All EyeLink 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!
2015 |
Cyril Vienne; Laurent Blondé; Pascal Mamassian Depth-of-focus affects 3d perception in stereoscopic displays Journal Article In: Perception, vol. 44, no. 6, pp. 613–627, 2015. @article{Vienne2015,Stereoscopic systems present binocular images on planar surface at a fixed distance. They induce cues to flatness, indicating that images are presented on a unique surface and specifying the relative depth of that surface. The center of interest of this study is on a second problem, arising when a 3D object distance differs from the display distance. As binocular disparity must be scaled using an estimate of viewing distance, object depth can thus be affected through disparity scaling. Two previous experiments revealed that stereoscopic displays can affect depth perception due to conflicting accommodation and vergence cues at near distances. In this study, depth perception is evaluated for farther accommodation and vergence distances using a commercially available 3D TV. In Experiment 1, we evaluated depth perception of 3D stimuli at different vergence distances for a large pool of participants. We observed a strong effect of vergence distance that was bigger for younger than for older participants, suggesting that the effect of accommodation was reduced in participants with emerging presbyopia. In Experiment 2, we extended 3D estimations by varying both the accommodation and vergence distances. We also tested the hypothesis that setting accommodation open loop by constricting pupil size could decrease the contribution of focus cues to perceived distance. We found that the depth constancy was affected by accommodation and vergence distances and that the accommodation distance effect was reduced with a larger depth-of-focus. We discuss these results with regard to the effectiveness of focus cues as a distance signal. Overall, these results highlight the importance of appropriate focus cues in stereoscopic displays at intermediate viewing distances. |
Renée M. Visser; Anna E. Kunze; Bianca Westhoff; H. Steven Scholte; Merel Kindt Representational similarity analysis offers a preview of the noradrenergic modulation of long-term fear memory at the time of encoding Journal Article In: Psychoneuroendocrinology, vol. 55, pp. 8–20, 2015. @article{Visser2015,Neuroimaging research on emotional memory has greatly advanced our understanding of the pathogenesis of anxiety disorders. While the behavioral expression of fear at the time of encoding does not predict whether an aversive experience will evolve into long-term fear memory, the application of multi-voxel pattern analysis (MVPA) for the analysis of BOLD-MRI data has recently provided a unique marker for memory formation. Here, we aimed to further investigate the utility of this marker by modulating the strength of fear memory with an α2-adrenoceptor antagonist (yohimbine HCl). Fifty-two healthy participants were randomly assigned to two conditions - either receiving 20. mg yohimbine or a placebo pill (double-blind) - prior to differential fear conditioning and MRI-scanning. We examined the strength of fear associations during acquisition and retention of fear (48. h later) by assessing the similarity of BOLD-MRI patterns and pupil dilation responses. Additionally, participants returned for a follow-up test outside the scanner (2-4 weeks), during which we assessed fear-potentiated startle responses. Replicating our previous findings, neural pattern similarity reflected the development of fear associations over time, and unlike average activation or pupil dilation, predicted the later expression of fear memory (pupil dilation 48. h later). While no effect of yohimbine was observed on markers of autonomic arousal, including salivary α-amylase (sAA), we obtained indirect evidence for the noradrenergic enhancement of fear memory consolidation: sAA levels showed a strong increase prior to fMRI scanning, irrespective of whether participants had received yohimbine, and this increase correlated with the subsequent expression of fear (48. h later). Remarkably, this noradrenergic enhancement of fear was associated with changes in neural response patterns at the time of learning. These findings provide further evidence that representational similarity analysis is a sensitive tool for studying (enhanced) memory formation. |
Caroline Voges; Christoph Helmchen; Wolfgang Heide; Andreas Sprenger Ganzfeld stimulation or sleep enhance long term motor memory consolidation compared to normal viewing in saccadic adaptation paradigm Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0123831, 2015. @article{Voges2015,Adaptation of saccade amplitude in response to intra-saccadic target displacement is a type of implicit motor learning which is required to compensate for physiological changes in saccade performance. Once established trials without intra-saccadic target displacement lead to de-adaptation or extinction, which has been attributed either to extra-retinal mechanisms of spatial constancy or to the influence of the stable visual surroundings. Therefore we investigated whether visual deprivation ("Ganzfeld"-stimulation or sleep) can partially maintain this motor learning compared to free viewing of the natural surroundings. Thirty-five healthy volunteers performed two adaptation blocks of 100 inward adaptation trials - interspersed by an extinction block - which were followed by a two-hour break with or without visual deprivation (VD). Using additional adaptation and extinction blocks short and long (4 weeks) term memory of this implicit motor learning were tested. In the short term, motor memory tested immediately after free viewing was superior to adaptation performance after VD. In the long run, however, effects were opposite: motor memory and relearning of adaptation was superior in the VD conditions. This could imply independent mechanisms that underlie the short-term ability of retrieving learned saccadic gain and its long term consolidation. We suggest that subjects mainly rely on visual cues (i.e., retinal error) in the free viewing condition which makes them prone to changes of the visual stimulus in the extinction block. This indicates the role of a stable visual array for resetting adapted saccade amplitudes. In contrast, visual deprivation (GS and sleep), might train subjects to rely on extra-retinal cues, e.g., efference copy or prediction to remap their internal representations of saccade targets, thus leading to better consolidation of saccadic adaptation. |
Simone Vossel; Christoph Mathys; Klaas E. Stephan; Karl J. Friston Cortical coupling reflects Bayesian belief updating in the deployment of spatial attention Journal Article In: Journal of Neuroscience, vol. 35, no. 33, pp. 11532–11542, 2015. @article{Vossel2015,The deployment of visuospatial attention and the programming of saccades are governed by the inferred likelihood of events. In the present study, we combined computational modeling of psychophysical data with fMRI to characterize the computational and neural mechanisms underlying this flexible attentional control. Sixteen healthy human subjects performed a modified version of Posner's location-cueing paradigm in which the percentage of cue validity varied in time and the targets required saccadic responses. Trialwise estimates of the certainty (precision) of the prediction that the target would appear at the cued location were derived from a hierarchical Bayesian model fitted to individual trialwise saccadic response speeds. Trial-specific model parameters then entered analyses of fMRI data as parametric regressors. Moreover, dynamic causal modeling (DCM) was performed to identify the most likely functional architecture of the attentional reorienting network and its modulation by (Bayes-optimal) precision-dependent attention. While the frontal eye fields (FEFs), intraparietal sulcus, and temporoparietal junction (TPJ) of both hemispheres showed higher activity on invalid relative to valid trials, reorienting responses in right FEF, TPJ, and the putamen were significantly modulated by precision-dependent attention. Our DCM results suggested that the precision of predictability underlies the attentional modulation of the coupling of TPJ with FEF and the putamen. Our results shed new light on the computational architecture and neuronal network dynamics underlying the context-sensitive deployment of visuospatial attention.$backslash$n$backslash$nSIGNIFICANCE STATEMENT: Spatial attention and its neural correlates in the human brain have been studied extensively with the help of fMRI and cueing paradigms in which the location of targets is pre-cued on a trial-by-trial basis. One aspect that has so far been neglected concerns the question of how the brain forms attentional expectancies when no a priori probability information is available but needs to be inferred from observations. This study elucidates the computational and neural mechanisms under which probabilistic inference governs attentional deployment. Our results show that Bayesian belief updating explains changes in cortical connectivity; in that directional influences from the temporoparietal junction on the frontal eye fields and the putamen were modulated by (Bayes-optimal) updates. |
Jeffrey Weiler; Cameron D. Hassall; Olave E. Krigolson; Matthew Heath The unidirectional prosaccade switch-cost: Electroencephalographic evidence of task-set inertia in oculomotor control Journal Article In: Behavioural Brain Research, vol. 278, pp. 323–329, 2015. @article{Weiler2015,The execution of an antisaccade selectively increases the reaction time (RT) of a subsequent prosaccade (the unidirectional prosaccade switch-cost). To explain this finding, the task-set inertia hypothesis asserts that an antisaccade requires a cognitively mediated non-standard task-set that persists inertially and delays the planning of a subsequent prosaccade. The present study sought to directly test the theoretical tenets of the task-set inertia hypothesis by examining the concurrent behavioural and the event-related brain potential (ERP) data associated with the unidirectional prosaccade switch-cost. Participants pseudo-randomly alternated between pro- and antisaccades while electroencephalography (EEG) data were recorded. As expected, the completion of an antisaccade selectively increased the RT of a subsequent prosaccade, whereas the converse switch did not influence RTs. Thus, the behavioural results demonstrated the unidirectional prosaccade switch-cost. In terms of the ERP findings, we observed a reliable change in the amplitude of the P3 - time-locked to task-instructions - when trials were switched from a prosaccade to an antisaccade; however, no reliable change was observed when switching from an antisaccade to a prosaccade. This is a salient finding because extensive work has shown that the P3 provides a neural index of the task-set required to execute a to-be-completed response. As such, results showing that prosaccades completed after antisaccades exhibited increased RTs in combination with a P3 amplitude comparable to antisaccades provides convergent evidence that the unidirectional prosaccade switch-cost is attributed to the persistent activation of a non-standard antisaccade task-set. |
Katharina Weiß; Werner X. Schneider; Arvid Herwig A "blanking effect" for surface features: Transsaccadic spatial-frequency discrimination is improved by postsaccadic blanking Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 5, pp. 1500–1506, 2015. @article{Weiss2015,Although saccadic eye movements occur frequently-about three or four times a second- humans are astonishingly blind to transsaccadic changes. Locational displacements of the saccade target of up to 2 deg of visual angle, and even large changes of a visual scene, can go unnoticed. For a long time, this insensitivity was ascribed to deficits in transsaccadic memory: Only a coarse, (spatially) imprecise representation would be retained across a saccade. This assumption was contradicted by Deubel's and Schneider's (Behavioral and Brain Sciences 17:259-260, 1994) striking finding that locational discrimination performance across a saccade is greatly improved by inserting a short postsaccadic blank. Surprisingly, the question of whether blanking effects occur also for other forms of transsaccadic changes (i.e., surface-feature changes) has been widely ignored. We tested this question by means of a transsaccadic change in spatial frequency. Postsaccadic blanking facilitated spatial-frequency discrimination, but to a smaller amount than the usual blanking effects obtained with locational displacements. This finding bears important implications for models of visual stability and transsaccadic memory. |
Dorothea Wendt; Birger Kollmeier; Thomas Brand How hearing impairment affects sentence comprehension: Using eye fixations to investigate the duration of speech processing Journal Article In: Trends in Hearing, vol. 19, 2015. @article{Wendt2015,The main objective of this study was to investigate the extent to which hearing impairment influences the duration of sentence processing. An eye-tracking paradigm is introduced that provides an online measure of how hearing impairment prolongs processing of linguistically complex sentences; this measure uses eye fixations recorded while the participant listens to a sentence. Eye fixations toward a target picture (which matches the aurally presented sentence) were measured in the presence of a competitor picture. Based on the recorded eye fixations, the single target detection amplitude, which reflects the tendency of the participant to fixate the target picture, was used as a metric to estimate the duration of sentence processing. The single target detection amplitude was calculated for sentence structures with different levels of linguistic complexity and for different listening conditions: in quiet and in two different noise conditions. Participants with hearing impairment spent more time processing sentences, even at high levels of speech intelligibility. In addition, the relationship between the proposed online measure and listener-specific factors, such as hearing aid use and cognitive abilities, was investigated. Longer processing durations were measured for participants with hearing impairment who were not accustomed to using a hearing aid. Moreover, significant correlations were found between sentence processing duration and individual cognitive abilities (such as working memory capacity or susceptibility to interference). These findings are discussed with respect to audiological applications. |
Jessica Werthmann; Anita Jansen; Anita C. E. Vreugdenhil; Chantal Nederkoorn; Ghislaine Schyns; Anne Roefs Food through the child's eye: An eye-tracking study on attentional bias for food in healthy-weight children and children with obesity. Journal Article In: Health Psychology, vol. 34, no. 12, pp. 1123–1132, 2015. @article{Werthmann2015,Objective: Obesity prevalence among children is high and knowledge on cognitive factors that contribute to children's reactivity to the "obesogenic" food environment could help to design effective treatment and prevention campaigns. Empirical studies in adults suggest that attention bias for food could be a risk factor for overeating. Accordingly, the current study tested if children with obesity have an elevated attention bias for food when compared to healthy-weight children. Another aim was to explore whether attention biases for food predicted weight-change after 3 and 6 months in obese children. Method: Obese children (n = 34) were recruited from an intervention program and tested prior to the start of this intervention. Healthy-weight children (n = 36) were recruited from local schools. First, attention biases for food were compared between children with obesity (n = 30) and matched healthy-weight children (n = 30). Second, regression analyses were conducted to test if food-related attention biases predicted weight changes after 3 and 6 months in children with obesity following a weight loss lifestyle intervention. Results: Results showed that obese children did not differ from healthy-weight children in their attention bias to food. Yet automatically directing attention toward food (i.e., initial orientation bias) was related to a reduced weight loss (R2 = .14 |
Alex L. White; Martin Rolfs; Marisa Carrasco Stimulus competition mediates the joint effects of spatial and feature-based attention Journal Article In: Journal of Vision, vol. 15, no. 14, pp. 1–21, 2015. @article{White2015,Distinct attentional mechanisms enhance the sensory processing of visual stimuli that appear at task-relevant locations and have task-relevant features. We used a combination of psychophysics and computational modeling to investigate how these two types of attention—spatial and feature based—interact to modulate sensitivity when combined in one task. Observers monitored overlapping groups of dots for a target change in color saturation, which they had to localize as being in the upper or lower visual hemifield. Pre-cues indicated the target's most likely location (left/ right), color (red/green), or both location and color. We measured sensitivity (d0) for every combination of the location cue and the color cue, each of which could be valid, neutral, or invalid. When three competing saturation changes occurred simultaneously with the target change, there was a clear interaction: The spatial cueing effect was strongest for the cued color, and the color cueing effect was strongest at the cued location. In a second experiment, only the target dot group changed saturation, such that stimulus competition was low. The resulting cueing effects were statistically independent and additive: The color cueing effect was equally strong at attended and unattended locations. We account for these data with a computational model in which spatial and feature-based attention independently modulate the gain of sensory responses, consistent with measurements of cortical activity. Multiple responses then compete via divisive normalization. Sufficient competition creates interactions between the two cueing effects, although the attentional systems are themselves independent. This model helps reconcile seemingly disparate behavioral and physiological findings. |
Sarah J. White; Kayleigh L. Warrington; Victoria A. McGowan; Kevin B. Paterson Eye movements during reading and topic scanning: Effects of word frequency Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 233–248, 2015. @article{White2015a,The study examined the nature of eye movement control and word recognition during scanning for a specific topic, compared with reading for comprehension. Experimental trials included a manipulation of word frequency: the critical word was frequent (and orthographically familiar) or infrequent (2 conditions: orthographically familiar and orthographically unfamiliar). First-pass reading times showed effects of word frequency for both reading and scanning, with no interactions between word characteristics and task. Therefore, in contrast to the task of searching for a single specific word (Rayner & Fischer, 1996), there were immediate and localized influences of lexical processing when scanning for a specific topic, indicating that early word recognition processes are similar during reading and topic scanning. In contrast, there were interactions for later measures, with larger effects of word frequency during reading than scanning, indicating that reading goals can modulate later processes such as the integration of words into sentence context. Additional analyses of the distribution of first-pass single fixation durations indicated that first-pass fixations of all durations were shortened during scanning compared with reading, and reading for comprehension produced a larger subset of longer first-pass fixations compared with scanning. The implications for the nature of word recognition and eye movement control are discussed. |
Veronica Whitford; Debra Titone In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 4, pp. 1118–1129, 2015. @article{Whitford2015,Eye movement measures demonstrate differences in first-language (L1) and second-language (L2) paragraph-level reading as a function of individual differences in current L2 exposure among bilinguals (Whitford & Titone, 2012). Specifically, as current L2 exposure increases, the ease of L2 word processing increases, but the ease of L1 word processing decreases. Here, we investigate whether current L2 exposure also relates to more general aspects of reading performance, including global eye movement measures and how bilinguals use parafoveal information to the right of fixation during L1 and L2 sentence-level reading, through use of a gaze-contingent moving window paradigm (McConkie & Rayner, 1975). We found that bilinguals with high versus low current L2 exposure exhibited increased L2 reading fluency (faster reading rates, shorter forward fixation durations), but decreased L1 reading fluency (slower reading rates, longer forward fixation durations). We also found that bilinguals with high versus low current L2 exposure were more affected by reductions in window size during L2 reading (indicative of a larger L2 perceptual span), but were less affected by reductions in window size during L1 reading (indicative of a smaller L1 perceptual span). Taken together, these findings suggest that individual differences in current L2 exposure among bilinguals also modulate more general aspects of reading behavior, including global measures of reading difficulty and the allocation of visual attention into the parafovea during both L1 and L2 sentence-level reading. |
