All EyeLink Eye Tracker Publications
All 13,000+ peer-reviewed EyeLink research publications up until 2024 (with some early 2025s) 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!
2011 |
Joseph Schmidt; Gregory J. Zelinsky Visual search guidance is best after a short delay Journal Article In: Vision Research, vol. 51, no. 6, pp. 535–545, 2011. @article{Schmidt2011,Search displays are typically presented immediately after a target cue, but in the real-world, delays often exist between target designation and search. Experiments 1 and 2 asked how search guidance changes with delay. Targets were cued using a picture or text label, each for 3000ms, followed by a delay up to 9000ms before the search display. Search stimuli were realistic objects, and guidance was quantified using multiple eye movement measures. Text-based cues showed a non-significant trend towards greater guidance following any delay relative to a no-delay condition. However, guidance from a pictorial cue increased sharply 300-600ms after preview offset. Experiment 3 replicated this guidance enhancement using shorter preview durations while equating the time from cue onset to search onset, demonstrating that the guidance benefit is linked to preview offset rather than a more complete encoding of the target. Experiment 4 showed that enhanced guidance persists even with a mask flashed at preview offset, suggesting an explanation other than visual priming. We interpret our findings as evidence for the rapid consolidation of target information into a guiding representation, which attains its maximum effectiveness shortly after preview offset. |
Fabian Schnier; Markus Lappe Differences in inter-saccadic adaptation transfer between inward and outward adaptation Journal Article In: Journal of Neurophysiology, vol. 106, no. 3, pp. 1399–1410, 2011. @article{Schnier2011,Saccadic adaptation is a mechanism to increase or decrease the ampli- tude gain of subsequent saccades, if a saccade is not on target. Recent research has shown that the mechanism of gain increasing, or outward adaptation, and the mechanism of gain decreasing, or inward adapta- tion, rely on partly different processes. We investigate how outward and inward adaptation of reactive saccades transfer to other types of saccades, namely scanning, overlap, memory-guided, and gap sac- cades. Previous research has shown that inward adaptation of reactive saccades transfers only partially to these other saccade types, suggest- ing differences in the control mechanisms between these saccade categories. We show that outward adaptation transfers stronger to scanning and overlap saccades than inward adaptation, and that the strength of transfer depends on the duration for which the saccade target is visible before saccade onset. Furthermore, we show that this transfer is mainly driven by an increase in saccade duration, which is apparent for all saccade categories. Inward adaptation, in contrast, is accompanied by a decrease in duration and in peak velocity, but only the peak velocity decrease transfers from reactive saccades to other saccade categories, i.e., saccadic duration remains constant or even increases for test saccades of the other categories. Our results, there- fore, show that duration and peak velocity are independent parameters of saccadic adaptation and that they are differently involved in the transfer of adaptation between saccade categories. Furthermore, our results add evidence that inward and outward adaptation are different processes. |
Nicholas M. Ross; Linda J. Lanyon; Jaya Viswanathan; Dara S. Manoach; Jason J. S. Barton Human prosaccades and antisaccades under risk: Effects of penalties and rewards on visual selection and the value of actions Journal Article In: Neuroscience, vol. 196, pp. 168–177, 2011. @article{Ross2011,Monkey studies report greater activity in the lateral intraparietal area and more efficient saccades when targets coincide with the location of prior reward cues, even when cue location does not indicate which responses will be rewarded. This suggests that reward can modulate spatial attention and visual selection independent of the "action value" of the motor response. Our goal was first to determine whether reward modulated visual selection similarly in humans, and next, to discover whether reward and penalty differed in effect, if cue effects were greater for cognitively demanding antisaccades, and if financial consequences that were contingent on stimulus location had spatially selective effects. We found that motivational cues reduced all latencies, more for reward than penalty. There was an "inhibition-of-return"-like effect at the location of the cue, but unlike the results in monkeys, cue valence did not modify this effect in prosaccades, and the inhibition-of-return effect was slightly increased rather than decreased in antisaccades. When financial consequences were contingent on target location, locations without reward or penalty consequences lost the benefits seen in noncontingent trials, whereas locations with consequences maintained their gains. We conclude that unlike monkeys, humans show reward effects not on visual selection but on the value of actions. The human saccadic system has both the capacity to enhance responses to multiple locations simultaneously, and the flexibility to focus motivational enhancement only on locations with financial consequences. Reward is more effective than penalty, and both interact with the additional attentional demands of the antisaccade task. |
Rachael D. Rubin; Sarah Brown-Schmidt; Melissa C. Duff; Daniel Tranel; Neal J. Cohen How do I remember that I know you know that I know? Journal Article In: Psychological Science, vol. 22, no. 12, pp. 1574–1582, 2011. @article{Rubin2011,Communication is aided greatly when speakers and listeners take advantage of mutually shared knowledge (i.e., common ground). How such information is represented in memory is not well known. Using a neuropsychological-psycholinguistic approach to real-time language understanding, we investigated the ability to form and use common ground during conversation in memory-impaired participants with hippocampal amnesia. Analyses of amnesics' eye fixations as they interpreted their partner's utterances about a set of objects demonstrated successful use of common ground when the amnesics had immediate access to common-ground information, but dramatic failures when they did not. These findings indicate a clear role for declarative memory in maintenance of common-ground representations. Even when amnesics were successful, however, the eye movement record revealed subtle deficits in resolving potential ambiguity among competing intended referents; this finding suggests that declarative memory may be critical to more basic aspects of the on-line resolution of linguistic ambiguity. |
Adam J. Sachs; Paul S. Khayat; Robert Niebergall; Julio C. Martinez-Trujillo A metric-based analysis of the contribution of spike timing to contrast and motion direction coding by single neurons in macaque area MT Journal Article In: Brain Research, vol. 1368, pp. 163–184, 2011. @article{Sachs2011,Spike timing is thought to contribute to the coding of motion direction information by neurons in macaque area MT. Here, we examined whether spike timing also contributes to the coding of stimulus contrast. We applied a metric-based approach to spike trains fired by MT neurons in response to stimuli that varied in contrast, or direction. We assessed the performance of three metrics, Dspikeand Dproduct(containing spike count and timing information), and the spike count metric Dcount. We analyzed responses elicited during the first 200 msec of stimulus presentation from 205 neurons. For both contrast and direction, the large majority of neurons showed the highest mutual information using Dspike, followed by Dproduct, and Dcount. This was corroborated by the performance of a theoretical observer model at discriminating contrast and direction using the three metrics. Our results demonstrate that spike timing can contribute to contrast coding in MT neurons, and support previous reports of its potential contribution to direction coding. Furthermore, they suggest that a combination of spike count with periodic and non-periodic spike timing information (contained in Dspike, but not in Dproductand Dcountwhich are insensitive to spike counts and timing respectively) provides the largest coding advantage in spike trains fired by MT neurons during contrast and direction discrimination. |
Navid G. Sadeghi; Vani Pariyadath; Sameer Apte; David M. Eagleman; Erik P. Cook Neural correlates of subsecond time distortion in the middle temporal area of visual cortex Journal Article In: Journal of Cognitive Neuroscience, vol. 23, no. 12, pp. 3829–3840, 2011. @article{Sadeghi2011,How does the brain represent the passage of time at the subsecond scale? Although different conceptual models for time perception have been proposed, its neurophysiological basis remains unknown. We took advantage of a visual duration illusion produced by stimulus novelty to link changes in cortical activity in monkeys with distortions of duration perception in humans. We found that human subjects perceived the duration of a subsecond motion pulse with a novel direction longer than a motion pulse with a repeated direction. Recording from monkeys viewing identical motion stimuli but performing a different behavioral task, we found that both the duration and amplitude of the neural response in the middle temporal area of visual cortex were positively correlated with the degree of novelty of the motion direction. In contrast to previous accounts that attribute distortions in duration perception to changes in the speed of a putative internal clock, our results suggest that the known adaptive properties of neural activity in visual cortex contributes to subsecond temporal distortions. |
Lily Riggs; Douglas A. McQuiggan; Adam K. Anderson; Jennifer D. Ryan Evaluation of anti bacterial activity of fruit rind extract of Garcinia mangostana Linn on enteric pathogens-an in vitro study Journal Article In: Frontiers in Psychology, vol. 4, pp. 205, 2011. @article{Riggs2011,Research shows that memory for emotional aspects of an event may be enhanced at the cost of impaired memory for surrounding peripheral details. However, this has only been assessed directly via verbal reports which reveal the outcome of a long stream of processing but cannot shed light on how/when emotion may affect the retrieval process. In the present experiment, eye movement monitoring (EMM) was used as an indirect measure of memory as it can reveal aspects of online memory processing. For example, do emotions modulate the nature of memory representations or the speed with which such memories can be accessed? Participants viewed central negative and neutral scenes surrounded by three neutral objects and after a brief delay, memory was assessed indirectly via EMM and then directly via verbal reports. Consistent with the previous literature, emotion enhanced central and impaired peripheral memory as indexed by eye movement scanning and verbal reports. This suggests that eye movement scanning may contribute and/or is related to conscious access of memory. However, the central/peripheral tradeoff effect was not observed in an early measure of eye movement behavior, i.e., participants were faster to orient to a critical region of change in the periphery irrespective of whether it was previously studied in a negative or neutral context. These findings demonstrate emotion's differential influences on different aspects of retrieval. In particular, emotion appears to affect the detail within, and/or the evaluation of, stored memory representations, but it may not affect the initial access to those representations. |
Lily Riggs; Douglas A. McQuiggan; Norman A. S. Farb; Adam K. Anderson; Jennifer D. Ryan The role of overt attention in emotion-modulated memory Journal Article In: Emotion, vol. 11, no. 4, pp. 776–785, 2011. @article{Riggs2011a,The presence of emotional stimuli results in a central/peripheral tradeoff effect in memory: memory for central details is enhanced at the cost of peripheral items. It has been assumed that emotion-modulated differences in memory are the result of differences in attention, but this has not been tested directly. The present experiment used eye movement monitoring as an index of overt attention allocation and mediation analysis to determine whether differences in attention were related to subsequent memory. Participants viewed negative and neutral scenes surrounded by three neutral objects and were then given a recognition memory test. The results revealed evidence in support of a central/peripheral tradeoff in both attention and memory. However, contrary with previous assumptions, whereas attention partially mediated emotion-enhanced memory for central pictures, it did not explain the entire relationship. Further, although centrally presented emotional stimuli led to decreased number of eye fixations toward the periphery, these differences in viewing did not contribute to emotion-impaired memory for specific details pertaining to the periphery. These findings suggest that the differential influence of negative emotion on central versus peripheral memory may result from other cognitive influences in addition to overt visual attention or on postencoding processes. |
Sarah Risse; Reinhold Kliegl Adult age differences in the perceptual span during reading Journal Article In: Psychology and Aging, vol. 26, no. 2, pp. 451–460, 2011. @article{Risse2011,Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N + 2-boundary paradigm in which a nonword preview of word N + 2 or word N + 2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N + 1 was always three letters long. Gaze durations on word N + 2 were significantly shorter for identical than nonword N + 2 preview both for young and for old adults, with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N + 1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults. |
Ardi Roelofs Attention, exposure duration, and gaze shifting in naming performance Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 3, pp. 860–873, 2011. @article{Roelofs2011,Two experiments are reported in which the role of attribute exposure duration in naming performance was examined by tracking eye movements. Participants were presented with color-word Stroop stimuli and left- or right-pointing arrows on different sides of a computer screen. They named the color attribute and shifted their gaze to the arrow to manually indicate its direction. The color attribute (Experiment 1) or the complete color-word stimulus (Experiment 2) was removed from the screen 100 ms after stimulus onset. Compared with presentation until trial offset, removing the color attribute diminished Stroop interference, as well as facilitation effects in color naming latencies, whereas removing the complete stimulus diminished interference only. Attribute and stimulus removal reduced the latency of gaze shifting, which suggests decreased rather than increased attentional demand. These results provide evidence that limiting exposure duration contributes to attribute naming performance by diminishing the extent to which irrelevant attributes are processed, which reduces attentional demand. |
Martin Rolfs; Donatas Jonikaitis; Heiner Deubel; Patrick Cavanagh Predictive remapping of attention across eye movements Journal Article In: Nature Neuroscience, vol. 14, no. 2, pp. 252–258, 2011. @article{Rolfs2011,Many cells in retinotopic brain areas increase their activity when saccades (rapid eye movements) are about to bring stimuli into their receptive fields. Although previous work has attempted to look at the functional correlates of such predictive remapping, no study has explicitly tested for better attentional performance at the future retinal locations of attended targets. We found that, briefly before the eyes start moving, attention drawn to the targets of upcoming saccades also shifted to those retinal locations that the targets would cover once the eyes had moved, facilitating future movements. This suggests that presaccadic visual attention shifts serve to both improve presaccadic perceptual processing at the target locations and speed subsequent eye movements to their new postsaccadic locations. Predictive remapping of attention provides a sparse, efficient mechanism for keeping track of relevant parts of the scene when frequent rapid eye movements provoke retinal smear and temporal masking. |
Anne Pier Salverda; Gerry T. M. Altmann Attentional capture of objects referred to by spoken language Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 4, pp. 1122–1133, 2011. @article{Salverda2011,Participants saw a small number of objects in a visual display and performed a visual detection or visual-discrimination task in the context of task-irrelevant spoken distractors. In each experiment, a visual cue was presented 400 ms after the onset of a spoken word. In experiments 1 and 2, the cue was an isoluminant color change and participants generated an eye movement to the target object. In experiment 1, responses were slower when the spoken word referred to the distractor object than when it referred to the target object. In experiment 2, responses were slower when the spoken word referred to a distractor object than when it referred to an object not in the display. In experiment 3, the cue was a small shift in location of the target object and participants indicated the direction of the shift. Responses were slowest when the word referred to the distractor object, faster when the word did not have a referent, and fastest when the word referred to the target object. Taken together, the results demonstrate that referents of spoken words capture attention. |
Raju P. Sapkota; Shahina Pardhan; Ian Linde The impact of extrafoveal information on visual short-term memory for object position Journal Article In: Journal of Cognitive Psychology, vol. 23, no. 5, pp. 574–585, 2011. @article{Sapkota2011,The role of extrafoveal information in visual short-term memory has been investigated relatively little, and, in most existing studies, using verbalisable stimuli susceptible to the recruitment of long-term memory (LTM). In addition, little is known about the impact of extrafoveal information available pre-and posttarget foveation, as it is typical to provide extrafoveal information prior to the foveation of memory targets. In this study, two object-position recognition experiments were conducted (each with two conditions) to establish the impact of extrafoveal information provided before and after the foveation of memory targets. Stimuli comprised 1/f noise discs that minimised the recruitment of LTM by eliminating verbal and semantic cues. Overall, a greater hit rate was found where extrafoveal information was available; however, performance analyses in which extrafoveal information was considered relative to the temporal lag at which target stimuli were foveated reveals both costs and benefits. A beneficial effect arose only where extrafoveal information was provided after the target had been foveated, but not prior to target foveation. Findings are discussed in terms of recency and extrafoveal perception effects, incorporating a postfoveation object-file refresh mechanism. |
