All EyeLink Eye Tracker Publications
All 14,000+ peer-reviewed EyeLink research publications up until 2025 (with some early 2026s) 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!
2016 |
Liu D. Liu; Ralf M. Haefner; Christopher C. Pack A neural basis for the spatial suppression of visual motion perception Journal Article In: eLife, vol. 5, pp. 1–20, 2016. @article{Liu2016c,In theory, sensory perception should be more accurate when more neurons contribute to the representation of a stimulus. However, psychophysical experiments that use larger stimuli to activate larger pools of neurons sometimes report impoverished perceptual performance. To determine the neural mechanisms underlying these paradoxical findings, we trained monkeys to discriminate the direction of motion of visual stimuli that varied in size across trials, while simultaneously recording from populations of motion-sensitive neurons in cortical area MT. We used the resulting data to constrain a computational model that explained the behavioral data as an interaction of three main mechanisms: noise correlations, which prevented stimulus information from growing with stimulus size; neural surround suppression, which decreased sensitivity for large stimuli; and a read-out strategy that emphasized neurons with receptive fields near the stimulus center. These results suggest that paradoxical percepts reflect tradeoffs between sensitivity and noise in neuronal populations. |
Jeroen Atsma; Femke Maij; Mathieu Koppen; David E. Irwin; W. Pieter Medendorp Causal inference for spatial constancy across saccades Journal Article In: PLoS Computational Biology, vol. 12, no. 3, pp. e1004766, 2016. @article{Atsma2016,Our ability to interact with the environment hinges on creating a stable visual world despite the continuous changes in retinal input. To achieve visual stability, the brain must distinguish the retinal image shifts caused by eye movements and shifts due to movements of the visual scene. This process appears not to be flawless: during saccades, we often fail to detect whether visual objects remain stable or move, which is called saccadic suppression of displacement (SSD). How does the brain evaluate the memorized information of the presaccadic scene and the actual visual feedback of the postsaccadic visual scene in the computations for visual stability? Using a SSD task, we test how participants localize the presaccadic position of the fixation target, the saccade target or a peripheral non-foveated target that was displaced parallel or orthogonal during a horizontal saccade, and subsequently viewed for three different durations. Results showed different localization errors of the three targets, depending on the viewing time of the postsaccadic stimulus and its spatial separation from the presaccadic location. We modeled the data through a Bayesian causal inference mechanism, in which at the trial level an optimal mixing of two possible strategies, integration vs. separation of the presaccadic memory and the postsaccadic sensory signals, is applied. Fits of this model generally outperformed other plausible decision strategies for producing SSD. Our findings suggest that humans exploit a Bayesian inference process with two causal structures to mediate visual stability. |
Emmanuel Ducrocq; Mark Wilson; Sam Vine; Nazanin Derakshan Training attentional control improves cognitive and motor task performance Journal Article In: Journal of Sport and Exercise Psychology, vol. 38, no. 5, pp. 521–533, 2016. @article{Ducrocq2016,Attentional control is a necessary function for the regulation of goal-directed behavior. In three experiments we investigated whether training inhibitory control using a visual search task could improve task specific measures of attentional control and performance. In experiment 1 results revealed that training elicited a near-transfer effect; improving performance on a cognitive (antisaccade) task assessing inhibitory control. In Experiment 2 an initial far-transfer effect of training was observed on an index of attentional control validated for tennis. The principal aim of Experiment 3 was to expand on these findings by assessing objective, gaze measures of inhibitory control during the performance of a tennis task. Training improved inhibitory control and performance when pressure was elevated, confirming the mechanisms by which cognitive anxiety impacts upon performance. These results suggest that attentional control training can improve inhibition and reduce task-specific distractibility with promise of transfer to more efficient sporting performance in competitive contexts. |
Benjamin Gagl Blue hypertext is a good design decision: No perceptual disadvantage in reading and successful highlighting of relevant information Journal Article In: PeerJ, vol. 4, pp. 1–11, 2016. @article{Gagl2016,BACKGROUND: Highlighted text in the Internet (i.e., hypertext) is predominantly blue and underlined. The perceptibility of these hypertext characteristics was heavily questioned by applied research and empirical tests resulted in inconclusive results. The ability to recognize blue text in foveal and parafoveal vision was identified as potentially constrained by the low number of foveally centered blue light sensitive retinal cells. The present study investigates if foveal and parafoveal perceptibility of blue hypertext is reduced in comparison to normal black text during reading. METHODS: A silent-sentence reading study with simultaneous eye movement recordings and the invisible boundary paradigm, which allows the investigation of foveal and parafoveal perceptibility, separately, was realized (comparing fixation times after degraded vs. un-degraded parafoveal previews). Target words in sentences were presented in either black or blue and either underlined or normal. RESULTS: No effect of color and underlining, but a preview benefit could be detected for first pass reading measures. Fixation time measures that included re-reading, e.g., total viewing times, showed, in addition to a preview effect, a reduced fixation time for not highlighted (black not underlined) in contrast to highlighted target words (either blue or underlined or both). DISCUSSION: The present pattern reflects no detectable perceptual disadvantage of hyperlink stimuli but increased attraction of attention resources, after first pass reading, through highlighting. Blue or underlined text allows readers to easily perceive hypertext and at the same time readers re-visited highlighted words longer. On the basis of the present evidence, blue hypertext can be safely recommended to web designers for future use. |
David C. Godlove; Jeffrey D. Schall Microsaccade production during saccade cancelation in a stop-signal task Journal Article In: Vision Research, vol. 118, pp. 5–16, 2016. @article{Godlove2016,We obtained behavioral data to evaluate two alternative hypotheses about the neural mechanisms of gaze control. The "fixation" hypothesis states that neurons in rostral superior colliculus (SC) enforce fixation of gaze. The "microsaccade" hypothesis states that neurons in rostral SC encode microsaccades rather than fixation per se. Previously reported neuronal activity in monkey SC during the saccade stop-signal task leads to specific, dissociable behavioral predictions of these two hypotheses. When subjects are required to cancel partially-prepared saccades, imbalanced activity spreads across rostral and caudal SC with a reliable temporal profile. The microsaccade hypothesis predicts that this imbalance will lead to elevated microsaccade production biased toward the target location, while the fixation hypothesis predicts reduced microsaccade production. We tested these predictions by analyzing the microsaccades produced by 4 monkeys while they voluntarily canceled partially prepared eye movements in response to explicit stop signals. Consistent with the fixation hypothesis and contradicting the microsaccade hypothesis, we found that each subject produced significantly fewer microsaccades when normal saccades were successfully canceled. The few microsaccades escaping this inhibition tended to be directed toward the target location. We additionally investigated interactions between initiating microsaccades and inhibiting normal saccades. Reaction times were longer when microsaccades immediately preceded target presentation. However, pre-target microsaccade production did not affect stop-signal reaction time or alter the probability of canceling saccades following stop signals. These findings demonstrate that imbalanced activity within SC does not necessarily produce microsaccades and add to evidence that saccade preparation and cancelation are separate processes. |
Gary J. Lewis; Timothy C. Bates In: Journal of Cognitive Neuroscience, vol. 28, no. 2, pp. 308–318, 2016. @article{Lewis2016,The ability to adaptively shift between exploration and exploitation control states is critical for optimizing behavioral performance. Converging evidence from primate electrophysiology and computational neural modeling has suggested that this ability may be mediated by the broad norepinephrine projections emanating from the locus coeruleus (LC) [Aston-Jones, G., & Cohen, J. D. An integrative theory of locus coeruleus-norepinephrine function: Adaptive gain and optimal performance. Annual Review of Neuroscience, 28, 403–450, 2005]. There is also evidence that pupil diameter covaries systematically with LC activity. Although imperfect and indirect, this link makes pupillometry a useful tool for studying the locus coeruleus norepinephrine system in humans and in high-level tasks. Here, we present a novel paradigm that examines how the pupillary response during exploration and exploitation covaries with individual differences in fluid intelligence during analogical reasoning on Raven's Advanced Progressive Matrices. Pupillometry was used as a noninvasive proxy for LC activity, and concurrent think-aloud verbal protocols were used to identify exploratory and exploitative solution periods. This novel combination of pupillometry and verbal protocols from 40 participants revealed a decrease inpupil diameter during exploitation and an increase during exploration. The temporal dynamics of the pupillary response was characterized by a steep increase during the transition to exploratory periods, sustained dilation for many seconds afterward, and followed by gradual return to baseline.Moreover, the individual differences in the relative magnitude of pupillary dilation accounted for 16% of the variance in Advanced Progressive Matrices scores. Assuming that pupil diameter is a valid index of LC activity, these results establish promising preliminary connections between the literature on locus coeruleus norepinephrine-mediated cognitive control and the literature on analogical reasoning and fluid intelligence. |