Thomas D. W. Wilcockson; E. M. Pothos Measuring inhibitory processes for alcohol-related attentional biases: Introducing a novel attentional bias measure Journal Article In: Addictive Behaviors, vol. 44, pp. 88–93, 2015. @article{Wilcockson2015,Introduction: Attentional biases for alcohol related information (AB) have often been reported for heavy drinkers. These attentional biases have been found to have predictive value regarding relapse in abstaining alcoholics. Similarly impaired inhibitory processes have also been found to be associated with heavy drinkers. This paper describes a new experimental paradigm that can be utilised to investigate attentional bias towards alcohol-related visual stimuli, specifically the ability to inhibit the orientation of initial and sustained attention, towards peripherally appearing stimuli. In this way we hope to study a novel aspect of attentional biases and how they relate to substance abuse. Methods: We used a novel eye-tracking task which aims to measure inhibitory processes for AB. The experiment utilised a gaze contingency paradigm to measure the compulsion to process or attend to alcohol stimuli. 86 undergraduate participants were recruited (31 males; 55 females), aged 18-49. years (m. =. 20.88; sd. =. 4.52). A 'break frequency' variable was computed for each participant. This was the number of times that participants tried to look at peripheral stimuli. We argue that this variable is a direct measure of how distracting peripheral stimuli were. Results: It was found that reported alcohol use was associated with the eye-tracking break frequency measure of inhibitory control. Thus, heavy drinking may be associated with decreased inhibitory control and increased attentional bias. Conclusions: Results suggest that attentional bias is not just a process of stimuli becoming prioritised, but also stimuli becoming compulsory to attend and process. |
Charlotte Willems; Atser Damsma; Stefan M. Wierda; Niels A. Taatgen; Sander Martens Training-induced changes in the dynamics of attention as reflected in pupil dilation Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 6, pp. 1161–1171, 2015. @article{Willems2015,One of the major topics in attention literature is the atten- tional blink (AB), which demonstrates a limited ability to iden- tify the second of two targets (T1 and T2) when presented in close temporal succession (200–500 msec). Given that the effect has been thought of as robust and resistant to training for over 2 decades, one of the most remarkable findings in recent years is that the AB can be eliminated after a 1-hr training with a color-salient T2. However, the underlying mechanism of the training effect as well as the AB itself is as of yet still poorly understood. To elucidate this training effect, we employed a refined version of our recently developed pupil dilation deconvolution method to track any training-induced changes in the amount and onset of attentional processing in response to target stimuli. Behaviorally, we replicated the orig- inal training effect with a color-salient T2. However, we showed that training without a salient target, but with a consistent short target interval, is already sufficient to attenuate the AB. Pupil deconvolution did not reveal any posttraining changes in T2- related dilation but instead an earlier onset of dilation around T1. Moreover, normalized pupil dilation was enhanced post- training compared with pretraining. We conclude that the AB can be eliminated by training without a salient cue. Further- more, our data point to the existence of temporal expectations at the time points of the trained targets posttraining. Therefore, we tentatively conclude that temporal expectations arise as a result of training. |
Charlotte Willems; Johannes Herdzin; Sander Martens Individual differences in temporal selective attention as reflected in pupil dilation Journal Article In: PLoS ONE, vol. 10, no. 12, pp. e0145056, 2015. @article{Willems2015a,Background Attention is restricted for the second of two targets when it is presented within 200–500 ms of the first target. This attentional blink (AB) phenomenon allows one to study the dynamics of temporal selective attention by varying the interval between the two targets (T1 and T2). Whereas the AB has long been considered as a robust and universal cognitive limitation, several studies have demonstrated that AB task performance greatly differs between individuals, with some individuals showing no AB whatsoever. Methodology/Principal Findings Here, we studied these individual differences in AB task performance in relation to differences in attentional timing. Furthermore, we investigated whether AB magnitude is predictive for the amount of attention allocated to T1. For both these purposes pupil dilation was measured, and analyzed with our recently developed deconvolution method. We found that the dynamics of temporal attention in small versus large blinkers differ in a number of ways. Individuals with a relatively small AB magnitude seem better able to preserve temporal order information. In addition, they are quicker to allocate attention to both T1 and T2 than large blinkers. Although a popular explanation of the AB is that it is caused by an unnecessary overinvestment of attention allocated to T1, a more complex picture emerged from our data, suggesting that this may depend on whether one is a small or a large blinker. Conclusion The use of pupil dilation deconvolution seems to be a powerful approach to study the temporal dynamics of attention, bringing us a step closer to understanding the elusive nature of the AB. We conclude that the timing of attention to targets may be more important than the amount of allocated attention in accounting for individual differences. |
Anna Wilschut; Jan Theeuwes; Christian N. L. Olivers Nonspecific competition underlies transient attention Journal Article In: Psychological Research, vol. 79, no. 5, pp. 844–860, 2015. @article{Wilschut2015,Cueing a target by abrupt visual stimuli enhances its perception in a rapid but short-lived fashion, an effect known as transient attention. Our recent study showed that when targets are cued at a constant, central location, the emergence of the transient performance pattern was dependent on the presence of competing distractors, whereas targets presented in isolation were enhanced in a sustained manner (Wilschut et al., PLoS ONE, 6:e27661, 2011). The current study examined in more detail whether the transience depends on the specific nature of the competition. We first replicated and extended the competition-dependent transient pattern for peripheral and variable target locations. We then investigated the role of feature similarity, compatibility, and proximity. Both competition by feature similarity and compatibility between the target and distractors were found to impair performance, but effects were additive with the effects of the cueing interval and did not change the transient performance function. Varying the spatial distance between target and distractors yielded mixed evidence, but here too a transient pattern could be observed for targets flanked by both close and far distractors. The results thus show that the presence or absence of competition determines whether attention appears transient or sustained, while the specific nature of the competition (in terms of location or feature) affects selection independent of time. |
Christian Wolf; Alexander C. Schütz Trans-saccadic integration of peripheral and foveal feature information is close to optimal Journal Article In: Journal of Vision, vol. 15, no. 16, pp. 1–18, 2015. @article{Wolf2015,Due to the inhomogenous visual representation across the visual field, humans use peripheral vision to select objects of interest and foveate them by saccadic eye movements for further scrutiny. Thus, there is usually peripheral information available before and foveal information after a saccade. In this study we investigated the integration of information across saccades. We measured reliabilities-i.e., the inverse of variance-separately in a presaccadic peripheral and a postsaccadic foveal orientation-discrimination task. From this, we predicted trans-saccadic performance and compared it to observed values. We show that the integration of incongruent peripheral and foveal information is biased according to their relative reliabilities and that the reliability of the trans-saccadic information equals the sum of the peripheral and foveal reliabilities. Both results are consistent with and indistinguishable from statistically optimal integration according to the maximum-likelihood principle. Additionally, we tracked the gathering of information around the time of the saccade with high temporal precision by using a reverse correlation method. Information gathering starts to decline between 100 and 50 ms before saccade onset and recovers immediately after saccade offset. Altogether, these findings show that the human visual system can effectively use peripheral and foveal information about object features and that visual perception does not simply correspond to disconnected snapshots during each fixation. |
Benjamin A. Wolfe; Anna A. Kosovicheva; Allison Yamanashi Leib; Katherine Wood; David Whitney Foveal input is not required for perception of crowd facial expression Journal Article In: Journal of Vision, vol. 15, no. 4, pp. 1–11, 2015. @article{Wolfe2015a,The visual system extracts average features from groups of objects (Ariely, 2001; Dakin & Watt, 1997; Watamaniuk & Sekuler, 1992), including high-level stimuli such as faces (Haberman & Whitney, 2007, 2009). This phenomenon, known as ensemble perception, implies a covert process, which would not require fixation of individual stimulus elements. However, some evidence suggests that ensemble perception may instead be a process of averaging foveal input across sequential fixations (Ji, Chen, & Fu, 2013; Jung, Bulthoff, Thornton, Lee, & Armann, 2013). To test directly whether foveating objects is necessary, we measured observers' sensitivity to average facial emotion in the absence of foveal input. Subjects viewed arrays of 24 faces, either in the presence or absence of a gaze-contingent foveal occluder, and adjusted a test face to match the average expression of the array. We found no difference in accuracy between the occluded and non-occluded conditions, demonstrating that foveal input is not required for ensemble perception. Unsurprisingly, without foveal input, subjects spent significantly less time directly fixating faces, but this did not translate into any difference in sensitivity to ensemble expression. Next, we varied the number of faces visible from the set to test whether subjects average multiple faces from the crowd. In both conditions, subjects' performance improved as more faces were presented, indicating that subjects integrated information from multiple faces in the display regardless of whether they had access to foveal information. Our results demonstrate that ensemble perception can be a covert process, not requiring access to direct foveal information. |
Benjamin A. Wolfe; David Whitney Saccadic remapping of object-selective information Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 7, pp. 2260–2269, 2015. @article{Wolfe2015,Saccadic remapping, a presaccadic increase in neural activity when a saccade is about to bring an object into a neuron's receptive field, may be crucial for our perception of a stable world. Studies of perception and saccadic remapping, like ours, focus on the presaccadic acquisition of information from the saccade target, with no direct reference to underlying physiology. While information is known to be acquired prior to a saccade, it is unclear whether object-selective or feature-specific information is remapped. To test this, we performed a series of psychophysical experiments in which we presented a peripheral, nonfoveated face as a presaccadic target. The target face disappeared at saccade onset. After making a saccade to the location of the peripheral target face (which was no longer visible), subjects misperceived the expression of a subsequent, foveally presented neutral face as being repelled away from the peripheral presaccadic face target. This effect was similar to a sequential shape contrast or negative aftereffect but required a saccade, because covert attention was not sufficient to generate the illusion. Additional experiments further revealed that inverting the faces disrupted the illusion, suggesting that presaccadic remapping is object-selective and not based on low-level features. Our results demonstrate that saccadic remapping can be an object-selective process, spatially tuned to the target of the saccade and distinct from covert attention in the absence of a saccade. |
Michael J. Wolff; Sabine Scholz; Elkan G. Akyürek; Hedderik Rijn Two visual targets for the price of one? Pupil dilation shows reduced mental effort through temporal integration Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 1, pp. 251–257, 2015. @article{Wolff2015,In dynamic sensory environments, successive stimuli may be combined perceptually and represented as a single, comprehensive event by means of temporal integration. Such perceptual segmentation across time is intuitively plausible. However, the possible costs and benefits of temporal integration in perception remain underspecified. In the present study pupil dilation was analyzed as a measure of mental effort. Observers viewed either one or two successive targets amidst distractors in rapid serial visual presentation, which they were asked to identify. Pupil dilation was examined dependent on participants' report: dilation associated with the report of a single target, of two targets, and of an integrated percept consisting of the features of both targets. There was a clear distinction between dilation observed for single-target reports and integrations on the one side, and two-target reports on the other. Regardless of report order, two-target reports produced increased pupil dilation, reflecting increased mental effort. The results thus suggested that temporal integration reduces mental effort and may thereby facilitate perceptual processing. |
Beth A. Stankevich; Joy J. Geng The modulation of reward priority by top-down knowledge Journal Article In: Visual Cognition, vol. 23, no. 1-2, pp. 206–228, 2015. @article{Stankevich2015,Reward-associated features capture attention automatically and continue to do so even when the reward contingencies are removed. This profile has led to the hypothesis that rewards belong to a separate class of attentional biases that is neither typically top-down nor bottom-up. The goal of these experiments was to understand the degree to which top-down knowledge can modulate value-driven attentional capture within (a) the timecourse of a single trial and (b) when the reward contingencies change explicitly over trials. The results suggested that top-down knowledge does not affect the size of value-driven attentional capture within a single trial. There were clear top-down modulations in the magnitude of value-driven capture when reward contingencies explicitly changed, but the original reward associations continued to have a persistent bias on attention. These results contribute to a growing body of evidence that reward associations bias attention through mechanisms separate from other top-down and bottom-up attentional biases. |
Michael Stengel; Pablo Bauszat; Martin Eisemann; Elmar Eisemann; Marcus Magnor Temporal video filtering and exposure control for perceptual motion blur Journal Article In: IEEE Transactions on Visualization and Computer Graphics, vol. 21, no. 5, pp. 663–671, 2015. @article{Stengel2015,We propose the computation of a perceptual motion blur in videos. Our technique takes the predicted eye motion into account when watching the video. Compared to traditional motion blur recorded by a video camera our approach results in a perceptual blur that is closer to reality. This postprocess can also be used to simulate different shutter effects or for other artistic purposes. It handles real and artificial video input, is easy to compute and has a low additional cost for rendered content. We illustrate its advantages in a user study using eye tracking. |
Tobias Stevens; Damien Brevers; Christopher D. Chambers; Aureliu Lavric; Ian P. L. McLaren; Myriam Mertens; Xavier Noël; Frederick Verbruggen How does response inhibition influence decision making when gambling? Journal Article In: Journal of Experimental Psychology: Applied, vol. 21, no. 1, pp. 15–36, 2015. @article{Stevens2015,Recent research suggests that response inhibition training can alter impulsive and compulsive behavior. When stop signals are introduced in a gambling task, people not only become more cautious when executing their choice responses, they also prefer lower bets when gambling. Here, we examined how stopping motor responses influences gambling. Experiment 1 showed that the reduced betting in stop-signal blocks was not caused by changes in information sampling styles or changes in arousal. In Experiments 2a and 2b, people preferred lower bets when they occasionally had to stop their response in a secondary decision-making task but not when they were instructed to respond as accurately as possible. Experiment 3 showed that merely introducing trials on which subjects could not gamble did not influence gambling preferences. Experiment 4 demonstrated that the effect of stopping on gambling generalized to different populations. Further, 2 combined analyses suggested that the effect of stopping on gambling preferences was reliable but small. Finally, Experiment 5 showed that the effect of stopping on gambling generalized to a different task. On the basis of our findings and earlier research, we propose that the presence of stop signals influences gambling by reducing approach behavior and altering the motivational value of the gambling outcome. |
Emma E. M. Stewart; Anna Ma-Wyatt The spatiotemporal characteristics of the attentional shift relative to a reach Journal Article In: Journal of Vision, vol. 15, no. 5, pp. 1–17, 2015. @article{Stewart2015,While the attentional shift preceding a saccadic eye movement has been well documented, the mechanisms surrounding the attentional shift preceding a reach are not well understood. It is unknown whether these mechanisms may be the same as those used in perceptual tasks, or those used in the planning of a saccade. We mapped the spatiotemporal properties of attention relative to a reach to determine the time course of attentional facilitation for hand movements alone. Participants had to reach toward a target and during the reach a perceptual probe could appear at one of six locations around the target, and at nine temporal offsets relative to the cue. Results showed a consistent pattern of facilitation in the planning stages of the reach, with attention increasing and then reaching a plateau during the completion of the movement before dropping off. These results demonstrate that planning a hand movement necessitates a shift in attention across the visual field around 150 ms before the onset of a reach. While these results are broadly consistent with the results of experiments mapping attentional shifts for saccades, the spatiotemporal profile of facilitation found shows that reaching without a concurrent eye movement also causes shifts in attention across the visual field. These results also suggest that the profile of the attentional shift preceding and during a hand movement is different at different locations across the visual field. |
