saccades are efficient when searching for a single target (Nature, 434 (2005) 387–391), but are inefficient when searching for an unknown number of targets in noise, particularly under time pressure (Vision Research 74 (2012), 61–71). In this study, we used a multiple-target search paradigm and explored whether altering the noise level or increasing saccadic latency improved efficiency. Experiments used stimuli with two levels of discriminability such that saccades to the less discriminable stimuli provided more information. When these two noise levels corresponded to low and moderate visibility, most observers did not preferentially select informative locations, but looked at uncertain and probable target locations equally often. We then examined whether eye movements could be made more efficient by increasing the discriminability of the two stimulus levels and by delaying the first saccade so that there was more time for decision processes to influence the saccade choices. Some observers did indeed increase the proportion of their saccades to informative locations under these conditions. Others, however, made as many saccades as they could during the limited time and were unselective about the saccade goal. A clear trend that emerges across all experiments is that conditions with a greater proportion of efficient saccades are associated with a longer latency to initiate saccades, suggesting that the choice of informative locations requires deliberate planning. |
Alma Gharib; Daniela Mier; Ralph Adolphs; Shinsuke Shimojo Eyetracking of social preference choices reveals normal but faster processing in autism Journal Article In: Neuropsychologia, vol. 72, pp. 70–79, 2015. @article{Gharib2015, People with Autism Spectrum Disorder (ASD) have been reported to show atypical attention and evaluative processing, in particular for social stimuli such as faces. The usual measure in these studies is an explicit, subjective judgment, which is the culmination of complex-temporally extended processes that are not typically dissected in detail. Here we addressed a neglected aspect of social decision-making in order to gain further insight into the underlying mechanisms: the temporal evolution of the choice. We investigated this issue by quantifying the alternating patterns of gaze onto faces, as well as nonsocial stimuli, while subjects had to decide which of the two stimuli they preferred. Surprisingly, the temporal profile of fixations relating to choice (the so-called "gaze cascade") was entirely normal in ASD, as were the eventual preference choices. Despite these similarities, we found two key abnormalities: people with ASD made choices more rapidly than did control subjects across the board, and their reaction times for social preference judgments were insensitive to choice difficulty. We suggest that ASD features an altered decision-making process when basing choice on social preferences. One hypothesis motivated by these data is that a choice criterion is reached in ASD regardless of the discriminability of the options. |
Fatema F. Ghasia; Aasef G. Shaikh Uncorrected myopic refractive error increases microsaccade amplitude Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 4, pp. 2531–2535, 2015. @article{Ghasia2015a, PURPOSE. Human brain generates miniature eye movements, such as microsaccades, to counteract image fading due to visual adaptation. Generation of microsaccade relies on the amount of retinal error or acuity demand for a desired visual task. The goal of this study was to assess the influence of visual blur, induced by uncorrected refractive error on microsaccades and saccades. METHODS. Ten subjects with myopia held their gaze on a visual target during two experiment conditions: corrected refractive error and uncorrected refractive error. Eye movements were measured with high-resolution video oculography under binocular viewing conditions during both tasks. Gaze holding function, microsaccades, and visually guided saccades were analyzed and compared during both tasks. RESULTS. We found an increase in the amplitude of microsaccades in the presence of uncorrected refractive error, but the microsaccade frequency and velocity remained unchanged. The microsaccade amplitude systematically increased with an increase in uncorrected refractive error. The main sequence relationship relating the saccade amplitude with respective peak velocity was not significantly different between two conditions. The onset latency, peak velocities, and accuracy of visually guided saccades also were unchanged between the two conditions. CONCLUSIONS. These results suggest that visual blur, hence the precision of an image on the fovea, has an important role in calibrating the amplitude of fixational eye movements, such as microsaccades. |
Fatema F. Ghasia; Aasef G. Shaikh Head oscillations in infantile nystagmus syndrome Journal Article In: Journal of AAPOS, vol. 19, no. 1, pp. 38–41, 2015. @article{Ghasia2015, PURPOSE: To quantitatively characterize eye and head oscillations in patients with infantile nystagmus syndrome (INS). METHODS: Vertical and horizontal eye and head position in INS patients were measured simultaneously at a sampling frequency of 500 Hz. Eye and head movements were measured continuously for 180 seconds. The data was calibrated and converted to angular vectors, which were further analyzed with custom software. RESULTS: A total of 10 patients with INS were included: 3 with pseudo-jerk, 3 with pure-jerk, 2 with pseudo-pendular with foveating saccade form of jerk, 1 with bidirectional jerk, and 1 with asymmetric pendular nystagmus waveforms. None of the patients had periodic, aperiodic, or a superimposed latent nystagmus component. Two types of head oscillations were observed: one with a frequency of 1-3 Hz, present in all patients; and another with a frequency range of 5-8 Hz, present in only 7 patients. High-frequency oscillations were episodic, whereas low-frequency oscillations were constantly present. Peak velocity of the high-frequency head oscillations and eye velocity of nystagmus were not correlated, suggesting that these oscillations did not influence foveation. CONCLUSIONS: Two types of head oscillations were found in INS patients: a constant, low-frequency and an episodic, high-frequency. Lack of correlation between the foveation period of nystagmus and peak head velocity during high-frequency oscillations suggests a coexisting pathological phenomenon rather than a compensatory mechanism used to improve the visual acuity. |
Fatema F. Ghasia; Aasef G. Shaikh; Jonathan B. Jacobs; Mark F. Walker Cross-coupled eye movement supports neural origin of pattern strabismus Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 5, pp. 2855–2866, 2015. @article{Ghasia2015b, PURPOSE: Pattern strabismus describes vertically incomitant horizontal strabismus. Conventional theories emphasized the role of orbital etiologies, such as abnormal fundus torsion and misaligned orbital pulleys as a cause of the pattern strabismus. Experiments in animal models, however, suggested the role of abnormal cross-connections between the neural circuits. We quantitatively assessed eye movements in patients with pattern strabismus with a goal to delineate the role of neural circuits versus orbital etiologies.$backslash$n$backslash$nMETHODS: We measured saccadic eye movements with high-precision video-oculography in 14 subjects with pattern strabismus, 5 with comitant strabismus, and 15 healthy controls. We assessed change in eye position in the direction orthogonal to that of the desired eye movement (cross-coupled responses). We used fundus photography to quantify the fundus torsion.$backslash$n$backslash$nRESULTS: We found cross-coupling of saccades in all patients with pattern strabismus. The cross-coupled responses were in the same direction in both eyes, but larger in the nonviewing eye. All patients had clinically apparent inferior oblique overaction with abnormal excylotorsion. There was no correlation between the amount of the fundus torsion or the grade of oblique overaction and the severity of cross-coupling. The disconjugacy in the saccade direction and amplitude in pattern strabismics did not have characteristics predicted by clinically apparent inferior oblique overaction.$backslash$n$backslash$nCONCLUSIONS: Our results validated primate models of pattern strabismus in human patients. We found no correlation between ocular torsion or oblique overaction and cross-coupling. Therefore, we could not ascribe cross-coupling exclusively to the orbital etiology. Patients with pattern strabismus could have abnormalities in the saccade generators. |
Frouke Hermens Fixation instruction influences gaze cueing Journal Article In: Visual Cognition, vol. 23, no. 4, pp. 432–449, 2015. @article{Hermens2015a, Studies have shown that perceiving another person's gaze shift facilitates responses in the direction of the perceived gaze shift. While it is often assumed that participants in these experiments remain fixated on the cue in the cueing interval, eye gaze is not always recorded to confirm this. The data presented here suggest that the effect of gaze cues on responses to peripheral targets depends on whether participants make eye movements prior to the onset of the target. Participants who were required to fixate showed cueing effects at short cue-target intervals, but no cueing at later intervals. Participants who could look around, often chose to do so, and showed the same positive cueing effects at the shorter interval, but negative cueing effects (suggestive of inhibition of return) at the longer interval. |
Frouke Hermens In: Journal of Eye Movement Research, vol. 8, no. 1, pp. 1–17, 2015. @article{Hermens2015b, Whereas early studies of microsaccades have predominantly relied on custom-built eye trackers and manual tagging of microsaccades, more recent work tends to use video-based eye tracking and automated algorithms for microsaccade detection. While data from these newer studies suggest that microsaccades can be reliably detected with video-based systems, this has not been systematically evaluated. I here present a method and data examining microsaccade detection in an often used video-based system (the Eyelink II system) and a commonly used detection algorithm (Engbert & Kliegl, 2003; Engbert & Mergenthaler, 2006). Recordings from human participants and those obtained using a pair of dummy eyes, mounted on a pair of glasses either worn by a human participant (i.e., with head motion) or a dummy head (no head motion) were compared. Three experiments were conducted. The first experiment suggests that when microsaccade measurements make use of the pupil detection mode, microsaccade detections in the absence of eye movements are sparse in the absence of head movements, but frequent with head movements (despite the use of a chin rest). A second experiment demonstrates that by using measurements that rely on a combination of corneal reflection and pupil detection, false microsaccade detections can be largely avoided as long as a binocular criterion is used. A third experiment examines whether past results may have been affected by possible incorrect detections due to small head movements. It shows that despite the many detections due to head movements, the typical modulation of microsaccade rate after stimulus onset is found only when recording from the participants' eyes. |
Frouke Hermens; Sunčica Zdravković Information extraction from shadowed regions in images: An eye movement study Journal Article In: Vision Research, vol. 113, pp. 87–96, 2015. @article{Hermens2015, Natural scenes often contain variations in local luminance as a result of cast shadows and illumination from different directions. When making judgments about such scenes, it may be hypothesized that darker regions (with lower relative contrast due to a lack of illumination) are avoided as they may provide less detailed information than well-illuminated areas. We here test this hypothesis, first by presenting participants images of faces that were digitally modified to simulate the effect of a shadow over half of the image, and second by presenting photographs of faces taken with side illumination, also resulting in the appearance of a shadow across half of the face. While participants viewed these images, they were asked to perform different tasks on the images, to allow for the presentation of the different versions of each image (left shadow, right shadow, no shadow), and to distract the observers from the contrast and illumination manipulations. The results confirm our hypothesis and demonstrate that observers fixate the better illuminated regions of the images. |
Richard W. Hertle; Dongsheng Yang; Tonia Adkinson; Michael Reed Topical brinzolamide (Azopt) versus placebo in the treatment of infantile nystagmus syndrome (INS) Journal Article In: British Journal of Ophthalmology, vol. 99, no. 4, pp. 471–476, 2015. @article{Hertle2015, PURPOSE:To test the hypothesis that the topical carbonic anhydrase inhibitor brinzolamide (Azopt) has beneficial effects versus placebo on measures of nystagmus and visual acuity in adult subjects with infantile nystagmus syndrome (INS). DESIGN:Prospective, cross-over, double masked clinical trial. METHODS: SETTING:Single centre. STUDY POPULATION:Five subjects ≥18 years old with typical INS and best-binocular visual acuity in their primary position null zone ETDRS 55 letters to 85 letters (20/200 to 20/50) and had no previous treatment for nystagmus. INTERVENTION:In a randomised order, each subject received one drop of Azopt or placebo in both eyes three times a day separated by a washout period of at least a week followed by Azopt or placebo in both eyes three times a day; thus each subject got the drug and placebo, each acting as his or her own control. OUTCOME MEASURES:The nystagmus acuity function and INS waveforms obtained from eye movement recordings, binocular optotype visual acuity, using the ETDRS protocol analysed individually and as a group before and after Azopt and placebo. RESULTS:Versus placebo and baseline measures, topical Azopt significantly improved; INS waveform characteristics in the primary position null zone, group mean values of the nystagmus acuity function across gaze (p<0.01) and group mean ETDRS binocular letter visual acuity (p<0.05). There was a predictable decrease in intraocular pressure (IOP) without any systemic or ocular adverse events. CONCLUSIONS:Although a prospective large-scale clinical trial is needed to prove effectiveness, an eye-drop-based therapy for INS may emerge as a viable addition to optical, surgical, behavioural and systemic drug therapies for INS. |
Arvid Herwig; Katharina Weiß; Werner X. Schneider When circles become triangular: How transsaccadic predictions shape the perception of shape Journal Article In: Annals of the New York Academy of Sciences, vol. 1339, no. 1, pp. 97–105, 2015. @article{Herwig2015, Human vision is characterized by a consistent pattern of saccadic eye movements. With each saccade, internal object representations change their retinal position and spatial resolution. This raises the question as to how peripheral perception is affected by imminent saccadic eye movements. Here, we suggest that saccades are accompanied by a prediction of their perceptual consequences (i.e., the foveation of the target object). Accordingly, peripheral perception should be biased toward previously associated foveal input. In this study, we first exposed participants to an altered visual stimulation where one object systematically changed its shape during saccades. Subsequently, participants had to judge the shape of briefly presented peripheral saccade targets. The results showed that targets were perceived as less curved for objects that previously changed from more circular in the periphery to more triangular in the fovea. Similarly, shapes were perceived as more curved for objects that previously changed from triangular to circular. Thus, peripheral perception seems to depend not solely on the current input but also on memorized experiences, enabling predictions about the perceptual consequences of saccadic eye movements. |
Florian Hintz; Antje S. Meyer Prediction and production of simple mathematical equations: Evidence from visual world eye-tracking Journal Article In: PLoS ONE, vol. 10, no. 7, pp. e0130766, 2015. @article{Hintz2015, The relationship between the production and the comprehension systems has recently become a topic of interest for many psycholinguists. It has been argued that these systems are tightly linked and in particular that listeners use the production system to predict upcoming content. In this study, we tested how similar production and prediction processes are in a novel version of the visual world paradigm. Dutch speaking participants (native speakers in Experiment 1; German-Dutch bilinguals in Experiment 2) listened to mathematical equations while looking at a clock face featuring the numbers 1 to 12. On alternating trials, they either heard a complete equation ("three plus eight is eleven") or they heard the first part ("three plus eight is") and had to produce the result ("eleven") themselves. Participants were encouraged to look at the relevant numbers throughout the trial. Their eye movements were recorded and analyzed. We found that the participants' eye movements in the two tasks were overall very similar. They fixated the first and second number of the equations shortly after they were mentioned, and fixated the result number well before they named it on production trials and well before the recorded speaker named it on comprehension trials. However, all fixation latencies were shorter on production than on comprehension trials. These findings suggest that the processes involved in planning to say a word and anticipating hearing a word are quite similar, but that people are more aroused or engaged when they intend to respond than when they merely listen to another person. |