Paige E. Scalf; Chandramalika Basak; Diane M. Beck Attention does more than modulate suppressive interactions: Attending to multiple items Journal Article In: Experimental Brain Research, vol. 212, no. 2, pp. 293–304, 2011. @article{Scalf2011,Directing attention to a visual item enhances its representations, making it more likely to guide behavior (Corbetta et al. 1991). Attention is thought to produce this enhancement by biasing suppressive interactions among multiple items in visual cortex in favor of the attended item (e.g., Desimone and Duncan 1995; Reynolds and Heeger 2009). We ask whether target enhancement and modulation of suppressive interactions are in fact inextricably linked or whether they can be decoupled. In particular, we ask whether simultaneously directing attention to multiple items may be one means of dissociating the influence of attention-related enhancement from the effects of inter-item suppression. When multiple items are attended, suppressive interactions in visual cortex limit the effectiveness with which attention may act on their representations, presumably because "biasing" the interactions in favor of a single item is no longer possible (Scalf and Beck 2010). In this experiment, we directly investigate whether applying attention to multiple competing stimulus items has any influence on either their evoked signal or their suppressive interactions. Both BOLD signal evoked by the items in V4 and behavioral responses to those items were significantly compromised by simultaneous presentation relative to simultaneous presentation, indicating that when the items appeared at the same time, they interacted in a mutually suppressive manner that compromised their ability to guide behavior. Attention significantly enhanced signal in V4. The attentional status of the items, however, had no influence on the suppressive effects of simultaneous presentation. To our knowledge, these data are the first to explicitly decouple the effects of top-down attention from those of inter-item suppression. |
Diego E. Shalom; Bruno Dagnino; Mariano Sigman Looking at Breakout: Urgency and predictability direct eye events Journal Article In: Vision Research, vol. 51, no. 11, pp. 1262–1272, 2011. @article{Shalom2011,We investigated the organization of eye-movement classes in a natural and dynamical setup. To mimic the goals and objectives of the natural world in a controlled environment, we studied eye-movements while participants played Breakout, an old Atari game which remains surprisingly entertaining, often addictive, in spite of its graphic and structural simplicity. Our results show that eye-movement dynamics can be explained in terms of simple principles of moments of prediction and urgency of action. We observed a consistent anticipatory behavior (gaze was directed ahead of ball trajectory) except during the moment in which the ball bounced either in the walls, or in the paddle. At these moments, we observed a refractory period during which there are no blinks and saccades. Saccade delay caused the gaze to fall behind the ball. This pattern is consistent with a model by which participants postpone saccades at the bounces while predicting the ball trajectory and subsequently make a catch-up saccade directed to a position which anticipates ball trajectory. During bounces, trajectories were smooth and curved interpolating the V-shape function of the ball with minimal acceleration. These results pave the path to understand the taxonomy of eye-movements on natural configurations in which stimuli and goals switch dynamically in time. |
Swetha Shankar; Dino P. Massoglia; Dantong Zhu; M. Gabriela Costello; Terrence R. Stanford; Emilio Salinas Tracking the temporal evolution of a perceptual judgment using a compelled-response task Journal Article In: Journal of Neuroscience, vol. 31, no. 23, pp. 8406–8421, 2011. @article{Shankar2011,Choice behavior and its neural correlates have been intensely studied with tasks in which a subject makes a perceptual judgment and indicates the result with a motor action. Yet a question crucial for relating behavior to neural activity remains unresolved: what fraction of a subject's reaction time (RT) is devoted to the perceptual evaluation step, as opposed to executing the motor report? Making such timing measurements accurately is complicated because RTs reflect both sensory and motor processing, and because speed and accuracy may be traded. To overcome these problems, we designed the compelled-saccade task, a two-alternative forced-choice task in which the instruction to initiate a saccade precedes the appearance of the relevant sensory information. With this paradigm, it is possible to track perceptual performance as a function of the amount of time during which sensory information is available to influence a subject's choice. The result-the tachometric curve-directly reveals a subject's perceptual processing capacity independently of motor demands. Psychophysical data, together with modeling and computer-simulation results, reveal that task performance depends on three separable components: the timing of the motor responses, the speed of the perceptual evaluation, and additional cognitive factors. Each can vary quickly, from one trial to the next, or can show stable, longer-term changes. This novel dissociation between sensory and motor processes yields a precise metric of how perceptual capacity varies under various experimental conditions and serves to interpret choice-related neuronal activity as perceptual, motor, or both. |
Hua Shu; Wei Zhou; Ming Yan; Reinhold Kliegl Font size modulates saccade-target selection in chinese reading Journal Article In: Attention, Perception, & Psychophysics, vol. 73, no. 2, pp. 482–490, 2011. @article{Shu2011,In alphabetic writing systems, saccade amplitude (a close correlate of reading speed) is independent of font size, presumably because an increase in the angular size of letters is compensated for by a decrease of visual acuity with eccentricity. We propose that this invariance may (also) be due to the presence of spaces between words, guiding the eyes across a large range of font sizes. Here, we test whether saccade amplitude is also invariant against manipulations of font size during reading Chinese, a character-based writing system without spaces as explicit word boundaries for saccade-target selection. In contrast to word-spaced alphabetic writing systems, saccade amplitude decreased significantly with increased font size, leading to an increase in the number of fixations at the beginning of words and in the number of refixations. These results are consistent with a model which assumes that word beginning (rather than word center) is the default saccade target if the length of the parafoveal word is not available. |
Jelmer P. Vries; Ignace T. C. Hooge; Marco A. Wiering; Frans A. J. Verstraten How longer saccade latencies lead to a competition for salience Journal Article In: Psychological Science, vol. 22, no. 7, pp. 916–923, 2011. @article{Vries2011,It has been suggested that independent bottom-up and top-down processes govern saccadic selection. However, recent findings are hard to explain in such terms. We hypothesized that differences in visual-processing time can explain these findings, and we tested this using search displays containing two deviating elements, one requiring a short processing time and one requiring a long processing time. Following short saccade latencies, the deviation requiring less processing time was selected most frequently. This bias disappeared following long saccade latencies. Our results suggest that an element that attracts eye movements following short saccade latencies does so because it is the only element processed at that time. The temporal constraints of processing visual information therefore seem to be a determining factor in saccadic selection. Thus, relative saliency is a time-dependent phenomenon. |
Jelmer P. De Vries; Ignace T. C. Hooge; Marco A. Wiering; Frans A. J. Verstraten Saccadic selection and crowding in visual search: Stronger lateral masking leads to shorter search times Journal Article In: Experimental Brain Research, vol. 211, no. 1, pp. 119–131, 2011. @article{DeVries2011,We investigated the role of crowding in saccadic selection during visual search. To guide eye movements, often information from the visual periphery is used. Crowding is known to deteriorate the quality of peripheral information. In four search experiments, we studied the role of crowding, by accompanying individual search elements by flankers. Varying the difference between target and flankers allowed us to manipulate crowding strength throughout the stimulus. We found that eye movements are biased toward areas with little crowding for conditions where a target could be discriminated peripherally. Interestingly, for conditions in which the target could not be discriminated peripherally, this bias reversed to areas with strong crowding. This led to shorter search times for a target presented in areas with stronger crowding, compared to a target presented in areas with less crowding. These findings suggest a dual role for crowding in visual search. The presence of flankers similar to the target deteriorates the quality of the peripheral target signal but can also attract eye movements, as more potential targets are present over the area. |
Louis F. Dell'Osso; Richard W. Hertle; R. John Leigh; Jonathan B. Jacobs; Susan King; Stacia Yaniglos Effects of topical brinzolamide on infantile nystagmus syndrome waveforms: Eyedrops for nystagmus Journal Article In: Journal of Neuro-Ophthalmology, vol. 31, no. 3, pp. 228–233, 2011. @article{DellOsso2011,BACKGROUND: Recent advances in infantile nystagmus syndrome (INS) surgery have uncovered the therapeutic importance of proprioception. In this report, we test the hypothesis that the topical carbonic anhydrase inhibitor (CAI) brinzolamide (Azopt) has beneficial effects on measures of nystagmus foveation quality in a subject with INS. METHODS: Eye movement data were taken, using a high-speed digital video recording system, before and after 3 days of the application of topical brinzolamide 3 times daily in each eye. Nystagmus waveforms were analyzed by applying the eXpanded Nystagmus Acuity Function (NAFX) at different gaze angles and determining the longest foveation domain (LFD) and compared to previously published data from the same subject after the use of a systemic CAI, contact lenses, and convergence and to other subjects before and after eye muscle surgery for INS. RESULTS:: Topical brinzolamide improved foveation by both a 51.9% increase in the peak value of the NAFX function (from 0.395 to 0.600) and a 50% broadening of the NAFX vs Gaze Angle curve (the LFD increased from 20 degrees to 30 degrees ). The improvements in NAFX after topical brinzolamide were equivalent to systemic acetazolamide or eye muscle surgery and were intermediate between those of soft contact lenses or convergence. Topical brinzolamide and contact lenses had equivalent LFD improvements and were less effective than convergence. CONCLUSIONS: In this subject with INS, topical brinzolamide resulted in improved-foveation INS waveforms over a broadened range of gaze angles. Its therapeutic effects were equivalent to systemic CAI. Although a prospective clinical trial is needed to prove efficacy or effectiveness in other subjects, an eyedrops-based therapy for INS may emerge as a viable addition to optical, surgical, behavioral, and systemic drug therapies. |
Stefan Van Stigchel; Puck Imants; K. Richard Ridderinkhof; Stefan Van Stigchel; Puck Imants; K. Richard Ridderinkhof Positive affect increases cognitive control in the antisaccade task Journal Article In: Brain and Cognition, vol. 75, no. 2, pp. 177–181, 2011. @article{Stigchel2011,To delineate the modulatory effects of induced positive affect on cognitive control, the current study investigated whether positive affect increases the ability to suppress a reflexive saccade in the antisaccade task. Results of the antisaccade task showed that participants made fewer erroneous prosaccades in the condition in which a positive mood was induced compared to the neutral condition (i.e. in which no emotional mood was induced). This improvement of oculomotor inhibition was restricted to saccades with an express latency. These results are in line with the idea that enhanced performance in the positive affect condition could be caused by increased dopaminergic neurotransmission the brain. © 2010 Elsevier Inc. |
Loni Desanghere; J. J. Marotta "Graspability" of objects affects gaze patterns during perception and action tasks Journal Article In: Experimental Brain Research, vol. 212, no. 2, pp. 177–187, 2011. @article{Desanghere2011,When grasping an object, our gaze marks key positions to which the fingertips are directed. In contrast, eye fixations during perceptual tasks are typically concentrated on an object's centre of mass (COM). However, previous studies have typically required subjects to either grasp the object at predetermined sites or just look at computer-generated shapes "as a whole". In the current study, we investigated gaze fixations during a reaching and grasping task to symmetrical objects and compared these fixations with those made during a perceptual size estimation task using real (Experiment 1) and computer-generated objects (Experiment 2). Our results demonstrated similar gaze patterns in both perception and action to real objects. Participants first fixated a location towards the top edge of the object, consistent with index finger location during grasping, followed by a subsequent fixation towards the object's COM. In contrast, during the perceptual task to computer-generated objects, an opposite pattern in fixation locations was observed, where first fixations were closer to the COM, followed by a subsequent fixation towards the top edge. Even though differential fixation patterns were observed between studies, the area in which these fixations occurred, between the centre of the object and top edge, was the same in all tasks. These results demonstrate for the first time consistencies in fixation locations across both perception and action tasks, particularly when the same type of information (e.g. object size) is important for the completion of both tasks, with fixation locations increasing relative to the object's COM with increases in block height. |
Joost C. Dessing; J. Douglas Crawford; W. Pieter Medendorp Spatial updating across saccades during manual interception Journal Article In: Journal of Vision, vol. 11, no. 10, pp. 1–18, 2011. @article{Dessing2011,We studied the effect of intervening saccades on the manual interception of a moving target. Previous studies suggest that stationary reach goals are coded and updated across saccades in gaze-centered coordinates, but whether this generalizes to interception is unknown. Subjects (n = 9) reached to manually intercept a moving target after it was rendered invisible. Subjects either fixated throughout the trial or made a saccade before reaching (both fixation points were in the range of -10° to 10°). Consistent with previous findings and our control experiment with stationary targets, the interception errors depended on the direction of the remembered moving goal relative to the new eye position, as if the target is coded and updated across the saccade in gaze-centered coordinates. However, our results were also more variable in that the interception errors for more than half of our subjects also depended on the goal direction relative to the initial gaze direction. This suggests that the feedforward transformations for interception differ from those for stationary targets. Our analyses show that the interception errors reflect a combination of biases in the (gaze-centered) representation of target motion and in the transformation of goal information into body-centered coordinates for action. |
Leandro Luigi Di Stasi; Adoración Antolí; José J. Cañas Main sequence: An index for detecting mental workload variation in complex tasks Journal Article In: Applied Ergonomics, vol. 42, no. 6, pp. 807–813, 2011. @article{DiStasi2011a,The primary aim of this study was to validate the saccadic main sequence, in particular the peak velocity [PV], as an alternative psychophysiological measure of Mental Workload [MW]. Taking the Wickens' multiple resource model as the theoretical framework of reference, an experiment was conducted using the Firechief®microworld. MW was manipulated by changing the task complexity (between groups) and the amount of training (within groups). There were significant effects on PV from both factors. These results provide additional empirical support for the sensitivity of PV to discriminate MW variation on visual-dynamic complex tasks. These findings and other recent results on PV could provide important information for the development of a new vigilance screening tool for the prevention of accidents in several fields of applied ergonomics. |
Leandro Luigi Di Stasi; Adoración Antolí; Miguel Gea; José J. Cañas A neuroergonomic approach to evaluating mental workload in hypermedia interactions Journal Article In: International Journal of Industrial Ergonomics, vol. 41, no. 3, pp. 298–304, 2011. @article{DiStasi2011b,Neuroergonomics could provide on-line methods for measuring mental effort while the operator interacts with hypermedia. We present an experimental study in which 28 participants interacted with a modified version of an existing Spanish e-commerce website in two searching tasks (Goal oriented shopping and Experiential shopping) that demand different amounts of cognitive resources. Mental workload was evaluated multidimensionally, using subjective rating, an interaction index, and eye-related indices. Eye movements and pupil diameter were recorded. The results showed visual scanning behaviour coincided with subjective test scores and performance data in showing a higher information processing load in Goal oriented shopping. However, pupil diameter was able to detect only the variation in user activation during the interaction task, a finding that replicates previous results on the validity of pupil size as an index of arousal. We conclude that a neuroergonomics approach could be a useful method for detecting variations in operators' attentional states. Relevance to industry: These results could provide important information for the development of a new attentional screening tool for the prevention of accidents in several application domains. |