Mallory C. Stites; Kara D. Federmeier Subsequent to suppression: Downstream comprehension consequences of noun/verb ambiguity in natural reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1497–1515, 2015. @article{Stites2015,We used eye tracking to investigate the downstream processing consequences of encountering noun/verb (NV) homographs (i.e., park) in semantically neutral but syntactically constraining contexts. Target words were followed by a prepositional phrase containing a noun that was plausible for only 1 meaning of the homograph. Replicating previous work, we found increased first fixation durations on NV homographs compared with unambiguous words, which persisted into the next sentence region. At the downstream noun, we found plausibility effects following ambiguous words that were correlated with the size of a reader's first fixation effect, suggesting that this effect reflects the recruitment of processing resources necessary to suppress the homograph's context-inappropriate meaning. Using these same stimuli, Lee and Federmeier (2012) found a sustained frontal negativity to the NV homographs, and, on the downstream noun, found a plausibility effect that was also positively correlated with the size of a reader's ambiguity effect. Together, these findings suggest that when only syntactic constraints are available, meaning selection recruits inhibitory mechanisms that can be measured in both first fixation slowdown and event-related potential ambiguity effects. |
Josef Stoll; Michael Thrun; Antje Nuthmann; Wolfgang Einhäuser Overt attention in natural scenes: Objects dominate features Journal Article In: Vision Research, vol. 107, pp. 36–48, 2015. @article{Stoll2015,Whether overt attention in natural scenes is guided by object content or by low-level stimulus features has become a matter of intense debate. Experimental evidence seemed to indicate that once object locations in a scene are known, salience models provide little extra explanatory power. This approach has recently been criticized for using inadequate models of early salience; and indeed, state-of-the-art salience models outperform trivial object-based models that assume a uniform distribution of fixations on objects. Here we propose to use object-based models that take a preferred viewing location (PVL) close to the centre of objects into account. In experiment 1, we demonstrate that, when including this comparably subtle modification, object-based models again are at par with state-of-the-art salience models in predicting fixations in natural scenes. One possible interpretation of these results is that objects rather than early salience dominate attentional guidance. In this view, early-salience models predict fixations through the correlation of their features with object locations. To test this hypothesis directly, in two additional experiments we reduced low-level salience in image areas of high object content. For these modified stimuli, the object-based model predicted fixations significantly better than early salience. This finding held in an object-naming task (experiment 2) and a free-viewing task (experiment 3). These results provide further evidence for object-based fixation selection - and by inference object-based attentional guidance - in natural scenes. |
Caleb E. Strait; Brianna J. Sleezer; Benjamin Y. Hayden Signatures of value comparison in ventral striatum neurons Journal Article In: PLoS Biology, vol. 13, no. 6, pp. 1–22, 2015. @article{Strait2015,The ventral striatum (VS), like its cortical afferents, is closely associated with processing of rewards, but the relative contributions of striatal and cortical reward systems remains unclear. Most theories posit distinct roles for these structures, despite their similarities. We compared responses of VS neurons to those of ventromedial prefrontal cortex (vmPFC) Area 14 neurons, recorded in a risky choice task. Five major response patterns observed in vmPFC were also observed in VS: (1) offer value encoding, (2) value difference encoding, (3) preferential encoding of chosen relative to unchosen value, (4) a correlation between residual variance in responses and choices, and (5) prominent encoding of outcomes. We did observe some differences as well; in particular, preferential encoding of the chosen option was stronger and started earlier in VS than in vmPFC. Nonetheless, the close match between vmPFC and VS suggests that cortex and its striatal targets make overlapping contributions to economic choice. |
Gregory P. Strauss; Emily S. Kappenman; Adam J. Culbreth; Lauren T. Catalano; Kathryn L. Ossenfort; Bern G. Lee; James M. Gold In: Journal of Abnormal Psychology, vol. 124, no. 2, pp. 288–301, 2015. @article{Strauss2015,Previous research provides evidence that individuals with schizophrenia (SZ) have emotion regulation abnormalities, particularly when attempting to use reappraisal to decrease negative emotion. The current study extended this literature by examining the effectiveness of a different form of emotion regulation, directed attention, which has been shown to be effective at reducing negative emotion in healthy individuals. Participants included outpatients with SZ (n = 28) and healthy controls (CN: n = 25), who viewed unpleasant and neutral images during separate event-related potential and eye-movement tasks. Trials included both passive viewing and directed attention segments. During directed attention, gaze was directed toward highly arousing aspects of an unpleasant image, less arousing aspects of an unpleasant image, or a nonarousing aspect of a neutral image. The late positive potential (LPP) event-related potential component indexed emotion regulation success. Directing attention to nonarousing aspects of unpleasant images decreased the LPP in CN; however, SZ showed similar LPP amplitude when attention was directed toward more or less arousing aspects of unpleasant scenes. Eye tracking indicated that SZ were more likely than CN to attend to arousing portions of unpleasant scenes when attention was directed toward less arousing scene regions. Furthermore, pupilary data suggested that SZ patients failed to engage effortful cognitive processes needed to inhibit the prepotent response of attending to arousing aspects of unpleasant scenes when attention was directed toward nonarousing scene regions. Findings add to the growing literature indicating that individuals with SZ display emotion regulation abnormalities and provide novel evidence that dysfunctional emotion-attention interactions and generalized cognitive control deficits are associated with ineffective use of directed attention strategies to regulate negative emotion. |
Heng Ru May Tan; Joachim Gross; P. J. Uhlhaas MEG-measured auditory steady-state oscillations show high test-retest reliability: A sensor and source-space analysis Journal Article In: NeuroImage, vol. 122, pp. 417–426, 2015. @article{Tan2015,Stability of oscillatory signatures across magnetoencephalography (MEG) measurements is an important prerequisite for basic and clinical research that has been insufficiently addressed. Here, we evaluated the test-retest reliability of auditory steady-state responses (ASSRs) over two MEG sessions. The study required participants (N. = 13) to detect the rare occurrence of pure tones interspersed within a stream of 5. Hz or 40. Hz amplitude-modulated (AM) tones. Intraclass correlations (ICC; Shrout and Fleiss, 1979) were derived to assess stability of spectral power changes and the inter-trial phase coherence (ITPC) of task-elicited neural responses. ASSRs source activity was estimated using eLORETA beamforming from bilateral auditory cortex. ASSRs to 40. Hz AM stimuli evoked stronger power modulation and phase-locking than 5. Hz stimulation. Overall, spectral power and ITPC values at both sensor- and source-level showed robust ICC values. Notably, ITPC measures yielded higher ICCs (~. 0.86-0.96) between sessions compared to the assessment of spectral power change (~. 0.61-0.82). Our data indicate that spectral modulations and phase consistency of ASSRs in MEG data are highly reproducible, providing support for MEG-measured oscillatory parameters in basic and clinical research. |
Jessica Taubert; Goedele Van Belle; Wim Vanduffel; Bruno Rossion; Rufin Vogels The effect of face inversion for neurons inside and outside fMRI-defined face-selective cortical regions Journal Article In: Journal of Neurophysiology, vol. 113, no. 5, pp. 1644–1655, 2015. @article{Taubert2015,It is widely believed that face processing in the primate brain occurs in a network of category-selective cortical regions. Combined functional MRI (fMRI)-single-cell recording studies in macaques have identified high concentrations of neurons that respond more to faces than objects within face-selective patches. However, cells with a preference for faces over objects are also found scattered throughout inferior temporal (IT) cortex, raising the question whether face-selective cells inside and outside of the face patches differ functionally. Here, we compare the properties of face-selective cells inside and outside of face-selective patches in the IT cortex by means of an image manipulation that reliably disrupts behavior toward face processing: inversion. We recorded IT neurons from two fMRI-defined face-patches (ML and AL) and a region outside of the face patches (herein labeled OUT) during upright and inverted face stimulation. Overall, turning faces upside down reduced the firing rate of face-selective cells. However, there were differences among the recording regions. First, the reduced neuronal response for inverted faces was independent of stimulus position, relative to fixation, in the face-selective patches (ML and AL) only. Additionally, the effect of inversion for face-selective cells in ML, but not those in AL or OUT, was impervious to whether the neurons were initially searched for using upright or inverted stimuli. Collectively, these results show that face-selective cells differ in their functional characteristics depending on their anatomicofunctional location, suggesting that upright faces are preferably coded by face-selective cells inside but not outside of the fMRI-defined face-selective regions of the posterior IT cortex. |
Jessica Taubert; Goedele Van Belle; Wim Vanduffel; Bruno Rossion; Rufin Vogels Neural correlate of the Thatcher face illusion in a monkey face-selective patch Journal Article In: Journal of Neuroscience, vol. 35, no. 27, pp. 9872–9878, 2015. @article{Taubert2015a,Compelling evidence that our sensitivity to facial structure is conserved across the primate order comes from studies of the “Thatcher face illusion”: humans and monkeys notice changes in the orientation of facial features (e.g., the eyes) only when faces are upright, not when faces are upside down. Although it is presumed that face perception in primates depends on face-selective neurons in the inferior temporal (IT) cortex, it is not known whether these neurons respond differentially to upright faces with inverted features. Using microelectrodes guided by functional MRI mapping, we recorded cell responses in three regions of monkey IT cortex.Wereport an interaction in the middle lateral face patch (ML) between the global orientation of a face and the local orientation of its eyes, a response profile consistent with the perception of the Thatcher illusion. This increased sensitivity to eye orientation in upright faces resisted changes in screen location and was not found among face-selective neurons in other areas of IT cortex, including neurons in another face-selective region, the anterior lateral face patch. We conclude that the Thatcher face illusion is correlated with a pattern of activity in the ML that encodes faces according to a flexible holistic template. |
Masahiko Terao; Ikuya Murakami; Shin'ya Nishida Enhancement of motion perception in the direction opposite to smooth pursuit eye movement Journal Article In: Journal of Vision, vol. 15, no. 13, pp. 1–11, 2015. @article{Terao2015,When eyes track a moving target, a stationary background environment moves in the direction opposite to the eye movement on the observer's retina. Here, we report a novel effect in which smooth pursuit can enhance the retinal motion in the direction opposite to eye movement, under certain conditions. While performing smooth pursuit, the observers were presented with a counterphase grating on the retina. The counterphase grating consisted of two drifting component gratings: one drifting in the direction opposite to the eye movement and the other drifting in the same direction as the pursuit. Although the overall perceived motion direction should be ambiguous if only retinal information is considered, our results indicated that the stimulus almost always appeared to be moving in the direction opposite to the pursuit direction. This effect was ascribable to the perceptual dominance of the environmentally stationary component over the other. The effect was robust at suprathreshold contrasts, but it disappeared at lower overall contrasts. The effect was not associated with motion capture by a reference frame served by peripheral moving images. Our findings also indicate that the brain exploits eye-movement information not only for eye-contingent image motion suppression but also to develop an ecologically plausible interpretation of ambiguous retinal motion signals. Based on this biological assumption, we argue that visual processing has the functional consequence of reducing the apparent motion blur of a stationary background pattern during eye movements and that it does so through integration of the trajectories of pattern and color signals. |
Katharine N. Thakkar; Jeffrey D. Schall; Stephan Heckers; Sohee Park Disrupted saccadic corollary discharge in schizophrenia Journal Article In: Journal of Neuroscience, vol. 35, no. 27, pp. 9935–9945, 2015. @article{Thakkar2015,Disruptions in corollary discharge (CD), motor signals that send information to sensory areas and allow for prediction of sensory states, are argued to underlie the perceived loss of agency in schizophrenia. Behavioral and neurophysiological evidence for CD in primates comes largely from the saccadic double-step task, which requires participants to make two visually triggered saccadic eye movements in brief succession. Healthy individuals use CD to anticipate the change in eye position resulting from the first saccade when preparing the second saccade. In the current study with human participants, schizophrenia patients and healthy controls of both sexes performed a modified double-step task. Most trials required a saccade to a single visual target (T1). On a subset of trials, a second target (T2) was flashed shortly following T1. Subjects were instructed to look directly at T2. Healthy individuals also use CD to make rapid, corrective responses following erroneous saccades to T1. To assess CD in schizophrenia, we examined the following on error trials: (1) frequency and latency of corrective saccades, and (2) mislocalization of the corrective (second) saccade in the direction predicted by a failure to use CD to account for the first eye movement. Consistent with disrupted CD, patients made fewer and slower error corrections. Importantly, the corrective saccade vector angle was biased in a manner consistent with disrupted CD. These results provide novel and clear evidence for dysfunctional CD in the oculomotor system in patients with schizophrenia. Based on neurophysiology work, these disturbances might have their basis in medial thalamus dysfunction. |
Katharine N. Thakkar; Jeffrey D. Schall; Gordon D. Logan; Sohee Park Cognitive control of gaze in bipolar disorder and schizophrenia Journal Article In: Psychiatry Research, vol. 225, no. 3, pp. 254–262, 2015. @article{Thakkar2015a,The objective of the present study was to compare two components of executive functioning, response monitoring and inhibition, in bipolar disorder (BP) and schizophrenia (SZ). The saccadic countermanding task is a translational paradigm optimized for detecting subtle abnormalities in response monitoring and response inhibition. We have previously reported countermanding performance abnormalities in SZ, but the degree to which these impairments are shared by other psychotic disorders is unknown. 18 BP, 17 SZ, and 16 demographically matched healthy controls (HC) participated in a saccadic countermanding task. Performance on the countermanding task is approximated as a race between movement generation and inhibition processes; this model provides an estimate of the time needed to cancel a planned movement. Response monitoring was assessed by the reaction time (RT) adjustments based on trial history. Like SZ patients, BP patients needed more time to cancel a planned movement. The two patient groups had equivalent inhibition efficiency. On trial history-based RT adjustments, however, we found a trend towards exaggerated trial history-based slowing in SZ compared to BP. Findings have implications for understanding the neurobiology of cognitive control, for defining the etiological overlap between schizophrenia and bipolar disorder, and for developing pharmacological treatments of cognitive impairments. |
Katharine N. Thakkar; Jeffrey D. Schall; Gordon D. Logan; Sohee Park Response inhibition and response monitoring in a saccadic double-step task in schizophrenia Journal Article In: Brain and Cognition, vol. 95, pp. 90–98, 2015. @article{Thakkar2015b,Background: Cognitive control impairments are linked to functional outcome in schizophrenia. The goal of the current study was to investigate precise abnormalities in two aspects of cognitive control: reactively changing a prepared response, and monitoring performance and adjusting behavior accordingly. We adapted an oculomotor task from neurophysiological studies of the cellular basis of cognitive control in nonhuman primates. Methods: 16 medicated outpatients with schizophrenia (SZ) and 18 demographically-matched healthy controls performed the modified double-step task. In this task, participants were required to make a saccade to a visual target. Infrequently, the target jumped to a new location and participants were instructed to rapidly inhibit and change their response. A race model provided an estimate of the time needed to cancel a planned movement. Response monitoring was assessed by measuring reaction time (RT) adjustments based on trial history. Results: SZ patients had normal visually-guided saccadic RTs but required more time to switch the response to the new target location. Additionally, the estimated latency of inhibition was longer in patients and related to employment. Finally, although both groups slowed down on trials that required inhibiting and changing a response, patients showed exaggerated performance-based adjustments in RTs, which was correlated with positive symptom severity. Conclusions: SZ patients have impairments in rapidly inhibiting eye movements and show idiosyncratic response monitoring. These results are consistent with functional abnormalities in a network involving cortical oculomotor regions, the superior colliculus, and basal ganglia, as described in neurophysiological studies of non-human primates using an identical paradigm, and provide a translational bridge for understanding cognitive symptoms of SZ. |
Alisha Siebold; Matthew David Weaver; Mieke Donk; Wieske Zoest Social salience does not transfer to oculomotor visual search Journal Article In: Visual Cognition, vol. 23, no. 8, pp. 989–1019, 2015. @article{Siebold2015,Evidence suggests that socially relevant information, such as self-referential information, leads to perceptual prioritization that is considered to be similar to prioritization based on physical stimulus salience. The current study used an oculomotor visual search paradigm to investigate whether self-prioritization affects visual selection early in time, akin to physical salience, or later in time, where it would relate to processing of top-down strategies. We report three experiments. Prior to each experiment, observers first performed a manual line-label matching task where they were asked to form associations between two orientation lines (right-tilted and left-tilted) and two labels (you and stranger). Participants then had to make a speeded eye-movement to one of the two lines without any task instructions (Experiment 1), to a dot probe target located on one of the two lines (Experiment 2), or to the line that was validly cued by its associated label (Experiment 3). We replicate previous findings with the manual stimulus-matching task. However, we did not find any evidence for increased salience of the self-relevant you stimulus during visual search, nor did we observe any self-prioritization due to later goal-driven or strategic processing. We argue that self-prioritization does not affect overt visual selection. The results suggest that the effects found in the manual matching task are unlikely to reflect self-prioritization during perceptual processing but might rather act on higher-level processing related to recognition or decision-making. |