Margit Hofler; Iain D. Gilchrist; Christof Korner Guidance toward and away from distractors in repeated visual search Journal Article In: Journal of Vision, vol. 15, no. 5, pp. 1–14, 2015. @article{Hofler2015, When searching for two targets consecutively in the same display, participants use memory of recently fixated distractors that become the target in the second search to find that target more quickly. Here we ask whether participants are also using memory for fixated distractors that do not become the target. In Experiment 1 we show that search is faster overall in the second search regardless of whether or not the second search target was fixated in the first search. We replicate this effect in Experiment 2 for different display sizes and further show that the effect is a result of the prioritization of locations that are more likely to contain the target. This suggests that representations of the fixated distractor items are retained across the two searches and that these representations can be used flexibly to optimize search performance. Furthermore, this suggests that the short-term memory processes that support search across consecutive searches not only facilitate guidance toward the target but also allow distractors to be excluded from the search process. |
Marcel R. Giezen; Henrike K. Blumenfeld; Anthony Shook; Viorica Marian; Karen Emmorey Parallel language activation and inhibitory control in bimodal bilinguals Journal Article In: Cognition, vol. 141, pp. 9–25, 2015. @article{Giezen2015, Findings from recent studies suggest that spoken-language bilinguals engage nonlinguistic inhibitory control mechanisms to resolve cross-linguistic competition during auditory word recognition. Bilingual advantages in inhibitory control might stem from the need to resolve perceptual competition between similar-sounding words both within and between their two languages. If so, these advantages should be lessened or eliminated when there is no perceptual competition between two languages. The present study investigated the extent of inhibitory control recruitment during bilingual language comprehension by examining associations between language co-activation and nonlinguistic inhibitory control abilities in bimodal bilinguals, whose two languages do not perceptually compete. Cross-linguistic distractor activation was identified in the visual world paradigm, and correlated significantly with performance on a nonlinguistic spatial Stroop task within a group of 27 hearing ASL-English bilinguals. Smaller Stroop effects (indexing more efficient inhibition) were associated with reduced co-activation of ASL signs during the early stages of auditory word recognition. These results suggest that inhibitory control in auditory word recognition is not limited to resolving perceptual linguistic competition in phonological input, but is also used to moderate competition that originates at the lexico-semantic level. |
Steven M. Gillespie; Pia Rotshtein; Laura Jean Wells; Anthony R. Beech; Ian J. Mitchell Psychopathic traits are associated with reduced attention to the eyes of emotional faces among adult male non-offenders Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 552, 2015. @article{Gillespie2015, Psychopathic traits are linked with impairments in emotional facial expression recognition. These impairments may, in part, reflect reduced attention to the eyes of emotional faces. Although reduced attention to the eyes has been noted among children with conduct problems and callous-unemotional traits, similar findings are yet to be found in relation to psychopathic traits among adult male participants. Here we investigated the relationship of primary (selfish, uncaring) and secondary (impulsive, antisocial) psychopathic traits with attention to the eyes among adult male non-offenders during an emotion recognition task. We measured the number of fixations, and overall dwell time, on the eyes, and the mouth of male and female faces showing the six basic emotions at varying levels of intensity. We found no relationship of primary or secondary psychopathic traits with recognition accuracy. However, primary psychopathic traits were associated with a reduced number of fixations, and lower overall dwell time, on the eyes relative to the mouth across expressions, intensity, and sex. Furthermore, the relationship of primary psychopathic traits with attention to the eyes of angry and fearful faces was influenced by the sex and intensity of the expression. We also showed that a greater number of fixations on the eyes, relative to the mouth, were associated with increased accuracy for angry and fearful expression recognition. These results are the first to show effects of psychopathic traits on attention to the eyes of emotional faces in an adult male sample, and may support amygdala based accounts of psychopathy. These findings may also have methodological implications for clinical studies of emotion recognition. |
Bruno Gingras; Manuela M. Marin; Estela Puig-Waldmüller; W. T. Fitch The eye is listening: Music-induced arousal and Iindividual differences predict pupillary responses Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 619, 2015. @article{Gingras2015, Pupillary responses are a well-known indicator of emotional arousal but have not yet been systematically investigated in response to music. Here, we measured pupillary dilations evoked by short musical excerpts normalized for intensity and selected for their stylistic uniformity. Thirty participants (15 females) provided subjective ratings of music-induced felt arousal, tension, pleasantness, and familiarity for 80 classical music excerpts. The pupillary responses evoked by these excerpts were measured in another thirty participants (15 females). We probed the role of listener-specific characteristics such as mood, stress reactivity, self-reported role of music in life, liking for the selected excerpts, as well as of subjective responses to music, in pupillary responses. Linear mixed model analyses showed that a greater role of music in life was associated with larger dilations, and that larger dilations were also predicted for excerpts rated as more arousing or tense. However, an interaction between arousal and liking for the excerpts suggested that pupillary responses were modulated less strongly by arousal when the excerpts were particularly liked. An analogous interaction was observed between tension and liking. Additionally, males exhibited larger dilations than females. Overall, these findings suggest a complex interplay between bottom-up and top-down influences on pupillary responses to music. |
Aline Godfroid; Shawn Loewen; Sehoon Jung; Ji-Hyun Park; Susan M. Gass; Rod Ellis Timed and untimed grammaticality judgments measure distinct types of knowledge: Evidence from eye-movement patterns Journal Article In: Studies in Second Language Acquisition, vol. 37, no. 2, pp. 269–297, 2015. @article{Godfroid2015a, Grammaticality judgment tests (GJTs) have been used to elicit data refl ecting second language (L2) speakers' knowledge of L2 grammar. However, the exact constructs measured by GJTs, whether primarily implicit or explicit knowledge, are disputed and have been argued to differ depending on test-related variables (i.e., time pressure and item grammaticality). Using eye-tracking, this study replicates the GJT results in R. Ellis (2005). Twenty native and 40 nonnative English speakers judged sentences with and without time pressure. Analyses revealed that time pressure suppressed regressions (right-to-left eye movements) in nonnative speakers only. Conversely, both groups regressed more on untimed, grammatical items. These findings suggest that timed and untimed GJTs measure different constructs, which could correspond to implicit and explicit knowledge, respectively. In particular, they point to a difference in the levels of automatic and controlled processing involved in responding to the timed and untimed tests. Furthermore, untimed grammatical items may induce GJT- specific task effects. |
Aline Godfroid; Le Anne Spino Reconceptualizing reactivity of think-alouds and eye tracking: Absence of evidence is not evidence of absence Journal Article In: Language Learning, vol. 65, no. 4, pp. 896–928, 2015. @article{Godfroid2015, This study extends previous reactivity research on the cognitive effects of think-alouds to include eye-tracking methodology. Unlike previous studies, we supplemented traditional superiority tests with equivalence tests, because only the latter are conceptually appropriate for demonstrating nonreactivity. Advanced learners of English read short English texts embedded with pseudowords in an eye-tracking (n = 28), think-aloud (n = 28), or silent control condition (n = 46). Results indicated that neither eye tracking nor thinking aloud affected text comprehension. In terms of vocabulary recognition, thinking aloud had a small, positive effect, and the results for eye tracking were mixed. We discuss challenges and opportunities of equivalence testing and explore ways to improve study quality more generally in second language acquisition research. |
Hayward J. Godwin; Simon P. Liversedge; Julie A. Kirkby; Michael Boardman; Katherine Cornes; Nick Donnelly The influence of experience upon information-sampling and decision-making behaviour during risk assessment in military personnel Journal Article In: Visual Cognition, vol. 23, no. 4, pp. 415–431, 2015. @article{Godwin2015, We examined the influence of experience upon information-sampling and decision-making behaviour in a group of military personnel as they conducted risk assessments of scenes photographed from patrol routes during the recent conflict in Afghanistan. Their risk assessment was based on an evaluation of Potential Risk Indicators (PRIs) during examination of each scene. We found that both participant groups were equally likely to fixate PRIs, demonstrating similarity in the selectivity of their information-sampling. However, the inexperienced participants made more revisits to PRIs, had longer response times, and were more likely to decide that the scenes contained a high level of risk. Together, these results suggest that experience primarily modulates decision-making behaviour. We discuss potential routes to train personnel to conduct risk assessments in a more similar manner to experienced participants. |
Hayward J. Godwin; Tamaryn Menneer; Kyle R. Cave; Michael Thaibsyah; Nick Donnelly The effects of increasing target prevalence on information processing during visual search Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 2, pp. 469–475, 2015. @article{Godwin2015a, The proportion of trials on which a target is presented (referred to as the target prevalence) during visual search influences the probability that the target will be detected. As prevalence increases, participants become biased toward reporting that the target is present. This bias results in an increase in detection rates for the target, coupled with an increased likelihood of making a false alarm. Previous work has demonstrated that, as prevalence increases, participants spend an increasing period of time searching on target-absent trials. The goal of the present study was to determine the information processing during the additional time spent searching on target-absent trials as prevalence increased. We recorded participants' eye movement behavior as they were engaged in low-prevalence (25% target-present trials), medium-prevalence (50%), or high-prevalence (75%) search. Increased prevalence primarily influenced search by increasing the time spent examining objects in the display, rather than by increasing the proportion of objects examined in each display. In addition, the additional time spent examining objects in high-prevalence target-absent trials was the result of revisiting objects. We discuss the implications of these results in relation to current models of search as well as ongoing efforts to alleviate the prevalence effect. |
Hayward J. Godwin; Tamaryn Menneer; Charlotte A. Riggs; Kyle R. Cave; Nick Donnelly Perceptual failures in the selection and identification of low-prevalence targets in relative prevalence visual search Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 1, pp. 150–159, 2015. @article{Godwin2015b, Previous research has shown that during visual search tasts target prevalence (the proportion of trials in which a target appears) influences both the probability that a target will be detected, and the speed at which participants will quit searching and provide an 'absent' response. When prevelence is low (e.g., target presented on 2% of trials), participants are less likely to detect the target than when the prevelence is higher (e.g., 50% of trials). In the present set of experiments we examined perceptula faliures to detect low prevalence targets in visual search. We used a relative prevelence search task in order to be able to present and overall 50% target prevalence and thereby prevent the results being accounted for by early quitting behavour. Participants searched for two targets, one of which appeared on 45% of trials and another tha appeared on 5% of trials, leaving overall target prevalence at 50%. In the first experiment, participants searched for two dissimilar targets; in the second experiment, participants searched for two similar targets. Overall the results supported the notion that a reduction in prevalence primarily influenced perceptulal faliures of identification, rather than of selection. Thogether, these experiments add to a growing body of research exploring how and why observers fail to detect low prevalence targets, espically in real-world tasks in which some targets are more likely to appear than others. |
Ahu Gokce; Hermann J. Müller; Thomas Geyer Positional priming of visual pop-out search is supported by multiple spatial reference frames Journal Article In: Frontiers in Psychology, vol. 6, pp. 838, 2015. @article{Gokce2015, The present study investigates the representations(s) underlying positional priming of visual ‘pop-out' search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. |
Elizabeth R. Goldenberg; Scott P. Johnson Category generalization in a new context: The role of visual attention Journal Article In: Infant Behavior and Development, vol. 38, pp. 49–56, 2015. @article{Goldenberg2015, Infants and children have difficulty categorizing objects in new contexts. However, learning in both same and varied contexts can help young word learners overcome contextual learning difficulties. We examined the relation between infants' visual attention to the category member and background context during learning and their ability to generalize a new category member in a new context. Of particular interest is how this relation is affected by learning in various contextual conditions. Infants (16-20 months; n= 48) were presented with eight novel noun categories in one of three contextual conditions (same context, varied context, or a combination of same and varied contexts), and tested for their generalization ability in a new context. Context was defined as the colored and patterned fabric upon which the object was presented. Results suggest that visual attention during learning is associated with category generalization ability in a new context only for infants whose learning took place in a combination of same and varied background contexts. The results are discussed in terms of the mechanisms by which context affects generalization. |
Julie D. Golomb Divided spatial attention and feature-mixing errors Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 8, pp. 2562–2569, 2015. @article{Golomb2015, Spatial attention is thought to play a critical role in feature binding. However, often multiple objects or locations are of interest in our environment, and we need to shift or split attention between them. Recent evidence has demonstrated that shifting and splitting spatial attention results in different types of feature-binding errors. In particular, when two locations are simultaneously sharing attentional resources, subjects are susceptible to feature-mixing errors; that is, they tend to report a color that is a subtle blend of the target color and the color at the other attended location. The present study was designed to test whether these feature-mixing errors are influenced by target-distractor similarity. Subjects were cued to split attention across two different spatial locations, and were subsequently presented with an array of colored stimuli, followed by a postcue indicating which color to report. Target-distractor similarity was manipulated by varying the distance in color space between the two attended stimuli. Probabilistic modeling in all cases revealed shifts in the response distribution consistent with feature-mixing errors; however, the patterns differed considerably across target-distractor color distances. With large differences in color, the findings replicated the mixing result, but with small color differences, repulsion was instead observed, with the reported target color shifted away from the other attended color. |
Pablo Gomez; Roger Ratcliff; Russ Childers Pointing, looking at, and pressing keys: A diffusion model account of response modality Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 6, pp. 1515–1523, 2015. @article{Gomez2015, Accumulation of evidence models of perceptual decision making have been able to account for data from a wide range of domains at an impressive level of precision. In particular, Ratcliff's (1978) diffusion model has been used across many different 2-choice tasks in which the response is executed via a key-press. In this article, we present 2 experiments in which we used a letter-discrimination task exploring 3 central aspects of a 2-choice task: the discriminability of the stimulus, the modality of the response execution (eye movement, key pressing, and pointing on a touchscreen), and the mapping of the response areas for the eye movement and the touchscreen conditions (consistent vs. inconsistent). We fitted the diffusion model to the data from these experiments and examined the behavior of the model's parameters. Fits of the model were consistent with the hypothesis that the same decision mechanism is used in the task with 3 different response methods. Drift rates are affected by the duration of the presentation of the stimulus while the response execution time changed as a function of the response modality. |