Leandro Luigi Di Stasi; D. Contreras; Antonio Cándido; José J. Cañas; A. Catena Behavioral and eye-movement measures to track improvements in driving skills of vulnerable road users: First-time motorcycle riders Journal Article In: Transportation Research Part F: Traffic Psychology and Behaviour, vol. 14, no. 1, pp. 26–35, 2011. @article{DiStasi2011,Motorcyclist deaths and injuries follow the trend in sales rather than in growth in the number of motorcycles, suggesting that fatalities are related to the lack of driver experience with recently purchased motorcycles. The aim of the present investigation was to assess the effects of experience and training in hazard perception. We compared first-time riders (people who are not yet riders/drivers) before and after training in six different riding scenarios to expert motorcycle riders. Thirty-three participants took part in the experiment. Volunteers rode a moped in a fixed-base virtual environment and were presented with a number of preset risky events. We used a multidimensional methodology, including behavioral, subjective and eye-movements data. The results revealed differences between experts and first-time riders, as well as the effect of training on the novice group. As expected, training led to an improvement in the riding skills of first-time riders, reducing the number of accidents, improving their capacity to adapt their speed to the situation, reducing trajectory-corrective movements, and changing their pattern of gaze exploration. We identified several behavioral and eye-related measures that are sensitive to both long-term experience and training in motorcycle riders. These findings will be useful for the design of on-line monitoring systems to evaluate changes in risk behavior and of programs for preventing and controlling risk behavior and improving situation awareness for novice riders, with the ultimate aim of reducing road-user mortality. |
Jan Drewes; Julia Trommershäuser; Karl R. Gegenfurtner Parallel visual search and rapid animal detection in natural scenes Journal Article In: Journal of Vision, vol. 11, no. 2, pp. 1–21, 2011. @article{Drewes2011,Human observers are capable of detecting animals within novel natural scenes with remarkable speed and accuracy. Recent studies found human response times to be as fast as 120 ms in a dual-presentation (2-AFC) setup (H. Kirchner & S. J. Thorpe, 2005). In most previous experiments, pairs of randomly chosen images were presented, frequently from very different contexts (e.g., a zebra in Africa vs. the New York Skyline). Here, we tested the effect of background size and contiguity on human performance by using a new, contiguous background image set. Individual images contained a single animal surrounded by a large, animal-free image area. The image could be positioned and cropped in such a manner that the animal could occur in one of eight evenly spaced positions on an imaginary circle (radius 10-deg visual angle). In the first (8-Choice) experiment, all eight positions were used, whereas in the second (2-Choice) and third (2-Image) experiments, the animals were only presented on the two positions to the left and right of the screen center. In the third experiment, additional rectangular frames were used to mimic the conditions of earlier studies. Average latencies on successful trials differed only slightly between conditions, indicating that the number of possible animal locations within the display does not affect decision latency. Detailed analysis of saccade targets revealed a preference toward both the head and the center of gravity of the target animal, affecting hit ratio, latency, and the number of saccades required to reach the target. These results illustrate that rapid animal detection operates scene-wide and is fast and efficient even when the animals are embedded in their natural backgrounds. |
Alan F. Dixson; Barnaby J. Dixson Venus figurines of the european paleolithic: Symbols of fertility or attractiveness? Journal Article In: Journal of Anthropology, vol. 2011, pp. 1–11, 2011. @article{Dixson2011,The earliest known representations of the human female form are the European Paleolithic “Venus figurines,” ranging in age from 23,000 to 25,000 years. We asked participants to rate images of Paleolithic figurines for their attractiveness, age grouping and reproductive status. Attractiveness was positively correlated with measures of the waist-to hip ratio (WHR) of figurines, consistent with the “sexually attractive symbolism” hypothesis. However, most figurines had high WHRs (>1.0) and received low attractiveness scores. Participants rated most figurines as representing middle-aged or young adult women, rather than being adolescent or older (postmenopausal). While some were considered to represent pregnant women, consistent with the “fertility symbol” hypothesis, most were judged as being non-pregnant. Some figurines depict obese, large-breasted women, who are in their mature reproductive years and usually regarded as being of lower attractiveness. At the time these figurines were made, Europe was in the grip of a severe ice age. Obesity and survival into middle age after multiple pregnancies may have been rare in the European Upper Paleolithic. We suggest that depictions of corpulent, middle-aged females were not “Venuses” in any conventional sense. They may, instead, have symbolized the hope for survival and longevity, within well-nourished and reproductively successful communities. |
Barnaby J. Dixson; Gina M. Grimshaw; Wayne L. Linklater; Alan F. Dixson Eye-tracking of men's preferences for waist-to-hip ratio and breast size of women Journal Article In: Archives of Sexual Behavior, vol. 40, no. 1, pp. 43–50, 2011. @article{Dixson2011a,Studies of human physical traits and mate preferences often use questionnaires asking participants to rate the attractiveness of images. Female waist-to-hip ratio (WHR), breast size, and facial appearance have all been implicated in assessments by men of female attractiveness. However, very little is known about how men make fine-grained visual assessments of such images. We used eye-tracking techniques to measure the numbers of visual fixations, dwell times, and initial fixations made by men who viewed front-posed photographs of the same woman, computer-morphed so as to differ in her WHR (0.7 or 0.9) and breast size (small, medium, or large). Men also rated these images for attractiveness. Results showed that the initial visual fixation (occurring within 200 ms from the start of each 5 s test) involved either the breasts or the waist. Both these body areas received more first fixations than the face or the lower body (pubic area and legs). Men looked more often and for longer at the breasts, irrespective of the WHR of the images. However, men rated images with an hourglass shape and a slim waist (0.7 WHR) as most attractive, irrespective of breast size. These results provide quantitative data on eye movements that occur during male judgments of the attractiveness of female images, and indicate that assessments of the female hourglass figure probably occur very rapidly. |
Barnaby J. Dixson; Gina M. Grimshaw; Wayne L. Linklater; Alan F. Dixson Eye tracking of men's preferences for female breast size and areola pigmentation Journal Article In: Archives of Sexual Behavior, vol. 40, no. 1, pp. 51–58, 2011. @article{Dixson2011b,Sexual selection via male mate choice has often been implicated in the evolution of permanently enlarged breasts in women. While questionnaire studies have shown that men find female breasts visually attractive, there is very little information about how they make such visual judgments. In this study, we used eye-tracking technology to test two hypotheses: (1) that larger breasts should receive the greatest number of visual fixations and longest dwell times, as well as being rated as most attractive; (2) that lightly pigmented areolae, indicative of youth and nubility, should receive most visual attention and be rated as most attractive. Results showed that men rated images with medium-sized or large breasts as significantly more attractive than small breasts. Images with dark and medium areolar pigmentation were rated as more attractive than images with light areolae. However, variations in breast size had no significant effect on eye-tracking measures (initial visual fixations, number of fixations, and dwell times). The majority of initial fixations during eye-tracking tests were on the areolae. However, areolar pigmentation did not affect measures of visual attention. While these results demonstrate that cues indicative of female sexual maturity (large breasts and dark areolae) are more attractive to men, patterns of eye movements did not differ based on breast size or areolar pigmentation. We conclude that areolar pigmentation, as well as breast size, plays a significant role in men's judgments of female attractiveness. However, fine-grained measures of men's visual attention to these morphological traits do not correlate, in a simplistic way, with their attractiveness judgments. |
Isabel Dombrowe; Mieke Donk; Christian N. L. Olivers The costs of switching attentional sets Journal Article In: Attention, Perception, & Psychophysics, vol. 73, no. 8, pp. 2481–2488, 2011. @article{Dombrowe2011,People prioritize those aspects of the visual environment that match their attentional set. In the present study, we investigated whether switching from one attentional set to another is associated with a cost. We asked observers to sequentially saccade toward two color-defined targets, one on the left side of the display, the other on the right, each among a set of heterogeneously colored distractors. The targets were of the same color (no attentional set switch required) or of different colors (switch of attentional sets necessary), with each color consistently tied to a side, to allow observers to maximally prepare for the switch. We found that saccades were less accurate and slower in the switch condition than in the no-switch condition. Furthermore, whenever one of the distractors had the color associated with the other attentional set, a substantial proportion of saccades did not end on the target, but on this distractor. A time course analysis revealed that this distractor preference turned into a target preference after about 250-300 ms, suggesting that this is the time required to switch attentional sets. |
Mieke Donk; Wieske Zoest No control in orientation search: The effects of instruction on oculomotor selection in visual search Journal Article In: Vision Research, vol. 51, no. 19, pp. 2156–2166, 2011. @article{Donk2011,The present study aimed to investigate whether people can selectively use salience information in search for a target. Observers were presented with a display consisting of multiple homogeneously oriented background lines and two orientation singletons. The orientation singletons differed in salience, where salience was defined by their orientation contrast relative to the background lines. Observers had the task to make a speeded eye movement towards a target, which was either the most or the least salient element of the two orientation singletons. The specific orientation of the target was either constant or variable over a block of trials such that observers had varying knowledge concerning the target identity. The results demonstrated that instruction - whether people were instructed to move to the most or the least salient item - only minimally affected the results. Short-latency eye movements were completely salience driven; here it did not matter whether people were searching for the most or least salient element. Long-latency eye movements were marginally affected by instruction, in particular when observers knew the target identity. These results suggest that even though people use salience information in oculomotor selection, they cannot use this information in a goal-driven manner. The results are discussed in terms of current models on visual selection. |
Ava Elahipanah; Bruce K. Christensen; Eyal M. Reingold What can eye movements tell us about Symbol Digit substitution by patients with schizophrenia? Journal Article In: Schizophrenia Research, vol. 127, no. 1-3, pp. 137–143, 2011. @article{Elahipanah2011,Substitution tests are sensitive to cognitive impairment and reliably discriminate patients with schizophrenia from healthy individuals better than most other neuropsychological instruments. However, due to their multifaceted nature, substitution test scores cannot pinpoint the specific cognitive deficits that lead to poor performance. The current study investigated eye movements during performance on a substitution test in order to better understand what aspect of substitution test performance underlies schizophrenia-related impairment. Twenty-five patients with schizophrenia and 25 healthy individuals performed a computerized version of the Symbol Digit Modalities Test while their eye movements were monitored. As expected, patients achieved lower overall performance scores. Moreover, analysis of participants' eye movements revealed that patients spent more time searching for the target symbol every time they visited the key area. Patients also made more visits to the key area for each response that they made. Regression analysis suggested that patients' impaired performance on substitution tasks is primarily related to a less efficient visual search and, secondarily, to impaired memory. |
Ava Elahipanah; Bruce K. Christensen; Eyal M. Reingold Attentional guidance during visual search among patients with schizophrenia Journal Article In: Schizophrenia Research, vol. 131, no. 1-3, pp. 224–230, 2011. @article{Elahipanah2011a,The current study investigated visual guidance and saccadic selectivity during visual search among patients with schizophrenia (SCZ). Data from a previous study (Elahipanah, A., Christensen, B.K., & Reingold, E.M., 2008. Visual selective attention among persons with schizophrenia: The distractor ratio effect. Schizophr. Res. 105, 61-67.) suggested that visual guidance for the less frequent distractors in a conjunction search display (i.e., the distractor ratio effect) is intact among SCZ patients. The current study investigated the distractor ratio effect among SCZ patients when: 1) search is more demanding, and 2) search involves motion perception. In addition, eye tracking was employed to directly study saccadic selectivity for the different types of distractors. Twenty-eight SCZ patients receiving a single antipsychotic medication and 26 healthy control participants performed two conjunction search tasks: a within-dimension (i.e., colour × colour) search task; and a cross-dimension (i.e., motion × colour) search task. In each task the relative frequency of distractors was manipulated across 5 levels. Despite slower search times, patients' eye movement data indicated unimpaired visual guidance in both tasks. However, in the motion × colour conjunction search task, patients displayed disproportionate difficulty detecting the moving target when the majority of distractors were also moving. Results demonstrate that bottom-up attentional guidance is unimpaired among patients with SCZ; however, patients' impairment in motion discrimination impedes their ability to detect a moving target against noisy backgrounds. |
Ava Elahipanah; Bruce K. Christensen; Eyal M. Reingold Controlling the spotlight of attention: Visual span size and flexibility in schizophrenia Journal Article In: Neuropsychologia, vol. 49, no. 12, pp. 3370–3376, 2011. @article{Elahipanah2011b,The current study investigated the size and flexible control of visual span among patients with schizophrenia during visual search performance. Visual span is the region of the visual field from which one extracts information during a single eye fixation, and a larger visual span size is linked to more efficient search performance. Therefore, a reduced visual span may explain patients' impaired performance on search tasks. The gaze-contingent moving window paradigm was used to estimate the visual span size of patients and healthy participants while they performed two different search tasks. In addition, changes in visual span size were measured as a function of two manipulations of task difficulty: target-distractor similarity and stimulus familiarity. Patients with schizophrenia searched more slowly across both tasks and conditions. Patients also demonstrated smaller visual span sizes on the easier search condition in each task. Moreover, healthy controls' visual span size increased as target discriminability or distractor familiarity increased. This modulation of visual span size, however, was reduced or not observed among patients. The implications of the present findings, with regard to previously reported visual search deficits, and other functional and structural abnormalities associated with schizophrenia, are discussed. |
Jessica J. Ellis; Mackenzie G. Glaholt; Eyal M. Reingold Eye movements reveal solution knowledge prior to insight Journal Article In: Consciousness and Cognition, vol. 20, no. 3, pp. 768–776, 2011. @article{Ellis2011,In two experiments, participants solved anagram problems while their eye movements were monitored. Each problem consisted of a circular array of five letters: a scrambled four-letter solution word containing three consonants and one vowel, and an additional randomly-placed distractor consonant. Viewing times on the distractor consonant compared to the solution consonants provided an online measure of knowledge of the solution. Viewing times on the distractor consonant and the solution consonants were indistinguishable early in the trial. In contrast, several seconds prior to the response, viewing times on the distractor consonant decreased in a gradual manner compared to viewing times on the solution consonants. Importantly, this pattern was obtained across both trials in which participants reported the subjective experience of insight and trials in which they did not. These findings are consistent with the availability of partial knowledge of the solution prior to such information being accessible to subjective phenomenal awareness. |