Heida M. Sigurdardottir; David L. Sheinberg The effects of short-term and long-term learning on the responses of lateral intraparietal neurons to visually presented objects Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 7, pp. 1360–1375, 2015. @article{Sigurdardottir2015,The lateral intraparietal area (LIP) is thought to play an important role in the guidance of where to look and pay attention. LIP can also respond selectively to differently shaped objects. We sought to understand to what extent short-term and long-term experience with visual orienting determines the responses of LIP to objects of different shapes. We taught monkeys to arbitrarily associate centrally presented objects of various shapes with orienting either toward or away from a preferred spatial location of a neuron. The training could last for less than a single day or for several months. We found that neural responses to objects are affected by such experience, but that the length of the learning period determines how this neural plasticity manifests. Short-term learning affects neural responses to objects, but these effects are only seen relatively late after visual onset; at this time, the responses to newly learned objects resemble those of familiar objects that share their meaning or arbitrary association. Long-term learning affects the earliest bottom–up responses to visual objects. These responses tend to be greater for objects that have been associated with looking toward, rather than away from, LIP neurons' preferred spatial locations. Responses to objects can nonetheless be distinct, although they have been similarly acted on in the past and will lead to the same orienting behavior in the future. Our results therefore indicate that a complete experience-driven override of LIP object responses may be difficult or impossible. We relate these results to behavioral work on visual attention. |
J. D. Silvis; Katya Olmos-Solis; M. Donk The nature of the global effect beyond the first eye movement Journal Article In: Vision Research, vol. 108, pp. 20–32, 2015. @article{Silvis2015,When two or more visual objects appear in close proximity, the initial oculomotor response is systematically aimed at a location in between the objects, a phenomenon named the global effect. The global effect is known to arise when saccades are initiated relatively quickly, immediately after the presentation of a display, but it has also been shown that a global effect may occur much later in time, even for eye movements beyond the first. That is, when participants are searching for a complex target among complex distractor objects, it can take several eye movements to hit the target, and these eye movements mainly land at intermediate locations. It is debatable whether these findings are caused by the same mechanisms as those involved in the more typical global effect studies, studies in which much simpler search tasks are employed. In the current two experiments, we examined whether and under which circumstances a global effect can be found for a second oculomotor response in a search display containing two simple objects. Experiment 1 showed that the global effect only occurs when the presentation of the target and distractor objects is delayed, until after the first oculomotor response is initiated. Experiment 2 demonstrated that identity information, rather than spatial information, is crucial for the occurrence of the global effect. These results suggest that the global effect is not due to a failure to dissociate between the locations of multiple objects, but a failure to determine which one is the target. |
Jeroen D. Silvis; Artem V. Belopolsky; Jozua W. I. Murris; Mieke Donk The effects of feature-based priming and visual working memory on oculomotor capture Journal Article In: PLoS ONE, vol. 10, no. 11, pp. e0142696, 2015. @article{Silvis2015a,Recently, it has been demonstrated that objects held in working memory can influence rapid oculomotor selection. This has been taken as evidence that perceptual salience can be modified by active working memory representations. The goal of the present study was to examine whether these results could also be caused by feature-based priming. In two experiments, participants were asked to saccade to a target line segment of a certain orientation that was presented together with a to-be-ignored distractor. Both objects were given a task-irrelevant color that varied per trial. In a secondary task, a color had to be memorized, and that color could either match the color of the target, match the color of the distractor, or it did not match the color of any of the objects in the search task. The memory task was completed either after the search task (Experiment 1), or before it (Experiment 2). The results showed that in both experiments the memorized color biased oculomotor selection. Eye movements were more frequently drawn towards objects that matched the memorized color, irrespective of whether the memory task was completed after (Experiment 1) or before (Experiment 2) the search task. This bias was particularly prevalent in short-latency saccades. The results show that early oculomotor selection performance is not only affected by properties that are actively maintained in working memory but also by those previously memorized. Both working memory and feature priming can cause early biases in oculomotor selection. |
Matúš Šimkovic; Birgit Träuble Pursuit tracks chase: Exploring the role of eye movements in the detection of chasing Journal Article In: PeerJ, vol. 3, pp. 1–36, 2015. @article{Simkovic2015,We explore the role of eye movements in a chase detection task. Unlike the previous studies, which focused on overall performance as indicated by response speed and chase detection accuracy, we decompose the search process into gaze events such as smooth eye movements and use a data-driven approach to separately describe these gaze events. We measured eye movements of four human subjects engaged in a chase detection task displayed on a computer screen. The subjects were asked to detect two chasing rings among twelve other randomly moving rings. Using principal component analysis and support vector machines, we looked at the template and classification images that describe various stages of the detection process. We showed that the subjects mostly search for pairs of rings that move one after another in the same direction with a distance of 3.5-3.8 degrees. To find such pairs, the subjects first looked for regions with a high ring density and then pursued the rings in this region. Most of these groups consisted of two rings. Three subjects preferred to pursue the pair as a single object, while the remaining subject pursued the group by alternating the gaze between the two individual rings. In the discussion, we argue that subjects do not compare the movement of the pursued pair to a singular preformed template that describes a chasing motion. Rather, subjects bring certain hypotheses about what motion may qualify as chase and then, through feedback, they learn to look for a motion pattern that maximizes their performance. |
Jaana Simola; Kevin Le Fevre; Jari Torniainen; Thierry Baccino Affective processing in natural scene viewing: Valence and arousal interactions in eye-fixation-related potentials Journal Article In: NeuroImage, vol. 106, pp. 21–33, 2015. @article{Simola2015,Attention is drawn to emotionally salient stimuli. The present study investigates processing of emotionally salient regions during free viewing of emotional scenes that were categorized according to the two-dimensional model comprising of valence (unpleasant, pleasant) and arousal (high, low). Recent studies have reported interactions between these dimensions, indicative of stimulus-evoked approach or withdrawal tendencies. We addressed the valence and arousal effects when emotional items were embedded in complex real-world scenes by analyzing both eye movement behavior and eye-fixation-related potentials (EFRPs) time-locked to the critical event of fixating the emotionally salient items for the first time. Both data sets showed an interaction between the valence and arousal dimensions. First, the fixation rates and gaze durations on emotionally salient regions were enhanced for unpleasant versus pleasant images in the high arousal condition. In the low arousal condition, both measures were enhanced for pleasant versus unpleasant images. Second, the EFRP results at 140-170. ms [P2] over the central site showed stronger responses for high versus low arousing images in the unpleasant condition. In addition, the parietal LPP responses at 400-500. ms post-fixation were enhanced for stimuli reflecting congruent stimulus dimensions, that is, stronger responses for high versus low arousing images in the unpleasant condition and stronger responses for low versus high arousing images in the pleasant condition. The present findings support the interactive two-dimensional approach, according to which the integration of valence and arousal recruits brain regions associated with action tendencies of approach or withdrawal. |
Chris R. Sims The cost of misremembering: Inferring the loss function in visual working memory Journal Article In: Journal of Vision, vol. 15, no. 3, pp. 1–27, 2015. @article{Sims2015,Visual working memory (VWM) is a highly limited storage system. A basic consequence of this fact is that visual memories cannot perfectly encode or represent the veridical structure of the world. However, in natural tasks, some memory errors might be more costly than others. This raises the intriguing possibility that the nature of memory error reflects the costs of committing different kinds of errors. Many existing theories assume that visual memories are noise-corrupted versions of afferent perceptual signals. However, this additive noise assumption oversimplifies the problem. Implicit in the behavioral phenomena of visual working memory is the concept of a loss function: a mathematical entity that describes the relative cost to the organism of making different types of memory errors. An optimally efficient memory system is one that minimizes the expected loss according to a particular loss function, while subject to a constraint on memory capacity. This paper describes a novel theoretical framework for characterizing visual working memory in terms of its implicit loss function. Using inverse decision theory, the empirical loss function is estimated from the results of a standard delayed recall visual memory experiment. These results are compared to the predicted behavior of a visual working memory system that is optimally efficient for a previously identified natural task, gaze correction following saccadic error. Finally, the approach is compared to alternative models of visual working memory, and shown to offer a superior account of the empirical data across a range of experimental datasets. |
Jedediah M. Singer; Joseph R. Madsen; William S. Anderson; Gabriel Kreiman Sensitivity to timing and order in human visual cortex Journal Article In: Journal of Neurophysiology, vol. 113, no. 5, pp. 1656–1669, 2015. @article{Singer2015,Visual recognition takes a small fraction of a second and relies on the cascade of signals along the ventral visual stream. Given the rapid path through multiple processing steps between photoreceptors and higher visual areas, information must progress from stage to stage very quickly. This rapid progression of information suggests that fine temporal details of the neural response may be important to the brain's encoding of visual signals. We investigated how changes in the relative timing of incoming visual stimulation affect the representation of object information by recording intracranial field potentials along the human ventral visual stream while subjects recognized objects whose parts were presented with varying asynchrony. Visual responses along the ventral stream were sensitive to timing differences as small as 17 ms between parts. In particular, there was a strong dependency on the temporal order of stimulus presentation, even at short asynchronies. From these observations we infer that the neural representation of complex information in visual cortex can be modulated by rapid dynamics on scales of tens of milliseconds. |
J. Suzanne Singh; Michelle C. Capozzoli; Michael D. Dodd; Debra A. Hope The effects of social anxiety and state anxiety on visual attention: Testing the vigilance–avoidance hypothesis Journal Article In: Cognitive Behaviour Therapy, vol. 44, no. 5, pp. 377–388, 2015. @article{Singh2015,A growing theoretical and research literature suggests that trait and state social anxiety can predict attentional patterns in the presence of emotional stimuli. The current study adds to this literature by examining the effects of state anxiety on visual attention and testing the vigilance–avoidance hypothesis, using a method of continuous visual attentional assessment. Participants were 91 undergraduate college students with high or low trait fear of negative evaluation (FNE), a core aspect of social anxiety, who were randomly assigned to either a high or low state anxiety condition. Participants engaged in a free view task in which pairs of emotional facial stimuli were presented and eye movements were continuously monitored. Overall, participants with high FNE avoided angry stimuli and participants with high state anxiety attended to positive stimuli. Participants with high state anxiety and high FNE were avoidant of angry faces, whereas participants with low state and low FNE exhibited a bias toward angry faces. The study provided partial support for the vigilance–avoidance hypothesis. The findings add to the mixed results in the literature that suggest that both positive and negative emotional stimuli may be important in understanding the complex attention patterns associated with social anxiety. Clinical implications and suggestions for future research are discussed. |
Matthias J. Sjerps; Antje S. Meyer Variation in dual-task performance reveals late initiation of speech planning in turn-taking Journal Article In: Cognition, vol. 136, pp. 304–324, 2015. @article{Sjerps2015,The smooth transitions between turns in natural conversation suggest that speakers often begin to plan their utterances while listening to their interlocutor. The presented study investigates whether this is indeed the case and, if so, when utterance planning begins. Two hypotheses were contrasted: that speakers begin to plan their turn as soon as possible (in our experiments less than a second after the onset of the interlocutor's turn), or that they do so close to the end of the interlocutor's turn. Turn-taking was combined with a finger tapping task to measure variations in cognitive load. We assumed that the onset of speech planning in addition to listening would be accompanied by deterioration in tapping performance. Two picture description experiments were conducted. In both experiments there were three conditions: (1) Tapping and Speaking, where participants tapped a complex pattern while taking over turns from a pre-recorded speaker, (2) Tapping and Listening, where participants carried out the tapping task while overhearing two pre-recorded speakers, and (3) Speaking Only, where participants took over turns as in the Tapping and Speaking condition but without tapping. The experiments differed in the amount of tapping training the participants received at the beginning of the session. In Experiment 2, the participants' eye-movements were recorded in addition to their speech and tapping. Analyses of the participants' tapping performance and eye movements showed that they initiated the cognitively demanding aspects of speech planning only shortly before the end of the turn of the preceding speaker. We argue that this is a smart planning strategy, which may be the speakers' default in many everyday situations. |
Adam C. Snyder; Michael J. Morais; Cory M. Willis; Matthew A. Smith Global network influences on local functional connectivity Journal Article In: Nature Neuroscience, vol. 18, no. 5, pp. 736–743, 2015. @article{Snyder2015a,A central neuroscientific pursuit is understanding neuronal interactions that support computations underlying cognition and behavior. Although neurons interact across disparate scales, from cortical columns to whole-brain networks, research has been restricted to one scale at a time. We measured local interactions through multi-neuronal recordings while accessing global networks using scalp electroencephalography (EEG) in rhesus macaques. We measured spike count correlation, an index of functional connectivity with computational relevance, and EEG oscillations, which have been linked to various cognitive functions. We found a non-monotonic relationship between EEG oscillation amplitude and spike count correlation, contrary to the intuitive expectation of a direct relationship. With a widely used network model, we replicated these findings by incorporating a private signal targeting inhibitory neurons, a common mechanism proposed for gain modulation. Finally, we found that spike count correlation explained nonlinearities in the relationship between EEG oscillations and response time in a spatial selective attention task. |
Adam C. Snyder; Matthew A. Smith Stimulus-dependent spiking relationships with the EEG Journal Article In: Journal of Neurophysiology, vol. 114, no. 3, pp. 1468–1482, 2015. @article{Snyder2015,The development and refinement of noninvasive techniques for imaging neural activity is of paramount importance for human neuroscience. Currently, the most accessible and popular technique is electroencephalography (EEG). However, nearly all of what we know about the neural events that underlie EEG signals is based on inference, because of the dearth of studies that have simultaneously paired EEG recordings with direct recordings of single neurons. From the perspective of electrophysiologists there is growing interest in understanding how spiking activ- ity coordinates with large-scale cortical networks. Evidence from recordings at both scales highlights that sensory neurons operate in very distinct states during spontaneous and visually evoked activity, which appear to form extremes in a continuum of coordination in neural networks. We hypothesized that individual neurons have idio- syncratic relationships to large-scale network activity indexed by EEG signals, owing to the neurons' distinct computational roles within the local circuitry. We tested this by recording neuronal populations in visual area V4 of rhesus macaques while we simultaneously recorded EEG. We found substantial heterogeneity in the timing and strength of spike-EEG relationships and that these relationships became more diverse during visual stimulation compared with the spontaneous state. The visual stimulus apparently shifts V4 neurons from a state in which they are relatively uniformly embedded in large-scale network activity to a state in which their distinct roles within the local population are more prominent, suggesting that the specific way in which individual neurons relate to EEG signals may hold clues regarding their computational roles. |
Alba Tuninetti; Tessa Warren; Natasha Tokowicz Cue strength in second-language processing: An eye-tracking study Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 3, pp. 568–584, 2015. @article{Tuninetti2015,This study used eye-tracking and grammaticality judgement measures to examine how second-language (L2) learners process syntactic violations in English. Participants were native Arabic and native Mandarin Chinese speakers studying English as an L2, and monolingual English-speaking controls. The violations involved incorrect word order and differed in two ways predicted to be important by the unified competition model [UCM; MacWhinney, B. (2005). A unified model of language acquisition. In J. F. Kroll & A. M. B. de Groot (Eds.), Handbook of bilingualism: Psycholinguistic approaches (pp. 49-67). Oxford: Oxford University Press.]. First, one violation had more and stronger cues to ungrammaticality than the other. Second, the grammaticality of these word orders varied in Arabic and Mandarin Chinese. Sensitivity to violations was relatively quick overall, across all groups. Sensitivity also was related to the number and strength of cues to ungrammaticality regardless of native language, which is consistent with the general principles of the UCM. However, there was little evidence of cross-language transfer effects in either eye movements or grammaticality judgements. |
Lisa M. Soederberg Miller; Diana L. Cassady; Elizabeth A. Applegate; Laurel A. Beckett; Machelle D. Wilson; Tanja N. Gibson; Kathleen Ellwood Relationships among food label use, motivation, and dietary quality Journal Article In: Nutrients, vol. 7, no. 2, pp. 1068–1080, 2015. @article{SoederbergMiller2015,Nutrition information on packaged foods supplies information that aids consumers in meeting the recommendations put forth in the US Dietary Guidelines for Americans such as reducing intake of solid fats and added sugars. It is important to understand how food label use is related to dietary intake. However, prior work is based only on self-reported use of food labels, making it unclear if subjective assessments are biased toward motivational influences. We assessed food label use using both self-reported and objective measures, the stage of change, and dietary quality in a sample of 392 stratified by income. Self-reported food label use was assessed using a questionnaire. Objective use was assessed using a mock shopping task in which participants viewed food labels and decided which foods to purchase. Eye movements were monitored to assess attention to nutrition information on the food labels. Individuals paid attention to nutrition information when selecting foods to buy. Self-reported and objective measures of label use showed some overlap with each other (r=0.29, p<0.001), and both predicted dietary quality (p<0.001 for both). The stage of change diminished the predictive power of subjective (p<0.09), but not objective (p<0.01), food label use. These data show both self-reported and objective measures of food label use are positively associated with dietary quality. However, self-reported measures appear to capture a greater motivational component of food label use than do more objective measures. |