Manon Mulckhuyse; Edwin S. Dalmaijer Distracted by danger: Temporal and spatial dynamics of visual selection in the presence of threat Journal Article In: Cognitive, Affective, & Behavioral Neuroscience, vol. 16, no. 2, pp. 315–324, 2016. @article{Mulckhuyse2016,Threatening stimuli are known to influence attentional and visual processes in order to prioritize selection. For example, previous research showed faster detection of threatening relative to nonthreatening stimuli. This has led to the proposal that threatening stimuli are prioritized automatically via a rapid subcortical route. However, in most studies, the threatening stimulus is always to some extent task relevant. Therefore, it is still unclear if threatening stimuli are automatically prioritized by the visual system. We used the additional singleton paradigm with task-irrelevant fear-conditioned distractors (CS+ and CS-) and indexed the time course of eye movement behavior. The results demonstrate automatic prioritization of threat. First, mean latency of saccades directed to the neutral target was increased in the presence of a threatening (CS+) relative to a nonthreatening distractor (CS-), indicating exogenous attentional capture and delayed disengagement of covert attention. Second, more error saccades were directed to the threatening than to the nonthreatening distractor, indicating a modulation of automatically driven saccades. Nevertheless, cumulative distributions of the saccade latencies showed no modulation of threat for the fastest goal-driven saccades, and threat did not affect the latency of the error saccades to the distractors. Together these results suggest that threatening stimuli are automatically prioritized in attentional and visual selection but not via faster processing. Rather, we suggest that prioritization results from an enhanced representation of the threatening stimulus in the oculomotor system, which drives attentional and visual selection. The current findings are interpreted in terms of a neurobiological model of saccade programming. |
Nada Attar; Matthew H. Schneps; Marc Pomplun Working memory load predicts visual search efficiency: Evidence from a novel pupillary response paradigm Journal Article In: Memory & Cognition, vol. 44, no. 7, pp. 1038–1049, 2016. @article{Attar2016,An observer's pupil dilates and constricts in response to variables such as ambient and focal luminance, cognitive effort, the emotional stimulus content, and working memory load. The pupil's memory load response is of particular interest, as it might be used for estimating observers' memory load while they are performing a complex task, without adding an interruptive and confounding memory test to the protocol. One important task in which working memory's involvement is still being debated is visual search, and indeed a previous experiment by Porter, Troscianko, and Gilchrist (Quarterly Journal of Experimental Psychology, 60, 211-229, 2007) analyzed observers' pupil sizes during search to study this issue. These authors found that pupil size increased over the course of the search, and they attributed this finding to accumulating working memory load. However, since the pupil response is slow and does not depend on memory load alone, this conclusion is rather speculative. In the present study, we estimated working memory load in visual search during the presentation of intermittent fixation screens, thought to induce a low, stable level of arousal and cognitive effort. Using standard visual search and control tasks, we showed that this paradigm reduces the influence of non-memory-related factors on pupil size. Furthermore, we found an early increase in working memory load to be associated with more efficient search, indicating a significant role of working memory in the search process. |
Sang-Hoon Yeo; David W. Franklin; Daniel M. Wolpert When optimal feedback control is not enough: Feedforward strategies are required for optimal control with active sensing Journal Article In: PLoS Computational Biology, vol. 12, no. 12, pp. e1005190, 2016. @article{Yeo2016,Movement planning is thought to be primarily determined by motor costs such as inaccuracy and effort. Solving for the optimal plan that minimizes these costs typically leads to specifying a time-varying feedback controller which both generates the movement and can optimally correct for errors that arise within a movement. However, the quality of the sensory feedback during a movement can depend substantially on the generated movement. We show that by incorporating such state-dependent sensory feedback, the optimal solution incorporates active sensing and is no longer a pure feedback process but includes a significant feedforward component. To examine whether people take into account such state-dependency in sensory feedback we asked people to make movements in which we controlled the reliability of sensory feedback. We made the visibility of the hand state-dependent, such that the visibility was proportional to the component of hand velocity in a particular direction. Subjects gradually adapted to such a sensory perturbation by making curved hand movements. In particular, they appeared to control the late visibility of the movement matching predictions of the optimal controller with state-dependent sensory noise. Our results show that trajectory planning is not only sensitive to motor costs but takes sensory costs into account and argues for optimal control of movement in which feedforward commands can play a significant role. |
Eckart Zimmermann; Ralph Weidner; R. O. Abdollahi; Gereon R. Fink Spatiotopic adaptation in visual areas Journal Article In: Journal of Neuroscience, vol. 36, no. 37, pp. 9526–9534, 2016. @article{Zimmermann2016b,The ability to perceive the visual world around us as spatially stable despite frequent eye movements is one of the long-standing mysteries of neuroscience. The existence of neural mechanisms processing spatiotopic information is indispensable for a successful interaction with the external world. However, how the brain handles spatiotopic information remains a matter of debate. We here combined behavioral and fMRI adaptation to investigate the coding of spatiotopic information in the human brain. Subjects were adapted by a prolonged presentation of a tilted grating. Thereafter, they performed a saccade followed by the brief presentation of a probe. This procedure allowed dissociating adaptation aftereffects at retinal and spatiotopic positions. We found significant behavioral and functional adaptation in both retinal and spatiotopic positions, indicating information transfer into a spatiotopic coordinate system. The brain regions involved were located in ventral visual areas V3, V4, and VO. Our findings suggest that spatiotopic representations involved in maintaining visual stability are constructed by dynamically remapping visual feature information between retinotopic regions within early visual areas. |
Lu Liu; Liang She; Ming Chen; Tianyi Liu; Haidong D. Lu; Yang Dan; Mu-ming Poo Spatial structure of neuronal receptive field in awake monkey secondary visual cortex (V2) Journal Article In: Proceedings of the National Academy of Sciences, vol. 113, no. 7, pp. 1913–1918, 2016. @article{Liu2016d,Visual processing depends critically on the receptive field (RF) properties of visual neurons. However, comprehensive characterization of RFs beyond the primary visual cortex (V1) remains a challenge. Here we report fine RF structures in secondary visual cortex (V2) of awake macaque monkeys, identified through a projection pursuit regression analysis of neuronal responses to natural images. We found that V2 RFs could be broadly classified as V1-like (typical Gabor-shaped subunits), ultralong (subunits with high aspect ratios), or complex-shaped (subunits with multiple oriented components). Furthermore, single-unit recordings from functional domains identified by intrinsic optical imaging showed that neurons with ultralong RFs were primarily localized within pale stripes, whereas neurons with complex-shaped RFs were more concentrated in thin stripes. Thus, by combining single-unit recording with optical imaging and a computational approach, we identified RF subunits underlying spatial feature selectivity of V2 neurons and demonstrated the functional organization of these RF properties. |
Katrine Sand; Thomas Habekost; Anders Petersen; Randi Starrfelt The Word Superiority Effect in central and peripheral vision Journal Article In: Visual Cognition, vol. 24, no. 4, pp. 293–303, 2016. @article{Sand2016,The Word Superiority Effect (WSE) is a well-known phenomenon in reading research, where words are reported more accurately than single letters or non-words. We report two experiments that investigate the WSE in the central and peripheral visual field, as well as laterality differences in the perception of words and letters, using methods based on the Theory of Visual Attention. The results show a WSE in the central visual field, reflected in mean scores, perception thresholds, and processing speed, whereas the effect is eliminated or reversed in the periphery. This may be caused by crowding, which prevents lexical analysis of a word in the periphery. We conclude that perception of words and letters differs according to location in the visual field. Linking our results to previous studies of crowding effects in patients with reading impairments, we hypothesize that similar mechanisms may limit normal word peripheral processing. |