Trevor J. Crawford; Elisabeth Parker; Ivonne Solis-Trapala; Jenny Mayes Is the relationship of prosaccade reaction times and antisaccade errors mediated by working memory? Journal Article In: Experimental Brain Research, vol. 208, no. 3, pp. 385–397, 2011. @article{Crawford2011,The mechanisms that control eye movements in the antisaccade task are not fully understood. One influential theory claims that the generation of antisaccades is dependent on the capacity of working memory. Previous research also suggests that antisaccades are influenced by the relative processing speeds of the exogenous and endogenous saccadic pathways. However, the relationship between these factors is unclear, in particular whether or not the effect of the relative speed of the pro and antisaccade pathways is mediated by working memory. The present study contrasted the performance of healthy individuals with high and low working memory in the antisaccade and prosaccade tasks. Path analyses revealed that antisaccade errors were strongly predicted by the mean reaction times of prosaccades and that this relationship was not mediated by differences in working memory. These data suggest that antisaccade errors are directly related to the speed of saccadic programming. These findings are discussed in terms of a race competition model of antisaccade control. |
Sarah C. Creel; Melanie A. Tumlin On-line acoustic and semantic interpretation of talker information Journal Article In: Journal of Memory and Language, vol. 65, no. 3, pp. 264–285, 2011. @article{Creel2011,Recent work demonstrates that listeners utilize talker-specific information in the speech signal to inform real-time language processing. However, there are multiple representational levels at which this may take place. Listeners might use acoustic cues in the speech signal to access the talker's identity and information about what they tend to talk about, which then immediately constrains processing. Alternatively, or simultaneously, listeners might compare the signal to acoustically-detailed representations of words, without awareness of the talker's identity. In a series of eye-tracked comprehension experiments, we explore the circumstances under which listeners utilize talker-specific information. Experiments 1 and 2 demonstrate talker-specific recognition benefits for newly-learned words both in isolation (Experiment 1) and with preceding context (Experiment 2), but suggest that listeners do not strongly semantically associate talkers with referents. Experiment 3 demonstrates that listeners can recognize talkers rapidly, almost as soon as acoustic information is available, and can associate talkers with multiple arbitrary referents. Experiment 4 demonstrates that if talker identity is highly diagnostic on each trial, listeners readily associate talkers with specific referents, but do not seem to make such associations when diagnostic value is low. Implications for speech processing, talker processing, and learning are discussed. © 2011 Elsevier Inc. |
Sebastian J. Crutch; Manja Lehmann; Nikos Gorgoraptis; Diego Kaski; Natalie Ryan; Masud Husain; Elizabeth K. Warrington Abnormal visual phenomena in posterior cortical atrophy Journal Article In: Neurocase, vol. 17, no. 2, pp. 160–177, 2011. @article{Crutch2011,Individuals with posterior cortical atrophy (PCA) report a host of unusual and poorly explained visual disturbances. This preliminary report describes a single patient (CRO), and documents and investigates abnormally prolonged colour afterimages (concurrent and prolonged perception of colours complimentary to the colour of an observed stimulus), perceived motion of static stimuli, and better reading of small than large letters. We also evaluate CRO's visual and vestibular functions in an effort to understand the origin of her experience of room tilt illusion, a disturbing phenomenon not previously observed in individuals with cortical degenerative disease. These visual symptoms are set in the context of a 4-year longitudinal neuropsychological and neuroimaging investigation of CRO's visual and other cognitive skills. We hypothesise that prolonged colour after-images are attributable to relative sparing of V1 inhibitory interneurons; perceived motion of static stimuli reflects weak magnocellular function; better reading of small than large letters indicates a reduced effective field of vision; and room tilt illusion effects are caused by disordered integration of visual and vestibular information. This study contributes to the growing characterisation of PCA whose atypical early visual symptoms are often heterogeneous and frequently under-recognised. |
Jie Cui; Jorge Otero-Millan; Stephen L. Macknik; Mac King; Susana Martinez-Conde Social misdirection fails to enhance a magic illusion Journal Article In: Frontiers in Human Neuroscience, vol. 5, pp. 103, 2011. @article{Cui2011,Visual, multisensory and cognitive illusions in magic performances provide new windows into the psychological and neural principles of perception, attention, and cognition. We investigated a magic effect consisting of a coin “vanish” (i.e., the perceptual disappear- ance of a coin after a simulated toss from hand to hand). Previous research has shown that magicians can use joint attention cues such as their own gaze direction to strengthen the observers' perception of magic. Herewe presented naïve observers with videos including real and simulated coin tosses to determine if joint attention might enhance the illusory perception of simulated coin tosses. The observers' eye positions were measured, and their perceptual responses simultaneously recorded via button press. To control for the magician's use of joint attention cues, we occluded his head in half of the trials.We found that subjects did not direct their gaze at the magician's face at the time of the coin toss, whether the face was visible or occluded, and that the presence of the magician's face did not enhance the illusion. Thus, our results show that joint attention is not necessary for the perception of this effect.We conclude that social misdirection is redundant and possibly detracting to this very robust sleight-of-hand illusion.We further determined that subjects required multiple trials to effectively distinguish real from simulated tosses; thus the illusion was resilient to repeated viewing. |
Chelsie L. Cushman; Rebecca L. Johnson Age-of-acquisition effects in pure alexia Journal Article In: Quarterly Journal of Experimental Psychology, vol. 64, no. 9, pp. 1726–1742, 2011. @article{Cushman2011,Pure alexia is an acquired reading disorder in which previously literate adults adopt a letter-by-letter processing strategy. Though these individuals display impaired reading, research shows that they are still able to use certain lexical information in order to facilitate visual word processing. The current experiment investigates the role that a word's age of acquisition (AoA) plays in the reading processes of an individual with pure alexia (G.J.) when other lexical variables have been controlled. Results from a sentence reading task in which eye movement patterns were recorded indicated that G.J. shows a strong effect of AoA, where late-acquired words are more difficult to process than early-acquired words. Furthermore, it was observed that the AoA effect is much greater for G.J. than for age-matched control participants. This indicates that patients with pure alexia rely heavily on intact top-down information, supporting the interactive activation model of reading. |
Kirsten A. Dalrymple; Elina Birmingham; Walter F. Bischof; Jason J. S. Barton; Alan Kingstone Experiencing simultanagnosia through windowed viewing of complex social scenes Journal Article In: Brain Research, vol. 1367, pp. 265–277, 2011. @article{Dalrymple2011a,Simultanagnosia is a disorder of visual attention, defined as an inability to see more than one object at once. It has been conceived as being due to a constriction of the visual "window" of attention, a metaphor that we examine in the present article. A simultanagnosic patient (SL) and two non-simultanagnosic control patients (KC and ES) described social scenes while their eye movements were monitored. These data were compared to a group of healthy subjects who described the same scenes under the same conditions as the patients, or through an aperture that restricted their vision to a small portion of the scene. Experiment 1 demonstrated that SL showed unusually low proportions of fixations to the eyes in social scenes, which contrasted with all other participants who demonstrated the standard preferential bias toward eyes. Experiments 2 and 3 revealed that when healthy participants viewed scenes through a window that was contingent on where they looked (Experiment 2) or where they moved a computer mouse (Experiment 3), their behavior closely mirrored that of patient SL. These findings suggest that a constricted window of visual processing has important consequences for how simultanagnosic patients explore their world. Our paradigm's capacity to mimic simultanagnosic behaviors while viewing complex scenes implies that it may be a valid way of modeling simultanagnosia in healthy individuals, providing a useful tool for future research. More broadly, our results support the thesis that people fixate the eyes in social scenes because they are informative to the meaning of the scene. |
Kirsten A. Dalrymple; Elina Birmingham; Walter F. Bischof; Jason J. S. Barton; Alan Kingstone Opening a window on attention: Documenting and simulating recovery from simultanagnosia Journal Article In: Cortex, vol. 47, no. 7, pp. 787–799, 2011. @article{Dalrymple2011,Simultanagnosia is a disorder of visual attention: the inability to see more than one object at one time. Some hypothesize that this is due to a constriction of the visual " window" of attention. Little is known about how simultanagnosics explore complex stimuli and how their behaviour changes with recovery. We monitored the eye movements of simultanagnosic patient SL to see how she scans social scenes shortly after onset of simultanagnosia (Time 1) and after some recovery (Time 2). At Time 1 SL had an abnormally low proportion of fixations to the eyes of the people in the scenes. She made a significantly larger proportion of fixations to the eyes at Time 2. We hypothesized that this change was related to an expansion of her restricted window of attention. Previously we simulated SL's behaviour in healthy subjects by having them view stimuli through a restricted viewing window. We used this simulation paradigm here to test our expanding window hypothesis. Subjects viewing social scenes through a larger window allocated more fixations to the eyes of people in the scenes than subjects viewing scenes through a smaller window, supporting our hypothesis. Recovery in simultanagnosia may be related to the expansion of the restricted attentional window that characterizes the disorder. |
Sangita Dandekar; Claudio M. Privitera; Thom Carney; Stanley A. Klein Neural saccadic response estimation during natural viewing Sangita Journal Article In: Journal of Neurophysiology, vol. 107, no. 4, pp. 1776–1790, 2011. @article{Dandekar2011,Studying neural activity during natural viewing conditions is not often attempted. Isolating the neural response of a single saccade is necessary to study neural activity during natural viewing; however, the close temporal spacing of saccades that occurs during natural viewing makes it difficult to determine the response to a single saccade. Herein, a general linear model (GLM) approach is applied to estimate the EEG neural saccadic response for different segments of the saccadic main sequence separately. It is determined that, in visual search conditions, neural responses estimated by conventional event-related averaging are significantly and systematically distorted relative to GLM estimates due to the close temporal spacing of saccades during visual search. Before the GLM is applied, analyses are applied that demonstrate that saccades during visual search with intersaccadic spacings as low as 100-150 ms do not exhibit significant refractory effects. Therefore, saccades displaying different intersaccadic spacings during visual search can be modeled using the same regressor in a GLM. With the use of the GLM approach, neural responses were separately estimated for five different ranges of saccade amplitudes during visual search. Occipital responses time locked to the onsets of saccades during visual search were found to account for, on average, 79 percent of the variance of EEG activity in a window 90-200 ms after the onsets of saccades for all five saccade amplitude ranges that spanned a range of 0.2-6.0 degrees. A GLM approach was also used to examine the lateralized ocular artifacts associated with saccades. Possible extensions of the methods presented here to account for the superposition of microsaccades in event-related EEG studies conducted in nominal fixation conditions are discussed. |
J. Rhys Davies; Tom C. A. Freeman Simultaneous adaptation to non-collinear retinal motion and smooth pursuit eye movement Journal Article In: Vision Research, vol. 51, no. 14, pp. 1637–1647, 2011. @article{Davies2011,Simultaneously adapting to retinal motion and non-collinear pursuit eye movement produces a motion aftereffect (MAE) that moves in a different direction to either of the individual adapting motions. Mack, Hill and Kahn (1989, Perception, 18, 649-655) suggested that the MAE was determined by the perceived motion experienced during adaptation. We tested the perceived-motion hypothesis by having observers report perceived direction during simultaneous adaptation. For both central and peripheral retinal motion adaptation, perceived direction did not predict the direction of subsequent MAE. To explain the findings we propose that the MAE is based on the vector sum of two components, one corresponding to a retinal MAE opposite to the adapting retinal motion and the other corresponding to an extra-retina MAE opposite to the eye movement. A vector model of this component hypothesis showed that the MAE directions reported in our experiments were the result of an extra-retinal component that was substantially larger in magnitude than the retinal component when the adapting retinal motion was positioned centrally. However, when retinal adaptation was peripheral, the model suggested the magnitude of the components should be about the same. These predictions were tested in a final experiment that used a magnitude estimation technique. Contrary to the predictions, the results showed no interaction between type of adaptation (retinal or pursuit) and the location of adapting retinal motion. Possible reasons for the failure of component hypothesis to fully explain the data are discussed. |
R. Contreras; Jamshid Ghajar; S. Bahar; M. Suh Effect of cognitive load on eye-target synchronization during smooth pursuit eye movement Journal Article In: Brain Research, vol. 1398, pp. 55–63, 2011. @article{Contreras2011,In mild traumatic brain injury (mTBI), the fiber tracts that connect the frontal cortex with the cerebellum may suffer shear damage, leading to attention deficits and performance variability. This damage also disrupts the enhancement of eye-target synchronization that can be affected by cognitive load when subjects are tested using a concurrent eye-tracking test and word-recall test. We investigated the effect of cognitive load on eye-target synchronization in normal and mTBI patients using the nonlinear dynamical technique of stochastic phase synchronization. Results demonstrate that eye-target synchronization was negatively affected by cognitive load in mTBI subjects. In contrast, eye-target synchronization improved under intermediate cognitive load in young (≤ 40 years old) normal subjects. |
Jennifer E. Corbett; Marisa Carrasco Visual performance fields: Frames of reference Journal Article In: PLoS ONE, vol. 6, no. 9, pp. e24470, 2011. @article{Corbett2011,Performance in most visual discrimination tasks is better along the horizontal than the vertical meridian (Horizontal-Vertical Anisotropy, HVA), and along the lower than the upper vertical meridian (Vertical Meridian Asymmetry, VMA), with intermediate performance at intercardinal locations. As these inhomogeneities are prevalent throughout visual tasks, it is important to understand the perceptual consequences of dissociating spatial reference frames. In all studies of performance fields so far, allocentric environmental references and egocentric observer reference frames were aligned. Here we quantified the effects of manipulating head-centric and retinotopic coordinates on the shape of visual performance fields. When observers viewed briefly presented radial arrays of Gabors and discriminated the tilt of a target relative to homogeneously oriented distractors, performance fields shifted with head tilt (Experiment 1), and fixation (Experiment 2). These results show that performance fields shift in-line with egocentric referents, corresponding to the retinal location of the stimulus. |
Julien Cotti; Gustavo Rohenkohl; Mark Stokes; Anna C. Nobre; Jennifer T. Coull Functionally dissociating temporal and motor components of response preparation in left intraparietal sulcus Journal Article In: NeuroImage, vol. 54, no. 2, pp. 1221–1230, 2011. @article{Cotti2011,To optimise speed and accuracy of motor behaviour, we can prepare not only the type of movement to be made but also the time at which it will be executed. Previous cued reaction-time paradigms have shown that anticipating the moment in time at which this response will be made ("temporal orienting") or selectively preparing the motor effector with which an imminent response will be made (motor intention or "motor orienting") recruits similar regions of left intraparietal sulcus (IPS), raising the possibility that these two preparatory processes are inextricably co-activated. We used a factorial design to independently cue motor and temporal components of response preparation within the same experimental paradigm. By differentially cueing either ocular or manual response systems, rather than spatially lateralised responses within just one of these systems, potential spatial confounds were removed. We demonstrated that temporal and motor orienting were behaviourally dissociable, each capable of improving performance alone. Crucially, fMRI data revealed that temporal orienting activated the left IPS even if the motor effector that would be used to execute the response was unpredictable. Moreover, temporal orienting activated left IPS whether the target required a saccadic or manual response, and whether this response was left- or right-sided, thus confirming the ubiquity of left IPS activation for temporal orienting. Finally, a small region of left IPS was also activated by motor orienting for manual, though not saccadic, responses. Despite their functional independence therefore, temporal orienting and manual motor orienting nevertheless engage partially overlapping regions of left IPS, possibly reflecting their shared ontogenetic roots. |