Lisa M. Soederberg Miller; Diana L. Cassady; Laurel A. Beckett; Elizabeth A. Applegate; Machelle D. Wilson; Tanja N. Gibson; Kathleen Ellwood Misunderstanding of front-of-package nutrition information on us food products Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0125306, 2015. @article{SoederbergMiller2015a,Front-of-package nutrition symbols (FOPs) are presumably readily noticeable and require minimal prior nutrition knowledge to use. Although there is evidence to support this notion, few studies have focused on Facts Up Front type symbols which are used in the US. Participants with varying levels of prior knowledge were asked to view two products and decide which was more healthful. FOPs on packages were manipulated so that one product was more healthful, allowing us to assess accuracy. Attention to nutrition information was assessed via eye tracking to determine what if any FOP information was used to make their decisions. Results showed that accuracy was below chance on half of the comparisons despite consulting FOPs. Negative correlations between attention to calories, fat, and sodium and accuracy indicated that consumers over-relied on these nutrients. Although relatively little attention was allocated to fiber and sugar, associations between attention and accuracy were positive. Attention to vitamin D showed no association to accuracy, indicating confusion surrounding what constitutes a meaningful change across products. Greater nutrition knowledge was associated with greater accuracy, even when less attention was paid. Individuals, particularly those with less knowledge, are misled by calorie, sodium, and fat information on FOPs. |
Maryam Soleimannejad; Mehdi Tehrani-Doost; Anahita Khorrami; Mohammad Taghi Joghataei; Ebrahim Pishyareh Evaluation of attention bias in morphine and methamphetamine abusers towards emotional scenes during early abstinence: An eye-tracking study Journal Article In: Basic and Clinical Neuroscience, vol. 6, no. 4, pp. 223–230, 2015. @article{Soleimannejad2015,INTRODUCTION: We hypothesized that inappropriate attention during the period of abstinence in individuals with substance use disorder can result in an inadequate perception of emotion and unsuitable reaction to emotional scenes. The main aim of this research was to evaluate the attentional bias towards emotional images in former substance abusers and compare it to healthy adults. METHODS: Paired images of general scenes consisting of pleasant, unpleasant, and neutral images were presented to subjects for 3 s while their attentional bias and eye movements were measured by eye tracking. The participants were 72 male adults consisting of 23 healthy control, 24 morphine former abusers, and 25 methamphetamine former abusers. The former abusers were recruited from a private addiction quitting center and addiction rehabilitation campus. The healthy individuals were selected from general population. Number and duration of first fixation, duration of first gaze, and sustained attention towards emotional scenes were measured as the main variables and the data were analyzed using the repeated measures ANOVA. RESULTS: A significant difference was observed between former morphine abusers and healthy control in terms of number and duration of first fixations and first gaze duration towards pleasant images. DISCUSSION: Individuals with morphine use disorder have more problems with attending to emotional images compared to methamphetamine abusers and healthy people. |
Guillermo Solovey; Guy Gerard Graney; Hakwan Lau A decisional account of subjective inflation of visual perception at the periphery Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 1, pp. 258–271, 2015. @article{Solovey2015,Human peripheral vision appears vivid compared to foveal vision; the subjectively perceived level of detail does not seem to drop abruptly with eccentricity. This compelling impression contrasts with the fact that spatial resolution is substantially lower at the periphery. A similar phenomenon occurs in visual attention, in which subjects usually overestimate their perceptual capacity in the unattended periphery. We have previously shown that at identical eccentricity, low spatial attention is associated with liberal detection biases, which we argue may reflect inflated subjective perceptual qualities. Our computational model suggests that this subjective inflation occurs because under the lack of attention, the trial-by-trial variability of the internal neural response is increased, resulting in more frequent surpassing of a detection criterion. In the current work, we hypothesized that the same mechanism may be at work in peripheral vision. We investigated this possibility in psychophysical experiments in which participants performed a simultaneous detection task at the center and at the periphery. Confirming our hypothesis, we found that participants adopted a conservative criterion at the center and liberal criterion at the periphery. Furthermore, an extension of our model predicts that detection bias will be similar at the center and at the periphery if the periphery stimuli are magnified. A second experiment successfully confirmed this prediction. These results suggest that, although other factors contribute to subjective inflation of visual perception in the periphery, such as top-down filling-in of information, the decision mechanism may be relevant too. |
Sabine Soltani; Kristin R. Newman; Leanne Quigley; Amanda Fernandez; Keith S. Dobson; Christopher Sears Temporal changes in attention to sad and happy faces distinguish currently and remitted depressed individuals from never depressed individuals Journal Article In: Psychiatry Research, vol. 230, no. 2, pp. 454–463, 2015. @article{Soltani2015,Depression is associated with attentional biases for emotional information that are proposed to reflect stable vulnerability factors for the development and recurrence of depression. A key question for researchers is whether those who have recovered from depression also exhibit attentional biases, and if so, how similar these biases are to those who are currently depressed. To address this question, the present study examined attention to emotional faces in remitted depressed (N=26), currently depressed (N=16), and never depressed (N=33) individuals. Participants viewed sets of four face images (happy, sad, threatening, and neutral) while their eye movements were tracked throughout an 8-s presentation. Like currently depressed participants, remitted depressed participants attended to sad faces significantly more than never depressed participants and attended to happy faces significantly less. Analyzing temporal changes in attention revealed that currently and remitted depressed participants did not reduce their attention to sad faces over the 8-s presentation, unlike never depressed participants. In contrast, remitted depressed participants attended to happy faces similarly to never depressed participants, increasing their attention to happy faces over the 8-s presentation. The implications for cognitive theories of depression and depression vulnerability are discussed. |
Suhad Sonbul Fatal mistake, awful mistake, or extreme mistake? Frequency effects on off-line/on-line collocational processing Journal Article In: Bilingualism: Language and Cognition, vol. 18, no. 3, pp. 419–437, 2015. @article{Sonbul2015,This study explored whether native speakers of English and non-natives are sensitive to corpus-derived frequency of synonymous adjective-noun collocations (e.g., fatal mistake, awful mistake, and extreme mistake) and whether level of proficiency can influence this sensitivity. Both off-line (typicality rating task) and on-line (eye-movement) measures were employed. Off-line results showed that both natives and non-natives were sensitive to collocational frequency with clearer effects for non-natives as their proficiency increased. On-line, however, proficiency had no effect on sensitivity to frequency; both natives and non-natives showed early sensitivity to collocational frequency (first pass reading time). This on-line sensitivity disappeared later in processing for both groups (total reading time and fixation count). Results are discussed in light of usage-based theories of language acquisition and processing. |
Joo-Hyun Song; Robert M. McPeek Neural correlates of target selection for reaching movements in superior colliculus Journal Article In: Journal of Neurophysiology, vol. 113, no. 5, pp. 1414–1422, 2015. @article{Song2015,We recently demonstrated that inactivation of the primate superior colliculus (SC) causes a deficit in target selection for arm-reaching movements when the reach target is located in the inactivated field (Song JH, Rafal RD, McPeek RM. Proc Natl Acad Sci USA 108: E1433–E1440, 2011). This is consistent with the notion that the SC is part of a general-purpose target selection network beyond eye movements. To understand better the role of SC activity in reach target selection, we examined how individual SC neurons in the intermediate layers discriminate a reach target from distractors. Monkeys reached to touch a color oddball target among distractors while maintaining fixation. We found that many SC neurons robustly discriminate the goal of the reaching movement before the onset of the reach even though no saccade is made. To identify these cells in the context of conventional SC cell classification schemes, we also recorded visual, delay-period, and saccade-related responses in a delayed saccade task. On average, SC cells that discriminated the reach target from distractors showed significantly higher visual and delay-period activity than nondiscriminating cells, but there was no significant difference in saccade-related activity. Whereas a majority of SC neurons that discriminated the reach target showed significant delay-period activity, all nondiscriminating cells lacked such activity. We also found that some cells without delay-period activity did discriminate the reach target from distractors. We conclude that the majority of intermediate-layer SC cells discriminate a reach target from distractors, consistent with the idea that the SC contains a priority map used for effector-independent target selection. |
Anja Sperlich; Daniel J. Schad; Jochen Laubrock When preview information starts to matter: Development of the perceptual span in German beginning readers Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 511–530, 2015. @article{Sperlich2015,How is reading development reflected in eye-movement measures? How does the perceptual span change during the initial years of reading instruction? Does parafoveal processing require competence in basic word-decoding processes? We report data from the first cross-sectional measurement of the perceptual span of German beginning readers (n = 139), collected in the context of the large longitudinal PIER (Potsdamer Intrapersonale Entwicklungsrisiken/Potsdam study of intra-personal developmental risk factors) study of intrapersonal developmental risk factors. Using the moving-window paradigm, eye movements of three groups of students (Grades 1–3) were measured with gaze-contingent presentation of a variable amount of text around fixation. Reading rate increased from Grades 1–3, with smaller increases for higher grades. Perceptual-span results showed the expected main effects of grade and window size: fixation durations and refixation probability decreased with grade and window size, whereas reading rate and saccade length increased. Critically, for reading rate, first-fixation duration, saccade length and refixation probability, there were significant interactions of grade and window size that were mainly based on the contrast between Grades 3 and 2 rather than Grades 2 and 1. Taken together, development of the perceptual span only really takes off between Grades 2 and 3, suggesting that efficient parafoveal processing presupposes that basic processes of reading have been mastered. |
Sara Spotorno; George L. Malcolm; Benjamin W. Tatler Disentangling the effects of spatial inconsistency of targets and distractors when searching in realistic scenes Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 1–21, 2015. @article{Spotorno2015,Previous research has suggested that correctly placed objects facilitate eye guidance, but also that objects violating spatial associations within scenes may be prioritized for selection and subsequent inspection. We analyzed the respective eye guidance of spatial expectations and target template (precise picture or verbal label) in visual search, while taking into account any impact of object spatial inconsistency on extrafoveal or foveal processing. Moreover, we isolated search disruption due to misleading spatial expectations about the target from the influence of spatial inconsistency within the scene upon search behavior. Reliable spatial expectations and precise target template improved oculomotor efficiency across all search phases. Spatial inconsistency resulted in preferential saccadic selection when guidance by template was insufficient to ensure effective search from the outset and the misplaced object was bigger than the objects consistently placed in the same scene region. This prioritization emerged principally during early inspection of the region, but the inconsistent object also tended to be preferentially fixated overall across region viewing. These results suggest that objects are first selected covertly on the basis of their relative size and that subsequent overt selection is made considering object-context associations processed in extrafoveal vision. Once the object was fixated, inconsistency resulted in longer first fixation duration and longer total dwell time. As a whole, our findings indicate that observed impairment of oculomotor behavior when searching for an implausibly placed target is the combined product of disruption due to unreliable spatial expectations and prioritization of inconsistent objects before and during object fixation. |
William W. Sprague; Emily A. Cooper; Ivana Tošić; Martin S. Banks Stereopsis is adaptive for the natural environment Journal Article In: Science Advances, vol. 1, pp. e1400254, 2015. @article{Sprague2015,Humans and many animals have forward-facing eyes providing different views of the environment. Precise depth estimates can be derived from the resulting binocular disparities, but determining which parts of the two retinal images correspond to one another is computationally challenging. To aid the computation, the visual system focuses the search on a small range of disparities. We asked whether the disparities encountered in the natural environment match that range. We did this by simultaneously measuring binocular eye position and three-dimensional scene geometry during natural tasks. The natural distribution of disparities is indeed matched to the smaller range of correspondence search. Furthermore, the distribution explains the perception of some ambiguous stereograms. Finally, disparity preferences of macaque cortical neurons are consistent with the natural distribution. |
Andreas Sprenger; Frederik D. Weber; Bjoern Machner; Silke Talamo; Sabine Scheffelmeier; Judith Bethke; Christoph Helmchen; Steffen Gais; Hubert Kimmig; Jan Born Deprivation and recovery of sleep in succession enhances reflexive motor behavior Journal Article In: Cerebral Cortex, vol. 25, no. 11, pp. 4610–4618, 2015. @article{Sprenger2015,Sleep deprivation impairs inhibitory control over reflexive behavior, and this impairment is commonly assumed to dissipate after recovery sleep. Contrary to this belief, here we show that fast reflexive behaviors, when practiced during sleep deprivation, is consolidated across recovery sleep and, thereby, becomes preserved. As a model for the study of sleep effects on prefrontal cortex-mediated inhibitory control in humans, we examined reflexive saccadic eye movements (express saccades), as well as speeded 2-choice finger motor responses. Different groups of subjects were trained on a standard prosaccade gap paradigm before periods of nocturnal sleep and sleep deprivation. Saccade performance was retested in the next morning and again 24 h later. The rate of express saccades was not affected by sleep after training, but slightly increased after sleep deprivation. Surprisingly, this increase augmented even further after recovery sleep and was still present 4 weeks later. Additional experiments revealed that the short testing after sleep deprivation was sufficient to increase express saccades across recovery sleep. An increase in speeded responses across recovery sleep was likewise found for finger motor responses. Our findings indicate that recovery sleep can consolidate motor disinhibition for behaviors practiced during prior sleep deprivation, thereby persistently enhancing response automatization. |
Kate M. Thompson; Tracy L. Taylor Memory instruction interacts with both visual and motoric inhibition of return Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 3, pp. 804–818, 2015. @article{Thompson2015,In the item-method directed forgetting paradigm, the magnitude of inhibition of return (IOR) is larger after an instruction to forget (F) than after an instruction to remember (R). In the present experiments, we further investigated this increased magnitude of IOR after F than after R memory instructions, to determine whether this F > R IOR pattern occurs only for the motoric form of IOR, as predicted, or also for the visual form. In three experiments, words were presented in one of two peripheral locations, followed by either an F or an R memory instruction. Then, a target appeared either at the same location as the previous word or at the other location. In Experiment 1, participants maintained fixation throughout the trial until the target appeared, at which point they made a saccade to the target. In Experiment 2, they maintained fixation throughout the entire trial and made a manual localization response to the target. The F > R IOR difference in reaction times occurred for both the saccadic and manual responses, suggesting that memory instructions modify both motoric and visual forms of IOR. In Experiment 3, participants made a perceptual discrimination response to report the identity of a target while the eyes remained fixed. The F > R IOR difference also occurred for these manual discrimination responses, increasing our confidence that memory instructions modify the visual form of IOR. We relate our findings to postulated differences in attentional withdrawal following F and R instructions and consider the implications of the findings for successful forgetting. |
Simon P. Tiffin-Richards; Sascha Schroeder Children's and adults' parafoveal processes in German: Phonological and orthographic effects Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 531–548, 2015. @article{TiffinRichards2015,Phonological and orthographic information has been shown to play an important role in parafoveal processing in skilled adult reading in English. In the present study, we investigated whether similar parafoveal effects can be found in children using the boundary eye tracking method. Children and adults read sentences in German with embedded target nouns which were presented in original, pseudohomophone (PsH), transposed-letter (TL), lower-case and control conditions to assess phonological and orthographic preview effects. We found evidence of PsH preview benefit effects for children. We also found TL preview benefit effects for adults, while children only showed these effects under specific conditions. Results are consistent with the developmental view that reading initially depends on phonological processes and that orthographic processes become increasingly important. |