Claudia C. Gonzalez; Mark Mon-Williams; Melanie R. Burke Children and older adults exhibit distinct sub-optimal cost-benefit functions when preparing to move their eyes and hands Journal Article In: PLoS ONE, vol. 10, no. 2, pp. e0117783, 2015. @article{Gonzalez2015, Numerous activities require an individual to respond quickly to the correct stimulus. The pro-vision of advance information allows response priming but heightened responses can cause errors (responding too early or reacting to the wrong stimulus). Thus, a balance is re-quired between the online cognitive mechanisms (inhibitory and anticipatory) used to pre-pare and execute a motor response at the appropriate time. We investigated the use of advance information in 71 participants across four different age groups: (i) children, (ii) young adults, (iii) middle-aged adults, and (iv) older adults. We implemented 'cued' and 'non-cued' conditions to assess age-related changes in saccadic and touch responses to targets in three movement conditions: (a) Eyes only; (b) Hands only; (c) Eyes and Hand. Children made less saccade errors compared to young adults, but they also exhibited lon-ger response times in cued versus non-cued conditions. In contrast, older adults showed faster responses in cued conditions but exhibited more errors. The results indicate that young adults (18–25 years) achieve an optimal balance between anticipation and execu-tion. In contrast, children show benefits (few errors) and costs (slow responses) of good in-hibition when preparing a motor response based on advance information; whilst older adults show the benefits and costs associated with a prospective response strategy (i.e., good anticipation). |
Samanthi C. Goonetilleke; Leor N. Katz; Daniel K. Wood; Chao Gu; Alexander C. Huk; Brian D. Corneil In: Journal of Neurophysiology, vol. 114, no. 2, pp. 902–913, 2015. @article{Goonetilleke2015, Recent studies have described a phenomenon wherein the onset of a peripheral visual stimulus elicits short-latency (<100 ms) stimulus-locked recruitment (SLR) of neck muscles in nonhuman primates (NHPs), well before any saccadic gaze shift. The SLR is thought to arise from visual responses within the intermediate layers of the superior colliculus (SCi), hence neck muscle recordings may reflect presaccadic activity within the SCi, even in humans. We obtained bilateral intramuscular recordings from splenius capitis (SPL, an ipsilateral head-turning muscle) from 28 human subjects performing leftward or rightward visually guided eye-head gaze shifts. Evidence of an SLR was obtained in 16/55 (29%) of samples; we also observed examples where the SLR was present only unilaterally. We compared these human results with those recorded from a sample of eight NHPs from which recordings of both SPL and deeper suboccipital muscles were available. Using the same criteria, evidence of an SLR was obtained in 8/14 (57%) of SPL recordings, but in 26/29 (90%) of recordings from suboccipital muscles. Thus, both species-specific and muscle- specific factors contribute to the low SLR prevalence in human SPL. Regardless of the presence of the SLR, neck muscle activity in both human SPL and in NHPs became predictive of the reaction time of the ensuing saccade gaze shift ~70 ms after target appearance; such pregaze recruitment likely reflects developing SCi activity, even if the tectoreticulospinal pathway does not reliably relay visually related activity to SPL in humans. |
Bruce C. Hansen; Pamela J. Rakhshan; Arnold K. Ho; Sebastian Pannasch Looking at others through implicitly or explicitly prejudiced eyes Journal Article In: Visual Cognition, vol. 23, no. 5, pp. 612–642, 2015. @article{Hansen2015, It is well known that we utilize internalized representations (or schemas) to direct our eyes when exploring visual stimuli. Interestingly, our schemas for human faces are known to reflect systematic differences that are consistent with one's level of racial prejudice. However, whether one's level or type of racial prejudice can differentially regulate how we visually explore faces that are the target of prejudice is currently unknown. Here, White participants varying in their level of implicit or explicit prejudice viewed Black faces and White faces (with the latter serving as a control) while having their gaze behaviour recorded with an eye-tracker. The results show that, regardless of prejudice type (i.e., implicit or explicit), participants high in racial prejudice examine faces differently than those low in racial prejudice. Specifically, individuals high in explicit racial prejudice were more likely to fixate on the mouth region of Black faces when compared to individuals low in explicit prejudice, and exhibited less consistency in their scanning of faces irrespective of race. On the other hand, individuals high in implicit racial prejudice tended to focus on the region between the eyes, regardless of face race. It therefore seems that racial prejudice guides target-race specific patterns of looking behaviour, and may also contribute to general patterns oflooking behaviour when visually exploring human faces. |
Anthony M. Harris; Stefanie I. Becker; Roger W. Remington Capture by colour: Evidence for dimension-specific singleton capture Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 7, pp. 2305–2321, 2015. @article{Harris2015a, Previous work on attentional capture has shown the attentional system to be quite flexible in the stimulus properties it can be set to respond to. Several different attentional "modes" have been identified. Feature search mode allows attention to be set for specific features of a target (e.g., red). Singleton detection mode sets attention to respond to any discrepant item ("singleton") in the display. Relational search sets attention for the relative properties of the target in relation to the distractors (e.g., redder, larger). Recently, a new attentional mode was proposed that sets attention to respond to any singleton within a particular feature dimension (e.g., colour; Folk & Anderson, 2010). We tested this proposal against the predictions of previously established attentional modes. In a spatial cueing paradigm, participants searched for a colour target that was randomly either red or green. The nature of the attentional control setting was probed by presenting an irrelevant singleton cue prior to the target display and assessing whether it attracted attention. In all experiments, the cues were red, green, blue, or a white stimulus rapidly rotated (motion cue). The results of three experiments support the existence of a "colour singleton set," finding that all colour cues captured attention strongly, while motion cues captured attention only weakly or not at all. Notably, we also found that capture by motion cues in search for colour targets was moderated by their frequency; rare motion cues captured attention (weakly), while frequent motion cues did not. |
Jesse A. Harris Structure modulates similarity-based interference in sluicing: An eye tracking study Journal Article In: Frontiers in Psychology, vol. 6, pp. 1839, 2015. @article{Harris2015, In cue-based content-addressable approaches to memory, a target and its competitors are retrieved in parallel from memory via a fast, associative cue-matching procedure under a severely limited focus of attention. Such a parallel matching procedure could in principle ignore the serial order or hierarchical structure characteristic of linguistic relations. I present an eye tracking while reading experiment that investigates whether the sentential position of a potential antecedent modulates the strength of similarity-based interference, a well-studied effect in which increased similarity in features between a target and its competitors results in slower and less accurate retrieval overall. The manipulation trades on an independently established Locality bias in sluiced structures to associate a wh-remnant (which ones) in clausal ellipsis with the most local correlate (some wines), as in "The tourists enjoyed some wines, but I don't know which ones." The findings generally support cue-based parsing models of sentence processing that are subject to similarity-based interference in retrieval, and provide additional support to the growing body of evidence that retrieval is sensitive to both the structural position of a target antecedent and its competitors, and the specificity of retrieval cues. |
Jonathan W. Harris; Christopher D. Cowper-Smith; Raymond M. Klein; David A. Westwood Further evidence against a momentum explanation for IOR Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0123666, 2015. @article{Harris2015b, Reaction times to targets presented in the same location as a preceding cue are greater than those to targets presented opposite the cued location. This observation can be explained as a result of inhibition at the attended location (IOR), or as facilitation at the location opposite the cue (opposite facilitation effect or OFE). Past research has demonstrated that IOR is observed reliably, whereas OFE is observed only occasionally. The present series of four experiments allows us to determine whether or not OFE can be explained by eye movements as suggested by previous authors. Participants' eye movements were monitored as they were presented with an array of four placeholders aligned with the four cardinal axes. Exogenous cues and targets were presented successively. Participants (N=37) completed either: i.) cue-manual and cue-saccade experiments, ignoring the cue and then responding with a keypress or saccade, respectively, or ii.) manual-manual and saccade-saccade experiments, responding to both the cue and the target with a keypress or saccade respectively. Results demonstrated a reliable IOR effect in each of the four experiments (reaction time greater for same versus adjacent and opposite cue-target trials). None of the four experiments demonstrated evidence of an OFE (reaction times were not significantly lower for opposite versus adjacent cue-target trials). These results are inconsistent with a momentum-based account of cue-target task performance, and furthermore suggest that the OFE cannot be attributed to occasional eye movements to the cue and/or target in previous studies. |
James J. Harrison; Tom C. A. Freeman; Petroc Sumner Saccadic compensation for reflexive optokinetic nystagmus just as good as compensation for volitional pursuit Journal Article In: Journal of Vision, vol. 15, no. 1, pp. 1–13, 2015. @article{Harrison2015a, The natural viewing behavior of moving observers ideally requires target-selecting saccades to be coordinated with automatic gaze-stabilizing eye movements such as optokinetic nystagmus. However, it is unknown whether saccade plans can compensate for reflexive movement of the eye during the variable saccade latency period, and it is unclear whether reflexive nystagmus is even accompanied by extraretinal signals carrying the eye movement information that could potentially underpin such compensation. We show that saccades do partially compensate for optokinetic nystagmus that displaces the eye during the saccade latency period. Moreover, this compensation is as good as for displacements due to voluntary smooth pursuit. In other words, the saccade system appears to be as well coordinated with reflexive nystagmus as it is with volitional pursuit, which in turn implies that extraretinal signals accompany nystagmus and are just as informative as those accompanying pursuit. |
James J. Harrison; Petroc Sumner; Matt J. Dunn; Jonathan T. Erichsen; Tom C. A. Freeman Quick phases of infantile nystagmus show the saccadic inhibition effect Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 3, pp. 1594–1600, 2015. @article{Harrison2015, PURPOSE: Infantile nystagmus (IN) is a pathological, involuntary oscillation of the eyes consisting of slow, drifting eye movements interspersed with rapid reorienting quick phases. The extent to which quick phases of IN are programmed similarly to saccadic eye movements remains unknown. We investigated whether IN quick phases exhibit 'saccadic inhibition,' a phenomenon typically related to normal targeting saccades, in which the initiation of the eye movement is systematically delayed by task-irrelevant visual distractors. METHODS: We recorded eye position from 10 observers with early-onset idiopathic nystagmus while task-irrelevant distractor stimuli were flashed along the top and bottom of a large screen at ±10° eccentricity. The latency distributions of quick phases were measured with respect to these distractor flashes. Two additional participants, one with possible albinism and one with fusion maldevelopment nystagmus syndrome, were also tested. RESULTS: All observers showed that a distractor flash delayed the execution of quick phases that would otherwise have occurred approximately 100 ms later, exactly as in the standard saccadic inhibition effect. The delay did not appear to differ between the two main nystagmus types under investigation (idiopathic IN with unidirectional and bidirectional jerk). CONCLUSIONS: The presence of the saccadic inhibition effect in IN quick phases is consistent with the idea that quick phases and saccades share a common programming pathway. This could allow quick phases to take on flexible, goal-directed behavior, at odds with the view that IN quick phases are stereotyped, involuntary eye movements. |
Nabil Hasshim; Benjamin A. Parris In: Attention, Perception, and Psychophysics, vol. 77, no. 8, pp. 2601–2610, 2015. @article{Hasshim2015, Conflict in the Stroop task is thought to come from various stages of processing, including semantics. Two-to-one response mappings, in which two response-set colors share a common response location, have been used to isolate stimulus-stimulus (semantic) from stimulus-response conflict in the Stroop task. However, the use of congruent trials as a baseline means that the measured effects could be exaggerated by facilitation, and recent research using neutral, non-color-word trials as a baseline has supported this notion. In the present study, we sought to provide evidence for stimulus-stimulus conflict using an oculomotor Stroop task and an early, preresponse pupillometric measure of effort. The results provided strong (Bayesian) evidence for no statistical difference between two-to-one response-mapping trials and neutral trials in both saccadic response latencies and preresponse pupillometric measures, supporting the notion that the difference between same-response and congruent trials indexes facilitation in congruent trials, and not stimulus-stimulus conflict, thus providing evidence against the presence of semantic conflict in the Stroop task. We also demonstrated the utility of preresponse pupillometry in measuring Stroop interference, supporting the idea that pupillary effects are not simply a residue of making a response. |
Stefan Hawelka; Sarah Schuster; Benjamin Gagl; Florian Hutzler On forward inferences of fast and slow readers. An eye movement study Journal Article In: Scientific Reports, vol. 5, pp. 8432, 2015. @article{Hawelka2015, Unimpaired readers process words incredibly fast and hence it was assumed that top-down processing, such as predicting upcoming words, would be too slow to play an appreciable role in reading. This runs counter the major postulate of the predictive coding framework that our brain continually predicts probable upcoming sensory events. This means, it may generate predictions about the probable upcoming word during reading (dubbed forward inferences). Trying to asses these contradictory assumptions, we evaluated the effect of the predictability of words in sentences on eye movement control during silent reading. Participants were a group of fluent (i.e., fast) and a group of speed-impaired (i.e., slow) readers. The findings indicate that fast readers generate forward inferences, whereas speed-impaired readers do so to a reduced extent - indicating a significant role of predictive coding for fluent reading. |
Rebecca Haworth; Stephanie Sobey; Jill M. Chorney; Michael Bezuhly; Paul Hong Measuring attentional bias in children with prominent ears: A prospective eye-tracking study Journal Article In: Journal of Plastic, Reconstructive & Aesthetic Surgery, vol. 68, no. 12, pp. 1662–1666, 2015. @article{Haworth2015, Background and aim: When observing new faces, most people focus their attention on the central triangle of the face containing the eyes, nose and mouth. When viewing faces with prominent ears, observers may divert their attention from the central triangle. The objective of this study was to determine whether there was an objective attentional bias to prominent ears in comparison to non-prominent ears. Methods: A total of 24 naïve participants (13 female; mean age 22.88 years) viewed 15 photographs of children with bilateral prominent ears, unilateral prominent ears and non-prominent ears. Both pre- and post-otoplasty photographs of two patients were included. The eye movements of participants were recorded using the EyeLink 1000, a table-mounted eye-tracking device. Results: Overall, the participants spent more time looking at the ear regions for faces with prominent ears in comparison to faces without prominent ears (p = 0.007 |
Michele Graffeo; Luca Polonio; Nicolao Bonini Individual differences in competent consumer choice: The role of cognitive reflection and numeracy skills Journal Article In: Frontiers in Psychology, vol. 6, pp. 844, 2015. @article{Graffeo2015, In this paper, we investigate whether cognitive reflection and numeracy skills affect the quality of the consumers' decision-making process in a purchase decision context. In a first (field) experiment, an identical product was on sale in two shops with different initial prices and discounts. One of the two deals was better than the other and the consumers were asked to choose the best one and to describe which arithmetic operations they used to solve the problem; then they were asked to complete the numeracy scale (Lipkus et al., 2001). The choice procedures used by the consumers were classified as "complete decision approach" when all the arithmetic operations needed to solve the problem were computed, and as "partial decision approach" when only some operations were computed. A mediation model shows that higher numeracy is associated with use of the complete decision approach. In turn, this approach is positively associated with the quality of the purchase decision. Given that these findings highlight the importance of the decision processes, in a second (laboratory) experiment we used a supplementary method to study the type of information search used by the participants: eye-tracking. In this experiment the participants were presented with decision problems similar to those used in Experiment 1 and they completed the Lipkus numeracy scale and the Cognitive Reflection Test (CRT; Frederick, 2005). Participants with a high CRT score chose the best deal more frequently, and showed a more profound and detailed information search pattern compared to participants with a low CRT score. Overall, results indicate that higher levels of cognitive reflection and numeracy skills predict the use of a more thorough decision process (measured with two different techniques: retrospective verbal reports and eye movements). In both experiments the decision process is a crucial factor which greatly affects the quality of the purchase decision. |