Julien Cotti; Jean-Louis Vercher; Alain Guillaume Hand-eye coordination relies on extra-retinal signals: Evidence from reactive saccade adaptation Journal Article In: Behavioural Brain Research, vol. 218, no. 1, pp. 248–252, 2011. @article{Cotti2011a,Execution of a saccadic eye movement towards the goal of a hand pointing movement improves the accuracy of this hand movement. Still controversial is the role of extra-retinal signals, i.e. efference copy of the saccadic command and/or ocular proprioception, in the definition of the hand pointing target. We report here that hand pointing movements produced without visual feedback, with accompanying saccades and towards a target extinguished at saccade onset, were modified after gain change of reactive saccades through saccadic adaptation. As we have previously shown that the adaptation of reactive saccades does not influence the target representations that are common to the eye and the hand motor sub-systems (Cotti J, Guillaume A, Alahyane N, Pelisson D, Vercher JL. Adaptation of voluntary saccades, but not of reactive saccades. Transfers to hand pointing movements. J Neurophysiol 2007;98:602-12), the results of the present study demonstrate that extra-retinal signals participate in defining the target of hand pointing movements. |
Reinier Cozijn; Edwin Commandeur; Wietske Vonk; Leo G. M. Noordman The time course of the use of implicit causality information in the processing of pronouns: A visual world paradigm study Journal Article In: Journal of Memory and Language, vol. 64, no. 4, pp. 381–403, 2011. @article{Cozijn2011,Several theoretical accounts have been proposed with respect to the issue how quickly the implicit causality verb bias affects the understanding of sentences such as "John beat Pete at the tennis match, because he had played very well" They can be considered as instances of two viewpoints: the focusing and the integration account. The focusing account claims that the bias should be manifest soon after the verb has been processed, whereas the integration account claims that the interpretation is deferred until disambiguating information is encountered. Up to now, this issue has remained unresolved because materials or methods have failed to address it conclusively. We conducted two experiments that exploited the visual world paradigm and ambiguous pronouns in subordinate because clauses. The first experiment presented implicit causality sentences with the task to resolve the ambiguous pronoun. To exclude strategic processing, in the second experiment, the task was to answer simple comprehension questions and only a minority of the sentences contained implicit causality verbs. In both experiments, the implicit causality of the verb had an effect before the disambiguating information was available. This result supported the focusing account. |
2010 |
Thérèse Collins; Tobias Heed; Karine Doré-Mazars; Brigitte Röder Presaccadic attention interferes with feature detection Journal Article In: Experimental Brain Research, vol. 201, no. 1, pp. 111–117, 2010. @article{Collins2010b,Preparing a saccadic eye movement to a particular spatial location enhances the perception of visual targets at this location and decreases perception of nearby targets prior to movement onset. This effect has been termed the orientation of pre-saccadic attention. Here, we investigated whether pre-saccadic attention influenced the detection of a simple visual feature-a process that has been hypothesized to occur without the need for attention. Participants prepared a saccade to a cued location and detected the occurrence of a "pop-out" feature embedded in distracters at the same or different location. The results show that preparing a saccade to a given location decreased detection of features at non-aimed-for locations, suggesting that the selection of a location as the next saccade endpoint influences sensitivity to basic visual features across the visual field. |
Thérèse Collins; Tobias Heed; Brigitte Röder Eye-movement driven changes in the perception of auditory space Journal Article In: Attention, Perception, & Psychophysics, vol. 72, no. 3, pp. 736–746, 2010. @article{Collins2010c,The perceptual localization of sensory stimuli often depends on body position, and, when action is required, sensory coordinates must be transformed into a motor reference frame. We investigated the role of such a refer- ence frame change on visual and auditory spatial cognition. Participants had to make a saccade to a visual or auditory target and subsequently compare the location of a visual or auditory probe to the remembered location of the target. Neither visual nor auditory localization depended on trial-by-trial variability in saccade endpoint, suggesting that target locations are remapped across saccades in a manner allowing for oculomotor noise. We also compared visual and auditory localization performance before and after the systematic modification of saccade metrics by saccadic adaptation. Adaptation introduced systematic biases into transsaccadic visual and auditory localization behavior. These results show that information about eye movements is taken into account in both visual and auditory spatial cognition. We propose that auditory stimuli are remapped across saccades and that this eye-centered representation contributes to normal auditory localization. |
Sébastien Coppe; Jean-Jacques Orban de Xivry; Marcus Missal; Philippe Lefèvre Biological motion influences the visuomotor transformation for smooth pursuit eye movements Journal Article In: Vision Research, vol. 50, no. 24, pp. 2721–2728, 2010. @article{Coppe2010,Humans are very sensitive to the presence of other living persons or animals in their surrounding. Human actions can readily be perceived, even in a noisy environment. We recently demonstrated that biological motion, which schematically represents human motion, influences smooth pursuit eye movements during the initiation period (Orban de Xivry, Coppe, Lef??vre, & Missal, 2010). This smooth pursuit response is driven both by a visuomotor pathway, which transforms retinal inputs into motor commands, and by a memory pathway, which is directly related to the predictive properties of smooth pursuit. To date, it is unknown which of these pathways is influenced by biological motion. In the present study, we first use a theoretical model to demonstrate that an influence of biological motion on the visuomotor and memory pathways might both explain its influence on smooth pursuit initiation. In light of this model, we made theoretical predictions of the possible influence of biological motion on smooth pursuit during and after the transient blanking of the stimulus. These qualitative predictions were then compared with recordings of eye movements acquired before, during and after the transient blanking of the stimulus. The absence of difference in smooth pursuit eye movements during blanking of the stimuli and the stronger visually guided smooth pursuit reacceleration after reappearance of the biological motion stimuli in comparison with control stimuli suggests that biological motion influences the visuomotor pathway but not the memory pathway. |
Martin Corley Making predictions from speech with repairs: Evidence from eye movements Journal Article In: Language and Cognitive Processes, vol. 25, no. 5, pp. 706–727, 2010. @article{Corley2010,When listeners hear a spoken utterance, they are able to predict upcoming information on the basis of what they have already heard. But what happens when the speaker changes his or her mind mid-utterance? The present paper investigates the immediate effects of repairs on listeners' linguistic predictions. Participants listened to sentences like the boy will eat/move the cake while viewing scenes depicting the agent, the theme, and distractor objects (which were not edible). Over 25% of items included conjoined verbs (eat and move) and 25% included repairs (eat- uh, move). Participants were sensitive to repairs: where eat was overridden by move, fixations on the theme patterned with the plain move condition, but where there was a conjunct, fixations patterned with eat. However, once the theme had been heard, there were more fixations to the cake in all conditions including eat, showing that the first verb maintained an influence on prediction, even following a repair. The results are compatible with the view that prediction during comprehension is updated incrementally, but not completely, as the linguistic input unfolds. |
Kenny R. Coventry; Dermot Lynott; Angelo Cangelosi; Lynn Monrouxe; Dan Joyce; Daniel C. Richardson Spatial language, visual attention, and perceptual simulation Journal Article In: Brain and Language, vol. 112, no. 3, pp. 202–213, 2010. @article{Coventry2010,Spatial language descriptions, such as The bottle is over the glass, direct the attention of the hearer to particular aspects of the visual world. This paper asks how they do so, and what brain mechanisms underlie this process. In two experiments employing behavioural and eye tracking methodologies we examined the effects of spatial language on people's judgements and parsing of a visual scene. The results underscore previous claims regarding the importance of object function in spatial language, but also show how spatial language differentially directs attention during examination of a visual scene. We discuss implications for existing models of spatial language, with associated brain mechanisms. |
Christopher D. Cowper-Smith; Esther Y. Y. Lau; Carl A. Helmick; Gail A. Eskes; David A. Westwood Neural coding of movement direction in the healthy human brain Journal Article In: PLoS ONE, vol. 5, no. 10, pp. e13330, 2010. @article{CowperSmith2010,Neurophysiological studies in monkeys show that activity of neurons in primary cortex (M1), pre-motor cortex (PMC), and cerebellum varies systematically with the direction of reaching movements. These neurons exhibit preferred direction tuning, where the level of neural activity is highest when movements are made in the preferred direction (PD), and gets progressively lower as movements are made at increasing degrees of offset from the PD. Using a functional magnetic resonance imaging adaptation (fMRI-A) paradigm, we show that PD coding does exist in regions of the human motor system that are homologous to those observed in non-human primates. Consistent with predictions of the PD model, we show adaptation (i.e., a lower level) of the blood oxygen level dependent (BOLD) time-course signal in M1, PMC, SMA, and cerebellum when consecutive wrist movements were made in the same direction (0 degrees offset) relative to movements offset by 90 degrees or 180 degrees . The BOLD signal in dorsolateral prefrontal cortex adapted equally in all movement offset conditions, mitigating against the possibility that the present results are the consequence of differential task complexity or attention to action in each movement offset condition. |
David P. Crabb; Nicholas D. Smith; Franziska G. Rauscher; Catharine M. Chisholm; John L. Barbur; David F. Edgar; David F. Garway-Heath Exploring eye movements in patients with glaucoma when viewing a driving scene Journal Article In: PLoS ONE, vol. 5, no. 3, pp. e9710, 2010. @article{Crabb2010,BACKGROUND: Glaucoma is a progressive eye disease and a leading cause of visual disability. Automated assessment of the visual field determines the different stages in the disease process: it would be desirable to link these measurements taken in the clinic with patient's actual function, or establish if patients compensate for their restricted field of view when performing everyday tasks. Hence, this study investigated eye movements in glaucomatous patients when viewing driving scenes in a hazard perception test (HPT). METHODOLOGY/PRINCIPAL FINDINGS: The HPT is a component of the UK driving licence test consisting of a series of short film clips of various traffic scenes viewed from the driver's perspective each containing hazardous situations that require the camera car to change direction or slow down. Data from nine glaucomatous patients with binocular visual field defects and ten age-matched control subjects were considered (all experienced drivers). Each subject viewed 26 different films with eye movements simultaneously monitored by an eye tracker. Computer software was purpose written to pre-process the data, co-register it to the film clips and to quantify eye movements and point-of-regard (using a dynamic bivariate contour ellipse analysis). On average, and across all HPT films, patients exhibited different eye movement characteristics to controls making, for example, significantly more saccades (P<0.001; 95% confidence interval for mean increase: 9.2 to 22.4%). Whilst the average region of 'point-of-regard' of the patients did not differ significantly from the controls, there were revealing cases where patients failed to see a hazard in relation to their binocular visual field defect. CONCLUSIONS/SIGNIFICANCE: Characteristics of eye movement patterns in patients with bilateral glaucoma can differ significantly from age-matched controls when viewing a traffic scene. Further studies of eye movements made by glaucomatous patients could provide useful information about the definition of the visual field component required for fitness to drive. |
M. Dyer Diehl; Peter E. Pidcoe The influence of gaze stabilization and fixation on stepping reactions in younger and older adults Journal Article In: Journal of Geriatric Physical Therapy, vol. 33, no. 1, pp. 19–25, 2010. @article{Diehl2010,PURPOSE: To date, there has been little evidence to suggest the importance of foveal viewing versus peripheral retina viewing when trying to recover from a perturbation. The purposes of this investigation were to (1) determine whether a visual target can be stabilized on the fovea during a perturbation, (2) determine whether stepping responses following a perturbation are influenced by foveal fixation, and (3) compare gaze stability and stepping responses between young and aging adults. MATERIALS/METHODS: Ten young adults and 10 aging adults were asked to wear an eye-tracking device linked to a kinematic tracking system during perturbations. Perturbations were delivered under 2 conditions: control (no instructions regarding gaze location were given) and earth-fixed (EF) (subjects were asked to fixate gaze on an EF target). Stepping responses were recorded via force plates. Gaze stability, reported as percent foveal fixation (% FF), was calculated from eye-tracking data. Step latencies (SLs) were computed from force plate data. A 2 x 2 analysis of variance was used to assess statistical significance between groups. For the young and aging adults, linear correlations were made to identify relationships between % FF and SL. RESULTS: For each condition, aging adults took longer to initiate a step (control |
Steve Dipaola; Caitlin Riebe; James T. Enns Rembrandt's textural agency: A shared perspective in visual art and science Journal Article In: Leonardo, vol. 43, no. 2, pp. 145–151, 2010. @article{Dipaola2010,This interdisciplinary paper hypothesizes that Rembrandt developed new painterly techniques — novel to the early modern period — in order to engage and direct the gaze of the observer. Though these methods were not based on scientific evidence at the time, we show that they nonetheless are consistent with a contemporary understanding of human vision. Here we propose that artists in the late ‘early modern' period developed the technique of textural agency — involving selective variation in image detail — to guide the observer's eye and thereby influence the viewing experience. The paper begins by establishing the well-known use of textural agency among modern portrait artists, before considering the possibility that Rembrandt developed these techniques in his late portraits in reaction to his Italian contemporaries. A final section brings the argument full circle, with the presentation of laboratory evidence that Rembrandt's techniques indeed guide the modern viewer's eye in the way we propose. |
Barnaby J. Dixson; Gina M. Grimshaw; Wayne L. Linklater; Alan F. Dixson Watching the hourglass: Eye tracking reveals men's appreciation of the female form Journal Article In: Human Nature, vol. 21, no. 4, pp. 355–370, 2010. @article{Dixson2010,Eye-tracking techniques were used to measure men's attention to back-posed and front-posed images of women varying in waist-to-hip ratio (WHR). Irrespective of body pose, men rated images with a 0.7 WHR as most attractive. For back-posed images, initial visual fixations (occurring within 200 milliseconds of commencement of the eye-tracking session) most frequently involved the midriff. Numbers of fixations and dwell times throughout each of the five-second viewing sessions were greatest for the midriff and buttocks. By contrast, visual attention to front-posed images (first fixations, numbers of fixations, and dwell times) mainly involved the breasts, with attention shifting more to the midriff of images with a higher WHR. This report is the first to compare men's eye-tracking responses to back-posed and front-posed images of the female body. Results show the importance of the female midriff and of WHR upon men's attractiveness judgments, especially when viewing back-posed images. |
Mieke Donk; Leroy Soesman Salience is only briefly represented: Evidence from probe-detection performance Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 36, no. 2, pp. 286–302, 2010. @article{Donk2010,Salient objects in the visual field tend to capture attention. The present study aimed to examine the time-course of salience effects using a probe-detection task. Eight experiments investigated how the salience of different orientation singletons affected probe reaction time as a function of stimulus onset asynchrony (SOA) between the presentation of a singleton display and a probe display. The results demonstrate that salience consistently affected probe reaction time at the shortest SOA. The effect of salience disappeared as SOA increased. These results suggest that contrary to the assumption of major theories on visual selection, salience is transiently represented in our visual system allowing the effects of salience on attentional selection to be only short-lived. |