Simon P. Tiffin-Richards; Sascha Schroeder Word length and frequency effects on children's eye movements during silent reading Journal Article In: Vision Research, vol. 113, pp. 33–43, 2015. @article{TiffinRichards2015a,In the present study we measured the eye movements of a large sample of 2nd grade German speaking children and a control group of adults during a silent reading task. To be able to directly investigate the interaction of word length and frequency effects we employed controlled sentence frames with embedded target words in an experimental design in which length and frequency were manipulated independently of one another. Unlike previous studies which have investigated the interaction of word length and frequency effects in children, we used age-appropriate word frequencies for children. We found significant effects of word length and frequency for both children and adults while effects were generally greater for children. The interaction of word length and frequency was significant for children in gaze duration and total viewing time eye movement measures but not for adults. Our results suggest that children rely on sublexical decoding of infrequent words, leading to greater length effects for infrequent than frequent words while adults do not show this effect when reading children's reading materials. |
Wei Lin Toh; David J. Castle; Susan Lee Rossell Facial affect recognition in body dysmorphic disorder versus obsessive-compulsive disorder: An eye-tracking study Journal Article In: Journal of Anxiety Disorders, vol. 35, pp. 49–59, 2015. @article{Toh2015,Background: Body dysmorphic disorder (BDD) is characterised by repetitive behaviours and/or mental acts occurring in response to preoccupations with perceived defects or flaws in physical appearance (American Psychiatric Association, 2013). This study aimed to investigate facial affect recognition in BDD using an integrated eye-tracking paradigm. Method: Participants were 21 BDD patients, 19 obsessive-compulsive disorder (OCD) patients and 21 healthy controls (HC), who were age-, sex-, and IQ-matched. Stimuli were from the Pictures of Facial Affect (Ekman & Friesen, 1975), and outcome measures were affect recognition accuracy as well as spatial and temporal scanpath parameters. Results: Relative to OCD and HC groups, BDD patients demonstrated significantly poorer facial affect perception and an angry recognition bias. An atypical scanning strategy encompassing significantly more blinks, fewer fixations of extended mean durations, higher mean saccade amplitudes, and less visual attention devoted to salient facial features was found. Conclusions: Patients with BDD were substantially impaired in the scanning of faces, and unable to extract affect-related information, likely indicating deficits in basic perceptual operations. |
Joseph C. Toscano; Bob McMurray The time-course of speaking rate compensation: Effects of sentential rate and vowel length on voicing judgments Journal Article In: Language, Cognition and Neuroscience, vol. 30, no. 5, pp. 529–543, 2015. @article{Toscano2015,Many sources of context information in speech (such as speaking rate) occur either before or after the phonetic cues they influence, yet there is little work examining the time-course of these effects. Here, we investigate how listeners compensate for preceding sentence rate and subsequent vowel length (VL; a secondary cue that has been used as a proxy for speaking rate) when categorising words varying in voice-onset time (VOT). Participants selected visual objects in a display while their eye-movements were recorded, allowing us to examine when each source of information had an effect on lexical processing. We found that the effect of VOT preceded that of VL, suggesting that each cue is used as it becomes available. In a second experiment, we found that, in contrast, the effect of preceding sentence rate occurred simultaneously with VOT, suggesting that listeners interpret VOT relative to preceding rate. |
Jon Touryan; James A. Mazer Linear and non-linear properties of feature selectivity in V4 neurons Journal Article In: Frontiers in Systems Neuroscience, vol. 9, pp. 82, 2015. @article{Touryan2015,Extrastriate area V4 is a critical component of visual form processing in both humans and non-human primates. Previous studies have shown that the tuning properties of V4 neurons demonstrate an intermediate level of complexity that lies between the narrow band orientation and spatial frequency tuning of neurons in primary visual cortex and the highly complex object selectivity seen in inferotemporal neurons. However, the nature of feature selectivity within this cortical area is not well understood, especially in the context of natural stimuli. Specifically, little is known about how the tuning properties of V4 neurons, measured in isolation, translate to feature selectivity within natural scenes. In this study, we assessed the degree to which preferences for natural image components can readily be inferred from classical orientation and spatial frequency tuning functions. Using a psychophysically-inspired method we isolated and identified the specific visual "driving features" occurring in natural scene photographs that reliably elicited spiking activity from single V4 neurons. We then compared the measured driving features to those predicted based on the spectral receptive field (SRF), estimated from responses to narrowband sinusoidal grating stimuli. This approach provided a quantitative framework for assessing the degree to which linear feature selectivity was preserved during natural vision. First, we found evidence of both spectrally and spatially tuned suppression within the receptive field, neither of which were present in the linear SRF. Second, we found driving features that were stable during translation of the image across the receptive field (due to small fixational eye movements). The degree of translation invariance fell along a continuum, with some cells showing nearly complete invariance across the receptive field and others exhibiting little to no position invariance. This form of limited translation invariance could indicate that a subset of V4 neurons are insensitive to small fixational eye movements, supporting perceptual stability during natural vision. |
J. J. Tramper; W. Pieter Medendorp Parallel updating and weighting of multiple spatial maps for visual stability during whole body motion Journal Article In: Journal of Neurophysiology, vol. 114, no. 6, pp. 3211–3219, 2015. @article{Tramper2015,It is known that the brain uses multiple reference frames to code spatial information, including eye-centered and body-centered frames. When we move our body in space, these internal representations are no longer in register with external space, unless they are actively updated. Whether the brain updates multiple spatial representations in parallel, or whether it restricts its updating mechanisms to a single reference frame from which other representations are constructed, remains an open question. We developed an optimal integration model to simulate the updating of visual space across body motion in multiple or single reference frames. To test this model, we designed an experiment in which participants had to remember the location of a briefly presented target while being translated sideways. The behavioral responses were in agreement with a model that uses a combination of eye- and body-centered representations, weighted according to the reliability in which the target location is stored, and updated in each reference frame. Our findings suggest that the brain simultaneously updates multiple spatial representations across body motion. Because both representations are kept in sync, they can be optimally combined to provide a more precise estimate of visual locations in space than based on single-frame updating mechanisms. |
Patrick Sturt; Nayoung Kwon The processing of raising and nominal control: An eye-tracking study Journal Article In: Frontiers in Psychology, vol. 6, pp. 331, 2015. @article{Sturt2015,According to some views of sentence processing, the memory retrieval processes involved in dependency formation may differ as a function of the type of dependency involved. For example, using closely matched materials in a single experiment, Dillon et al. (2013) found evidence for retrieval interference in subject-verb agreement, but not in reflexive-antecedent agreement. We report four eye-tracking experiments that examine examine reflexive-antecedent dependencies, combined with raising (e.g., "John seemed to Tom to be kind to himself…"), or nominal control (e.g., "John's agreement with Tom to be kind to himself…"). We hypothesized that dependencies involving raising would (a) be processed more quickly, and (b) be less subject to retrieval interference, relative to those involving nominal control. This is due to the fact that the interpretation of raising is structurally constrained, while the interpretation of nominal control depends crucially on lexical properties of the control nominal. The results showed evidence of interference when the reflexive-antecedent dependency was mediated by raising or nominal control, but very little evidence that could be interpreted in terms of interference for direct reflexive-antecedent dependencies that did not involve raising or control. However, there was no evidence either for greater interference, or for quicker dependency formation, for raising than for nominal control. |
Aditi Subramaniam; Sri Mahavir Agarwal; Sunil Kalmady; Venkataram Shivakumar; Harleen Chhabra; Anushree Bose; Dinakaran Damodharan; Janardhanan C. Narayanaswamy; Samuel B. Hutton; Ganesan Venkatasubramanian In: Indian Journal of Psychological Medicine, vol. 37, no. 4, pp. 419–422, 2015. @article{Subramaniam2015,Background: Deficient prefrontal cortex inhibitory control is of particular interest with regard to the pathogenesis of auditory hallucinations (AHs) in schizophrenia. Antisaccade task performance is a sensitive index of prefrontal inhibitory function and has been consistently found to be abnormal in schizophrenia. Methods: This study investigated the effect of transcranial direct current stimulation (tDCS) on antisaccade performance in 13 schizophrenia patients. Results: The tDCS resulted in significant reduction in antisaccade error percentage (t = 3.4; P = 0.005), final eye position gain (t = 2.3; P = 0.042), and AHs severity (t = 4.1; P = 0.003). Conclusion: Our results raise the possibility that improvement in antisaccade performance and severity of AH may be mechanistically related. |
Brian Sullivan; Laura Walker Comparing the fixational and functional preferred retinal location in a pointing task Journal Article In: Vision Research, vol. 116, pp. 68–79, 2015. @article{Sullivan2015a,Patients with central vision loss (CVL) typically adopt eccentric viewing strategies using a preferred retinal locus (PRL) in peripheral retina. Clinically, the PRL is defined monocularly as the area of peripheral retina used to fixate small stimuli. It is not clear if this fixational PRL describes the same portion of peripheral retina used during dynamic binocular eye-hand coordination tasks. We studied this question with four participants each with a unique CVL history. Using a scanning laser ophthalmoscope, we measured participants' monocular visual fields and the location and stability of their fixational PRLs. Participants' monocular and binocular visual fields were also evaluated using a computer monitor and eye tracker. Lastly, eye-hand coordination was tested over several trials where participants pointed to and touched a small target on a touchscreen monitor. Trials were blocked and carried out monocularly and binocularly, with a target appearing at 5° or 15° from screen center, in one of 8 locations. During pointing, our participants often exhibited long movement durations, an increased number of eye movements and impaired accuracy, especially in monocular conditions. However, these compensatory changes in behavior did not consistently worsen when loci beyond the fixational PRL were used. While fixational PRL size, location and fixation stability provide a necessary description of behavior, they are not sufficient to capture the pointing PRL used in this task. Generally, patients use a larger portion of peripheral retina than one might expect from measures of the fixational PRL alone, when pointing to a salient target without time constraints. While the fixational and pointing PRLs often overlap, the fixational PRL does not predict the large area of peripheral retina that can be used. |
Lalitta Suriya-Arunroj; Alexander Gail I plan therefore I choose: Free-choice bias due to prior action-probability but not action-value Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 315, 2015. @article{SuriyaArunroj2015,According to an emerging view, decision-making, and motor planning are tightly entangled at the level of neural processing. Choice is influenced not only by the values associated with different options, but also biased by other factors. Here we test the hypothesis that preliminary action planning can induce choice biases gradually and independently of objective value when planning overlaps with one of the potential action alternatives. Subjects performed center-out reaches obeying either a clockwise or counterclockwise cue-response rule in two tasks. In the probabilistic task, a pre-cue indicated the probability of each of the two potential rules to become valid. When the subsequent rule-cue unambiguously indicated which of the pre-cued rules was actually valid (instructed trials), subjects responded faster to rules pre-cued with higher probability. When subjects were allowed to choose freely between two equally rewarded rules (choice trials) they chose the originally more likely rule more often and faster, despite the lack of an objective advantage in selecting this target. In the amount task, the pre-cue indicated the amount of potential reward associated with each rule. Subjects responded faster to rules pre-cued with higher reward amount in instructed trials of the amount task, equivalent to the more likely rule in the probabilistic task. Yet, in contrast, subjects showed hardly any choice bias and no increase in response speed in favor of the original high-reward target in the choice trials of the amount task. We conclude that free-choice behavior is robustly biased when predictability encourages the planning of one of the potential responses, while prior reward expectations without action planning do not induce such strong bias. Our results provide behavioral evidence for distinct contributions of expected value and action planning in decision-making and a tight interdependence of motor planning and action selection, supporting the idea that the underlying neural mechanisms overlap. |
Aiga Švede; Elīna Treija; Wolfgang Jaschinski; Gunta Krūmiņa Monocular versus binocular calibrations in evaluating fixation disparity with a video-based eye-tracker Journal Article In: Perception, vol. 44, no. 8-9, pp. 1110–1128, 2015. @article{Svede2015,When measuring fixation disparity (an oculomotor vergence error), the question arises as to whether a monocular or binocular calibration is more precise and physiologically more appropriate. In monocular calibrations, a single eye fixates on a calibration target that is taken as having been projected onto the center of the fovea; the corresponding vergence state represents the heterophoria (the resting vergence position), which has no effect on the calibration procedure. In binocular calibrations, a vergence error may be present and may affect the subsequent measurement of the fixation disparity during binocular recordings. This study includes a test of the precision of both monocular and binocular calibrations and an evaluation of the impact of the calibration procedure on the measurement of fixation disparity during a dot scanning task. Our results show that 11 participants (out of 19) each exhibited a significant difference in fixation disparity with the two types of calibration procedures. In addition, the fixation disparity was more strongly affected by heterophoria undergoing monocular calibration, as opposed to binocular calibration. This serves as additional evidence showing that the monocular calibration produces a physiologically more plausible fixation disparity and seems to be more appropriate for studying the full extent of fixation disparity |
Martin Szinte; Marisa Carrasco; Patrick Cavanagh; Martin Rolfs Attentional trade-offs maintain the tracking of moving objects across saccades Journal Article In: Journal of Neurophysiology, vol. 113, no. 7, pp. 2220–2231, 2015. @article{Szinte2015,In many situations like playing sports or driving a car, we keep track of moving objects, despite the frequent eye movements that drastically interrupt their retinal motion trajectory. Here we report evidence that transsaccadic tracking relies on trade-offs of attentional resources from a tracked object's motion path to its remapped location. While participants covertly tracked a moving object, we presented pulses of coherent motion at different locations to probe the allocation of spatial attention along the object's entire motion path. Changes in the sensitivity for these pulses showed that during fixation attention shifted smoothly in anticipation of the tracked object's displacement. However, just before a saccade, atten- tional resources were withdrawn from the object's current motion path and reflexively drawn to the retinal location the object would have after saccade. This finding demonstrates the predictive choice the visual system makes to maintain the tracking of moving objects across saccades. |
Ryosuke Tachibana; Yasuki Noguchi Unconscious analyses of visual scenes based on feature conjunctions Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 3, pp. 639–648, 2015. @article{Tachibana2015,To efficiently process a cluttered scene, the visual system analyzes statistical properties or regularities of visual elements embedded in the scene. It is controversial, however, whether those scene analyses could also work for stimuli unconsciously perceived. Here we show that our brain performs the unconscious scene analyses not only using a single featural cue (e.g., orientation) but also based on conjunctions of multiple visual features (e.g., combinations of color and orientation information). Subjects foveally viewed a stimulus array (duration: 50 ms) where 4 types of bars (red-horizontal, red-vertical, greenhorizontal, and green-vertical) were intermixed. Although a conscious perception of those bars was inhibited by a subsequent mask stimulus, the brain correctly analyzed the information about color, orientation, and color-orientation conjunctions of those invisible bars. The information of those features was then used for the unconscious configuration analysis (statistical processing) of the central bars, which induced a perceptual bias and illusory feature binding in visible stimuli at peripheral locations. While statistical analyses and feature binding are normally 2 key functions of the visual system to construct coherent percepts of visual scenes, our results show that a high-level analysis combining those 2 functions is correctly performed by unconscious computations in the brain. |
Alexandre Zenon; Mariam Sidibe; Etienne Olivier Disrupting the supplementary motor area makes physical effort appear less effortful Journal Article In: Journal of Neuroscience, vol. 35, no. 23, pp. 8737–8744, 2015. @article{Zenon2015,The perception of physical effort is relatively unaffected by the suppression of sensory afferences, indicating that this function relies mostly on the processing of the central motor command. Neural signals in the supplementary motor area (SMA) correlate with the intensity of effort, suggesting that the motor signal involved in effort perception could originate from this area, but experimental evidence supporting this view is still lacking. Here, we tested this hypothesis by disrupting neural activity in SMA, in primary motor cortex (M1), or in a control site by means of continuous theta-burst transcranial magnetic stimulation, while measuring effort perception during grip forces of different intensities. After each grip force exertion, participants had the opportunity to either accept or refuse to replicate the same effort for varying amounts of reward. In addition to the subjective rating of perceived exertion, effort perception was estimated on the basis of the acceptance rate, the effort replication accuracy, the influence of the effort exerted in trial t on trial t+1, and pupil dilation. We found that disruption of SMA activity, but not of M1, led to a consistent decrease in effort perception, whatever the measure used to assess it. Accordingly, we modeled effort perception in a structural equation model and found that only SMA disruption led to a significant alteration of effort perception. These findings indicate that effort perception relies on the processing of a signal originating from motor-related neural circuits upstream of M1 and that SMA is a key node of this network. |