Joshua A. Granek; Lauren E. Sergio Evidence for distinct brain networks in the control of rule-based motor behavior Journal Article In: Journal of Neurophysiology, vol. 114, no. 2, pp. 1298–1309, 2015. @article{Granek2015, Reach guidance when the spatial location of the viewed target and hand movement are incongruent (i.e., decoupled) necessitates use of explicit cognitive rules (strategic control) or implicit recalibration of gaze and limb position (senso- rimotor recalibration). In a patient with optic ataxia (OA) and bilateral superior parietal lobule damage, we recently demonstrated an in- creased reliance on strategic control when the patient performed a decoupled reach (Granek JA, Pisella L, Stemberger J, Vighetto A, Rossetti Y, Sergio LE. PLoS One 8: e86138, 2013). To more generally understand the fundamental mechanisms of decoupled visuomotor control and to more specifically test whether we could distinguish these two modes of movement control, we tested healthy participants in a cognitively demanding dual task. Participants continuously counted backward while simultaneously reaching toward horizontal (left or right) or diagonal (equivalent to top-left or top-right) targets with either veridical or rotated (90°) cursor feedback. By increasing the overall neural load and selectively compromising potentially overlapping neural circuits responsible for strategic control, the com- plex dual task served as a noninvasive means to disrupt the integration of a cognitive rule into a motor action. Complementary to our previous results observed in patients with optic ataxia, here our dual task led to greater performance deficits during movements that re- quired an explicit rule, implying a selective disruption of strategic control in decoupled reaching. Our results suggest that distinct neural processing is required to control these different types of reaching because in considering the current results and previous patient results together, the two classes of movement could be differentiated depend- ing on the type of interference. |
Leigh D. Grant; Alison C. Bowling Gambling attitudes and beliefs predict attentional bias in non-problem gamblers Journal Article In: Journal of Gambling Studies, vol. 31, no. 4, pp. 1487–1503, 2015. @article{Grant2015, Problem gambling has been identified as a public health concern in Australia, and a considerable proportion of regular gamblers may be at risk of developing gambling related problems. Attentional bias to salient cues has been observed in substance addictions, and to some extent, in problem gamblers. This bias appears to be indicative of an increase in sensitisation to salient cues as a result of continued reforcement of a related behaviour. To test for an attentional bias to gambling-related stimuli in non-problem gamblers, the relationships between gambling frequency, gambling attitudes and beliefs (GABS-23), and attentional bias were investigated. Participants (N = 38) viewed simultaneous pairs of gambling-related and neutral images and performed a dot probe task, during which their eye-movements were recorded. This enabled both direct and indirect measures of attentional bias to be obtained. Gambling frequency and GABS-23 scores predicted both direct and indirect measures of a bias in the maintenance of attention to gambling cues. No bias in attentional engagement was found. These results suggest that regular gamblers who have not yet developed any related problems show signs of sensitisation to gambling cues and may be at risk of progressing further towards problem gambling. |
Michael J. Gray; Hans Peter Frey; Tommy J. Wilson; John J. Foxe Oscillatory recruitment of bilateral visual cortex during spatial attention to competing rhythmic inputs Journal Article In: Journal of Neuroscience, vol. 35, no. 14, pp. 5489–5503, 2015. @article{Gray2015, Selective attention uses temporal regularity of relevant inputs to bias the phase of ongoing population-level neuronal oscillations. This phase entrainment streamlines processing, allowing attended information to arrive at moments of high neural excitability. How entrainment resolves competition between spatially segregated inputs during visuospatial tasks is not yet established. Using high-density electroencephalography in humans, a bilateral entrainment response to the rhythm (1.3 or 1.5 Hz) of an attended stimulation stream was observed, concurrent with a considerably weaker contralateral entrainment to a competing rhythm. That ipsilateral visual areas strongly entrained to the attended stimulus is notable because competitive inputs to these regions were being driven at an entirely different rhythm. Strong modulations of phase locking and weak modulations of single-trial power suggest that entrainment was primarily driven by phase-alignment of ongoing oscillatory activity. In addition, interhemispheric differences in entrained phase were found to be modulated by attended hemifield, implying that the bilateral nature of the response reflected a functional flow of information between hemispheres. This modulation was strongest at the third of at least four harmonics that were strongly entrained. Ipsilateral increases in alpha-band (8-12 Hz) power were also observed during bilateral entrainment, reflecting suppression of the ignored stimulation stream. Furthermore, both entrainment and alpha lateralization significantly affected task performance. We conclude that oscillatory entrainment is a functionally relevant mechanism that synchronizes endogenous activity across the cortical hierarchy to resolve spatial competition. We further speculate that concurrent suppression of ignored input might facilitate the widespread propagation of attended information during spatial attention. |
Nicola J. Gregory; Beatriz López; Gemma Graham; Paul Marshman; Sarah Bate; Niko Kargas Reduced gaze following and attention to heads when viewing a "live" social scene Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0121792, 2015. @article{Gregory2015, Social stimuli are known to both attract and direct our attention, but most research on social attention has been conducted in highly controlled laboratory settings lacking in social context. This study examined the role of social context on viewing behaviour of participants whilst they watched a dynamic social scene, under three different conditions. In two social groups, participants believed they were watching a live webcam of other participants. The socially-engaged group believed they would later complete a group task with the people in the video, whilst the non-engaged group believed they would not meet the people in the scene. In a third condition, participants simply free-viewed the same video with the knowledge that it was pre-recorded, with no suggestion of a later interaction. Results demonstrated that the social context in which the stimulus was viewed significantly influenced viewing behaviour. Specifically, participants in the social conditions allocated less visual attention towards the heads of the actors in the scene and followed their gaze less than those in the free-viewing group. These findings suggest that by underestimating the impact of social context in social attention, researchers risk coming to inaccurate conclusions about how we attend to others in the real world. |
Joseph C. Griffis; Abdurahman S. Elkhetali; Ryan J. Vaden; Kristina M. Visscher Distinct effects of trial-driven and task set-related control in primary visual cortex Journal Article In: NeuroImage, vol. 120, pp. 285–297, 2015. @article{Griffis2015, Task sets are task-specific configurations of cognitive processes that facilitate task-appropriate reactions to stimuli. While it is established that the trial-by-trial deployment of visual attention to expected stimuli influences neural responses in primary visual cortex (V1) in a retinotopically specific manner, it is not clear whether the mechanisms that help maintain a task set over many trials also operate with similar retinotopic specificity. Here, we address this question by using BOLD fMRI to characterize how portions of V1 that are specialized for different eccentricities respond during distinct components of an attention-demanding discrimination task: cue-driven preparation for a trial, trial-driven processing, task-initiation at the beginning of a block of trials, and task-maintenance throughout a block of trials. Tasks required either unimodal attention to an auditory or a visual stimulus or selective intermodal attention to the visual or auditory component of simultaneously presented visual and auditory stimuli. We found that while the retinotopic patterns of trial-driven and cue-driven activity depended on the attended stimulus, the retinotopic patterns of task-initiation and task-maintenance activity did not. Further, only the retinotopic patterns of trial-driven activity were found to depend on the presence of inter-modal distraction. Participants who performed well on the intermodal selective attention tasks showed strong task-specific modulations of both trial-driven and task-maintenance activity. Importantly, task-related modulations of trial-driven and task-maintenance activity were in opposite directions. Together, these results confirm that there are (at least) two different processes for top-down control of V1: One, working trial-by-trial, differently modulates activity across different eccentricity sectors - portions of V1 corresponding to different visual eccentricities. The second process works across longer epochs of task performance, and does not differ among eccentricity sectors. These results are discussed in the context of previous literature examining top-down control of visual cortical areas. |
Marcus Grueschow; Rafael Polania; Todd A. Hare; Christian C. Ruff Automatic versus choice-dependent value representations in the human brain Journal Article In: Neuron, vol. 85, no. 4, pp. 874–885, 2015. @article{Grueschow2015, The subjective values of choice options can impact on behavior in two fundamentally different types of situations: first, when people explicitly base their actions on such values, and second, when values attract attention despite being irrelevant for current behavior. Here we show with functional magnetic resonance imaging (fMRI) that these two behavioral functions of values are encoded in distinct regions of the human brain. In the medial prefrontal cortex, value-related activity is enhanced when subjective value becomes choice-relevant, and the magnitude of this increase relates directly to the outcome and reliability of the value-based choice. In contrast, activity in the posterior cingulate cortex represents values similarly when they are relevant or irrelevant for the present choice, and the strength of this representation predicts attentional capture by choice-irrelevant values. Our results suggest that distinct components of the brain's valuation network encode value in context-dependent manners that serve fundamentally different behavioral aims. |
Junjuan Gu; Xingshan Li The effects of character transposition within and across words in Chinese reading Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 1, pp. 272–281, 2015. @article{Gu2015, Given the lack of spaces between words in Chinese text, Chinese readers must parse these characters into words using their word knowledge. In this situation, are the characters belonging to a single word or to different words understood via different character-order encoding processes? In this study, we explored the effects of word boundaries in Chinese text on character-order encoding. We used four-character words (the one-word condition) and two two-character words (the two-word condition) as our targets. We embedded the target words into sentences and then manipulated the previews of the words using the boundary paradigm. The preview was identical to the target word (identity condition), had the two middle characters of the target word transposed (TC condition), or had two middle characters that were different from those in the target word (SC condition). Fixation durations on the target word in the TC condition were much longer than those in the identity condition for the two-word condition, but they were not significantly different for the one-word condition. Furthermore, for the one-word condition, gaze durations were longer in the SC than in the TC condition, whereas for the two-word condition, the difference between the TC and SC conditions was not significant. Word boundaries were found to affect the character-order encoding in Chinese reading, further suggesting the early occurrence of word segmentation. |
Junjuan Gu; Xingshan Li; Simon P. Liversedge Character order processing in Chinese reading Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 127–137, 2015. @article{Gu2015a, We explored how character order information is encoded in isolated word processing or Chinese sentence reading in 2 experiments using a masked priming paradigm and a gaze-contingent display-change paradigm. The results showed that response latencies in the lexical decision task and reading times on the target word region were longer in the unrelated condition (the prime or the preview was unrelated with the target word) than the transposed-character condition (the prime or the preview was a transposition of the 2 characters of the target word), which were respectively longer than in the identity condition (the prime or preview was identical to the target word). These results show that character order is encoded at an early stage of processing in Chinese reading, but character position encoding was not strict. We also found that character order encoding was similar for single-morpheme and multiple-morpheme words, suggesting that morphemic status does not affect character order encoding. The current results represent an early contribution to our understanding of character order encoding during Chinese reading. |
Maryam Ziaei; William Hippel; Julie D. Henry; Stefanie I. Becker Are age effects in positivity influenced by the valence of distractors? Journal Article In: PLoS ONE, vol. 10, no. 9, pp. e0137604, 2015. @article{Ziaei2015, An age-related ‘positivity' effect has been identified, in which older adults show an information- processing bias towards positive emotional items in attention and memory. In the present study, we examined this positivity bias by using a novel paradigm in which emotional and neutral distractors were presented along with emotionally valenced targets. Thirty-five older and 37 younger adults were asked during encoding to attend to emotional targets paired with distractors that were either neutral or opposite in valence to the target. Pupillary responses were recorded during initial encoding as well as a later incidental recognition task. Memory and pupillary responses for negative items were not affected by the valence of distractors, suggesting that positive distractors did not automatically attract older adults' attention while they were encoding negative targets. Additionally, the pupil dilation to negative items mediated the relation between age and positivity in memory. Overall, memory and pupillary responses provide converging support for a cognitive control account of positivity effects in late adulthood and suggest a link between attentional processes and the memory positivity effect. |
Eckart Zimmermann Visual mislocalization during double-step saccades Journal Article In: Frontiers in Systems Neuroscience, vol. 9, pp. 132, 2015. @article{Zimmermann2015, Visual objects presented briefly at the time of saccade onset appear compressed toward the saccade target. Compression strength depends on the presentation of a visual saccade target signal and is strongly reduced during the second saccade of a double-step saccade sequence (Zimmermann et al., 2014b). Here, I tested whether perisaccadic compression is linked to saccade planning by contrasting two double-step paradigms. In the same-direction double-step paradigm, subjects were required to perform two rightward 10° saccades successively. At various times around execution of the saccade sequence a probe dot was briefly flashed. Subjects had to localize the position of the probe dot after they had completed both saccades. I found compression of visual space only at the time of the first but not at the time of the second saccade. In the reverse-direction paradigm, subjects performed first a rightward 10° saccade followed by a leftward 10° saccade back to initial fixation. In this paradigm compression was found in similar magnitude during both saccades. Analysis of the saccade parameters did not reveal indications of saccade sequence preplanning in this paradigm. I therefore conclude that saccade planning, rather than saccade execution factors, is involved in perisaccadic compression. |
Eckart Zimmermann; M. Concetta Morrone; David C. Burr Visual mislocalization during saccade sequences Journal Article In: Experimental Brain Research, vol. 233, no. 2, pp. 577–585, 2015. @article{Zimmermann2015a, Visual objects briefly presented around the time of saccadic eye movements are perceived compressed towards the saccade target. Here, we investigated perisaccadic mislocalization with a double-step saccade paradigm, measuring localization of small probe dots briefly flashed at various times around the sequence of the two saccades. At onset of the first saccade, probe dots were mislocalized towards the first and, to a lesser extent, also towards the second saccade target. However, there was very little mislocalization at the onset of the second saccade. When we increased the presentation duration of the saccade targets prior to onset of the saccade sequence, perisaccadic mislocalization did occur at the onset of the second saccade. |