Michael Dorr; T. Martinetz; Karl R. Gegenfurtner; E. Barth Variability of eye movements when viewing dynamic natural scenes Journal Article In: Journal of Vision, vol. 10, no. 10, pp. 1–17, 2010. @article{Dorr2010,How similar are the eye movement patterns of different subjects when free viewing dynamic natural scenes? We collected a large database of eye movements from 54 subjects on 18 high-resolution videos of outdoor scenes and measured their variability using the Normalized Scanpath Saliency, which we extended to the temporal domain. Even though up to about 80% of subjects looked at the same image region in some video parts, variability usually was much greater. Eye movements on natural movies were then compared with eye movements in several control conditions. "Stop-motion" movies had almost identical semantic content as the original videos but lacked continuous motion. Hollywood action movie trailers were used to probe the upper limit of eye movement coherence that can be achieved by deliberate camera work, scene cuts, etc. In a "repetitive" condition, subjects viewed the same movies ten times each over the course of 2 days. Results show several systematic differences between conditions both for general eye movement parameters such as saccade amplitude and fixation duration and for eye movement variability. Most importantly, eye movements on static images are initially driven by stimulus onset effects and later, more so than on continuous videos, by subject-specific idiosyncrasies; eye movements on Hollywood movies are significantly more coherent than those on natural movies. We conclude that the stimuli types often used in laboratory experiments, static images and professionally cut material, are not very representative of natural viewing behavior. All stimuli and gaze data are publicly available at http://www.inb.uni-luebeck.de/tools-demos/gaze. |
Kurt Debono; Alexander C. Schütz; Miriam Spering; Karl R. Gegenfurtner Receptive fields for smooth pursuit eye movements and motion perception Journal Article In: Vision Research, vol. 50, no. 24, pp. 2729–2739, 2010. @article{Debono2010,Humans use smooth pursuit eye movements to track moving objects of interest. In order to track an object accurately, motion signals from the target have to be integrated and segmented from motion signals in the visual context. Most studies on pursuit eye movements used small visual targets against a featureless background, disregarding the requirements of our natural visual environment. Here, we tested the ability of the pursuit and the perceptual system to integrate motion signals across larger areas of the visual field. Stimuli were random-dot kinematograms containing a horizontal motion signal, which was perturbed by a spatially localized, peripheral motion signal. Perturbations appeared in a gaze-contingent coordinate system and had a different direction than the main motion including a vertical component. We measured pursuit and perceptual direction discrimination decisions and found that both steady-state pursuit and perception were influenced most by perturbation angles close to that of the main motion signal and only in regions close to the center of gaze. The narrow direction bandwidth (26 angular degrees full width at half height) and small spatial extent (8 degrees of visual angle standard deviation) correspond closely to tuning parameters of neurons in the middle temporal area (MT). |
Adriana M. Degani; Alessander Danna-Dos-Santos; Thomas Robert; Mark L. Latash Kinematic synergies during saccades involving whole-body rotation: A study based on the uncontrolled manifold hypothesis Journal Article In: Human Movement Science, vol. 29, no. 2, pp. 243–258, 2010. @article{Degani2010,We used the framework of the uncontrolled manifold hypothesis to study the coordination of body segments and eye movements in standing persons during the task of shifting the gaze to a target positioned behind the body. The task was performed at a comfortable speed and fast. Multi-segment and head-eye synergies were quantified as co-varied changes in elemental variables (body segment rotations and eye rotation) that stabilized (reduced the across trials variability) of head rotation in space and gaze trajectory. Head position in space was stabilized by co-varied rotations of body segments prior to the action, during its later stages, and after its completion. The synergy index showed a drop that started prior to the action initiation (anticipatory synergy adjustment) and continued during the phase of quick head rotation. Gaze direction was stabilized only at movement completion and immediately after the saccade at movement initiation under the " fast" instruction. The study documents for the first time anticipatory synergy adjustments during whole-body actions. It shows multi-joint synergies stabilizing head trajectory in space. In contrast, there was no synergy between head and eye rotations during saccades that would achieve a relatively invariant gaze trajectory. |
Francesca Delogu; Francesco Vespignani; Anthony J. Sanford Effects of intensionality on sentence and discourse processing: Evidence from eye-movements Journal Article In: Journal of Memory and Language, vol. 62, no. 4, pp. 352–379, 2010. @article{Delogu2010,Intensional verbs like want select for clausal complements expressing propositions, though they can be perfectly natural when combined with a direct object. There are two interesting phenomena associated with intensional transitive expressions. First, it has been suggested that their interpretation requires enriched compositional operations, similarly to expressions like began the book (e.g., Pustejovsky, 1995). Secondly, when the object position is filled by an indefinite NP, it preferentially receives an unspecific reading, under which definite anaphora is not supported (e.g., Moltmann, 1997). We report three eye-tracking experiments investigating the time-course of processing of sentence pairs like John wanted a beer. The beer was warm. Consistent with the enriched composition hypothesis, results showed that intensional transitive constructions (e.g., wanted a beer) take longer to process than control expressions (e.g., drank/wanted to drink a beer). However, contrary to previous findings, the processing of the continuation sentence appears to be not affected by whether the definite NP (the beer) can be interpreted as coreferential with the indefinite or not. We interpret the results with respect to accounts of semantic processing relying on the notions of enriched composition and non-actuality implicature. |
T. M. Desrochers; D. Z. Jin; N. D. Goodman; Ann M. Graybiel Optimal habits can develop spontaneously through sensitivity to local cost Journal Article In: Proceedings of the National Academy of Sciences, vol. 107, no. 47, pp. 20512–20517, 2010. @article{Desrochers2010,Habits and rituals are expressed universally across animal species. These behaviors are advantageous in allowing sequential behaviors to be performed without cognitive overload, and appear to rely on neural circuits that are relatively benign but vulnerable to takeover by extreme contexts, neuropsychiatric sequelae, and processes leading to addiction. Reinforcement learning (RL) is thought to underlie the formation of optimal habits. However, this theoretic formulation has principally been tested experimentally in simple stimulus-response tasks with relatively few available responses. We asked whether RL could also account for the emergence of habitual action sequences in realistically complex situations in which no repetitive stimulus-response links were present and in which many response options were present. We exposed naïve macaque monkeys to such experimental conditions by introducing a unique free saccade scan task. Despite the highly uncertain conditions and no instruction, the monkeys developed a succession of stereotypical, self-chosen saccade sequence patterns. Remarkably, these continued to morph for months, long after session-averaged reward and cost (eye movement distance) reached asymptote. Prima facie, these continued behavioral changes appeared to challenge RL. However, trial-by-trial analysis showed that pattern changes on adjacent trials were predicted by lowered cost, and RL simulations that reduced the cost reproduced the monkeys' behavior. Ultimately, the patterns settled into stereotypical saccade sequences that minimized the cost of obtaining the reward on average. These findings suggest that brain mechanisms underlying the emergence of habits, and perhaps unwanted repetitive behaviors in clinical disorders, could follow RL algorithms capturing extremely local explore/exploit tradeoffs. |
Leandro Luigi Di Stasi; Mauro Marchitto; Adoracíon Antolí; Thierry Baccino; José J. Cañas Approximation of on-line mental workload index in ATC simulated multitasks Journal Article In: Journal of Air Transport Management, vol. 16, no. 6, pp. 330–333, 2010. @article{DiStasi2010,To assess the effects of workload pressures, participants interacted with a modified version of air traffic control simulated tasks requiring different levels of cognitive resources. Changes in mental workload between the levels were evaluated multidimensionally using a subjective rating, performance in a secondary task, and other behavioural indices. Saccadic movements were measured using a video-based eye tracking system. The Wickens multiple resource model is used as a theoretical reference framework. Saccadic peak velocity decreases with increasing cognitive load, in agreement with subjective test scores and performance data. That saccadic peak velocity is sensitive to variations in mental workload during ecologically valid tasks is demonstrated. |
Leandro Luigi Di Stasi; Rebekka Renner; Peggy Staehr; Jens R. Helmert; Boris M. Velichkovsky; Jose J. Canas; Andrés Catena; Sebastian Pannasch Saccadic Peak Velocity Sensitivity to Variations in Mental Workload Journal Article In: Aviation Space and Environmental Medicine, vol. 81, no. 4, pp. 413–417, 2010. @article{DiStasi2010a,Introduction: For research and applications in the field of (neuro)ergonomics, it is of increasing importance to have reliable methods for measuring mental workload. In the present study we examined the hypothesis that saccadic eye movements can be used for an online assessment of mental workload. Methods: Saccadic main sequence (amplitude, dura- tion and peak velocity) was used as a diagnostic measure of mental workload in a virtual driving task with three complexity levels. We tested 18 drivers in the SIRCA driving simulator while their eye movements were recorded. The Wickens' multiple resources model was used as theoretical framework. Changes in mental workload between the complexity levels were evaluated multidimensionally, using subjective rating, performance in a secondary task, and other behavioral indices. Results: Saccadic peak velocity decreased (7.2 visual °/s) as the mental workload increased, as measured by scores of mental workload test (15.2 scores) and the increase of the reaction time on the secondary task (46 ms). Discussion: Saccadic peak velocity is affected by variations in mental workload during ecologically valid tasks. We conclude that saccadic peak velocity could be a useful diagnostic index for the assessment of operators' mental workload and attentional state in hazardous environments. |
Denis Drieghe; Alexander Pollatsek; Barbara J. Juhasz; Keith Rayner Parafoveal processing during reading is reduced across a morphological boundary Journal Article In: Cognition, vol. 116, no. 1, pp. 136–142, 2010. @article{Drieghe2010,A boundary change manipulation was implemented within a monomorphemic word (e.g., fountaom as a preview for fountain), where parallel processing should occur given adequate visual acuity, and within an unspaced compound (bathroan as a preview for bathroom), where some serial processing of the constituents is likely. Consistent with that hypothesis, there was no effect of the preview manipulation on fixation time on the 1st constituent of the compound, whereas there was on the corresponding letters of the monomorphemic word. There was also a larger preview disruption on gaze duration on the whole monomorphemic word than on the compound, suggesting more parallel processing within monomorphemic words. |
Jacob Duijnhouwer; Bart Krekelberg; Albert V. Berg; Richard J. A. Wezel Temporal integration of focus position signal during compensation for pursuit in optic flow. Journal Article In: Journal of Vision, vol. 10, no. 14, pp. 1–15, 2010. @article{Duijnhouwer2010,Observer translation results in optic flow that specifies heading. Concurrent smooth pursuit causes distortion of the retinal flow pattern for which the visual system compensates. The distortion and its perceptual compensation are usually modeled in terms of instantaneous velocities. However, apart from adding a velocity to the flow field, pursuit also incrementally changes the direction of gaze. The effect of gaze displacement on optic flow perception has received little attention. Here we separated the effects of velocity and gaze displacement by measuring the perceived two-dimensional focus position of rotating flow patterns during pursuit. Such stimuli are useful in the current context because the two effects work in orthogonal directions. As expected, the instantaneous pursuit velocity shifted the perceived focus orthogonally to the pursuit direction. Additionally, the focus was mislocalized in the direction of the pursuit. Experiments that manipulated the presentation duration, flow speed, and uncertainty of the focus location supported the idea that the latter component of mislocalization resulted from temporal integration of the retinal trajectory of the focus. Finally, a comparison of the shift magnitudes obtained in conditions with and without pursuit (but with similar retinal stimulation) suggested that the compensation for both effects uses extraretinal information. |
Kirsten A. Dalrymple; Walter F. Bischof; David Cameron; Jason J. S. Barton; Alan Kingstone Simulating simultanagnosia: Spatially constricted vision mimics local capture and the global processing deficit Journal Article In: Experimental Brain Research, vol. 202, no. 2, pp. 445–455, 2010. @article{Dalrymple2010,Patients with simultanagnosia, which is a component of Bálint syndrome, have a restricted spatial window of visual attention and cannot see more than one object at a time. As a result, these patients see the world in a piecemeal fashion, seeing the local components of objects or scenes at the expense of the global picture. To directly test the relationship between the restriction of the attentional window in simultanagnosia and patients' difficulty with global-level processing, we used a gaze-contingent display to create a literal restriction of vision for healthy participants while they performed a global/local identification task. Participants in this viewing condition were instructed to identify the global and local aspects of hierarchical letter stimuli of different sizes and densities. They performed well at the local identification task, and their patterns of inaccuracies for the global level task were highly similar to the pattern of inaccuracies typically seen with simultanagnosic patients. This suggests that a restricted spatial area of visual processing, combined with normal limits to visual processing, can lead to difficulties with global-level perception. |
Rong-Fuh Day Examining the validity of the Needleman-Wunsch algorithm in identifying decision strategy with eye-movement data Journal Article In: Decision Support Systems, vol. 49, no. 4, pp. 396–403, 2010. @article{Day2010,A new generation of eye trackers shows us a promising alternative approach to tracing decision processes beyond the popular computerized-information-board approach. In order to exploit the eye-movement data, this study examined the validity of the Needleman-Wunsch algorithm (NWA) to characterize the decision process, and proposed an NWA-based classification method to predict which typical strategy an empirical search behavior might belong to. An eye-tracking based experiment was conducted. Our results showed that the resemblance score by NWA conformed to the assumption that the pair of information search behaviors based on the same strategy should have the closest resemblance. Moreover, with respect to our NWA-based classification method, our result showed that its overall prediction accuracy, hit-ratio, in identifying underlying strategies achieved 88%, significantly much higher than that gained from chance. On the whole, the combination of eye-fixation data and our NWA-based classification method is qualified. © 2010 Elsevier B.V. All rights reserved. |
Denise D. J. Grave; Nicola Bruno The effect of the Müller-Lyer illusion on saccades is modulated by spatial predictability and saccadic latency Journal Article In: Experimental Brain Research, vol. 203, no. 4, pp. 671–679, 2010. @article{Grave2010,Studies investigating the effect of visual illusions on saccadic eye movements have provided a wide variety of results. In this study, we test three factors that might explain this variability: the spatial predictability of the stimulus, the duration of the stimulus and the latency of the saccades. Participants made a saccade from one end of a Muller-Lyer figure to the other end. By changing the spatial predictability of the stimulus, we find that the illusion has a clear effect on saccades (16%) when the stimulus is at a highly predictable location. Even stronger effects of the illusion are found when the stimulus location becomes more unpredictable (19-23%). Conversely, manipulating the duration of the stimulus fails to reveal a clear difference in illusion effect. Finally, by computing the illusion effect for different saccadic latencies, we find a maximum illusion effect (about 30%) for very short latencies, which decreases by 7% with every 100 ms latency increase. We conclude that spatial predictability of the stimulus and saccadic latency influences the effect of the Muller-Lyer illusion on saccades. |
C. Hemptinne; G. R. Barnes; Marcus Missal Influence of previous target motion on anticipatory pursuit deceleration Journal Article In: Experimental Brain Research, vol. 207, no. 3-4, pp. 173–184, 2010. @article{Hemptinne2010,During visual pursuit of a moving target, expected changes in its trajectory often evoke anticipatory smooth pursuit responses. In the present study, we investigated characteristics of anticipatory smooth pursuit decelerations before a change or the end of a target trajectory. Healthy humans had to pursue with the eyes a target moving along a circular path that predictably or unpredictably reversed direction and then retraced its movement back to the starting position. We found that anticipatory eye decelerations were often evoked in temporal expectation of target reversal and of the end of the trajectory. The latency of anticipatory decelerations initiated before target reversal was variable, had poor temporal accuracy and depended on the history of previous trials. Anticipations of the end of the trajectory were more accurate, more precise and were not influenced by previous trials. In this case, subjects probably based their estimate of the end of the trajectory on the duration just experienced before target motion reversal. These results suggest that anticipatory eye decelerations are based on the characteristics of the current or preceding trials depending on the most reliable information available. |