Likan Zhan; Stephen Crain; Peng Zhou The online processing of only if and even if conditional statements: Implications for mental models Journal Article In: Journal of Cognitive Psychology, vol. 27, pp. 367–379, 2015. @article{Zhan2015,A sentential connective like only if or even if merges two simple propositions into a complex statement. This study used a visual world paradigm experiment to explore how this merging process proceeds online. We first presented participants with a short animation, illustrating different simple propositions that are possible to be merged by the sentential connectives. We then auditorily played an only if or an even if statement and recorded participants' eye movements on the concurrent test image. We observed that hearing the sentential connective results in more fixations on the tokens of the appropriate propositions that are eligible to be merged by the sentential connective. Each sentential connective elicited anticipatory effect suggests that once they heard the sentential connective, participants knew which propositions could be merged. We then discussed the implications of our results to the mental model theory of conditionals and the experimental studies reported in literature. |
Jiedong Zhang; Jia Liu; Yaoda Xu Neural decoding reveals impaired face configural processing in the right fusiform face area of individuals with developmental prosopagnosia Journal Article In: Journal of Neuroscience, vol. 35, no. 4, pp. 1539–1548, 2015. @article{Zhang2015,Most of human daily social interactions rely on the ability to successfully recognize faces. Yet ∼2% of the human population suffers from face blindness without any acquired brain damage [this is also known as developmental prosopagnosia (DP) or congenital prosopagnosia]). Despite the presence of severe behavioral face recognition deficits, surprisingly, a majority of DP individuals exhibit normal face selectivity in the right fusiform face area (FFA), a key brain region involved in face configural processing. This finding, together with evidence showing impairments downstream from the right FFA in DP individuals, has led some to argue that perhaps the right FFA is largely intact in DP individuals. Using fMRI multivoxel pattern analysis, here we report the discovery of a neural impairment in the right FFA of DP individuals that may play a critical role in mediating their face-processing deficits. In seven individuals with DP, we discovered that, despite the right FFA's preference for faces and it showing decoding for the different face parts, it exhibited impaired face configural decoding and did not contain distinct neural response patterns for the intact and the scrambled face configurations. This abnormality was not present throughout the ventral visual cortex, as normal neural decoding was found in an adjacent object-processing region. To our knowledge, this is the first direct neural evidence showing impaired face configural processing in the right FFA in individuals with DP. The discovery of this neural impairment provides a new clue to our understanding of the neural basis of DP. |
Luming Zhang; Meng Wang; Liqiang Nie; Liang Hong; Yong Rui; Qi Tian Retargeting semantically-rich photos Journal Article In: IEEE Transactions on Multimedia, vol. 17, no. 9, pp. 1538–1549, 2015. @article{Zhang2015a,Semantically-rich photos contain a rich variety of semantic objects (e.g., pedestrians and bicycles). Retargeting these photos is a challenging task since each semantic object has fixed geometric characteristics. Shrinking these objects simultaneously during retargeting is prone to distortion. In this paper, we propose to retarget semantically-rich photos by detecting photo semantics from image tags, which are predicted by a multi-label SVM. The key technique is a generative model termed latent stability discovery (LSD). It can robustly localize various semantic objects in a photo by making use of the predicted noisy image tags. BasedonLSD,afeaturefusionalgorithm is proposed to detect salient regions at both the low-level and high-level. These salient regions are linked into a path sequentially to simulate human visual perception. Finally, we learn the prior distribution of such paths from aesthetically pleasing training photos. The prior enforces the path of a retargeted photo to be maximally similar to those from the training photos. In the experiment, we collect 217 1600x1200 photos, each containing over seven salient objects. Comprehensive user studies demonstrate the competitiveness of our method. |
Wenjia Zhang; Nan Li; Xiaoyue Wang; Suiping Wang Integration of sentence-level semantic information in parafovea: Evidence from the RSVP-flanker paradigm Journal Article In: PLoS ONE, vol. 10, no. 9, pp. e0139016, 2015. @article{Zhang2015b,During text reading, the parafoveal word was usually presented between 2° and 5° from the point of fixation. Whether semantic information of parafoveal words can be processed during sentence reading is a critical and long-standing issue. Recently, studies using the RSVP-flanker paradigm have shown that the incongruent parafoveal word, presented as right flanker, elicited a more negative N400 compared with the congruent parafoveal word. This suggests that the semantic information of parafoveal words can be extracted and integrated during sentence reading, because the N400 effect is a classical index of semantic integration. However, as most previous studies did not control the word-pair congruency of the parafoveal and the foveal words that were presented in the critical triad, it is still unclear whether such integration happened at the sentence level or just at the word-pair level. The present study addressed this question by manipulating verbs in Chinese sentences to yield either a semantically congruent or semantically incongruent context for the critical noun. In particular, the interval between the critical nouns and verbs was controlled to be 4 or 5 characters. Thus, to detect the incongruence of the parafoveal noun, participants had to integrate it with the global sentential context. The results revealed that the N400 time-locked to the critical triads was more negative in incongruent than in congruent sentences, suggesting that parafoveal semantic information can be integrated at the sentence level during Chinese reading. |
Youming Zhang; Jorma Laurikkala; Martti Juhola; Youming Zhang; Jorma Laurikkala; Martti Juhola Biometric verification with eye movements: Results from a long-term recording series Journal Article In: IET Biometrics, vol. 4, no. 3, pp. 162–168, 2015. @article{Zhang2015c,The authors present the author's results of using saccadic eye movements for biometric user verification. The method can be applied to computers or other devices, in which it is possible to include an eye movement camera system. Thus far, this idea has been little researched. As they have extensively studied eye movement signals for medical applications, they saw an opportunity for the biometric use of saccades. Saccades are the fastest of all eye movements, and are easy to stimulate and detect from signals. As signals measured from a physiological origin, the properties of eye movements (e.g. latency and maximum angular velocity) may contain considerable variability between different times of day, between days or weeks and so on. Since such variability might impair biometric verification based on saccades, they attempted to tackle this issue. In contrast to their earlier results, where they did not include such long intervals between sessions of eye movement recordings as in the present research, their results showed that – notwithstanding some variability present in saccadic variables – this variability was not considerable enough to essentially disturb or impair verification results. The only exception was a test series of very long intervals ∼16 or 32 months in length. For the best results obtained with various classification methods, false rejection and false acceptance rates were <5%. Thus, they conclude that saccadic eye movements can provide a realistic basis for biometric user verification. |
Thomas D. Wright; Aaron Margolis; Jamie Ward Using an auditory sensory substitution device to augment vision: evidence from eye movements Journal Article In: Experimental Brain Research, vol. 233, no. 3, pp. 851–860, 2015. @article{Wright2015,Sensory substitution devices convert information normally associated with one sense into another sense (e.g. converting vision into sound). This is often done to compensate for an impaired sense. The present research uses a multimodal approach in which both natural vision and sound-from-vision ('soundscapes') are simultaneously presented. Although there is a systematic correspondence between what is seen and what is heard, we introduce a local discrepancy between the signals (the presence of a target object that is heard but not seen) that the participant is required to locate. In addition to behavioural responses, the participants' gaze is monitored with eye-tracking. Although the target object is only presented in the auditory channel, behavioural performance is enhanced when visual information relating to the non-target background is presented. In this instance, vision may be used to generate predictions about the soundscape that enhances the ability to detect the hidden auditory object. The eye-tracking data reveal that participants look for longer in the quadrant containing the auditory target even when they subsequently judge it to be located elsewhere. As such, eye movements generated by soundscapes reveal the knowledge of the target location that does not necessarily correspond to the actual judgment made. The results provide a proof of principle that multimodal sensory substitution may be of benefit to visually impaired people with some residual vision and, in normally sighted participants, for guiding search within complex scenes. |
Timothy J. Wright; Walter R. Boot; James R. Brockmole Functional fixedness: The functional significance of delayed disengagement based on attention set. Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 17–21, 2015. @article{Wright2015a,During search, the disengagement of attention is automatically delayed when a fixated but task-irrelevant object shares features of the search target. We examined whether delayed disengagement based on top-down attention set is potentially functional, resulting in additional processing of the fixated item. To accomplish this, we adapted the oculomotor disengagement paradigm. Participants saccaded to a peripheral object of a particular color and responded to the identity of the letter within it. To initiate search participants made a saccade away from an always irrelevant object at the center of the screen that matched or mismatched the target's color and contained a letter that was congruent or incongruent with the target letter. We found that delayed disengagement based on attention set was associated with deeper processing of the center item: a congruency effect between the center letter and peripheral target letter was only observed when the center object's color matched participants' attention set. Results are consistent with the proposal that delayed disengagement based on attention set is functionally significant, automatically encouraging deeper levels of processing of target-like objects that fall within the focus of attention. |
Timothy J. Wright; Walter R. Boot; John L. Jones Exploring the breadth of the top-down representations that control attentional disengagement Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 5, pp. 993–1006, 2015. @article{Wright2015b,A cross-sectional prospective study was conducted between the period December 1991 and November 1992, to identify the extent of smoking among practising doctors and other health professionals in general hospitals and health clinics in Al-Ain, United Arab Emirates. The study population consisted of 300 health professionals (doctors, specialists both clinical and non-clinical, pharmacists and dentists). They were handed self-administered questionnaires adapted from the World Health Organization standard questionnaire on smoking among health professionals. Among the responding 268 (89%) health professionals 197 (73.5%) were men, and 71 (26.5%) women. Among the men health professionals 86 (43.7%) were current smokers, 24 (12.2%) were ex-smokers and 87 (44.2%) were non-smokers, while among the women health professionals 4 (5.6%) were smokers, 1 (1.4%) was an ex-smoker and 66 (93%) were non-smokers. Doctors were uniformly aware of the detrimental effects of smoking, particularly its association with lung cancer, coronary artery disease, chronic bronchitis, and laryngeal cancer, and this was the major reason for their abstaining or wanting to quit the habit. The relationship of smoking with bladder cancer, soft tissue lesion (mouth and lip) and neonatal death was not well appreciated. Counselling patients about the hazards of smoking was practised significantly less often by doctors who smoked. The majority (83.6%) expressed the need for specific training for counselling patients to stop smoking. The options favoured by the health professionals for preventing smoking included a ban on tobacco advertising, specific health warnings on cigarette packets and restriction on smoking in public places, particularly in hospitals and clinics. |
Timothy J. Wright; Thomas Vitale; Walter R. Boot; Neil Charness The impact of red light running camera flashes on younger and older drivers' attention and oculomotor control Journal Article In: Psychology and Aging, vol. 30, no. 4, pp. 755–767, 2015. @article{Wright2015c,Recent empirical evidence suggests that the flashes associated with red light running cameras (RLRCs) distract younger drivers, pulling attention away from the roadway and delaying processing of safety-relevant events. Considering the perceptual and attentional declines that occur with age, older drivers may be especially susceptible to the distracting effects of RLRC flashes, particularly in situations in which the flash is more salient (a bright flash at night compared to the day). The current study examined how age and situational factors potentially influence attention capture by RLRC flashes using covert (cuing effects) and overt (eye movement) indices of capture. We manipulated the salience of the flash by varying its luminance and contrast with respect to the background of the driving scene (either day or night scenes). Results of two experiments suggest that simulated RLRC flashes capture observers' attention, but, surprisingly, no age differences in capture were observed. However, an analysis examining early and late eye movements revealed that older adults may have been strategically delaying their eye movements in order to avoid capture. Additionally, older adults took longer to disengage attention following capture, suggesting at least one age-related disadvantage in capture situations. Findings have theoretical implications for understanding age differences in attention capture, especially with respect to capture in real-world scenes, and inform future work that should examine how the distracting effects of RLRC flashes influence driver behavior. |
Valentin Wyart; Nicholas E. Myers; Christopher Summerfield Neural mechanisms of human perceptual choice under focused and divided attention Journal Article In: Journal of Neuroscience, vol. 35, no. 8, pp. 3485–3498, 2015. @article{Wyart2015,Perceptual decisions occur after the evaluation and integration of momentary sensory inputs, and dividing attention between spatially disparate sources of information impairs decision performance. However, it remains unknown whether dividing attention degrades the precision of sensory signals, precludes their conversion into decision signals, or dampens the integration of decision information toward an appropriate response. Here we recorded human electroencephalographic (EEG) activity while participants categorized one of two simultaneous and independent streams of visual gratings according to their average tilt. By analyzing trial-by-trial correlations between EEG activity and the information offered by each sample, we obtained converging behavioral and neural evidence that dividing attention between left and right visual fields does not dampen the encoding of sensory or decision information. Under divided attention, momentary decision information from both visual streams was encoded in slow parietal signals without interference but was lost downstream during their integration as reflected in motor mu- and beta-band (10-30 Hz) signals, resulting in a "leaky" accumulation process that conferred greater behavioral influence to more recent samples. By contrast, sensory inputs that were explicitly cued as irrelevant were not converted into decision signals. These findings reveal that a late cognitive bottleneck on information integration limits decision performance under divided attention, and places new capacity constraints on decision-theoretic models of information integration under cognitive load. |
Ming Xiang; Sui Ping Wang; Yan Ling Cui Constructing covert dependencies-The case of Mandarin wh-in-situ dependency Journal Article In: Journal of Memory and Language, vol. 84, pp. 139–166, 2015. @article{Xiang2015,Wh-in-situ constructions in Mandarin Chinese, as opposed to their English counterparts that front wh-phrases to the beginning of the sentence, have the same word order as regular non-wh declaratives. We argue that despite their surface word order, processing wh-in-situ constructions involves constructing a covert non-local syntactic dependency between the in-situ wh-phrase and a higher scope position at a clause boundary, leading to behavioral patterns similar to those associated with the processing of overt dependencies. In two comprehension experiments, we showed that the process of linking an in-situ wh-phrase and its scope position induces a similarity-based memory interference effect if another clause boundary position intervenes. In addition, a set of sentence completion studies also showed that the production of wh-in-situ constructions is heavily modulated by the increased working memory burden that results from planning and maintaining a non-local dependency. |
Jianbo Xiao; Xin Huang Distributed and dynamic neural encoding of multiple motion directions of transparently moving stimuli in cortical area MT Journal Article In: Journal of Neuroscience, vol. 35, no. 49, pp. 16180–16198, 2015. @article{Xiao2015,Segmenting visual scenes into distinct objects and surfaces is a fundamental visual function. To better understand the underlying neural mechanism, we investigated how neurons in the middle temporal cortex (MT) of macaque monkeys represent overlapping random-dot stimuli moving transparently in slightly different directions. It has been shown that the neuronal response elicited by two stimuli approximately follows the average of the responses elicited by the constituent stimulus components presented alone. In this scheme of response pooling, the ability to segment two simultaneously presented motion directions is limited by the width of the tuning curve to motion in a single direction. We found that, although the population-averaged neuronal tuning showed response averaging, subgroups of neurons showed distinct patterns of response tuning and were capable of representing component directions that were separated by a small angle—less than the tuning width to unidirectional stimuli. One group of neurons preferentially represented the component direction at a specific side of the bidirectional stimuli, weighting one stimulus component more strongly than the other. Another group of neurons pooled the component responses nonlinearly and showed two separate peaks in their tuning curves even when the average of the component responses was unimodal. We also show for the first time that the direction tuning of MT neurons evolved from initially representing the vector-averaged direction of slightly different stimuli to gradually representing the component directions. Our results reveal important neural processes underlying image segmentation and suggest that information about slightly different stimulus com- ponents is computed dynamically and distributed across neurons. |
Ying-Zi Xiong; Cong Yu; Jun-Yun Zhang Perceptual learning eases crowding by reducing recognition errors but not position errors Journal Article In: Journal of Vision, vol. 15, no. 11, pp. 16, 2015. @article{Xiong2015,When an observer reports a letter flanked by additional letters in the visual periphery, the response errors (the crowding effect) may result from failure to recognize the target letter (recognition errors), from mislocating a correctly recognized target letter at a flanker location (target misplacement errors), or from reporting a flanker as the target letter (flanker substitution errors). Crowding can be reduced through perceptual learning. However, it is not known how perceptual learning operates to reduce crowding. In this study we trained observers with a partial-report task (Experiment 1), in which they reported the central target letter of a three- letter string presented in the visual periphery, or a whole-report task (Experiment 2), in which they reported all three letters in order.We then assessed the impact of training on recognition of both unflanked and flanked targets, with particular attention to how perceptual learning affected the types of errors. Our results show that training improved target recognition but not single-letter recognition, indicating that training indeed affected crowding. However, training did not reduce target misplacement errors or flanker substitution errors. This dissociation between target recognition and flanker substitution errors supports the view that flanker substitution may be more likely a by- product (due to response bias), rather than a cause, of crowding. Moreover, the dissociation is not consistent with hypothesized mechanisms of crowding that would predict reduced positional errors. |