Eckart Zimmermann; Florian Ostendorf; C. J. Ploner; Markus Lappe Impairment of saccade adaptation in a patient with a focal thalamic lesion Journal Article In: Journal of Neurophysiology, vol. 113, no. 7, pp. 2351–2359, 2015. @article{Zimmermann2015b, The frequent jumps of the eyeballs-called saccades-imply the need for a constant correction of motor errors. If systematic errors are detected in saccade landing, the saccade amplitude adapts to compensate for the error. In the laboratory, saccade adaptation can be studied by displacing the saccade target. Functional selectivity of adaptation for different saccade types suggests that adaptation occurs at multiple sites in the oculomotor system. Saccade motor learning might be the result of a comparison between a prediction of the saccade landing position and its actual postsaccadic location. To investigate whether a thalamic feedback pathway might carry such a prediction signal, we studied a patient with a lesion in the posterior ventrolateral thalamic nucleus. Saccade adaptation was tested for reactive saccades, which are performed to suddenly appearing targets, and for scanning saccades, which are performed to stationary targets. For reactive saccades, we found a clear impairment in adaptation retention ipsilateral to the lesioned side and a larger-than-normal adaptation on the contralesional side. For scanning saccades, adaptation was intact on both sides and not different from the control group. Our results provide the first lesion evidence that adaptation of reactive and scanning saccades relies on distinct feedback pathways from cerebellum to cortex. They further demonstrate that saccade adaptation in humans is not restricted to the cerebellum but also involves cortical areas. The paradoxically strong adaptation for outward target steps can be explained by stronger reliance on visual targeting errors when prediction error signaling is impaired. |
Sandrine Zufferey; Willem M. Mak; Liesbeth Degand; Ted J. M. Sanders Advanced learners' comprehension of discourse connectives: The role of L1 transfer across on-line and off-line tasks Journal Article In: Second Language Research, vol. 31, no. 3, pp. 389–411, 2015. @article{Zufferey2015, Discourse connectives are important indicators of textual coherence, and mastering them is an essential part of acquiring a language. In this article, we compare advanced learners' sensitivity to the meaning conveyed by connectives in an off-line grammaticality judgment task and an on-line reading experiment using eye-tracking. We also assess the influence of first language (L1) transfer by comparing learners' comprehension of two non-native-like semantic uses of connectives in English, often produced by learners due to transfer from French and Dutch. Our results indicate that in an off-line task transfer is an important factor accounting for French-and Dutch-speaking learners' non-native-like comprehension of connectives. During on-line processing, however, learners are as sensitive as native speakers to the meaning conveyed by connectives. These results raise intriguing questions regarding explicit vs. implicit knowledge in language learners. |
Benjamin A. Wolfe; David Whitney Saccadic remapping of object-selective information Journal Article In: Attention, Perception, and Psychophysics, vol. 77, no. 7, pp. 2260–2269, 2015. @article{Wolfe2015, Saccadic remapping, a presaccadic increase in neural activity when a saccade is about to bring an object into a neuron's receptive field, may be crucial for our perception of a stable world. Studies of perception and saccadic remapping, like ours, focus on the presaccadic acquisition of information from the saccade target, with no direct reference to underlying physiology. While information is known to be acquired prior to a saccade, it is unclear whether object-selective or feature-specific information is remapped. To test this, we performed a series of psychophysical experiments in which we presented a peripheral, nonfoveated face as a presaccadic target. The target face disappeared at saccade onset. After making a saccade to the location of the peripheral target face (which was no longer visible), subjects misperceived the expression of a subsequent, foveally presented neutral face as being repelled away from the peripheral presaccadic face target. This effect was similar to a sequential shape contrast or negative aftereffect but required a saccade, because covert attention was not sufficient to generate the illusion. Additional experiments further revealed that inverting the faces disrupted the illusion, suggesting that presaccadic remapping is object-selective and not based on low-level features. Our results demonstrate that saccadic remapping can be an object-selective process, spatially tuned to the target of the saccade and distinct from covert attention in the absence of a saccade. |
Michael J. Wolff; Sabine Scholz; Elkan G. Akyürek; Hedderik Rijn Two visual targets for the price of one? Pupil dilation shows reduced mental effort through temporal integration Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 1, pp. 251–257, 2015. @article{Wolff2015, In dynamic sensory environments, successive stimuli may be combined perceptually and represented as a single, comprehensive event by means of temporal integration. Such perceptual segmentation across time is intuitively plausible. However, the possible costs and benefits of temporal integration in perception remain underspecified. In the present study pupil dilation was analyzed as a measure of mental effort. Observers viewed either one or two successive targets amidst distractors in rapid serial visual presentation, which they were asked to identify. Pupil dilation was examined dependent on participants' report: dilation associated with the report of a single target, of two targets, and of an integrated percept consisting of the features of both targets. There was a clear distinction between dilation observed for single-target reports and integrations on the one side, and two-target reports on the other. Regardless of report order, two-target reports produced increased pupil dilation, reflecting increased mental effort. The results thus suggested that temporal integration reduces mental effort and may thereby facilitate perceptual processing. |
Thomas D. Wright; Aaron Margolis; Jamie Ward Using an auditory sensory substitution device to augment vision: evidence from eye movements Journal Article In: Experimental Brain Research, vol. 233, no. 3, pp. 851–860, 2015. @article{Wright2015, Sensory substitution devices convert information normally associated with one sense into another sense (e.g. converting vision into sound). This is often done to compensate for an impaired sense. The present research uses a multimodal approach in which both natural vision and sound-from-vision ('soundscapes') are simultaneously presented. Although there is a systematic correspondence between what is seen and what is heard, we introduce a local discrepancy between the signals (the presence of a target object that is heard but not seen) that the participant is required to locate. In addition to behavioural responses, the participants' gaze is monitored with eye-tracking. Although the target object is only presented in the auditory channel, behavioural performance is enhanced when visual information relating to the non-target background is presented. In this instance, vision may be used to generate predictions about the soundscape that enhances the ability to detect the hidden auditory object. The eye-tracking data reveal that participants look for longer in the quadrant containing the auditory target even when they subsequently judge it to be located elsewhere. As such, eye movements generated by soundscapes reveal the knowledge of the target location that does not necessarily correspond to the actual judgment made. The results provide a proof of principle that multimodal sensory substitution may be of benefit to visually impaired people with some residual vision and, in normally sighted participants, for guiding search within complex scenes. |
Timothy J. Wright; Walter R. Boot; James R. Brockmole Functional fixedness: The functional significance of delayed disengagement based on attention set. Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 17–21, 2015. @article{Wright2015a, During search, the disengagement of attention is automatically delayed when a fixated but task-irrelevant object shares features of the search target. We examined whether delayed disengagement based on top-down attention set is potentially functional, resulting in additional processing of the fixated item. To accomplish this, we adapted the oculomotor disengagement paradigm. Participants saccaded to a peripheral object of a particular color and responded to the identity of the letter within it. To initiate search participants made a saccade away from an always irrelevant object at the center of the screen that matched or mismatched the target's color and contained a letter that was congruent or incongruent with the target letter. We found that delayed disengagement based on attention set was associated with deeper processing of the center item: a congruency effect between the center letter and peripheral target letter was only observed when the center object's color matched participants' attention set. Results are consistent with the proposal that delayed disengagement based on attention set is functionally significant, automatically encouraging deeper levels of processing of target-like objects that fall within the focus of attention. |
Timothy J. Wright; Walter R. Boot; John L. Jones Exploring the breadth of the top-down representations that control attentional disengagement Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 5, pp. 993–1006, 2015. @article{Wright2015b, A cross-sectional prospective study was conducted between the period December 1991 and November 1992, to identify the extent of smoking among practising doctors and other health professionals in general hospitals and health clinics in Al-Ain, United Arab Emirates. The study population consisted of 300 health professionals (doctors, specialists both clinical and non-clinical, pharmacists and dentists). They were handed self-administered questionnaires adapted from the World Health Organization standard questionnaire on smoking among health professionals. Among the responding 268 (89%) health professionals 197 (73.5%) were men, and 71 (26.5%) women. Among the men health professionals 86 (43.7%) were current smokers, 24 (12.2%) were ex-smokers and 87 (44.2%) were non-smokers, while among the women health professionals 4 (5.6%) were smokers, 1 (1.4%) was an ex-smoker and 66 (93%) were non-smokers. Doctors were uniformly aware of the detrimental effects of smoking, particularly its association with lung cancer, coronary artery disease, chronic bronchitis, and laryngeal cancer, and this was the major reason for their abstaining or wanting to quit the habit. The relationship of smoking with bladder cancer, soft tissue lesion (mouth and lip) and neonatal death was not well appreciated. Counselling patients about the hazards of smoking was practised significantly less often by doctors who smoked. The majority (83.6%) expressed the need for specific training for counselling patients to stop smoking. The options favoured by the health professionals for preventing smoking included a ban on tobacco advertising, specific health warnings on cigarette packets and restriction on smoking in public places, particularly in hospitals and clinics. |
Timothy J. Wright; Thomas Vitale; Walter R. Boot; Neil Charness The impact of red light running camera flashes on younger and older drivers' attention and oculomotor control Journal Article In: Psychology and Aging, vol. 30, no. 4, pp. 755–767, 2015. @article{Wright2015c, Recent empirical evidence suggests that the flashes associated with red light running cameras (RLRCs) distract younger drivers, pulling attention away from the roadway and delaying processing of safety-relevant events. Considering the perceptual and attentional declines that occur with age, older drivers may be especially susceptible to the distracting effects of RLRC flashes, particularly in situations in which the flash is more salient (a bright flash at night compared to the day). The current study examined how age and situational factors potentially influence attention capture by RLRC flashes using covert (cuing effects) and overt (eye movement) indices of capture. We manipulated the salience of the flash by varying its luminance and contrast with respect to the background of the driving scene (either day or night scenes). Results of two experiments suggest that simulated RLRC flashes capture observers' attention, but, surprisingly, no age differences in capture were observed. However, an analysis examining early and late eye movements revealed that older adults may have been strategically delaying their eye movements in order to avoid capture. Additionally, older adults took longer to disengage attention following capture, suggesting at least one age-related disadvantage in capture situations. Findings have theoretical implications for understanding age differences in attention capture, especially with respect to capture in real-world scenes, and inform future work that should examine how the distracting effects of RLRC flashes influence driver behavior. |
Valentin Wyart; Nicholas E. Myers; Christopher Summerfield Neural mechanisms of human perceptual choice under focused and divided attention Journal Article In: Journal of Neuroscience, vol. 35, no. 8, pp. 3485–3498, 2015. @article{Wyart2015, Perceptual decisions occur after the evaluation and integration of momentary sensory inputs, and dividing attention between spatially disparate sources of information impairs decision performance. However, it remains unknown whether dividing attention degrades the precision of sensory signals, precludes their conversion into decision signals, or dampens the integration of decision information toward an appropriate response. Here we recorded human electroencephalographic (EEG) activity while participants categorized one of two simultaneous and independent streams of visual gratings according to their average tilt. By analyzing trial-by-trial correlations between EEG activity and the information offered by each sample, we obtained converging behavioral and neural evidence that dividing attention between left and right visual fields does not dampen the encoding of sensory or decision information. Under divided attention, momentary decision information from both visual streams was encoded in slow parietal signals without interference but was lost downstream during their integration as reflected in motor mu- and beta-band (10-30 Hz) signals, resulting in a "leaky" accumulation process that conferred greater behavioral influence to more recent samples. By contrast, sensory inputs that were explicitly cued as irrelevant were not converted into decision signals. These findings reveal that a late cognitive bottleneck on information integration limits decision performance under divided attention, and places new capacity constraints on decision-theoretic models of information integration under cognitive load. |
Ming Xiang; Sui Ping Wang; Yan Ling Cui Constructing covert dependencies-The case of Mandarin wh-in-situ dependency Journal Article In: Journal of Memory and Language, vol. 84, pp. 139–166, 2015. @article{Xiang2015, Wh-in-situ constructions in Mandarin Chinese, as opposed to their English counterparts that front wh-phrases to the beginning of the sentence, have the same word order as regular non-wh declaratives. We argue that despite their surface word order, processing wh-in-situ constructions involves constructing a covert non-local syntactic dependency between the in-situ wh-phrase and a higher scope position at a clause boundary, leading to behavioral patterns similar to those associated with the processing of overt dependencies. In two comprehension experiments, we showed that the process of linking an in-situ wh-phrase and its scope position induces a similarity-based memory interference effect if another clause boundary position intervenes. In addition, a set of sentence completion studies also showed that the production of wh-in-situ constructions is heavily modulated by the increased working memory burden that results from planning and maintaining a non-local dependency. |
Jianbo Xiao; Xin Huang Distributed and dynamic neural encoding of multiple motion directions of transparently moving stimuli in cortical area MT Journal Article In: Journal of Neuroscience, vol. 35, no. 49, pp. 16180–16198, 2015. @article{Xiao2015, Segmenting visual scenes into distinct objects and surfaces is a fundamental visual function. To better understand the underlying neural mechanism, we investigated how neurons in the middle temporal cortex (MT) of macaque monkeys represent overlapping random-dot stimuli moving transparently in slightly different directions. It has been shown that the neuronal response elicited by two stimuli approximately follows the average of the responses elicited by the constituent stimulus components presented alone. In this scheme of response pooling, the ability to segment two simultaneously presented motion directions is limited by the width of the tuning curve to motion in a single direction. We found that, although the population-averaged neuronal tuning showed response averaging, subgroups of neurons showed distinct patterns of response tuning and were capable of representing component directions that were separated by a small angle—less than the tuning width to unidirectional stimuli. One group of neurons preferentially represented the component direction at a specific side of the bidirectional stimuli, weighting one stimulus component more strongly than the other. Another group of neurons pooled the component responses nonlinearly and showed two separate peaks in their tuning curves even when the average of the component responses was unimodal. We also show for the first time that the direction tuning of MT neurons evolved from initially representing the vector-averaged direction of slightly different stimuli to gradually representing the component directions. Our results reveal important neural processes underlying image segmentation and suggest that information about slightly different stimulus com- ponents is computed dynamically and distributed across neurons. |