Wolfgang Einhäuser; Christof Koch; Olivia Carter Pupil dilation betrays the timing of decisions Journal Article In: Frontiers in Human Neuroscience, vol. 4, pp. 18, 2010. @article{Einhaeuser2010,The notion of "mind-reading" by carefully observing another individual's physiological responses has recently become commonplace in popular culture, particularly in the context of brain imaging. The question remains, however, whether outwardly accessible physiological signals indeed betray a decision before a person voluntarily reports it. In one experiment we asked observers to push a button at any time during a 10-s period ("immediate overt response"). In a series of three additional experiments observers were asked to select one number from five sequentially presented digits but concealed their decision until the trial's end ("covert choice"). In these experiments observers either had to choose the digit themselves under conditions of reward and no reward, or were instructed which digit to select via an external cue provided at the time of the digit presentation. In all cases pupil dilation alone predicted the choice (timing of button response or chosen digit, respectively). Consideration of the average pupil-dilation responses, across all experiments, showed that this prediction of timing was distinct from a general arousal or reward-anticipation response. Furthermore, the pupil dilation appeared to reflect the post-decisional consolidation of the selected outcome rather than the pre-decisional cognitive appraisal component of the decision. Given the tight link between pupil dilation and norepinephrine levels during constant illumination, our results have implications beyond the tantalizing mind-reading speculations. These findings suggest that similar noradrenergic mechanisms may underlie the consolidation of both overt and covert decisions. |
Brianna M. Eiter; Albrecht W. Inhoff Visual word recognition during reading is followed by subvocal articulation Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 36, no. 2, pp. 457–470, 2010. @article{Eiter2010,Three experiments examined whether the identification of a visual word is followed by its subvocal articulation during reading. An irrelevant spoken word (ISW) that was identical, phonologically similar, or dissimilar to a visual target word was presented when the eyes moved to the target in the course of sentence reading. Sentence reading was further accompanied by either a sequential finger tapping task (Experiment 1) or an articulatory suppression task (Experiment 2). Experiment 1 revealed sound-specific interference from a phonologically similar ISW during posttarget viewing. This interference was absent in Experiment 2, where similar and dissimilar ISWs impeded target and posttarget reading equally. Experiment 3 showed that articulatory suppression left the lexical processing of visual words intact and that it did not diminish the influence of visual word recognition on eye guidance. The presence of sound-specific interference during posttarget reading in Experiment 1 is attributed to deleterious effects of a phonologically similar ISW on the subvocal articulation of a target. Its absence in Experiment 2 is attributed to the suppression of a target's subvocal articulation. |
Ava Elahipanah; Bruce K. Christensen; Eyal M. Reingold Visual search performance among persons with schizophrenia as a function of target eccentricity Journal Article In: Neuropsychology, vol. 24, no. 2, pp. 192–198, 2010. @article{Elahipanah2010,The current study investigated one possible mechanism of impaired visual attention among patients with schizophrenia: a reduced visual span. Visual span is the region of the visual field from which one can extract information during a single eye fixation. This study hypothesized that schizophrenia-related visual search impairment is mediated, in part, by a smaller visual span. To test this hypothesis, 23 patients with schizophrenia and 22 healthy controls completed a visual search task where the target was pseudorandomly presented at different distances from the center of the display. Response times were analyzed as a function of search condition (feature vs. conjunctive), display size, and target eccentricity. Consistent with previous reports, patient search times were more adversely affected as the number of search items increased in the conjunctive search condition. It was important however, that patients' conjunctive search times were also impacted to a greater degree by target eccentricity. Moreover, a significant impairment in patients' visual search performance was only evident when targets were more eccentric and their performance was more similar to healthy controls when the target was located closer to the center of the search display. These results support the hypothesis that a narrower visual span may underlie impaired visual search performance among patients with schizophrenia. |
Nick C. Ellis; Nuria Sagarra Learned attention effects in L2 temporal reference: The first hour and the next eight semesters Journal Article In: Language Learning, vol. 60, pp. 85–108, 2010. @article{Ellis2010,This article relates adults' difficulty acquiring foreign languages to the associative learn- ing phenomena of cue salience, cue complexity, and the blocking of later experienced cues by earlier learned ones. It examines short- and long-term learned attention effects in adult acquisition of lexical (adverbs) and morphological cues (verbal inflections) for temporal reference in Latin (1 hr of controlled laboratory learning) and Spanish (three to eight semesters of classroom learning). Our experiments indicate that early adult learning is characterized by a general tendency to focus on lexical cues because of their physical salience in the input and their psychological salience resulting from their simplicity of form-function mapping and from learners' prior first language knowledge. Later, attention to verbal morphology is modulated by cue complexity and language experience: Acquisition is better in cases of cues of lesser complexity, speakers of morphologically rich native languages, and longer periods of study. Finally, instruc- tional practices that emphasize morphological cues by means either of preexposure or typographical enhancement increase attention to inflections thus to block reliance on adverbial cues. This |
Ralf Engbert; André Krügel Readers use bayesian estimation for eye movement control Journal Article In: Psychological Science, vol. 21, no. 3, pp. 366–371, 2010. @article{Engbert2010,During reading, saccadic landing positions within words show a pronounced peak close to the word center, with an additional systematic error that is modulated by the distance from the launch site and the length of the target word. Here we show that the systematic variation of fixation positions within words, the saccadic range error, can be derived from Bayesian decision theory. We present the first mathematical model for the saccadic range error; this model makes explicit assumptions regarding underlying visual and oculomotor processes. Analyzing a corpus of eye movement recordings, we obtained results that are consistent with the view that readers use Bayesian estimation for saccade planning. Furthermore, we show that alternative models fail to reproduce the experimental data. |
Paul E. Engelhardt; Fernanda Ferreira; Elena G. Patsenko Pupillometry reveals processing load during spoken language comprehension Journal Article In: Quarterly Journal of Experimental Psychology, vol. 63, no. 4, pp. 639–645, 2010. @article{Engelhardt2010,This study investigated processing effort by measuring peoples' pupil diameter as they listened to sentences containing a temporary syntactic ambiguity. In the first experiment, we manipulated prosody. The results showed that when prosodic structure conflicted with syntactic structure, pupil diameter reliably increased. In the second experiment, we manipulated both prosody and visual context. The results showed that when visual context was consistent with the correct interpretation, prosody had very little effect on processing effort. However, when visual context was inconsistent with the correct interpretation, prosody had a large effect on processing effort. The interaction between visual context and prosody shows that visual context has an effect on online processing and that it can modulate the influence of linguistic sources of information, such as prosody. Pupillometry is a sensitive measure of processing effort during spoken language comprehension. |
Filipe Cristino; Sebastiaan Mathôt; Jan Theeuwes; Iain D. Gilchrist ScanMatch: A novel method for comparing fixation sequences Journal Article In: Behavior Research Methods, vol. 42, no. 3, pp. 692–700, 2010. @article{Cristino2010,We present a novel approach to comparing saccadic eye movement sequences based on the Needleman– Wunsch algorithm used in bioinformatics to compare DNA sequences. In the proposed method, the saccade sequence is spatially and temporally binned and then recoded to create a sequence of letters that retains fixa- tion location, time, and order information. The comparison of two letter sequences is made by maximizing the similarity score computed from a substitution matrix that provides the score for all letter pair substitutions and a penalty gap. The substitution matrix provides a meaningful link between each location coded by the individual letters. This link could be distance but could also encode any useful dimension, including perceptual or semantic space. We show, by using synthetic and behavioral data, the benefits of this method over existing methods. The ScanMatch toolbox for MATLAB is freely available online (www.scanmatch.co.uk). |
Lester C. Loschky; Bruce C. Hansen; Amit Sethi; Tejaswi N. Pydimarri The role of higher order image statistics in masking scene gist recognition Journal Article In: Attention, Perception, & Psychophysics, vol. 72, no. 2, pp. 427–444, 2010. @article{Loschky2010,In the present article, we investigated whether higher order image statistics, which are known to be carried by the Fourier phase spectrum, are sufficient to affect scene gist recognition. In Experiment 1, we compared the scene gist masking strength of four masking image types that varied in their degrees of second- and higher order relationships: normal scene images, scene textures, phase-randomized scene images, and white noise. Masking effects were the largest for masking images that possessed significant higher order image statistics (scene images and scene textures) as compared with masking images that did not (phase-randomized scenes and white noise), with scene image masks yielding the largest masking effects. In a control study, we eliminated all differences in the second-order statistics of the masks, while maintaining differences in their higher order statistics by comparing masking by scene textures rather than by their phase-randomized versions, and showed that the former produced significantly stronger gist masking. Experiments 2 and 3 were designed to test whether conceptual masking could account for the differences in the strength of the scene texture and phase-randomized masks used in Experiment 1, and revealed that the recognizability of scene texture masks explained just 1% of their masking variance. Together, the results suggest that (1) masks containing the higher order statistical structure of scenes are more effective at masking scene gist processing than are masks lacking such structure, and (2) much of the disruption of scene gist recognition that one might be tempted to attribute to conceptual masking is due to spatial masking. |
Gang Luo; Tyler W. Garaas; Marc Pomplun; Eli Peli Inconsistency between peri-saccadic mislocalization and compression: evidence for separate "what" and "where" visual systems Journal Article In: Journal of Vision, vol. 10, no. 12, pp. 1–8, 2010. @article{Luo2010,The view of two separate "what" and "where" visual systems is supported by compelling neurophysiological evidence. However, very little direct psychophysical evidence has been presented to suggest that the two functions can be separated in neurologically intact persons. Using a peri-saccadic perception paradigm in which bars of different lengths were flashed around saccade onset, we directly measured the perceived object size (a "what" attribute) and location (a "where" attribute). We found that the perceived object location shifted toward the saccade target to show strongly compressed localization, whereas the perceived object size was not compressed accordingly. This dissociation indicates that the perceived size is not determined by spatial localization of the object boundary, providing direct psychophysical evidence to support that "what" and "where" attributes of objects are indeed processed separately. |
Chia-Lun Liu; Hui-Yan Chiau; Philip Tseng; Daisy L. Hung; Ovid J. L. Tzeng; Neil G. Muggleton; Chi-Hung Juan Antisaccade cost is modulated by contextual experience of location probability Journal Article In: Journal of Neurophysiology, vol. 103, no. 3, pp. 1438–1447, 2010. @article{Liu2010,It is well known that pro- and antisaccades may deploy different cognitive processes. However, the specific reason why antisaccades have longer latencies than prosaccades is still under debate. In three experiments, we studied the factors contributing to the antisaccade cost by taking attentional orienting and target location probabilities into account. In experiment 1, using a new antisaccade paradigm, we directly tested Olk and Kingstone's hypothesis, which attributes longer antisaccade latency to the time it takes to reorient from the visual target to the opposite saccadic target. By eliminating the reorienting component in our paradigm, we found no significant difference between the latencies of the two saccade types. In experiment 2, we varied the proportion of prosaccades made to certain locations and found that latencies in the high location-probability (75%) condition were faster than those in the low location-probability condition. Moreover, antisaccade latencies were significantly longer when location probability was high. This pattern can be explained by the notion of competing pathways for pro- and antisaccades in findings of others. In experiment 3, we further explored the degrees of modulation of location probability by decreasing the magnitude of high probability from 75 to 65%. We again observed a pattern similar to that seen in experiment 2 but with smaller modulation effects. Together, these experiments indicate that the reorienting process is a critical factor in producing the antisaccade cost. Furthermore, the antisaccade cost can be modulated by probabilistic contextual information such as location probabilities. |
Xingshan Li; Gordon D. Logan; N. Jane Zbrodoff Where do we look when we count? The role of eye movements in enumeration Journal Article In: Attention, Perception, & Psychophysics, vol. 72, no. 2, pp. 409–426, 2010. @article{Li2010,Two experiments addressed the coupling between eye movements and the cognitive processes underlying enumeration. Experiment 1 compared eye movements in a counting task with those in a “look” task, in which subjects were told to look at each dot in a pattern once and only once. Experiment 2 presented the same dot patterns to every subject twice, to measure the consistency with which dots were fixated between and within subjects. In both experiments, the number of fixations increased linearly with the number of objects to be enu- merated, consistent with tight coupling between eye movements and enumeration. However, analyses of fixation locations showed that subjects tended to look at dots in dense, central regions of the display and tended not to look at dots in sparse, peripheral regions of the display, suggesting a looser coupling between eye movements and enumeration. Thus, the eyes do not mirror the enumeration process very directly. |
Hanneke Liesker; Eli Brenner; Jeroen B. J. Smeets Eye-hand coupling is not the cause of manual return movements when searching Journal Article In: Experimental Brain Research, vol. 201, no. 2, pp. 221–227, 2010. @article{Liesker2010,When searching for a target with eye movements, saccades are planned and initiated while the visual information is still being processed, so that subjects often make saccades away from the target and then have to make an additional return saccade. Presumably, the cost of the additional saccades is outweighed by the advantage of short fixations. We previously showed that when the cost of passing the target was increased, by having subjects manually move a window through which they could see the visual scene, subjects still passed the target and made return movements (with their hand). When moving a window in this manner, the eyes and hand follow the same path. To find out whether the hand still passes the target and then returns when eye and hand movements are uncoupled, we here compared moving a window across a scene with moving a scene behind a stationary window. We ensured that the required movement of the hand was identical in both conditions. Subjects found the target faster when moving the window across the scene than when moving the scene behind the window, but at the expense of making larger return movements. The relationship between the return movements and movement speed when comparing the two conditions was the same as the relationship between these two when comparing different window sizes. We conclude that the hand passing the target and then returning is not directly related to the eyes doing so, but rather that moving on before the information has been fully processed is a general principle of visuomotor control. |
Angelika Lingnau; Jens Schwarzbach; Dirk Vorberg (Un)-coupling gaze and attention outside central vision Journal Article In: Journal of Vision, vol. 10, no. 11, pp. 1–13, 2010. @article{Lingnau2010,In normal vision, shifts of attention and gaze are tightly coupled. Here we ask if this coupling affects performance also when central vision is not available. To this aim, we trained normal-sighted participants to perform a visual search task while vision was restricted to a gaze-contingent viewing window (" forced field location ") either in the left, right, upper, or lower visual field. Gaze direction was manipulated within a continuous visual search task that required leftward, rightward, upward, or downward eye movements. We found no general performance advantage for a particular part of the visual field or for a specific gaze direction. Rather, performance depended on the coordination of visual attention and eye movements, with impaired performance when sustained attention and gaze have to be moved in opposite directions. Our results suggest that during early stages of central visual field loss, the optimal location for the substitution of foveal vision does not depend on the particular retinal location alone, as has previously been thought, but also on the gaze direction required by the task the patient wishes to perform. |