Rosanne M. Diepen; Lee M. Miller; Ali Mazaheri; Joy J. Geng The role of alpha activity in spatial and feature-based attention. Journal Article In: eNeuro, vol. 3, no. 5, pp. 1–11, 2016. @article{Diepen2016,Modulations in alpha oscillations (?10 Hz) are typically studied in the context of anticipating upcoming stimuli. Alpha power decreases in sensory regions processing upcoming targets compared to regions processing distracting input, thereby likely facilitating processing of relevant information while suppressing irrelevant. In this electroencephalography study using healthy human volunteers, we examined whether modulations in alpha power also occur after the onset of a bilaterally presented target and distractor. Spatial attentionwasmanipulated through spatial cues and feature-based attention through adjusting the color-similarity of distractors to the target. Consistent with previous studies, we found that informative spatial cues induced a relative decrease of pretarget alpha power at occipital electrodes contralateral to the expected target location. Interestingly, this pattern reemerged relatively late (300–750 ms) after stimulus onset, suggesting that lateralized alpha reflects not only preparatory attention, but also ongoing attentive stimulus processing. Uninformative cues (i.e., conveying no information about the spatial location of the target) resulted in an interaction between spatial attention and feature-based attention in post-target alpha lateralization. When the target was paired with a low-similarity distractor, post-target alpha was lateralized (500–900 ms). Crucially, the lateralization was absent when target selection was ambig- uous because the distractor was highly similar to the target. Instead, during this condition, midfrontal theta was increased, indicative of reactive conflict resolution. Behaviorally, the degree of alpha lateralization was negatively correlated with the reaction time distraction cost induced by target–distractor similarity. These results suggest a pivotal role for poststimulus alpha lateralization in protecting sensory processing of target information. |
Hui Kou; Yanhua Su; Taiyong Bi; Xiao Gao; Hong Chen Attentional biases toward face-related stimuli among face dissatisfied women: Orienting and maintenance of attention revealed by eye-movement Journal Article In: Frontiers in Psychology, vol. 7, pp. 919, 2016. @article{Kou2016,The present study was aimed to examine attentional biases toward attractive and unattractive faces among face dissatisfied women. Twenty-seven women with high face dissatisfaction (HFD) and 27 women with low face dissatisfaction (LFD) completed a visual dot-probe task while their eye-movements were tracking. Under the condition of faces-neutral stimuli (vases) pairs, compared to LFD women, HFD women directed their first fixations more often toward faces, directed their first fixations toward unattractive faces more quickly, and had longer first fixation duration on such faces. All participants had longer overall gaze duration on attractive faces than on unattractive ones. Our behavioral data revealed that HFD women had difficulty in disengaging their attention from faces. However, there are no group differences in stimulus pairs containing an attractive and an unattractive face. In sum, when faces were paired with neutral stimuli (vases) HFD women showed an attention pattern characterized by orienting and maintenance, at least initially, toward unattractive faces but showed overall attention maintenance to attractive ones, but any attention bias wasn't found in attractive - unattractive face pairs. |
Kaitlin E. W. Laidlaw; Mona J. H. Zhu; Alan Kingstone Looking away: Distractor influences on saccadic trajectory and endpoint in prosaccade and antisaccade tasks Journal Article In: Experimental Brain Research, vol. 234, no. 6, pp. 1637–1648, 2016. @article{Laidlaw2016,Successful target selection often occurs concurrently with distractor inhibition. A better understanding of the former thus requires a thorough study of the competition that arises between target and distractor representations. In the present study, we explore whether the presence of a distractor influences saccade processing via interfering with visual target and/or saccade goal representations. To do this, we asked participants to make either pro- or antisaccade eye movements to a target and measured the change in their saccade trajectory and landing position (collectively referred to as deviation) in response to distractors placed near or far from the saccade goal. The use of an antisaccade paradigm may help to distinguish between stimulus- and goal-related distractor interference, as unlike with prosaccades, these two features are dissociated in space when making a goal-directed antisaccade response away from a visual target stimulus. The present results demonstrate that for both pro- and antisaccades, distractors near the saccade goal elicited the strongest competition, as indicated by greater saccade trajectory deviation and landing position error. Though distractors far from the saccade goal elicited, on average, greater deviation away in antisaccades than in prosaccades, a time-course analysis revealed a significant effect of far-from-goal distractors in prosaccades as well. Considered together, the present findings support the view that goal-related representations most strongly influence the saccade metrics tested, though stimulus-related representations may play a smaller role in determining distractor-based interference effects on saccade execution under certain circumstances. Further, the results highlight the advantage of considering temporal changes in distractor-based interference. |
Jelle A. Dijk; Benjamin Haas; Christina Moutsiana; D. Samuel Schwarzkopf Intersession reliability of population receptive field estimates Journal Article In: NeuroImage, vol. 143, pp. 293–303, 2016. @article{Dijk2016,Population receptive field (pRF) analysis is a popular method to infer spatial selectivity of voxels in visual cortex. However, it remains largely untested how stable pRF estimates are over time. Here we measured the intersession reliability of pRF parameter estimates for the central visual field and near periphery, using a combined wedge and ring stimulus containing natural images. Sixteen healthy human participants completed two scanning sessions separated by 10–114 days. Individual participants showed very similar visual field maps for V1-V4 on both sessions. Intersession reliability for eccentricity and polar angle estimates was close to ceiling for most visual field maps (r>.8 for V1-3). PRF size and cortical magnification (CMF) estimates showed strong but lower overall intersession reliability (r≈.4–.6). Group level results for pRF size and CMF were highly similar between sessions. Additional control experiments confirmed that reliability does not depend on the carrier stimulus used and that reliability for pRF size and CMF is high for sessions acquired on the same day (r>.6). Our results demonstrate that pRF mapping is highly reliable across sessions. |
Veronica Whitford; Debra Titone Eye movements and the perceptual span during first- and second-language sentence reading in bilingual older adults Journal Article In: Psychology and Aging, vol. 31, no. 1, pp. 58–70, 2016. @article{Whitford2016,This study addressed a central yet previously unexplored issue in the psychological science of aging, namely, whether the advantages of healthy aging (e.g., greater lifelong experience with language) or disadvantages (e.g., decreases in cognitive and sensory processing) drive L1 and L2 reading performance in bilingual older adults. To this end, we used a gaze-contingent moving window paradigm to examine both global aspects of reading fluency (e.g., reading rates, number of regressions) and the perceptual span (i.e., allocation of visual attention into the parafovea) in bilingual older adults during L1 and L2 sentence reading, as a function of individual differences in current L2 experience. Across the L1 and L2, older adults exhibited reduced reading fluency (e.g., slower reading rates, more regressions), but a similar perceptual span compared with matched younger adults. Also similar to matched younger adults, older adults' reading fluency was lower for L2 reading than for L1 reading as a function of current L2 experience. Specifically, greater current L2 experience increased L2 reading fluency, but decreased L1 reading fluency (for global reading measures only). Taken together, the dissociation between intact perceptual span and impaired global reading measures suggests that older adults may prioritize parafoveal processing despite age-related encoding difficulties. Consistent with this interpretation, post hoc analyses revealed that older adults with higher versus lower executive control were more likely to adopt this strategy. |
Mario Dalmaso; S. Gareth Edwards; Andrew P. Bayliss Re-encountering individuals who previously engaged in joint gaze modulates subsequent gaze cueing Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 42, no. 2, pp. 271–284, 2016. @article{Dalmaso2016,We assessed the extent to which previous experience of joint gaze with people (i.e., looking toward the same object) modulates later gaze cueing of attention elicited by those individuals. Participants in Experiments 1 and 2a/b first completed a saccade/antisaccade task while a to-be-ignored face either looked at, or away from, the participants' eye movement target. Two faces always engaged in joint gaze with the participant, whereas 2 other faces never engaged in joint gaze. Then, we assessed standard gaze cueing in response to these faces to ascertain the effect of these prior interactions on subsequent social attention episodes. In Experiment 1, the face's eyes moved before the participant's target appeared, meaning that the participant always gaze-followed 2 faces and never gaze-followed 2 other faces. We found that this prior experience modulated the timecourse of subsequent gaze cueing. In Experiments 2a/b, the participant looked at the target first, then was either followed (i.e., the participant initiated joint gaze), or was not followed. These participants then showed an overall decrement of gaze cueing with individuals who had previously followed participants' eyes (Experiment 2a), an effect that was associated with autism spectrum quotient scores and modulated perceived trustworthiness of the faces (Experiment 2b). Experiment 3 demonstrated that these modulations are unlikely to be because of the association of different levels of task difficulty with particular faces. These findings suggest that establishing joint gaze with others influences subsequent social attention processes that are generally thought to be relatively insensitive to learning from prior episodes. |