Ying-Zi Xiong; Cong Yu; Jun-Yun Zhang Perceptual learning eases crowding by reducing recognition errors but not position errors Journal Article In: Journal of Vision, vol. 15, no. 11, pp. 16, 2015. @article{Xiong2015, When an observer reports a letter flanked by additional letters in the visual periphery, the response errors (the crowding effect) may result from failure to recognize the target letter (recognition errors), from mislocating a correctly recognized target letter at a flanker location (target misplacement errors), or from reporting a flanker as the target letter (flanker substitution errors). Crowding can be reduced through perceptual learning. However, it is not known how perceptual learning operates to reduce crowding. In this study we trained observers with a partial-report task (Experiment 1), in which they reported the central target letter of a three- letter string presented in the visual periphery, or a whole-report task (Experiment 2), in which they reported all three letters in order.We then assessed the impact of training on recognition of both unflanked and flanked targets, with particular attention to how perceptual learning affected the types of errors. Our results show that training improved target recognition but not single-letter recognition, indicating that training indeed affected crowding. However, training did not reduce target misplacement errors or flanker substitution errors. This dissociation between target recognition and flanker substitution errors supports the view that flanker substitution may be more likely a by- product (due to response bias), rather than a cause, of crowding. Moreover, the dissociation is not consistent with hypothesized mechanisms of crowding that would predict reduced positional errors. |
Yangqing Xu; Steven L. Franconeri Capacity for visual features in mental rotation Journal Article In: Psychological Science, vol. 26, no. 8, pp. 1241–1251, 2015. @article{Xu2015, Although mental rotation is a core component of scientific reasoning, little is known about its underlying mechanisms. For instance, how much visual information can someone rotate at once? We asked participants to rotate a simple multipart shape, requiring them to maintain attachments between features and moving parts. The capacity of this aspect of mental rotation was strikingly low: Only one feature could remain attached to one part. Behavioral and eye-tracking data showed that this single feature remained "glued" via a singular focus of attention, typically on the object's top. We argue that the architecture of the human visual system is not suited for keeping multiple features attached to multiple parts during mental rotation. Such measurement of capacity limits may prove to be a critical step in dissecting the suite of visuospatial tools involved in mental rotation, leading to insights for improvement of pedagogy in science-education contexts. |
Jiedong Zhang; Jia Liu; Yaoda Xu Neural decoding reveals impaired face configural processing in the right fusiform face area of individuals with developmental prosopagnosia Journal Article In: Journal of Neuroscience, vol. 35, no. 4, pp. 1539–1548, 2015. @article{Zhang2015, Most of human daily social interactions rely on the ability to successfully recognize faces. Yet ∼2% of the human population suffers from face blindness without any acquired brain damage [this is also known as developmental prosopagnosia (DP) or congenital prosopagnosia]). Despite the presence of severe behavioral face recognition deficits, surprisingly, a majority of DP individuals exhibit normal face selectivity in the right fusiform face area (FFA), a key brain region involved in face configural processing. This finding, together with evidence showing impairments downstream from the right FFA in DP individuals, has led some to argue that perhaps the right FFA is largely intact in DP individuals. Using fMRI multivoxel pattern analysis, here we report the discovery of a neural impairment in the right FFA of DP individuals that may play a critical role in mediating their face-processing deficits. In seven individuals with DP, we discovered that, despite the right FFA's preference for faces and it showing decoding for the different face parts, it exhibited impaired face configural decoding and did not contain distinct neural response patterns for the intact and the scrambled face configurations. This abnormality was not present throughout the ventral visual cortex, as normal neural decoding was found in an adjacent object-processing region. To our knowledge, this is the first direct neural evidence showing impaired face configural processing in the right FFA in individuals with DP. The discovery of this neural impairment provides a new clue to our understanding of the neural basis of DP. |
Luming Zhang; Meng Wang; Liqiang Nie; Liang Hong; Yong Rui; Qi Tian Retargeting semantically-rich photos Journal Article In: IEEE Transactions on Multimedia, vol. 17, no. 9, pp. 1538–1549, 2015. @article{Zhang2015a, Semantically-rich photos contain a rich variety of semantic objects (e.g., pedestrians and bicycles). Retargeting these photos is a challenging task since each semantic object has fixed geometric characteristics. Shrinking these objects simultaneously during retargeting is prone to distortion. In this paper, we propose to retarget semantically-rich photos by detecting photo semantics from image tags, which are predicted by a multi-label SVM. The key technique is a generative model termed latent stability discovery (LSD). It can robustly localize various semantic objects in a photo by making use of the predicted noisy image tags. BasedonLSD,afeaturefusionalgorithm is proposed to detect salient regions at both the low-level and high-level. These salient regions are linked into a path sequentially to simulate human visual perception. Finally, we learn the prior distribution of such paths from aesthetically pleasing training photos. The prior enforces the path of a retargeted photo to be maximally similar to those from the training photos. In the experiment, we collect 217 1600x1200 photos, each containing over seven salient objects. Comprehensive user studies demonstrate the competitiveness of our method. |
Wenjia Zhang; Nan Li; Xiaoyue Wang; Suiping Wang Integration of sentence-level semantic information in parafovea: Evidence from the RSVP-flanker paradigm Journal Article In: PLoS ONE, vol. 10, no. 9, pp. e0139016, 2015. @article{Zhang2015b, During text reading, the parafoveal word was usually presented between 2° and 5° from the point of fixation. Whether semantic information of parafoveal words can be processed during sentence reading is a critical and long-standing issue. Recently, studies using the RSVP-flanker paradigm have shown that the incongruent parafoveal word, presented as right flanker, elicited a more negative N400 compared with the congruent parafoveal word. This suggests that the semantic information of parafoveal words can be extracted and integrated during sentence reading, because the N400 effect is a classical index of semantic integration. However, as most previous studies did not control the word-pair congruency of the parafoveal and the foveal words that were presented in the critical triad, it is still unclear whether such integration happened at the sentence level or just at the word-pair level. The present study addressed this question by manipulating verbs in Chinese sentences to yield either a semantically congruent or semantically incongruent context for the critical noun. In particular, the interval between the critical nouns and verbs was controlled to be 4 or 5 characters. Thus, to detect the incongruence of the parafoveal noun, participants had to integrate it with the global sentential context. The results revealed that the N400 time-locked to the critical triads was more negative in incongruent than in congruent sentences, suggesting that parafoveal semantic information can be integrated at the sentence level during Chinese reading. |
Youming Zhang; Jorma Laurikkala; Martti Juhola; Youming Zhang; Jorma Laurikkala; Martti Juhola Biometric verification with eye movements: Results from a long-term recording series Journal Article In: IET Biometrics, vol. 4, no. 3, pp. 162–168, 2015. @article{Zhang2015c, The authors present the author's results of using saccadic eye movements for biometric user verification. The method can be applied to computers or other devices, in which it is possible to include an eye movement camera system. Thus far, this idea has been little researched. As they have extensively studied eye movement signals for medical applications, they saw an opportunity for the biometric use of saccades. Saccades are the fastest of all eye movements, and are easy to stimulate and detect from signals. As signals measured from a physiological origin, the properties of eye movements (e.g. latency and maximum angular velocity) may contain considerable variability between different times of day, between days or weeks and so on. Since such variability might impair biometric verification based on saccades, they attempted to tackle this issue. In contrast to their earlier results, where they did not include such long intervals between sessions of eye movement recordings as in the present research, their results showed that – notwithstanding some variability present in saccadic variables – this variability was not considerable enough to essentially disturb or impair verification results. The only exception was a test series of very long intervals ∼16 or 32 months in length. For the best results obtained with various classification methods, false rejection and false acceptance rates were <5%. Thus, they conclude that saccadic eye movements can provide a realistic basis for biometric user verification. |
Jingjing Zhao; Yonghui Wang; Donglai Liu; Liang Zhao; Peng Liu In: Attention, Perception, and Psychophysics, vol. 77, no. 7, pp. 2284–2292, 2015. @article{Zhao2015, It was found in previous studies that two types of objects (rectangles formed according to the Gestalt principle and Chinese words formed in a top-down fashion) can both induce an object-based effect. The aim of the present study was to investigate how the strength of an object representation affects the result of the competition between these two types of objects based on research carried out by Liu, Wang and Zhou [(2011) Acta Psychologica, 138(3), 397-404]. In Experiment 1, the rectangles were filled with two different colors to increase the strength of Gestalt object representation, and we found that the object effect changed significantly for the different stimulus types. Experiment 2 used Chinese words with various familiarities to manipulate the strength of the top-down object representation. As a result, the object-based effect induced by rectangles was observed only when the Chinese word familiarity was low. These results suggest that the strength of object representation determines the result of competition between different types of objects. |
Takumi Yokosaka; Scinob Kuroki; Shin'ya Nishida; Junji Watanabe Apparent time interval of visual stimuli is compressed during fast hand movement Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0124901, 2015. @article{Yokosaka2015, The influence of body movements on visual time perception is receiving increased attention. Past studies showed apparent expansion of visual time before and after the execution of hand movements and apparent compression of visual time during the execution of eye movements. Here we examined whether the estimation of sub-second time intervals between visual events is expanded, compressed, or unaffected during the execution of hand movements. The results show that hand movements, at least the fast ones, reduced the apparent time interval between visual events. A control experiment indicated that the apparent time compression was not produced by the participants' involuntary eye movements during the hand movements. These results, together with earlier findings, suggest hand movement can change apparent visual time either in a compressive way or in an expansive way, depending on the relative timing between the hand movement and visual stimulus. |
Keir X. X. Yong; Kishan Rajdev; Timothy J. Shakespeare; Alexander P. Leff; Sebastian J. Crutch Facilitating text reading in posterior cortical atrophy Journal Article In: Neurology, vol. 85, no. 4, pp. 339–348, 2015. @article{Yong2015, OBJECTIVE: We report (1) the quantitative investigation of text reading in posterior cortical atrophy (PCA), and (2) the effects of 2 novel software-based reading aids that result in dramatic improvements in the reading ability of patients with PCA. METHODS: Reading performance, eye movements, and fixations were assessed in patients with PCA and typical Alzheimer disease and in healthy controls (experiment 1). Two reading aids (single- and double-word) were evaluated based on the notion that reducing the spatial and oculomotor demands of text reading might support reading in PCA (experiment 2). RESULTS: Mean reading accuracy in patients with PCA was significantly worse (57%) compared with both patients with typical Alzheimer disease (98%) and healthy controls (99%); spatial aspects of passages were the primary determinants of text reading ability in PCA. Both aids led to considerable gains in reading accuracy (PCA mean reading accuracy: single-word reading aid = 96%; individual patient improvement range: 6%-270%) and self-rated measures of reading. Data suggest a greater efficiency of fixations and eye movements under the single-word reading aid in patients with PCA. CONCLUSIONS: These findings demonstrate how neurologic characterization of a neurodegenerative syndrome (PCA) and detailed cognitive analysis of an important everyday skill (reading) can combine to yield aids capable of supporting important everyday functional abilities. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for patients with PCA, 2 software-based reading aids (single-word and double-word) improve reading accuracy. |
Steffi Zander; Maria Reichelt; Stefanie Wetzel; Frauke Kämmerer; Sven Bertel Does personalisation promote learners' attention? An eye-tracking study Journal Article In: Frontline Learning Research, vol. 3, no. 4, pp. 1–13, 2015. @article{Zander2015, The personalisation principle is a design recommendation and states that multimedia presentations using personalised language promote learning better than those using formal language (e.g., using ‘your' instead of ‘the'). It is often assumed that this design recommendation affects motivation and therefore allocation of attention. To gain further insight into the processes underlying personalisation effects we conducted an eye tracking experiment with 37 German university students who were presented with either personalised or formal learning materials. We examined group differences in attention allocation parameters (fixation count, fixation duration, transition count). The eye-tracking data was combined with self-reports concerning motivation, cognitive load, and learning outcomes. Eye-tracking data revealed a significantly higher reading depth for the main picture areas of interest in the personalised condition. Additionally, participants found the personalised version more appealing and inviting. For learning outcomes, there was a significant positive effect of personalisation for retention, not for transfer. We discuss additional explanatory variables as well as methodological and practical implications for instructional design. |
Xuelian Zang; Lina Jia; Hermann J. Müller; Zhuanghua Shi Invariant spatial context is learned but not retrieved in gaze-contingent limited-viewing search Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 3, pp. 807–819, 2015. @article{Zang2015, Our visual brain is remarkable in extracting invariant properties from the noisy environment, guiding selection of where to look and what to identify. However, how the brain achieves this is still poorly understood. Here we explore interactions of local context and global structure in the long-term learning and retrieval of invariant display properties. Participants searched for a target among distractors, without knowing that some “old” configurations were presented repeatedly (randomly inserted among “new” configurations). We simulated tunnel vision, limiting the visible region around fixation. Robust facilitation of performance for old versus new contexts was observed when the visible region was large but not when it was small. However, once the display was made fully visible during the subsequent transfer phase, facilitation did become manifest. Furthermore, when participants were given a brief preview of the total display layout prior to tunnel view search with 2 items visible, facilitation was already obtained during the learning phase. The eye movement results revealed contextual facilitation to be coupled with changes of saccadic planning, characterized by slightly extended gaze durations but a reduced number of fixations and shortened scan paths for old displays. Taken together, our findings show that invariant spatial display properties can be acquired based on scarce, para-/foveal information, while their effective retrieval for search guidance requires the availability (even if brief) of a certain extent of peripheral information. |
Theodoros P. Zanos; Patrick J. Mineault; Konstantinos T. Nasiotis; Daniel Guitton; Christopher C. Pack A sensorimotor role for traveling waves in primate visual cortex Journal Article In: Neuron, vol. 85, no. 3, pp. 615–627, 2015. @article{Zanos2015, Traveling waves of neural activity are frequently observed to occur in concert with the presentation of a sensory stimulus or the execution of a movement. Although such waves have been studied for decades, little is known about their function. Here we show that traveling waves in the primate extrastriate visual cortex provide a means of integrating sensory and motor signals. Specifically, we describe a traveling wave of local field potential (LFP) activity in cortical area V4 of macaque monkeys that is triggered by the execution of saccadic eye movements. These waves sweep across the V4 retinotopic map, following a consistent path from the foveal to the peripheral representations of space; their amplitudes correlate with the direction and size of each saccade. Moreover, these waves are associated with a reorganization of the postsaccadic neuronal firing patterns, which follow a similar retinotopic progression, potentially prioritizing the processing of behaviorally relevant stimuli. |