Debra Malpass; Antje S. Meyer The time course of name retrieval during multiple-object naming: Evidence from extrafoveal-on-foveal effects Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 36, no. 2, pp. 523–537, 2010. @article{Malpass2010,The goal of the study was to examine whether speakers naming pairs of objects would retrieve the names of the objects in parallel or in sequence. To this end, we recorded the speakers' eye movements and determined whether the difficulty of retrieving the name of the 2nd object affected the duration of the gazes to the 1st object. Two experiments, which differed in the spatial arrangement of the objects, showed that the speakers looked longer at the 1st object when the name of the 2nd object was easy than when it was more difficult to retrieve. Thus, the easy 2nd-object names interfered more with the processing of the 1st object than the more difficult 2nd-object names. In the 3rd experiment, the processing of the 1st object was rendered more difficult by presenting it upside down. No effect of 2nd-object difficulty on the gaze duration for the 1st object was found. These results suggest that speakers can retrieve the names of a foveated and an extrafoveal object in parallel, provided that the processing of the foveated object is not too demanding. |
Sabira K. Mannan; Christopher Kennard; Daniela Potter; Yi Pan; David Soto Early oculomotor capture by new onsets driven by the contents of working memory Journal Article In: Vision Research, vol. 50, no. 16, pp. 1590–1597, 2010. @article{Mannan2010,Oculomotor capture can occur automatically in a bottom-up way through the sudden appearance of a new object or in a top-down fashion when a stimulus in the array matches the contents of working memory. However, it is not clear whether or not working memory processing can influence the early stages of oculomotor capture by abrupt onsets. Here we present clear evidence for an early modulation driven by stimulus matches to the contents of working memory in the colour dimension. Interestingly, verbal as well as visual information in working memory influenced the direction of the fastest saccades made in search, saccadic latencies and the curvature of the scan paths made to the search target. This pattern of results arose even though the contents of working memory were detrimental for search, demonstrating an early, automatic top-down mediation of oculomotor onset capture by the contents of working memory. |
Jun Maruta; Minah Suh; Sumit N. Niogi; Pratik Mukherjee; Jamshid Ghajar Visual tracking synchronization as a metric for concussion screening Journal Article In: Journal of Head Trauma Rehabilitation, vol. 25, no. 4, pp. 293–305, 2010. @article{Maruta2010,Our goal was to determine whether performance variability during predictive visual tracking can provide a screening measure for mild traumatic brain injury (mTBI). Seventeen subjects with chronic postconcussive syndrome and 9 healthy control subjects were included in this study. Eye movements were recorded with video-oculography as the subject visually tracked a target that moved through a circular trajectory. We compared the variability of gaze positional errors relative to the target with the microstructural integrity of white matter tracts as measured by the fractional anisotropy (FA) parameter of diffusion tensor imaging. Gaze error variability was significantly correlated with the mean FA values of the right anterior corona radiata (ACR) and the left superior cerebellar peduncle, tracts that support spatial processing and sustenance of attention, and the genu of the corpus callosum. Because the ACR and the genu are among the most frequently damaged white matter tracts in mTBI, the correlations imply that gaze error variability during visual tracking may provide a useful screening tool for mTBI. Gaze error variability was also significantly correlated with attention and working memory measures in neurocognitive testing; thus, measurement of visual tracking performance is promising as a fast and practical screening tool for mTBI. |
Kaitlin E. W. Laidlaw; Alan Kingstone The time course of vertical, horizontal and oblique saccade trajectories: Evidence for greater distractor interference during vertical saccades Journal Article In: Vision Research, vol. 50, no. 9, pp. 829–837, 2010. @article{Laidlaw2010,The present study aimed to characterize the effect of a nearby distractor on vertical, horizontal, and oblique saccade curvature under normal saccade preparation times. Consistent with previous findings, longer-latency vertical saccades showed greater curvature away from a distractor than did oblique or horizontal saccades. At short latencies, vertical saccades also showed greater curvature towards the distractor. A neural explanation for why vertical saccades show greater interference from a distractor is theorized. |
Maren Lappe-Osthege; Silke Talamo; Christoph Helmchen; Andreas Sprenger Overestimation of saccadic peak velocity recorded by electro-oculography compared to video-oculography and scleral search coil Journal Article In: Clinical Neurophysiology, vol. 121, no. 10, pp. 1786–1787, 2010. @article{LappeOsthege2010,Peak velocity of saccadic eye movements is a crucial motor parameter in clinical neurology and oculomotor research. It may help to assign patients' lesions to even very small brain regions which are not (yet) recognizable with magnetic resonance imaging (MRI). Horizontal slowing of saccades is associated with pontine lesions of the paramedian pontine reticular formation while saccades in cerebellar or cortical lesions are usually not slowed. Accordingly, saccade velocity helps to classify and distinguish neurodegenerative and genetic movement disorders, e.g. Parkinson's disease or spinocerebellar ataxias. However, related studies are often not easily comparable as different recording techniques (e.g. electro-oculography, video-oculography, and scleral search coil) and different paradigms (e.g., reflexive, self-paced saccades) are used irrespective of their influence on saccade velocity. Therefore, we intraindividually compared saccadic peak velocities using electro-oculography (EOG), video-oculography (VOG) and scleral search coil (SSC) in a variety of saccade types and conditions to assess the comparability of these methods. |
Jochen Laubrock; Reinhold Kliegl; Martin Rolfs; Ralf Engbert When do microsaccades follow spatial attention? Journal Article In: Attention, Perception, & Psychophysics, vol. 72, no. 3, pp. 683–694, 2010. @article{Laubrock2010,Following up on an exchange about the relation between microsaccades and spatial attention (Horowitz, Fenc- sik, Fine, Yurgenson, & Wolfe, 2007; Horowitz, Fine, Fencsik, Yurgenson, & Wolfe, 2007; Laubrock, Engbert, Rolfs, & Kliegl, 2007), we examine the effects of selection criteria and response modality. We show that for Posner cuing with saccadic responses, microsaccades go with attention in at least 75% of cases (almost 90% if probability matching is assumed) when they are first (or only) microsaccades in the cue–target interval and when they occur between 200 and 400 msec after the cue. The relation between spatial attention and the direction of microsaccades drops to chance level for unselected microsaccades collected during manual-response conditions. Analyses of data from four cross-modal cuing experiments demonstrate an above-chance, intermediate link for visual cues, but no systematic relation for auditory cues. Thus, the link between spatial attention and direction of microsaccades depends on the experimental condition and time of occurrence, but it can be very strong. |
Hyung Lee; Mathias Abegg; Amadeo Rodriguez; John D. Koehn; Jason J. S. Barton Why do humans make antisaccade errors? Journal Article In: Experimental Brain Research, vol. 201, no. 1, pp. 65–73, 2010. @article{Lee2010,Antisaccade errors are attributed to failure to inhibit the habitual prosaccade. We investigated whether the amount of information about the required response the patient has before the trial begins also contributes to error rate. Participants performed antisaccades in five conditions. The traditional design had two goals on the left and right horizontal meridians. In the second condition, stimulus-goal confusability between trials was eliminated by displacing one goal upward. In the third, hemifield uncertainty was eliminated by placing both goals in the same hemifield. In the fourth, goal uncertainty was eliminated by having only one goal, but interspersed with no-go trials. The fifth condition eliminated all uncertainty by having the same goal on every trial. Antisaccade error rate increased by 2% with each additional source of uncertainty, with the main effect being hemifield information, and a trend for stimulus-goal confusability. A control experiment for the effects of increasing angular separation between targets without changing these types of prior response information showed no effects on latency or error rate. We conclude that other factors besides prosaccade inhibition contribute to antisaccade error rates in traditional designs, possibly by modulating the strength of goal activation. |
B. Machner; C. Klein; Andreas Sprenger; P. Baumbach; P. P. Pramstaller; Christoph Helmchen; Wolfgang Heide Eye movement disorders are different in Parkin-linked and idiopathic early-onset PD Journal Article In: Neurology, vol. 75, pp. 125–128, 2010. @article{Machner2010,OBJECTIVES Parkin gene mutations are the most common cause of early-onset parkinsonism. Patients with Parkin mutations may be clinically indistinguishable from patients with idiopathic early-onset Parkinson disease (EOPD) without Parkin mutations. Eye movement disorders have been shown to differentiate parkinsonian syndromes, but have never been systematically studied in Parkin mutation carriers. METHODS Eye movements were recorded in symptomatic (n = 9) and asymptomatic Parkin mutation carriers (n = 13), patients with idiopathic EOPD (n = 14), and age-matched control subjects (n = 27) during established oculomotor tasks. RESULTS Both patients with EOPD and symptomatic Parkin mutation carriers showed hypometric prosaccades toward visual stimuli, as well as deficits in suppressing reflexive saccades toward unintended targets (antisaccade task). When directing gaze toward memorized target positions, patients with EOPD exhibited hypometric saccades, whereas symptomatic Parkin mutation carriers showed normal saccades. In contrast to patients with EOPD, the symptomatic Parkin mutation carriers showed impaired tracking of a moving target (reduced smooth pursuit gain). The asymptomatic Parkin mutation carriers did not differ from healthy control subjects in any of the tasks. CONCLUSIONS Although clinically similarly affected, symptomatic Parkin mutation carriers and patients with idiopathic EOPD differed in several oculomotor tasks. This finding may point to distinct anatomic structures underlying either condition: dysfunctions of cortical areas involved in smooth pursuit (V5, frontal eye field) in Parkin-linked parkinsonism vs greater impairment of basal ganglia circuits in idiopathic Parkinson disease. |
Kevin J. MacKenzie; David M. Hoffman; Simon J. Watt Accommodation to multiple-focal-plane displays: Implications for improving stereoscopic displays and for accommodation control Journal Article In: Journal of Vision, vol. 10, no. 8, pp. 1–22, 2010. @article{MacKenzie2010,Most stereoscopic displays present images at a single focal plane, resulting in "conflicts" between the stimuli to vergence and accommodation. Minimizing these conflicts is beneficial because they can cause distorted depth percepts, visual fatigue, and reduced stereoscopic performance. One proposed solution is to present a sum of images at multiple focal planes and to vary focal depth continuously by distributing image intensity across planes-a technique referred to as depth filtering. We evaluated this digital approximation to real-world variations in focal depth by measuring accommodation responses to depth-filtered stimuli at various simulated distances. Specifically, we determined the maximum image-plane separation that supported accurate and reliable accommodation. We used an analysis of retinal-image formation to predict when responses might be inaccurate. Accommodation to depth-filtered images was accurate and precise for image-plane separations up to ∼1 diopter, suggesting that depth filtering can be used to precisely match accommodation and vergence demands in a practical display. At larger plane separations, responses broke down in a manner consistent with our analysis. We develop this approach to consider how different spatial frequencies contribute to accommodation control. The results suggest that higher spatial frequencies contribute less to the accommodation response than has previously been thought. |
Vincenzo Maffei; Emiliano Macaluso; Iole Indovina; Guy A. Orban; Francesco Lacquaniti Processing of targets in smooth or apparent motion along the vertical in the human brain: An fMRI study Journal Article In: Journal of Neurophysiology, vol. 103, no. 1, pp. 360–370, 2010. @article{Maffei2010,Neural substrates for processing constant speed visual motion have been extensively studied. Less is known about the brain activity patterns when the target speed changes continuously, for instance under the influence of gravity. Using functional MRI (fMRI), here we compared brain responses to accelerating/decelerating targets with the responses to constant speed targets. The target could move along the vertical under gravity (1g), under reversed gravity (-1g), or at constant speed (0g). In the first experiment, subjects observed targets moving in smooth motion and responded to a GO signal delivered at a random time after target arrival. As expected, we found that the timing of the motor responses did not depend significantly on the specific motion law. Therefore brain activity in the contrast between different motion laws was not related to motor timing responses. Average BOLD signals were significantly greater for 1g targets than either 0g or -1g targets in a distributed network including bilateral insulae, left lingual gyrus, and brain stem. Moreover, in these regions, the mean activity decreased monotonically from 1g to 0g and to -1g. In the second experiment, subjects intercepted 1g, 0g, and -1g targets either in smooth motion (RM) or in long-range apparent motion (LAM). We found that the sites in the right insula and left lingual gyrus, which were selectively engaged by 1g targets in the first experiment, were also significantly more active during 1g trials than during -1g trials both in RM and LAM. The activity in 0g trials was again intermediate between that in 1g trials and that in -1g trials. Therefore in these regions the global activity modulation with the law of vertical motion appears to hold for both RM and LAM. Instead, a region in the inferior parietal lobule showed a preference for visual gravitational motion only in LAM but not RM. |
Alexander Maier; Geoffrey K. Adams; Christopher Aura; David A. Leopold Distinct superficial and deep laminar domains of activity in the visual cortex during rest and stimulation Journal Article In: Frontiers in Systems Neuroscience, vol. 4, pp. 1–11, 2010. @article{Maier2010,Spatial patterns of spontaneous neural activity at rest have previously been associated with specific networks in the brain, including those pertaining to the functional architecture of the primary visual cortex (V1). However, despite the prominent anatomical differences between cortical layers, little is known about the laminar pattern of spontaneous activity in V1. We address this topic by investigating the amplitude and coherence of ongoing local field potential (LFP) signals measured from different layers in V1 of macaque monkeys during rest and upon presentation of a visual stimulus. We used a linear microelectrode array to measure LFP signals at multiple, evenly spaced positions throughout the cortical thickness. Analyzing both the mean LFP amplitudes and between-contact LFP coherences, we identified two distinct zones of activity, roughly corresponding to superficial and deep layers, divided by a sharp transition near the bottom of layer 4. The LFP signals within each laminar zone were highly coherent, whereas those between zones were not. This functional compartmentalization was found not only during rest, but also when the receptive field was stimulated during a visual task. These results demonstrate the existence of distinct superficial and deep functional domains of coherent LFP activity in V1 that may reflect the intrinsic interplay of V1 microcircuitry with cortical and subcortical targets, respectively. |
Femke Maij; Eli Brenner; Hyung-Chul O. Li; Frans W. Cornelissen; Jeroen B. J. Smeets The use of the saccade target as a visual reference when localizing flashes during saccades Journal Article In: Journal of Vision, vol. 10, no. 4, pp. 1–9, 2010. @article{Maij2010,Flashes presented around the time of a saccade are often mislocalized. Such mislocalization is influenced by various factors. Here, we evaluate the role of the saccade target as a landmark when localizing flashes. The experiment was performed in a normally illuminated room to provide ample other visual references. Subjects were instructed to follow a randomly jumping target with their eyes. We flashed a black dot on the screen around the time of saccade onset. The subjects were asked to localize the black dot by touching the appropriate location on the screen. In a first experiment, the saccade target was displaced during the saccade. In a second experiment, it disappeared at different moments. Both manipulations affected the mislocalization. We conclude that our subjects' judgments are partly based on the flashed dot's position relative to the saccade target. |
George L. Malcolm; John M. Henderson Combining top-down processes to guide eye movements during real-world scene search Journal Article In: Journal of Vision, vol. 10, no. 2, pp. 1–11, 2010. @article{Malcolm2010,Eye movements can be guided by various types of information in real-world scenes. Here we investigated how the visual system combines multiple types of top-down information to facilitate search. We manipulated independently the specificity of the search target template and the usefulness of contextual constraint in an object search task. An eye tracker was used to segment search time into three behaviorally defined epochs so that influences on specific search processes could be identified. The results support previous studies indicating that the availability of either a specific target template or scene context facilitates search. The results also show that target template and contextual constraints combine additively in facilitating search. The results extend recent eye guidance models by suggesting the manner in which our visual system utilizes multiple types of top-down information. |