Nonie J. Finlayson; Julie D. Golomb Feature-location binding in 3D: Feature judgments are biased by 2D location but not position-in-depth Journal Article In: Vision Research, vol. 127, pp. 49–56, 2016. @article{Finlayson2016,A fundamental aspect of human visual perception is the ability to recognize and locate objects in the environment. Importantly, our environment is predominantly three-dimensional (3D), but while there is considerable research exploring the binding of object features and location, it is unknown how depth information interacts with features in the object binding process. A recent paradigm called the spatial congruency bias demonstrated that 2D location is fundamentally bound to object features, such that irrelevant location information biases judgments of object features, but irrelevant feature information does not bias judgments of location or other features. Here, using the spatial congruency bias paradigm, we asked whether depth is processed as another type of location, or more like other features. We initially found that depth cued by binocular disparity biased judgments of object color. However, this result seemed to be driven more by the disparity differences than the depth percept: Depth cued by occlusion and size did not bias color judgments, whereas vertical disparity information (with no depth percept) did bias color judgments. Our results suggest that despite the 3D nature of our visual environment, only 2D location information – not position-in-depth – seems to be automatically bound to object features, with depth information processed more similarly to other features than to 2D location. |
Ralph S. Redden; Matthew D. Hilchey; Raymond M. Klein Peripheral stimuli generate different forms of inhibition of return when participants make prosaccades versus antisaccades to them Journal Article In: Attention, Perception, & Psychophysics, vol. 78, no. 8, pp. 2283–2291, 2016. @article{rhk16,Inhibition of return (IOR) is usually viewed as an inhibitory aftermath ofvisual orienting typically seen in the form ofslower responses to targets presented in a previously oriented to location. As shown by Taylor and Klein (2000. Journal of Experimental Psychology: Human Perception and Performance, 26, 1639–1656), the nature ofthe inhibitory effects resulting from an uninformative cue seemto be contingent on the activation state ofthe oculomotor system. Herewe contrast target discrimination performance following either a prosaccade or antisaccade in the spatial cueing paradigm. Our findings suggest that the level of activation of the reflexive oculomotor system determines the dynamics of the inhibitory effect, wherein an effect nearer to the input end of processing is observed when the reflexive oculomotor system is actively suppressed, and an effect nearer to the output end ofprocessing is observedwhen the reflexive oculomotor system is actively engaged. These effects interact differently with the Simon effect—providing converging evidence that they are dissociable inhibitory phenomena. |
Janice Attard-Johnson; Markus Bindemann; Caoilte Ó Ciardha Pupillary response as an age-specific measure of sexual interest Journal Article In: Archives of Sexual Behavior, vol. 45, no. 4, pp. 855–870, 2016. @article{AttardJohnson2016,In the visual processing of sexual content, pupil dilation is an indicator of arousal that has been linked to observers' sexual orientation. This study investigated whether this measure can be extended to determine age-specific sexual interest. In two experiments, the pupillary responses of heterosexual adults to images of males and females of different ages were related to self-reported sexual interest, sexual appeal to the stimuli, and a child molestation proclivity scale. In both experiments, the pupils of male observers dilated to photographs ofwomen but not men, children, or neutral stimuli. These pupillary responses corresponded with observer's self-reported sexual interests and their sexual appeal ratings of the stimuli. Female observers showed pupil dilation to photographs of men and women but not children. In women,pupillary responses also correlated poorly with sexual appeal ratings ofthe stimuli. These experiments provide initial evidence that eye-tracking could be used as ameasure of sex-specific interest in male observers, and as an age-specific index in male and female observers. |
Kohitij Kar; Bart Krekelberg Testing the assumptions underlying fMRI adaptation using intracortical recordings in area MT Journal Article In: Cortex, vol. 80, pp. 21–34, 2016. @article{Kar2016,We investigated how neural activity in the middle temporal area of the macaque monkey changes after 3 sec of exposure to a visual stimulus and used this to gain insight into the assumptions underlying the fMRI adaptation method (fMRIa). We studied both changes in tuning curves following weak and strong motion stimuli (adaptation) and the differences between a first and second exposure to the same stimulus (repetition suppression). Typically, tuning curves had smaller amplitudes and narrower tuning widths after strong adaptation; this was true for single neurons, multi-unit activity (MUA), the evoked local field potential (LFP), as well as gamma band activity. Repetition typically led to reduced responses. This reduction was correlated with direction selectivity and not explained by neural fatigue. Our data, however, warn against a simplistic view of the consequences of adaptation. First, a considerable fraction of neurons and sites showed response enhancements after adaptation, especially when probed with a stimulus that moved opposite to the direction of the adapting stimulus. Second, adaptation was stimulus selective only on a time scale of ∼100 msec. Third, aggregate measures of neural activity (MUA, LFPs) had substantially different adaptation effects. Fourth, there were qualitative differences between our findings in MT and earlier findings in IT cortex. We conclude that selective adaptation effects in fMRIa are relatively easy to miss even when they exist (for instance by presenting stimuli for too long, or because neurons that enhance after adaptation cancel out the effect of neurons that suppress). Moreover, we argue that adaptation should be understood in the context of the computations that a neural circuit perform. Using fMRIa as a tool to uncover neural selectivity requires a better understanding of this circuitry and its consequences for adaptation. |
Mauro Marchitto; Simone Benedetto; Thierry Baccino; José J. Cañas Air traffic control: Ocular metrics reflect cognitive complexity Journal Article In: International Journal of Industrial Ergonomics, vol. 54, pp. 120–130, 2016. @article{Marchitto2016,The objective of the study was to evaluate effects of complexity on cognitive workload in a simulated air traffic control conflict detection task by means of eye movements recording. We manipulated two complexity factors, convergence angle and aircrafts minimum distance at closest approach, in a multidimensional workload assessment method based on psychophysiological, performance, and subjective measures. Conflict trials resulted more complex and time-consuming than no conflicts, requiring more frequent fixations and saccades. Moreover, large saccades showed reduced burst power with higher task complexity. A motion-based and a ratio-based strategy were suggested for conflicts and no conflicts on the basis of ocular metrics analysis: aircrafts differential speed and distance to convergence point at trial start were considered determinant for strategy adoption. Relevance to industry: Eye metrics measurement for online workload assessment enhances better identification of workload-inducing scenarios and adopted strategy for traffic management. System design, as well as air traffic control operators training programs, might benefit from on line workload measurement. |
Iris Mulders; Kriszta Szendroi Early association of prosodic focus with alleen 'only': Evidence from eye movements in the visual-world paradigm Journal Article In: Frontiers in Psychology, vol. 7, pp. 150, 2016. @article{Mulders2016,In three visual-world eye tracking studies, we investigated the processing of sentences containing the focus-sensitive operator alleen 'only' and different pitch accents, such as the Dutch Ik heb alleen SELDERIJ aan de brandweerman gegeven 'I only gave CELERY to the fireman' versus Ik heb alleen selderij aan de BRANDWEERMAN gegeven 'I only gave celery to the FIREMAN'. Dutch, like English, allows accent shift to express different focus possibilities. Participants judged whether these utterances match different pictures: in Experiment 1 the Early Stress utterance matched the picture, in Experiment 2 both the Early and Late Stress utterance did, and in Experiment 3 neither did. We found that eye-gaze patterns start to diverge across the conditions already as the indirect object is being heard. Our data also indicate that participants perform anticipatory eye-movements based on the presence of prosodic focus during auditory sentence processing. Our investigation is the first to report the effect of varied prosodic accent placement on different arguments in sentences with a semantic operator, alleen 'only', on the time course of looks in the visual world paradigm. Using an operator in the visual world paradigm allowed us to confirm that prosodic focus information immediately gets integrated into the semantic parse of the proposition. Our study thus provides further evidence for fast, incremental prosodic focus processing in natural language. |