Yangqing Xu; Steven L. Franconeri Capacity for visual features in mental rotation Journal Article In: Psychological Science, vol. 26, no. 8, pp. 1241–1251, 2015. @article{Xu2015,Although mental rotation is a core component of scientific reasoning, little is known about its underlying mechanisms. For instance, how much visual information can someone rotate at once? We asked participants to rotate a simple multipart shape, requiring them to maintain attachments between features and moving parts. The capacity of this aspect of mental rotation was strikingly low: Only one feature could remain attached to one part. Behavioral and eye-tracking data showed that this single feature remained "glued" via a singular focus of attention, typically on the object's top. We argue that the architecture of the human visual system is not suited for keeping multiple features attached to multiple parts during mental rotation. Such measurement of capacity limits may prove to be a critical step in dissecting the suite of visuospatial tools involved in mental rotation, leading to insights for improvement of pedagogy in science-education contexts. |
Jingjing Zhao; Yonghui Wang; Donglai Liu; Liang Zhao; Peng Liu In: Attention, Perception, & Psychophysics, vol. 77, no. 7, pp. 2284–2292, 2015. @article{Zhao2015,It was found in previous studies that two types of objects (rectangles formed according to the Gestalt principle and Chinese words formed in a top-down fashion) can both induce an object-based effect. The aim of the present study was to investigate how the strength of an object representation affects the result of the competition between these two types of objects based on research carried out by Liu, Wang and Zhou [(2011) Acta Psychologica, 138(3), 397-404]. In Experiment 1, the rectangles were filled with two different colors to increase the strength of Gestalt object representation, and we found that the object effect changed significantly for the different stimulus types. Experiment 2 used Chinese words with various familiarities to manipulate the strength of the top-down object representation. As a result, the object-based effect induced by rectangles was observed only when the Chinese word familiarity was low. These results suggest that the strength of object representation determines the result of competition between different types of objects. |
Maryam Ziaei; William Hippel; Julie D. Henry; Stefanie I. Becker Are age effects in positivity influenced by the valence of distractors? Journal Article In: PLoS ONE, vol. 10, no. 9, pp. e0137604, 2015. @article{Ziaei2015,An age-related ‘positivity' effect has been identified, in which older adults show an information- processing bias towards positive emotional items in attention and memory. In the present study, we examined this positivity bias by using a novel paradigm in which emotional and neutral distractors were presented along with emotionally valenced targets. Thirty-five older and 37 younger adults were asked during encoding to attend to emotional targets paired with distractors that were either neutral or opposite in valence to the target. Pupillary responses were recorded during initial encoding as well as a later incidental recognition task. Memory and pupillary responses for negative items were not affected by the valence of distractors, suggesting that positive distractors did not automatically attract older adults' attention while they were encoding negative targets. Additionally, the pupil dilation to negative items mediated the relation between age and positivity in memory. Overall, memory and pupillary responses provide converging support for a cognitive control account of positivity effects in late adulthood and suggest a link between attentional processes and the memory positivity effect. |
Eckart Zimmermann Visual mislocalization during double-step saccades Journal Article In: Frontiers in Systems Neuroscience, vol. 9, pp. 132, 2015. @article{Zimmermann2015,Visual objects presented briefly at the time of saccade onset appear compressed toward the saccade target. Compression strength depends on the presentation of a visual saccade target signal and is strongly reduced during the second saccade of a double-step saccade sequence (Zimmermann et al., 2014b). Here, I tested whether perisaccadic compression is linked to saccade planning by contrasting two double-step paradigms. In the same-direction double-step paradigm, subjects were required to perform two rightward 10° saccades successively. At various times around execution of the saccade sequence a probe dot was briefly flashed. Subjects had to localize the position of the probe dot after they had completed both saccades. I found compression of visual space only at the time of the first but not at the time of the second saccade. In the reverse-direction paradigm, subjects performed first a rightward 10° saccade followed by a leftward 10° saccade back to initial fixation. In this paradigm compression was found in similar magnitude during both saccades. Analysis of the saccade parameters did not reveal indications of saccade sequence preplanning in this paradigm. I therefore conclude that saccade planning, rather than saccade execution factors, is involved in perisaccadic compression. |
Funda Yildirim; Frans W. Cornelissen Saccades follow perception when judging location Journal Article In: i-Perception, vol. 6, no. 6, pp. 1–10, 2015. @article{Yildirim2015,An unresolved question in vision research is whether perceptual decision making and action are based on the same or on different neural representations. Here, we address this question for a straightforward task, the judgment of location. In our experiment, observers decided on the closer of two peripheral objects-situated on the horizontal meridian in opposite hemifields-and made a saccade to indicate their choice. Correct saccades landed close to the actual (physical) location of the target. However, in case of errors, saccades went in the direction of the more distant object, yet landed on a position approximating that of the closer one. Our finding supports the notion that perception and action-related decisions on object location rely on the same neural representation. |
Funda Yildirim; Vincent Meyer; Frans W. Cornelissen Eyes on crowding: Crowding is preserved when responding by eye and similarly affects identity and position accuracy Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 1–14, 2015. @article{Yildirim2015a,Peripheral vision guides recognition and selection of targets for eye movements. Crowding—a decline in recognition performance that occurs when a potential target is surrounded by other, similar, objects—influences peripheral object recognition. A recent model study suggests that crowding may be due to increased uncertainty about both the identity and the location of peripheral target objects, but very few studies have assessed these properties in tandem. Eye tracking can integrally provide information on both the perceived identity and the position of a target and therefore could become an important approach in crowding studies. However, recent reports suggest that around the moment of saccade preparation crowding may be significantly modified. If these effects were to generalize to regular crowding tasks, it would complicate the interpretation of results obtained with eye tracking and the comparison to results obtained using manual responses. For this reason, we first assessed whether the manner by which participants responded—manually or by eye—affected their performance.We found that neither recognition performance nor response time was affected by the response type. Hence, we conclude that crowding magnitude was preserved when observers responded by eye. In our main experiment, observers made eye movements to the location of a tilted Gabor target while we varied flanker tilt to manipulate target–flanker similarity. The results indicate that this similarly affected the accuracy of peripheral recognition and saccadic target localization. Our results inform about the importance of both location and identity uncertainty in crowding. |
Takumi Yokosaka; Scinob Kuroki; Shin'ya Nishida; Junji Watanabe Apparent time interval of visual stimuli is compressed during fast hand movement Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0124901, 2015. @article{Yokosaka2015,The influence of body movements on visual time perception is receiving increased attention. Past studies showed apparent expansion of visual time before and after the execution of hand movements and apparent compression of visual time during the execution of eye movements. Here we examined whether the estimation of sub-second time intervals between visual events is expanded, compressed, or unaffected during the execution of hand movements. The results show that hand movements, at least the fast ones, reduced the apparent time interval between visual events. A control experiment indicated that the apparent time compression was not produced by the participants' involuntary eye movements during the hand movements. These results, together with earlier findings, suggest hand movement can change apparent visual time either in a compressive way or in an expansive way, depending on the relative timing between the hand movement and visual stimulus. |
Keir X. X. Yong; Kishan Rajdev; Timothy J. Shakespeare; Alexander P. Leff; Sebastian J. Crutch Facilitating text reading in posterior cortical atrophy Journal Article In: Neurology, vol. 85, no. 4, pp. 339–348, 2015. @article{Yong2015,OBJECTIVE: We report (1) the quantitative investigation of text reading in posterior cortical atrophy (PCA), and (2) the effects of 2 novel software-based reading aids that result in dramatic improvements in the reading ability of patients with PCA. METHODS: Reading performance, eye movements, and fixations were assessed in patients with PCA and typical Alzheimer disease and in healthy controls (experiment 1). Two reading aids (single- and double-word) were evaluated based on the notion that reducing the spatial and oculomotor demands of text reading might support reading in PCA (experiment 2). RESULTS: Mean reading accuracy in patients with PCA was significantly worse (57%) compared with both patients with typical Alzheimer disease (98%) and healthy controls (99%); spatial aspects of passages were the primary determinants of text reading ability in PCA. Both aids led to considerable gains in reading accuracy (PCA mean reading accuracy: single-word reading aid = 96%; individual patient improvement range: 6%-270%) and self-rated measures of reading. Data suggest a greater efficiency of fixations and eye movements under the single-word reading aid in patients with PCA. CONCLUSIONS: These findings demonstrate how neurologic characterization of a neurodegenerative syndrome (PCA) and detailed cognitive analysis of an important everyday skill (reading) can combine to yield aids capable of supporting important everyday functional abilities. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for patients with PCA, 2 software-based reading aids (single-word and double-word) improve reading accuracy. |
Steffi Zander; Maria Reichelt; Stefanie Wetzel; Frauke Kämmerer; Sven Bertel Does personalisation promote learners' attention? An eye-tracking study Journal Article In: Frontline Learning Research, vol. 3, no. 4, pp. 1–13, 2015. @article{Zander2015,The personalisation principle is a design recommendation and states that multimedia presentations using personalised language promote learning better than those using formal language (e.g., using ‘your' instead of ‘the'). It is often assumed that this design recommendation affects motivation and therefore allocation of attention. To gain further insight into the processes underlying personalisation effects we conducted an eye tracking experiment with 37 German university students who were presented with either personalised or formal learning materials. We examined group differences in attention allocation parameters (fixation count, fixation duration, transition count). The eye-tracking data was combined with self-reports concerning motivation, cognitive load, and learning outcomes. Eye-tracking data revealed a significantly higher reading depth for the main picture areas of interest in the personalised condition. Additionally, participants found the personalised version more appealing and inviting. For learning outcomes, there was a significant positive effect of personalisation for retention, not for transfer. We discuss additional explanatory variables as well as methodological and practical implications for instructional design. |
Xuelian Zang; Lina Jia; Hermann J. Müller; Zhuanghua Shi Invariant spatial context is learned but not retrieved in gaze-contingent limited-viewing search Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 3, pp. 807–819, 2015. @article{Zang2015,Our visual brain is remarkable in extracting invariant properties from the noisy environment, guiding selection of where to look and what to identify. However, how the brain achieves this is still poorly understood. Here we explore interactions of local context and global structure in the long-term learning and retrieval of invariant display properties. Participants searched for a target among distractors, without knowing that some “old” configurations were presented repeatedly (randomly inserted among “new” configurations). We simulated tunnel vision, limiting the visible region around fixation. Robust facilitation of performance for old versus new contexts was observed when the visible region was large but not when it was small. However, once the display was made fully visible during the subsequent transfer phase, facilitation did become manifest. Furthermore, when participants were given a brief preview of the total display layout prior to tunnel view search with 2 items visible, facilitation was already obtained during the learning phase. The eye movement results revealed contextual facilitation to be coupled with changes of saccadic planning, characterized by slightly extended gaze durations but a reduced number of fixations and shortened scan paths for old displays. Taken together, our findings show that invariant spatial display properties can be acquired based on scarce, para-/foveal information, while their effective retrieval for search guidance requires the availability (even if brief) of a certain extent of peripheral information. |
Theodoros P. Zanos; Patrick J. Mineault; Konstantinos T. Nasiotis; Daniel Guitton; Christopher C. Pack A sensorimotor role for traveling waves in primate visual cortex Journal Article In: Neuron, vol. 85, no. 3, pp. 615–627, 2015. @article{Zanos2015,Traveling waves of neural activity are frequently observed to occur in concert with the presentation of a sensory stimulus or the execution of a movement. Although such waves have been studied for decades, little is known about their function. Here we show that traveling waves in the primate extrastriate visual cortex provide a means of integrating sensory and motor signals. Specifically, we describe a traveling wave of local field potential (LFP) activity in cortical area V4 of macaque monkeys that is triggered by the execution of saccadic eye movements. These waves sweep across the V4 retinotopic map, following a consistent path from the foveal to the peripheral representations of space; their amplitudes correlate with the direction and size of each saccade. Moreover, these waves are associated with a reorganization of the postsaccadic neuronal firing patterns, which follow a similar retinotopic progression, potentially prioritizing the processing of behaviorally relevant stimuli. |
Andrea M. Zawoyski; Scott P. Ardoin; Katherine S. Binder Using eye tracking to observe differential effects of repeated readings for second-grade students as a function of achievement level Journal Article In: Reading Research Quarterly, vol. 50, no. 2, pp. 171–184, 2015. @article{Zawoyski2015,Repeated readings (RR) is an evidence-based instructional technique in which students read the same text multiple times. Currently, little is known about how effects of RR may differ based on students' achievement levels. Eye tracking provides a means for closely examining instructional effects because it permits measurement of subtle changes that occur during RR. The current study measured changes in the reading behavior of second-grade students who were divided into two groups of 22 students each based on their reading achievement levels. Participants read a grade-level passage embedded with low-and high-frequency target words four times in a single session while their eye movements were recorded. Findings replicated those of previous research, suggesting that RR facilitated reading for students in both groups, particularly on low-frequency target words. Results indicated both similarities and differences in patterns of performance between lower and higher performing readers. Additionally, results implied that effects were greater for lower performing readers because they made greater improvements on high-frequency target words, whereas effects were diminished for higher performing readers. The findings have implications for improving future eye movement research investigating young students' reading and the efficiency of RR in the classroom. |
Eckart Zimmermann; Florian Ostendorf; C. J. Ploner; Markus Lappe Impairment of saccade adaptation in a patient with a focal thalamic lesion Journal Article In: Journal of Neurophysiology, vol. 113, no. 7, pp. 2351–2359, 2015. @article{Zimmermann2015b,The frequent jumps of the eyeballs-called saccades-imply the need for a constant correction of motor errors. If systematic errors are detected in saccade landing, the saccade amplitude adapts to compensate for the error. In the laboratory, saccade adaptation can be studied by displacing the saccade target. Functional selectivity of adaptation for different saccade types suggests that adaptation occurs at multiple sites in the oculomotor system. Saccade motor learning might be the result of a comparison between a prediction of the saccade landing position and its actual postsaccadic location. To investigate whether a thalamic feedback pathway might carry such a prediction signal, we studied a patient with a lesion in the posterior ventrolateral thalamic nucleus. Saccade adaptation was tested for reactive saccades, which are performed to suddenly appearing targets, and for scanning saccades, which are performed to stationary targets. For reactive saccades, we found a clear impairment in adaptation retention ipsilateral to the lesioned side and a larger-than-normal adaptation on the contralesional side. For scanning saccades, adaptation was intact on both sides and not different from the control group. Our results provide the first lesion evidence that adaptation of reactive and scanning saccades relies on distinct feedback pathways from cerebellum to cortex. They further demonstrate that saccade adaptation in humans is not restricted to the cerebellum but also involves cortical areas. The paradoxically strong adaptation for outward target steps can be explained by stronger reliance on visual targeting errors when prediction error signaling is impaired. |
Eckart Zimmermann; M. Concetta Morrone; David C. Burr Visual mislocalization during saccade sequences Journal Article In: Experimental Brain Research, vol. 233, no. 2, pp. 577–585, 2015. @article{Zimmermann2015a,Visual objects briefly presented around the time of saccadic eye movements are perceived compressed towards the saccade target. Here, we investigated perisaccadic mislocalization with a double-step saccade paradigm, measuring localization of small probe dots briefly flashed at various times around the sequence of the two saccades. At onset of the first saccade, probe dots were mislocalized towards the first and, to a lesser extent, also towards the second saccade target. However, there was very little mislocalization at the onset of the second saccade. When we increased the presentation duration of the saccade targets prior to onset of the saccade sequence, perisaccadic mislocalization did occur at the onset of the second saccade. |