Andrea M. Zawoyski; Scott P. Ardoin; Katherine S. Binder Using eye tracking to observe differential effects of repeated readings for second-grade students as a function of achievement level Journal Article In: Reading Research Quarterly, vol. 50, no. 2, pp. 171–184, 2015. @article{Zawoyski2015, Repeated readings (RR) is an evidence-based instructional technique in which students read the same text multiple times. Currently, little is known about how effects of RR may differ based on students' achievement levels. Eye tracking provides a means for closely examining instructional effects because it permits measurement of subtle changes that occur during RR. The current study measured changes in the reading behavior of second-grade students who were divided into two groups of 22 students each based on their reading achievement levels. Participants read a grade-level passage embedded with low-and high-frequency target words four times in a single session while their eye movements were recorded. Findings replicated those of previous research, suggesting that RR facilitated reading for students in both groups, particularly on low-frequency target words. Results indicated both similarities and differences in patterns of performance between lower and higher performing readers. Additionally, results implied that effects were greater for lower performing readers because they made greater improvements on high-frequency target words, whereas effects were diminished for higher performing readers. The findings have implications for improving future eye movement research investigating young students' reading and the efficiency of RR in the classroom. |
Alexandre Zenon; Mariam Sidibe; Etienne Olivier Disrupting the supplementary motor area makes physical effort appear less effortful Journal Article In: Journal of Neuroscience, vol. 35, no. 23, pp. 8737–8744, 2015. @article{Zenon2015, The perception of physical effort is relatively unaffected by the suppression of sensory afferences, indicating that this function relies mostly on the processing of the central motor command. Neural signals in the supplementary motor area (SMA) correlate with the intensity of effort, suggesting that the motor signal involved in effort perception could originate from this area, but experimental evidence supporting this view is still lacking. Here, we tested this hypothesis by disrupting neural activity in SMA, in primary motor cortex (M1), or in a control site by means of continuous theta-burst transcranial magnetic stimulation, while measuring effort perception during grip forces of different intensities. After each grip force exertion, participants had the opportunity to either accept or refuse to replicate the same effort for varying amounts of reward. In addition to the subjective rating of perceived exertion, effort perception was estimated on the basis of the acceptance rate, the effort replication accuracy, the influence of the effort exerted in trial t on trial t+1, and pupil dilation. We found that disruption of SMA activity, but not of M1, led to a consistent decrease in effort perception, whatever the measure used to assess it. Accordingly, we modeled effort perception in a structural equation model and found that only SMA disruption led to a significant alteration of effort perception. These findings indicate that effort perception relies on the processing of a signal originating from motor-related neural circuits upstream of M1 and that SMA is a key node of this network. |
Likan Zhan; Stephen Crain; Peng Zhou The online processing of only if and even if conditional statements: Implications for mental models Journal Article In: Journal of Cognitive Psychology, vol. 27, pp. 367–379, 2015. @article{Zhan2015, A sentential connective like only if or even if merges two simple propositions into a complex statement. This study used a visual world paradigm experiment to explore how this merging process proceeds online. We first presented participants with a short animation, illustrating different simple propositions that are possible to be merged by the sentential connectives. We then auditorily played an only if or an even if statement and recorded participants' eye movements on the concurrent test image. We observed that hearing the sentential connective results in more fixations on the tokens of the appropriate propositions that are eligible to be merged by the sentential connective. Each sentential connective elicited anticipatory effect suggests that once they heard the sentential connective, participants knew which propositions could be merged. We then discussed the implications of our results to the mental model theory of conditionals and the experimental studies reported in literature. |
Yoshiko Yabe; Melvyn A. Goodale Time flies when we intend to act: Temporal distortion in a Go/No-Go task Journal Article In: Journal of Neuroscience, vol. 35, no. 12, pp. 5023–5029, 2015. @article{Yabe2015, Although many of our actions are triggered by sensory events, almost nothing is known about our perception of the timing of those sensory events. Here we show that, when people react to a sudden visual stimulus that triggers an action, that stimulus is perceived to occur later than an identical stimulus that does not trigger an action. In our experiments, participants fixated the center of a clock face with a rotating second hand. When the clock changed color, they were required to make a motor response and then to report the position of the second hand at the moment the clock changed color. In Experiment 1, in which participants made a target-directed saccade, the color change was perceived to occur 59 ms later than when they maintained fixation. In Experiment 2, in which we used a go/no-go paradigm, this temporal distortion was observed even when participants were required to cancel a prepared saccade. Finally, in Exper-iment 3, the same distortion in perceived time was observed for both go and no-go trials in a manual task in which no eye movements were required. These results suggest that, when a visual stimulus triggers an action, it is perceived to occur significantly later than an identical stimulus unrelated to action. Moreover, this temporal distortion appears to be related not to the execution of the action (or its effect) but rather to the programming of the action. In short, there seems to be a temporal binding between a triggering event and the triggered action |
Ming Yan Visually complex foveal words increase the amount of parafoveal information acquired Journal Article In: Vision Research, vol. 111, no. Part A, pp. 91–96, 2015. @article{Yan2015, This study investigates the effect of foveal load (i.e., processing difficulty of currently fixated words) on parafoveal information processing. Contrary to the commonly accepted view that high foveal load leads to reduced parafoveal processing efficiency, results of the present study showed that increasing foveal visual (but not linguistic) processing load actually increased the amount of parafoveal information acquired, presumably due to the fact that longer fixation duration on the pretarget word provided more time for parafoveal processing of the target word. It is therefore proposed in the present study that foveal linguistic processing load is not the only factor that determines parafoveal processing; preview time (afforded by foveal word visual processing load) may jointly influence parafoveal processing. |
Ming Yan; Reinhold Kliegl Perceptual Span Depends on Font Size During the Reading of Chinese Sentences Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 1, pp. 209–219, 2015. @article{Yan2015a, The present study explored the perceptual span (i.e., the physical extent of an area from which useful visual information is extracted during a single fixation) during the reading of Chinese sentences in 2 experiments. In Experiment 1, we tested whether the rightward span can go beyond 3 characters when visually similar masks were used. Results showed that Chinese readers needed at least 4 characters to the right of fixation to maintain a normal reading behavior when visually similar masks were used and when characters were displayed in small fonts, indicating that the span is dynamically influenced by masking materials. In Experiments 2 and 3, we asked whether the perceptual span varies as a function of font size in spaced (German) and unspaced (Chinese) scripts. Results clearly suggest perceptual span depends on font size in Chinese, but we failed to find such evidence for German. We propose that the perceptual span in Chinese is flexible; it is strongly constrained by its language-specific properties such as high information density and lack of word spacing. Implications for saccade-target selection during the reading of Chinese sentences are discussed. |
Ming Yan; Jinger Pan; Nathalie N. Bélanger; Hua Shu Chinese deaf readers have early access to parafoveal semantics Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 1, pp. 254–261, 2015. @article{Yan2015c, In the present study, we manipulated different types of information available in the parafovea during the reading of Chinese sentences and examined how deaf readers make use of the parafoveal information. Results clearly indicate that although the reading-level matched hearing readers make greater use of orthographic information in the parafovea, parafoveal semantic information is obtained earlier among the deaf readers. In addition, a phonological preview benefit effect was found for the better deaf readers (relative to less-skilled deaf readers), although we also provide an alternative explanation for this effect. Providing evidence that Chinese deaf readers have higher efficiency when processing parafoveal semantics, the study indicates flexibility across individuals in the mechanisms underlying word recognition adapting to the inputs available in the linguistic environment. |
Ming Yan; Werner Sommer Parafoveal-on-foveal effects of emotional word semantics in reading chinese sentences: Evidence from eye movements Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 4, pp. 1237–1243, 2015. @article{Yan2015b, Despite the well-known influence of emotional meaning on cognition, relatively less is known about its effects on reading behavior. We investigated whether fixation behavior during the reading of Chinese sentences is influenced by emotional word meaning in the parafovea. Two-character target words embedded into the same sentence frames provided emotionally positive, negative, or neutral contents. Fixation durations on neutral pretarget words were prolonged for positive parafoveal words and for highly frequent negative parafoveal words. In addition, fixation durations on foveal emotional words were shorter than those on neutral words. We also found that the role of emotional words varied as a function of their valence during foveal and parafoveal processing. These findings suggest a processing advantage for emotional words relative to emotionally neutral stimuli in foveal and parafoveal vision. We discuss implications for the notion of attention attraction due to emotional content. |
Ying Yan; Huazhi Yuan; Xiaofei Wang; Ting Xu; Haoxue Liu Study on driver's fixation variation at entrance and inside sections of tunnel on highway Journal Article In: Advances in Mechanical Engineering, vol. 7, no. 1, pp. 1–10, 2015. @article{Yan2015d, How drivers' visual characteristics change as they pass tunnels was studied. Firstly, nine drivers' test data at tunnel entrance and inside sections using eye movement tracking devices were recorded. Then the transfer function of BP artificial neural network was employed to simulate and analyze the variation of the drivers' eye movement parameters. The relation models between eye movement parameters and the distance of the tunnels were established. In the analysis of the fixation point distributions, the analytic coordinates of fixations in visual field were clustered to obtain different visual area of fixations by utilizing dynamic cluster theory. The results indicated that, at 100 meters before the entrance, the average fixation duration increased, but the fixations number decreased substantially. After 100 meters into the tunnel, the fixation duration started to decrease first and then increased. The variations of drivers' fixation points demonstrated such a pattern of change as scatter, focus, and scatter again. While driving through the tunnels, drivers presented a long time fixation. Nearly 61.5% subjects' average fixation duration increased significantly. In the tunnel, these drivers pay attention to seven fixation points areas from the car dashboard area to the road area in front of the car. |
Lingling Yang; Howard Leung; Markus Plank; Joe Snider; Howard Poizner EEG activity during movement planning encodes upcoming peak speed and acceleration and improves the accuracy in predicting hand kinematics Journal Article In: IEEE Journal of Biomedical and Health Informatics, vol. 19, no. 1, pp. 22–28, 2015. @article{Yang2015, The relationship between movement kinematics and human brain activity is an important and fundamental question for the development of neural prosthesis. The peak velocity and the peak acceleration could best reflect the feedforward-type movement thus it is worthwhile to investigate them further. Most related studies focused on the correlation between kinematics and brain activity during the movement execution or imagery. However, human movement is the result of the motor planning phase as well as the execution phase and researchers have demonstrated that statistical correlations exist between EEG activity during the motor planning and the peak velocity and the peak acceleration using grand-average analysis. In this paper, we examined whether the correlations were concealed in trial-to-trial decoding from the low signal-to-noise ratio of EEG activity. The alpha and beta powers from the movement planning phase were combined with the alpha and beta powers from the movement execution phase to predict the peak tangential speed and acceleration. The results showed that EEG activity from the motor planning phase could also predict the peak speed and the peak acceleration with a reasonable accuracy. Furthermore, the decoding accuracy of the peak speed and the peak acceleration could both be improved by combining band powers from the motor planning phase with the band powers from the movement execution. |
Shu-Fei Yang An eye-tracking study of the Elaboration Likelihood Model in online shopping Journal Article In: Electronic Commerce Research and Applications, vol. 14, no. 4, pp. 233–240, 2015. @article{Yang2015a, This study uses eye-tracking to explore the Elaboration Likelihood Model (ELM) in online shopping. The results show that the peripheral cue did not have moderating effect on purchase intention, but had moderating effect on eye movement. Regarding purchase intention, the high elaboration had higher purchase intention than the low elaboration with a positive peripheral cue, but there was no difference in purchase intention between the high and low elaboration with a negative peripheral cue. Regarding eye movement, with a positive peripheral cue, the high elaboration group was observed to have longer fixation duration than the low elaboration group in two areas of interest (AOIs); however, with a negative peripheral cue, the low elaboration group had longer fixation on the whole page and two AOIs. In addition, the relationship between purchase intention and eye movement of the AOIs is more significant in the high elaboration group when given a negative peripheral cue and in the low elaboration group when given a positive peripheral cue. This study not only examines the postulates of the ELM, but also contributes to a better understanding of the cognitive processes of the ELM. These findings have practical implications for e-sellers to identify characteristics of consumers' elaboration in eye movement and designing customization and persuasive context for different elaboration groups in e-commerce. |
Ting Yang; Hong Chen; Yuanyan Hu; Yingcan Zheng; Wei Wang Preferences for sexual dimorphism on attractiveness levels: An eye-tracking study Journal Article In: Personality and Individual Differences, vol. 77, pp. 179–185, 2015. @article{Yang2015b, Previous studies on sexual dimorphism showed feminine preferences in female faces and mixed findings in male faces by choosing which is more attractive in a pair of a masculine face and a feminine face. However, very little is known about how people make fine-grained visual assessments of such images and the attractiveness levels of faces are not received much attention. Recently a large number of androgynous stars appear in the media, which triggers a hot phenomenon of imitating them. Here we examine the influence of androgynous stars on people's facial preferences for sexual dimorphism in male and female faces on different attractiveness levels using eye-tracking techniques. In male faces we found both male and female participants preferred masculine faces to androgynous faces in high attractiveness, but mixed results in low attractiveness. In female faces we found both male and female participants preferred feminine faces to androgynous faces in high attractiveness, but no preferences in low attractiveness. Results suggest that attractiveness levels of faces might be a factor causing inconsistency in sexual dimorphism preference for male faces and that androgynous faces are not preferred, which reveals that androgynous phenomenon might not be caused by facial attractiveness. |