H. Henny Yeung; Stephanie Denison; Scott P. Johnson Infants' looking to surprising events: When eye-tracking reveals more than looking time Journal Article In: PLoS ONE, vol. 11, no. 12, pp. e0164277, 2016. @article{Yeung2016,Research on infants' reasoning abilities often rely on looking times, which are longer to surprising and unexpected visual scenes compared to unsurprising and expected ones. Few researchers have examined more precise visual scanning patterns in these scenes, and so, here, we recorded 8- to 11-month-olds' gaze with an eye tracker as we presented a sampling event whose outcome was either surprising, neutral, or unsurprising: A red (or yellow) ball was drawn from one of three visible containers populated 0%, 50%, or 100% with identically colored balls. When measuring looking time to the whole scene, infants were insensitive to the likelihood of the sampling event, replicating failures in similar paradigms. Nevertheless, a new analysis of visual scanning showed that infants did spend more time fixating specific areas-of-interest as a function of the event likelihood. The drawn ball and its associated container attracted more looking than the other containers in the 0% condition, but this pattern was weaker in the 50% condition, and even less strong in the 100% condition. Results suggest that measuring where infants look may be more sensitive than simply how much looking there is to the whole scene. The advantages of eye tracking measures over traditional looking measures are discussed. |
Guilhem Ibos; David J. Freedman Interaction between spatial and feature attention in posterior parietal cortex Journal Article In: Neuron, vol. 91, no. 4, pp. 931–943, 2016. @article{Ibos2016,Lateral intraparietal (LIP) neurons encode a vast array of sensory and cognitive variables. Recently, we proposed that the flexibility of feature representations in LIP reflect the bottom-up integration of sensory signals, modulated by feature-based attention (FBA), from upstream feature-selective cortical neurons. Moreover, LIP activity is also strongly modulated by the position of space-based attention (SBA). However, the mechanisms by which SBA and FBA interact to facilitate the representation of task-relevant spatial and non-spatial features in LIP remain unclear. We recorded from LIP neurons during performance of a task that required monkeys to detect specific conjunctions of color, motion direction, and stimulus position. Here we show that FBA and SBA potentiate each other's effect in a manner consistent with attention gating the flow of visual information along the cortical visual pathway. Our results suggest that linear bottom-up integrative mechanisms allow LIP neurons to emphasize task-relevant spatial and non-spatial features. |
Natale Stucchi; Lisa Scocchia; Alessandro Carlini When geometry constrains vision: Systematic misperceptions within geometrical configurations Journal Article In: PLoS ONE, vol. 11, no. 3, pp. e0151488, 2016. @article{Stucchi2016,How accurate are we in reproducing a point within a simple shape? This is the empirical question we addressed in this work. Participants were presented with a tiny disk embedded in an empty circle (Experiment 1 and 3) or in a square (Experiment 2). Shortly afterwards, the disk vanished and they had to reproduce the previously seen disk position within the empty shape by means of the mouse cursor, as accurately as possible. Several loci inside each shape were tested. We found that the space delimited by a circle and by a square is not homogeneous and the observed distortion appears to be consistent across observers and specific for the two tested shapes. However, a common pattern can be identified when reproducing geometrical loci enclosed in a shape: errors are shifted toward the periphery in the region around the centre and toward the centre in the region nearby the edges. The error absolute value declines progressively as we approach an equilibrium contour line between the centre and the outline of the shape where the error is null. These results suggest that enclosing an empty space within a shape imposes an organization to it an warps its metrics: not only the perceived loci inside a shape are not the same as the geometrical loci, but they are misperceived in a systematic way that is functional to the correct identification of the centre of the shape. Eye movements recordings (Experiment 3) are consistent with this interpretation of the data. |
Federica Bianchi; Sébastien Santurette; Dorothea Wendt; Torsten Dau Pitch discrimination in musicians and non-musicians: Effects of harmonic resolvability and processing effort Journal Article In: JARO - Journal of the Association for Research in Otolaryngology, vol. 17, no. 1, pp. 69–79, 2016. @article{Bianchi2016,Musicians typically show enhanced pitch discrimination abilities compared to non-musicians. The present study investigated this perceptual enhancement behaviorally and objectively for resolved and unresolved complex tones to clarify whether the enhanced performance in musicians can be ascribed to increased peripheral frequency selectivity and/or to a different processing effort in performing the task. In a first experiment, pitch discrimination thresholds were obtained for harmonic complex tones with fundamental frequencies (F0s) between 100 and 500 Hz, filtered in either a low- or a high-frequency region, leading to variations in the resolvability of audible harmonics. The results showed that pitch discrimination performance in musicians was enhanced for resolved and unresolved complexes to a similar extent. Additionally, the harmonics became resolved at a similar F0 in musicians and non-musicians, suggesting similar peripheral frequency selectivity in the two groups of listeners. In a follow-up experiment, listeners' pupil dilations were measured as an indicator of the required effort in performing the same pitch discrimination task for conditions of varying resolvability and task difficulty. Pupillometry responses indicated a lower processing effort in the musicians versus the non-musicians, although the processing demand imposed by the pitch discrimination task was individually adjusted according to the behavioral thresholds. Overall, these findings indicate that the enhanced pitch discrimination abilities in musicians are unlikely to be related to higher peripheral frequency selectivity and may suggest an enhanced pitch representation at more central stages of the auditory system in musically trained listeners. |
Hayward J. Godwin; Tamaryn Menneer; Charlotte A. Riggs; Dominic Taunton; Kyle R. Cave; Nick Donnel Understanding the contribution of target repetition and target expectation to the emergence of the prevalence effect in visual search Journal Article In: Psychonomic Bulletin & Review, vol. 23, no. 3, pp. 809–816, 2016. @article{Godwin2016,Behavior in visual search tasks is influenced by the proportion of trials on which a target is presented (the target prevalence). Previous research has shown that when target prevalence is low (2 % prevalence), participants tend to miss targets, as compared with higher prevalence levels (e.g., 50 % prevalence). There is an ongoing debate regarding the relative contributions of target repetition and the expectation that a target will occur in the emergence of prevalence effects. In order to disentangle these two factors, we went beyond previ- ous studies by directly manipulating participants' expectations regarding how likely a target was to appear on a given trial. This we achieved without using cues or feedback. Our results indicated that both target repetition and target expectation contribute to the emergence of the prevalence effect. |
Jana Annina Müller; Dorothea Wendt; Birger Kollmeier; Thomas Brand Comparing eye tracking with electrooculography for measuring individual sentence comprehension duration Journal Article In: PLoS ONE, vol. 11, no. 10, pp. e0164627, 2016. @article{Mueller2016b,The aim of this study was to validate a procedure for performing the audio-visual paradigm introduced by Wendt et al. (2015) with reduced practical challenges. The original paradigm records eye fixations using an eye tracker and calculates the duration of sentence comprehension based on a bootstrap procedure. In order to reduce practical challenges, we first reduced the measurement time by evaluating a smaller measurement set with fewer trials. The results of 16 listeners showed effects comparable to those obtained when testing the original full measurement set on a different collective of listeners. Secondly, we introduced electrooculography as an alternative technique for recording eye movements. The correlation between the results of the two recording techniques (eye tracker and electrooculography) was r = 0.97, indicating that both methods are suitable for estimating the processing duration of individual participants. Similar changes in processing duration arising from sentence complexity were found using the eye tracker and the electrooculography procedure. Thirdly, the time course of eye fixations was estimated with an alternative procedure, growth curve analysis, which is more commonly used in recent studies analyzing eye tracking data. The results of the growth curve analysis were compared with the results of the bootstrap procedure. Both analysis methods show similar processing durations. |
Isabel Orenes; Linda M. Moxey; Christoph Scheepers; Carlos Santamaría Negation in context: Evidence from the visual world paradigm Journal Article In: Quarterly Journal of Experimental Psychology, vol. 69, no. 6, pp. 1082–1092, 2016. @article{Orenes2016,Literature assumes that negation is more difficult to understand than affirmation, but this might depend on the pragmatic context. The goal of this paper is to show that pragmatic knowledge modulates the unfolding processing of negation due to the previous activation of the negated situation. To test this, we used the visual world paradigm. In this task, we presented affirmative (e.g., her dad was rich) and negative sentences (e.g., her dadwas not poor) while viewing two images ofthe affirmed and denied enti- ties. The critical sentence in each item was preceded by one of three types of contexts: an inconsistent context (e.g., She supposed that her dad had little savings) that activates the negated situation (a poor man), a consistent context (e.g., She supposed that her dad had enough savings) that activates the actual situation (a rich man), or a neutral context (e.g., her dad lived on the other side oftown) that activates neither of the two models previously suggested. The results corroborated our hypothesis. Pragmatics is implicated in the unfolding processing of negation. We found an increase in fixations on the target compared to the baseline for negative sentences at 800 ms in the neutral context, 600 ms in the inconsistent context, and 1450 ms in the consistent context. Thus, when the negated situation has been previously introduced via an inconsistent context, negation is facilitated. |
Jacob Duijnhouwer; Bart Krekelberg Evidence and counterevidence in motion perception Journal Article In: Cerebral Cortex, vol. 26, pp. 4602–4612, 2016. @article{Duijnhouwer2016,Sensory neurons gather evidence in favor ofthe specific stimuli to which they are tuned, but they could improve their sensitivity by also taking counterevidence into account. The Bours–Lankheet model for motion detection uses counterevidence that relies on a specific combination ofthe ON and OFF channels in the early visual system. Specifically, the model detects pairs offlashes that occur separated in space and time. Ifthe flashes have the same contrast polarity, they are interpreted as evidence in favorof the corresponding motion. But if they have opposite contrasts, they are interpreted as evidence against it. This mechanism provides an explanation for reverse-phi (the perceived reversal of an apparent motion stimulus due to periodic contrast-inversions) that is a conceptual departure from the standard explanations of the effect. Here, we investigate this counterevidence mechanism by measuring directional tuning curves of neurons in the primary visual and middle temporal cortex areas of awake, behaving macaques using constant-contrast and inverting-contrast moving dot stimuli. Our electrophysiological data support the Bours–Lankheet model and suggest that the counterevidence computation occurs at an early stage of neural processing not captured by the standard models. |
Wuyi Wang; Shivakumar Viswanathan; Taraz Lee; Scott T. Grafton In: PLoS ONE, vol. 11, no. 7, pp. e0158465, 2016. @article{Wang2016g,Cortical theta band oscillations (4-8 Hz) in EEG signals have been shown to be important for a variety of different cognitive control operations in visual attention paradigms. However the synchronization source of these signals as defined by fMRI BOLD activity and the extent to which theta oscillations play a role in multimodal attention remains unknown. Here we investigated the extent to which cross-modal visual and auditory attention impacts theta oscillations. Using a simultaneous EEG-fMRI paradigm, healthy human participants performed an attentional vigilance task with six cross-modal conditions using naturalistic stimuli. To assess supramodal mechanisms, modulation of theta oscillation amplitude for attention to either visual or auditory stimuli was correlated with BOLD activity by conjunction analysis. Negative correlation was localized to cortical regions associated with the default mode network and positively with ventral premotor areas. Modality-associated attention to visual stimuli was marked by a positive correlation of theta and BOLD activity in fronto-parietal area that was not observed in the auditory condition. A positive correlation of theta and BOLD activity was observed in auditory cortex, while a negative correlation of theta and BOLD activity was observed in visual cortex during auditory attention. The data support a supramodal interaction of theta activity with of DMN function, and modality-associated processes within fronto-parietal networks related to top-down theta related cognitive control in cross-modal visual attention. On the other hand, in sensory cortices there are opposing effects of theta activity during cross-modal auditory attention. |
Frouke Hermens; Robin Walker The influence of social and symbolic cues on observers' gaze behaviour Journal Article In: British Journal of Psychology, vol. 107, no. 3, pp. 484–502, 2016. @article{Hermens2016,Research has shown that social and symbolic cues presented in isolation and at fixation have strong effects on observers, but it is unclear how cues compare when they are presented away from fixation and embedded in natural scenes. We here compare the effects of two types of social cue (gaze and pointing gestures) and one type of symbolic cue (arrow signs) on eye movements of observers under two viewing conditions (free viewing vs. a memory task). The results suggest that social cues are looked at more quickly, for longer and more frequently than the symbolic arrow cues. An analysis of saccades initiated from the cue suggests that the pointing cue leads to stronger cueing than the gaze and the arrow cue. While the task had only a weak influence on gaze orienting to the cues, stronger cue following was found for free viewing compared to the memory task. |
Joseph L. Sanguinetti; Mary A. Peterson A behavioral task sets an upper bound on the time required to access object memories before object segregation Journal Article In: Journal of Vision, vol. 16, no. 15, pp. 1–16, 2016. @article{sp16,Traditional theories of vision assume that object segregation occurs before access to object memories. Yet, behavioral evidence shows that familiar configuration is a prior for segregation, and electrophysiological experiments demonstrate these memories are accessed rapidly. A behavioral index of the speed of access is lacking, however. Here we asked how quickly behavior is influenced by object memories that are accessed in the course of object segregation. We investigated whether access to object memories on the groundside of a border can slow behavior during a rapid categorization task. Participants viewed two silhouettes that depicted a real-world and a novel object. Their task was to saccade toward the real-world object as quickly as possible. Half of the nontarget novel objects were ambiguous in that a portion of a real-world object was suggested, but not consciously perceived, on the groundside of their borders. The rest of the nontargets were unambiguous.We tested whether saccadic reaction times were perturbed by the real-world objects suggested on the groundside of ambiguous novel silhouettes. In Experiments 1 and 2, saccadic reaction times were slowed when nontargets were ambiguous rather than unambiguous. Experiment 2 set an upper limit of 190 ms on the time required for object memories in grounds to influence behavior. Experiment 3 ruled out factors that could have produced longer latencies other than access to object memories. These results provide the first behavioral index of how quickly memories of objects suggested in grounds can influence behavior, placing the upper limit at 190 ms. |
Margreet Vogelzang; Petra Hendriks; Hedderik Rijn Pupillary responses reflect ambiguity resolution in pronoun processing Journal Article In: Language, Cognition and Neuroscience, vol. 31, no. 7, pp. 876–885, 2016. @article{Vogelzang2016,ABSTRACTThe resolution of ambiguous pronouns is influenced by the preceding linguistic discourse. This raises the question whether the processing of an object pronoun is also influenced by the preceding sentential subject. In an experiment with Dutch adults, we recorded pupil dilation as a measure of the cognitive effort involved in resolving pronominal versus full noun phrase (NP) subjects and pronominal versus reflexive objects. Our results indicate that more effort is needed to resolve a pronominal subject or object compared to a less ambiguous full NP subject or reflexive object. These results support the hypothesis that the ambiguity of a referring expression influences processing. Contrary to our expectations, no evidence was found that the form of the subject influences the processing of a subsequent pronominal object. We conclude that pupillary responses reflect ambiguity resolution in pronoun processing, and that the process to resolve pronouns commences as soon as the pronoun is encountered. |
Xi Wang; Bin Cai; Yang Cao; Chen Zhou; Le Yang; Runzhong Liu; Xiaojing Long; Weicai Wang; Dingguo Gao; Baicheng Bao Objective method for evaluating orthodontic treatment from the lay perspective: An eye-tracking study Journal Article In: American Journal of Orthodontics and Dentofacial Orthopedics, vol. 150, no. 4, pp. 601–610, 2016. @article{Wang2016b,Introduction Currently, few methods are available to measure orthodontic treatment need and treatment outcome from the lay perspective. The objective of this study was to explore the function of an eye-tracking method to evaluate orthodontic treatment need and treatment outcome from the lay perspective as a novel and objective way when compared with traditional assessments. Methods The scanpaths of 88 laypersons observing the repose and smiling photographs of normal subjects and pretreatment and posttreatment malocclusion patients were recorded by an eye-tracking device. The total fixation time and the first fixation time on the areas of interest (eyes, nose, and mouth) for each group of faces were compared and analyzed using mixed-effects linear regression and a support vector machine. The aesthetic component of the Index of Orthodontic Treatment Need was used to categorize treatment need and outcome levels to determine the accuracy of the support vector machine in identifying these variables. Results Significant deviations in the scanpaths of laypersons viewing pretreatment smiling faces were noted, with less fixation time (P <0.05) and later attention capture (P <0.05) on the eyes, and more fixation time (P <0.05) and earlier attention capture (P <0.05) on the mouth than for the scanpaths of laypersons viewing normal smiling subjects. The same results were obtained when comparing posttreatment smiling patients, with less fixation time (P <0.05) and later attention capture on the eyes (P <0.05), and more fixation time (P <0.05) and earlier attention capture on the mouth (P <0.05). The pretreatment repose faces exhibited an earlier attention capture on the mouth than did the normal subjects (P <0.05) and posttreatment patients (P <0.05). Linear support vector machine classification showed accuracies of 97.2% and 93.4% in distinguishing pretreatment patients from normal subjects (treatment need), and pretreatment patients from posttreatment patients (treatment outcome), respectively. Conclusions The eye-tracking device was able to objectively quantify the effect of malocclusion on facial perception and the impact of orthodontic treatment on malocclusion from the lay perspective. The support vector machine for classification of selected features achieved high accuracy of judging treatment need and treatment outcome. This approach may represent a new method for objectively evaluating orthodontic treatment need and treatment outcome from the perspective of laypersons. |