Amit Yashar; Jiageng Chen; Marisa Carrasco Rapid and long-lasting reduction of crowding through training Journal Article In: Journal of Vision, vol. 15, no. 10, pp. 1–15, 2015. @article{Yashar2015, Crowding is the failure to identify an object in the peripheral visual field in the presence of nearby objects. Recent studies have shown that crowding can be alleviated after several days of training, but the processes underlying this improvement are still unclear. Here we tested whether a few hundred trials within a short period of training can alleviate crowding, whether the learning is location specific, and whether the improvement reflects facilitation by target enhancement or flankers suppression. Observers were asked to identify the orientation of a letter in the periphery surrounded by two flanker letters. Observers were tested before (pretest) and after (posttest) training (600 trials). In Experiment 1 we tested whether learning is location specific or can transfer to a different location; the training and test occurred at the same or different hemifields. In a control experiment, we ruled out alternative explanations for the learning effect in Experiment 1. In Experiment 2, we assessed different components of feature selection by training with either the same flanker polarity as the pre/posttest but opposite polarity group (flanker polarity group) or the same target polarity as the pre/posttest but opposite flanker polarity (target polarity group). Following training, overall performance increased in all four conditions, but only the same-location group (Experiment 1) and the same flanker polarity (Experiment 2) showed a significant reduction in crowding as assessed by the distance at which the flankers no longer interfere with target identification, that is, the critical spacing. These results show that training can rapidly reduce crowding and that improvement primarily reflects learning to ignore the irrelevant flankers. Remarkably, in the two conditions in which training significantly reduced crowding, the benefit of short training persisted for up to a year. |
Menahem Yeari; Paul W. Broek; Marja Oudega Processing and memory of central versus peripheral information as a function of reading goals: evidence from eye-movements Journal Article In: Reading and Writing, vol. 28, no. 8, pp. 1071–1097, 2015. @article{Yeari2015, The present study examined the effect of reading goals on the processing and memory of central and peripheral textual information. Using eye-tracking methodology, we compared the effect of four common reading goals—entertainment, presentation, studying for a close-ended (multiple-choice) questions test, and studying for an open-ended questions test—on the specific reading time of central and peripheral information and the overall reading time of expository texts. Text memory was tested using multiple-choice questions. Results showed that readers devoted more time to central information than peripheral information during initial reading, regardless of reading goal, but that they adjusted their rereading to the reading goal, with total reading time being longer for central information under some (entertainment and presentation) but not all (open-ended and close-ended questions tests) reading goals. Moreover, readers devoted more time to reading the texts for a study purpose (test or presentation) than for an entertainment purpose, and devoted more time in reading the texts to answer open-ended questions than close-ended questions. Finally, we found that readers remembered more central information than peripheral information under all reading goals. These findings suggest that centrality affects readers' early processing of text whereas reading goals only affect subsequent processing. Interestingly, processing time during reading predicted memory for peripheral information but not for central information. |
Dov Yellin; Aviva Berkovich-Ohana; Rafael Malach Coupling between pupil fluctuations and resting-state fMRI uncovers a slow build-up of antagonistic responses in the human cortex Journal Article In: NeuroImage, vol. 106, pp. 414–427, 2015. @article{Yellin2015, Even in absence of overt tasks, the human cortex manifests rich patterns of spontaneous "resting state" BOLD-fMRI fluctuations. However, the link of these spontaneous fluctuations to behavior is presently unclear. Attempts to directly investigate this link invariably lead to disruptions of the resting state. Here we took advantage of the well-established association between pupil diameter and attentional gain to address this issue by examining the correlation between the resting state BOLD and pupil fluctuations. Our results uncover a spontaneously emerging spatiotemporal pupil-BOLD correlation whereby a slow buildup of activity in default mode areas preceded both pupil dilation and wide-spread BOLD suppression in sensorimotor cortex. Control experiments excluded a role for luminance fluctuations or fixation. Comparing the pupil-correlated patterns to activation maps during visual imagery revealed a substantial overlap. Our results indicate a link between behavior, as indexed by pupil diameter, and resting state BOLD fluctuations. These pupil dilations, assumed to be related to attentional gain, were associated with spontaneously emerging antagonism between fundamental cortical networks. |
Yaffa Yeshurun; Einat Rashal; Shira Tkacz-Domb Temporal crowding and its interplay with spatial crowding Journal Article In: Journal of Vision, vol. 15, no. 3, pp. 11, 1–16, 2015. @article{Yeshurun2015, Spatial crowding refers to impaired target identification when the target is surrounded by other stimuli in space temporal crowding refers to impaired target identification when the target is surrounded by other stimuli in time previously, when spatial and temporal crowding were measured in the fovea they were interrelated with amblyopic observers but almost absent with normal observers bonneh, sagi, & polat, 2007. In the current study we examined whether reliable temporal crowding can be found for normal observers with peripheral presentation 9° of eccentricity, and whether similar relations between temporal and spatial crowding will emerge to that end, we presented a sequence of three displays separated by a varying interstimulus interval (ISI). Each display included either one letter : experiments 1a ,: 1b ,: 1c or three letters separated by a varying interletter spacing: Experiments 2a ,: 2b). One of these displays included an oriented T. Observers indicated the T's orientation. As expected, we found spatial crowding: accuracy improved as the interletter spacing increased. Critically, we also found temporal crowding: in all experiments accuracy increased as the ISI increased, even when only stimulus-onset asynchronies (SOAs) larger than 150 ms were included, ensuring this effect does not reflect mere ordinary masking. Thus, with peripheral presentation, temporal crowding also emerged for normal observers. However, only a weak interaction between temporal and spatial crowding was found. |
Funda Yildirim; Frans W. Cornelissen Saccades follow perception when judging location Journal Article In: i-Perception, vol. 6, no. 6, pp. 1–10, 2015. @article{Yildirim2015, An unresolved question in vision research is whether perceptual decision making and action are based on the same or on different neural representations. Here, we address this question for a straightforward task, the judgment of location. In our experiment, observers decided on the closer of two peripheral objects-situated on the horizontal meridian in opposite hemifields-and made a saccade to indicate their choice. Correct saccades landed close to the actual (physical) location of the target. However, in case of errors, saccades went in the direction of the more distant object, yet landed on a position approximating that of the closer one. Our finding supports the notion that perception and action-related decisions on object location rely on the same neural representation. |
Funda Yildirim; Vincent Meyer; Frans W. Cornelissen Eyes on crowding: Crowding is preserved when responding by eye and similarly affects identity and position accuracy Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 1–14, 2015. @article{Yildirim2015a, Peripheral vision guides recognition and selection of targets for eye movements. Crowding—a decline in recognition performance that occurs when a potential target is surrounded by other, similar, objects—influences peripheral object recognition. A recent model study suggests that crowding may be due to increased uncertainty about both the identity and the location of peripheral target objects, but very few studies have assessed these properties in tandem. Eye tracking can integrally provide information on both the perceived identity and the position of a target and therefore could become an important approach in crowding studies. However, recent reports suggest that around the moment of saccade preparation crowding may be significantly modified. If these effects were to generalize to regular crowding tasks, it would complicate the interpretation of results obtained with eye tracking and the comparison to results obtained using manual responses. For this reason, we first assessed whether the manner by which participants responded—manually or by eye—affected their performance.We found that neither recognition performance nor response time was affected by the response type. Hence, we conclude that crowding magnitude was preserved when observers responded by eye. In our main experiment, observers made eye movements to the location of a tilted Gabor target while we varied flanker tilt to manipulate target–flanker similarity. The results indicate that this similarly affected the accuracy of peripheral recognition and saccadic target localization. Our results inform about the importance of both location and identity uncertainty in crowding. |
Tinne Dewolf; Wim Van Dooren; Frouke Hermens; Lieven Verschaffel Do students attend to representational illustrations of non-standard mathematical word problems, and, if so, how helpful are they? Journal Article In: Instructional Science, vol. 43, no. 1, pp. 147–171, 2015. @article{Dewolf2015, During the last two decades various researchers confronted upper elementary and lower secondary school pupils with word problems that were problematic from a realistic modelling point of view (so-called P-items), and found that pupils in general did not use their everyday knowledge to solve such P-items. Several attempts were undertaken to encourage learners to use their everyday knowledge more when solving such problems, e.g., by presenting the P-items together with representational illustrations that represent the problematic situation described in the problem. These illustrations were expected to help learners to mentally imagine the situation and consequently solve the items more realis- tically. However, no effect of the illustrations was found. In this article we build further on the use of representational illustrations. We report two related experiments with higher education students that investigated whether and how illustrations that represent the problematic situation described in a P-item help to imagine the problem situation and thereby solve the problem more realistically. In Experiment 1 we measured students' eye movements when solving P-items that were accompanied by representational illustrations, to analyse whether the illustrations are processed at all. In Experiment 2 we manipulated the presentation of the illustrations so students could not but look at them, before the word problem appeared. We found that students scarcely looked at the representational illus- trations (Experiment 1) and when they did, there was no effect of the illustrations on the realistic nature of their solutions (Experiment 2). Possible explanations for these findings are discussed. |
Matteo Visconti Di Oleggio Castello; M. Ida Gobbini Familiar face detection in 180ms Journal Article In: PLoS ONE, vol. 10, no. 8, pp. e0136548, 2015. @article{DiOleggioCastello2015, The visual system is tuned for rapid detection of faces, with the fastest choice saccade to a face at 100ms. Familiar faces have a more robust representation than do unfamiliar faces, and are detected faster in the absence of awareness and with reduced attentional resources. Faces of familiar and close friends become familiar over a protracted period involving learning the unique visual appearance, including a view-invariant representation, as well as person knowledge. We investigated the effect of personal familiarity on the earliest stages of face processing by using a saccadic-choice task to measure how fast familiar face detection can happen. Subjects made correct and reliable saccades to familiar faces when unfamiliar faces were distractors at 180ms-very rapid saccades that are 30 to 70ms earlier than the earliest evoked potential modulated by familiarity. By contrast, accuracy of saccades to unfarmiliar faces with familiar faces as distractors did not exceed chance. Saccades to faces with object distractors were even faster (110 to 120ms) and equivalent for familiar and unfamiliar faces, including that familiarity does not affect ultra-rapid saccades. We propose that detectors of diagnostic facial features for familiar faces develop in visual cortices through learning and allow rapid detection that procedes expicit recognition of identity. |
Leandro Luigi Di Stasi; Michael B. McCamy; Sebastian Pannasch; Rebekka Renner; Andrés Catena; José J. Cañas; Boris M. Velichkovsky; Susana Martinez-Conde Effects of driving time on microsaccadic dynamics Journal Article In: Experimental Brain Research, vol. 233, no. 2, pp. 599–605, 2015. @article{DiStasi2015, Driver fatigue is a common cause of car acci- dents. Thus, the objective detection of driver fatigue is a first step toward the effective management of fatigue- related traffic accidents. Here, we investigated the effects of driving time, a common inducer of driver fatigue, on the dynamics of fixational eye movements. Participants drove for 2 h in a virtual driving environment while we recorded their eye movements. Microsaccade velocities decreased with driving time, suggesting a potential effect of fatigue on microsaccades during driving. |
Ivan Diaz; Sabine Schmidt; Francis R. Verdun; François O. Bochud Eye‐tracking of nodule detection in lung CT volumetric data Journal Article In: Medical Physics, vol. 42, no. 6, pp. 2925–2932, 2015. @article{Diaz2015, PURPOSE: Signal detection on 3D medical images depends on many factors, such as foveal and peripheral vision, the type of signal, and background complexity, and the speed at which the frames are displayed. In this paper, the authors focus on the speed with which radiologists and naïve observers search through medical images. Prior to the study, the authors asked the radiologists to estimate the speed at which they scrolled through CT sets. They gave a subjective estimate of 5 frames per second (fps). The aim of this paper is to measure and analyze the speed with which humans scroll through image stacks, showing a method to visually display the behavior of observers as the search is made as well as measuring the accuracy of the decisions. This information will be useful in the development of model observers, mathematical algorithms that can be used to evaluate diagnostic imaging systems.$backslash$n$backslash$nMETHODS: The authors performed a series of 3D 4-alternative forced-choice lung nodule detection tasks on volumetric stacks of chest CT images iteratively reconstructed in lung algorithm. The strategy used by three radiologists and three naïve observers was assessed using an eye-tracker in order to establish where their gaze was fixed during the experiment and to verify that when a decision was made, a correct answer was not due only to chance. In a first set of experiments, the observers were restricted to read the images at three fixed speeds of image scrolling and were allowed to see each alternative once. In the second set of experiments, the subjects were allowed to scroll through the image stacks at will with no time or gaze limits. In both static-speed and free-scrolling conditions, the four image stacks were displayed simultaneously. All trials were shown at two different image contrasts.$backslash$n$backslash$nRESULTS: The authors were able to determine a histogram of scrolling speeds in frames per second. The scrolling speed of the naïve observers and the radiologists at the moment the signal was detected was measured at 25-30 fps. For the task chosen, the performance of the observers was not affected by the contrast or experience of the observer. However, the naïve observers exhibited a different pattern of scrolling than the radiologists, which included a tendency toward higher number of direction changes and number of slices viewed.$backslash$n$backslash$nCONCLUSIONS: The authors have determined a distribution of speeds for volumetric detection tasks. The speed at detection was higher than that subjectively estimated by the radiologists before the experiment. The speed information that was measured will be useful in the development of 3D model observers, especially anthropomorphic model observers which try to mimic human behavior. |
Gregory J. DiGirolamo; David Smelson; Nathan Guevremont Cue-induced craving in patients with cocaine use disorder predicts cognitive control deficits toward cocaine cues Journal Article In: Addictive Behaviors, vol. 47, pp. 86–90, 2015. @article{DiGirolamo2015, Introduction: Cue-induced craving is a clinically important aspect of cocaine addiction influencing ongoing use and sobriety. However, little is known about the relationship between cue-induced craving and cognitive control toward cocaine cues. While studies suggest that cocaine users have an attentional bias toward cocaine cues, the present study extends this research by testing if cocaine use disorder patients (CDPs) can control their eye movements toward cocaine cues and whether their response varied by cue-induced craving intensity. Methods: Thirty CDPs underwent a cue exposure procedure to dichotomize them into high and low craving groups followed by a modified antisaccade task in which subjects were asked to control their eye movements toward either a cocaine or neutral drug cue by looking away from the suddenly presented cue. The relationship between breakdowns in cognitive control (as measured by eye errors) and cue-induced craving (changes in self-reported craving following cocaine cue exposure) was investigated. Results: CDPs overall made significantly more errors toward cocaine cues compared to neutral cues, with higher cravers making significantly more errors than lower cravers even though they did not differ significantly in addiction severity, impulsivity, anxiety, or depression levels. Cue-induced craving was the only specific and significant predictor of subsequent errors toward cocaine cues. Conclusion: Cue-induced craving directly and specifically relates to breakdowns of cognitive control toward cocaine cues in CDPs, with higher cravers being more susceptible. Hence, it may be useful identifying high cravers and target treatment toward curbing craving to decrease the likelihood of a subsequent breakdown in control. |