Chadwick B. Boulay; Florian Pieper; Matthew L. Leavitt; Julio C. Martinez-Trujillo; Adam J. Sachs Single-trial decoding of intended eye movement goals from lateral prefrontal cortex neural ensembles Journal Article In: Journal of Neurophysiology, vol. 115, no. 1, pp. 486–499, 2016. @article{Boulay2016,Neurons in the lateral prefrontal cortex (LPFC) encode sensory and cognitive signals, as well as commands for goal-directed actions. Therefore, the LPFC might be a good signal source for a goal-selection brain-computer interface (BCI) that decodes the intended goal of a motor action previous to its execution. As a first step in the development of a goal-selection BCI, we set out to determine if we could decode simple behavioral intentions to direct gaze to eight different locations in space from single-trial LPFC neural activity. We recorded neuronal spiking activity from microelectrode arrays implanted in area 8A of the LPFC of two adult macaques while they made visually guided saccades to one of eight targets in a center-out task. Neuronal activity encoded target location immediately after target presentation, during a delay epoch, during the execution of the saccade, and every combination thereof. Many (40%) of the neurons that encoded target location during multiple epochs preferred different locations during different epochs. Despite heterogeneous and dynamic responses, the neuronal feature set that best predicted target location was the averaged firing rates from the entire trial and it was best classified using linear discriminant analysis (63.6$backslash$textendash96.9% in 12 sessions, mean 80.3%; information transfer rate: 21$backslash$textendash59, mean 32.8 bits/min). Our results demonstrate that it is possible to decode intended saccade target location from single-trial LPFC activity and suggest that the LPFC is a suitable signal source for a goal-selection cognitive BCI. |
Melanie R. Burke; R. O. Coats Dissociation of the rostral and dorsolateral prefrontal cortex during sequence learning in saccades: A TMS investigation Journal Article In: Experimental Brain Research, vol. 234, no. 2, pp. 597–604, 2016. @article{Burke2016,This experiment sought to find whether differences exist between the dorsolateral prefrontal cortex (DLPFC) and the medial rostral prefrontal cortex (MRPFC) for performing stimulus-independent and stimulus-oriented tasks, respectively. To find a causal relationship in these areas, we employed the use of trans-cranial magnetic stimulation (TMS). Prefrontal areas were stimulated whilst participants performed random or predictable sequence learning tasks at stimulus onset (1st presentation of the sequence only for both Random and Predictable), or during the inter-sequence interval. Overall, we found that during the predictable task a significant decrease in saccade latency, gain and duration was found when compared to the randomised conditions, as expected and observed previously. However, TMS stimulation in DLPFC during the delay in the predictive sequence learning task reduced this predictive ability by delaying the saccadic onset and generating abnormal reductions in saccadic gains during prediction. In contrast, we found that stimulation during a delay in MRPFC reversed the normal effects on peak velocity of the task with the predictive task revealing higher peak velocity than the randomised task. These findings provide causal evidence for independent functions of DLPFC and MRPFC in performing stimulus-independent processing during sequence learning in saccades. |
Omid Kardan; John M. Henderson; Grigori Yourganov; Marc G. Berman Observers' cognitive states modulate how visual inputs relate to gaze control Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 9, pp. 1429–1442, 2016. @article{Kardan2016,Previous research has shown that eye-movements change depending on both the visual features of our environment, and the viewer's top-down knowledge. One important question that is unclear is the degree to which the visual goals of the viewer modulate how visual features of scenes guide eye-movements. Here, we propose a systematic framework to investigate this question. In our study, participants performed 3 different visual tasks on 135 scenes: search, memorization, and aesthetic judgment, while their eye-movements were tracked. Canonical correlation analyses showed that eye-movements were reliably more related to low-level visual features at fixations during the visual search task compared to the aesthetic judgment and scene memorization tasks. Different visual features also had different relevance to eye-movements between tasks. This modulation of the relationship between visual features and eye-movements by task was also demonstrated with classification analyses, where classifiers were trained to predict the viewing task based on eye movements and visual features at fixations. Feature loadings showed that the visual features at fixations could signal task differences independent of temporal and spatial properties of eye-movements. When classifying across participants, edge density and saliency at fixations were as important as eye-movements in the successful prediction of task, with entropy and hue also being significant, but with smaller effect sizes. When classifying within participants, brightness and saturation were also significant contributors. Canonical correlation and classification results, together with a test of moderation versus mediation, suggest that the cognitive state of the observer moderates the relationship between stimulus-driven visual features and eye-movements. |
Maria C. Romero; Peter Janssen Receptive field properties of neurons in the macaque anterior intraparietal area Journal Article In: Journal of Neurophysiology, vol. 115, no. 3, pp. 1542–1555, 2016. @article{rj16,Visual object information is necessary for grasping. In primates, the anterior intraparietal area (AIP) plays an essential role in visually guided grasping. Neurons in AIP encode features of objects, but no study has systematically investigated the receptive field (RF) of AIP neurons. We mapped the RF of posterior AIP (pAIP) neurons in the central visual field, using images of objects and small line fragments that evoked robust responses, together with less effective stimuli. The RF sizes we measured varied between 3°(2)and 90°(2), with the highest response either at the fixation point or at parafoveal positions. A large fraction of pAIP neurons showed nonuniform RFs, with multiple local maxima in both ipsilateral and contralateral hemifields. Moreover, the RF profile could depend strongly on the stimulus used to map the RF. Highly similar results were obtained with the smallest stimulus that evoked reliable responses (line fragments measuring 1-2°). The nonuniformity and dependence of the RF profile on the stimulus in pAIP were comparable to previous observations in the anterior part of the lateral intraparietal area (aLIP), but the average RF of pAIP neurons was located at the fovea whereas the average RF of aLIP neurons was located parafoveally. Thus nonuniformity and stimulus dependence of the RF may represent general RF properties of neurons in the dorsal visual stream involved in object analysis, which contrast markedly with those of neurons in the ventral visual stream. |
Alexander C. Schütz; Pascal Mamassian; Alexander C. Schu; Pascal Mamassian; Alexander C. Schütz; Pascal Mamassian Early, local motion signals generate directional preferences in depth ordering of transparent motion Journal Article In: Journal of Vision, vol. 16, no. 10, pp. 1–20, 2016. @article{sm16,Superposition of two dot clouds moving in different directions results in the perception of two transparent layers. Despite the ambiguous depth order of the layers, there are consistent preferences to perceive the layer, which is moving either rightward or downward in front of the other layer. Here we investigated the origin of these depth order biases. For this purpose, we measured the interaction with stereoscopic disparity and the influence of global and local motion properties. Motion direction and stereoscopic disparity were equally effective in determining depth order at a disparity of one arcmin. Global motion properties, such as the aperture location in the visual field or the aperture's motion direction did not affect directional biases. Local motion properties however were effective. When the moving elements were oriented lines rather than dots, the directional biases were shifted towards the direction orthogonal to the lines rather than the actual motion direction of the lines. Therefore, depth order was determined before the aperture problem was fully resolved. Varying the duration of the stimuli, we found that the time constant of the aperture problem was much lower for depth order than for perceived motion direction. Altogether, our results indicate that depth order is determined in one shot on the basis of an early motion signal, while perceived motion direction is continuously updated. Thus, depth ordering in transparent motion appears to be a surprisingly fast process, that relies on early, local motion signals and that precedes high-level motion analysis. |
Kyoung Whan Choe; Randolph Blake; Sang-Hun Lee Pupil size dynamics during fixation impact the accuracy and precision of video-based gaze estimation Journal Article In: Vision Research, vol. 118, pp. 48–59, 2016. @article{Choe2016,Video-based eye tracking relies on locating pupil center to measure gaze positions. Although widely used, the technique is known to generate spurious gaze position shifts up to several degrees in visual angle because pupil centration can change without eye movement during pupil constriction or dilation. Since pupil size can fluctuate markedly from moment to moment, reflecting arousal state and cognitive processing during human behavioral and neuroimaging experiments, the pupil size artifact is prevalent and thus weakens the quality of the video-based eye tracking measurements reliant on small fixational eye movements. Moreover, the artifact may lead to erroneous conclusions if the spurious signal is taken as an actual eye movement. Here, we measured pupil size and gaze position from 23 human observers performing a fixation task and examined the relationship between these two measures. Results disclosed that the pupils contracted as fixation was prolonged, at both small (<16 s) and large (~4 min) time scales, and these pupil contractions were accompanied by systematic errors in gaze position estimation, in both the ellipse and the centroid methods of pupil tracking. When pupil size was regressed out, the accuracy and reliability of gaze position measurements were substantially improved, enabling differentiation of 0.1° difference in eye position. We confirmed the presence of systematic changes in pupil size, again at both small and large scales, and its tight relationship with gaze position estimates when observers were engaged in a demanding visual discrimination task. |
Sihem Kime; Francesco Galluppi; Xavier Lagorce; Ryad B. Benosman; Jean Lorenceau Psychophysical assessment of perceptual performance with varying display frame rates Journal Article In: Journal of Display Technology, vol. 12, no. 11, pp. 1372–1382, 2016. @article{Kime2016,This study assesses the impact of display refresh rate on the perception of dynamic visual stimuli in humans. A projection platform was developed in that context, allowing control of the frame rate on a trial-by-trial basis. Using this display, we introduce a series of psychophysical experiments aimed to quantitatively assess objective perceptual performance at different frame rates. Tasks that are often implicitly performed when watching movies on a television set, or when wearing a head mounted display, were chosen: speed discrimination, spatial discrimination, and reading abilities, with stimuli undergoing horizontal motion in awide range ofspeeds (16–38 deg/s). The results show that whatever the stimuli or the task, performance is significantly better at high frame rate (HFR) compared to 60 Hz, providing clear-cut evidence that low refresh rates limit the ability to reliably analyze moving stimuli. These results extend those of previous psychophysical experiments performed at low refresh rates, further characterize genuine visual performance in humans and provide an objective benchmarking methodology allowing to assess visual performance with a variety of displays. Results indicate that for low resolution displays, where increasing spatial resolution is not an option, increasing frame rate could benefit motion perception. We discuss these results and their implications with regards to current and emerging categories of visual displays, such as head mounted displays. |
Bogusława Whyatt; Katarzyna Stachowiak; Marta Kajzer-Wietrzny Similar and different: Cognitive rhythm and effort in translation and paraphrasing Journal Article In: Poznan Studies in Contemporary Linguistics, vol. 52, no. 2, pp. 175–208, 2016. @article{Whyatt2016,Although Jakobson's (1959) seminal classification of translation into three kinds: interlingual, intralingual and intersemiotic has been widely accepted in Translation Studies, so far most research interest has focused on interlingual translation, defined as “translation proper”. Intralingual translation, more often understood as rewording, paraphrasing or reformulation within the same language, is a less prototypical kind of translation, yet we believe that the underlying mental operations needed to perform both tasks include similar processing stages. Bearing in mind the lack of research comparing inter-and intralingual translation we designed the ParaTrans project in which we investigate how translators make decisions in both tasks. In this article we present the results of a comparative analysis of processing effort and cognitive rhythm demonstrated by professional translators who were asked to translate and paraphrase similar texts. Having collected three streams of translation process data with such tools as key-logging, eye-tracking and screen-capture software, we are able to draw some tentative conclusions concerning the similarities and differences between language processing for interlingual translation and intralingual paraphrasing. The results confirm a higher processing effort in interlingual translation most likely due to the need to switch between languages. |
Katri K. Cornelissen; Piers L. Cornelissen; Peter J. B. Hancock; Martin J. Tovée Fixation patterns, not clinical diagnosis, predict body size over-estimation in eating disordered women and healthy controls Journal Article In: International Journal of Eating Disorders, vol. 49, no. 5, pp. 507–518, 2016. @article{Cornelissen2016,OBJECTIVE: A core feature of anorexia nervosa (AN) is an over-estimation of body size. Women with AN have a different pattern of eye-movements when judging bodies, but it is unclear whether this is specific to their diagnosis or whether it is found in anyone over-estimating body size. METHOD: To address this question, we compared the eye movement patterns from three participant groups while they carried out a body size estimation task: (i) 20 women with recovering/recovered anorexia (rAN) who had concerns about body shape and weight and who over-estimated body size, (ii) 20 healthy controls who had normative levels of concern about body shape and who estimated body size accurately (iii) 20 healthy controls who had normative levels of concern about body shape but who did over-estimate body size. RESULTS: Comparisons between the three groups showed that: (i) accurate body size estimators tended to look more in the waist region, and this was independent of clinical diagnosis; (ii) there is a pattern of looking at images of bodies, particularly viewing the upper parts of the torso and face, which is specific to participants with rAN but which is independent of accuracy in body size estimation. DISCUSSION: Since the over-estimating controls did not share the same body image concerns that women with rAN report, their over-estimation cannot be explained by attitudinal concerns about body shape and weight. These results suggest that a distributed fixation pattern is associated with over-estimation of body size and should be addressed in treatment programs. |
Malcolm Proudfoot; Ricarda A. L. Menke; Rakesh Sharma; Claire M. Berna; Stephen L. Hicks; Christopher Kennard; Kevin Talbot; Martin R. Turner Eye-tracking in amyotrophic lateral sclerosis: A longitudinal study of saccadic and cognitive tasks Journal Article In: Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, vol. 17, no. 1-2, pp. 101–111, 2016. @article{Proudfoot2016,A relative preservation of eye movements is notable in ALS, but saccadic functions have not been studied longitudinally. ALS overlaps with FTD, typically involving executive dysfunction, and eye-tracking offers additional potential for the assessment of extramotor pathology where writing and speaking are both impaired. Eye-tracking measures (including anti- saccade, trail-making and visual search tasks) were assessed at six-monthly intervals for up to two years in a group of ALS (n ? 61) and primary lateral sclerosis (n ? 7) patients, compared to healthy age-matched controls (n ? 39) assessed on a single occasion. Task performance was explored speculatively in relation to resting-state functional MRI (R-FMRI) network connectivity. Results showed that ALS patients were impaired on executive and visual search tasks despite normal basic saccadic function, and impairments in the PLS patients were unexpectedly often more severe. No significant progression was detected longitudinally in either group. No changes in R-FMRI network connectivity were identified in relation to patient performance. In conclusion, eye-tracking offers an objective means to assess extramotor cerebral involvement in ALS. The relative resistance of pure oculomotor function is confirmed, and higher-level executive impairments do not follow the same rate of decline as physical disability. PLS patients may have more cortical dysfunction than has been previously appreciated. |
Petra Fischer; José P. Ossandón; Johannes Keyser; Alessandro Gulberti; Niklas Wilming; Wolfgang Hamel; Johannes Köppen; Carsten Buhmann; Manfred Westphal; Christian Gerloff; Christian K. E. Moll; Andreas K. Engel; Peter König STN-DBS reduces saccadic hypometria but not visuospatial bias in Parkinson's disease patients Journal Article In: Frontiers in Behavioral Neuroscience, vol. 10, pp. 85, 2016. @article{Fischer2016,In contrast to its well-established role in alleviating skeleto-motor symptoms in Parkinson's disease, little is known about the impact of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on oculomotor control and attention. Eye-tracking data of 17 patients with left-hemibody symptom onset was compared with 17 age-matched control subjects. Free-viewing of natural images was assessed without stimulation as baseline and during bilateral DBS. To examine the involvement of ventral STN territories in oculomotion and spatial attention, we employed unilateral stimulation via the left and right ventralmost contacts respectively. When DBS was off, patients showed shorter saccades and a rightward viewing bias compared with controls. Bilateral stimulation in therapeutic settings improved saccadic hypometria but not the visuospatial bias. At a group level, unilateral ventral stimulation yielded no consistent effects. However, the evaluation of electrode position within normalized MNI coordinate space revealed that the extent of early exploration bias correlated with the precise stimulation site within the left subthalamic area. These results suggest that oculomotor impairments "but not higher-level exploration patterns" are effectively ameliorable by DBS in therapeutic settings. Our findings highlight the relevance of the STN topography in selecting contacts for chronic stimulation especially upon appearance of visuospatial attention deficits. |
Chia-Ling Li; M. Pilar Aivar; Dmitry M. Kit; Matthew H. Tong; Mary Hayhoe Memory and visual search in naturalistic 2D and 3D environments Journal Article In: Journal of Vision, vol. 16, no. 8, pp. 1–20, 2016. @article{Li2016a,The role of memory in guiding attention allocation in daily behaviors is not well understood. In experiments with two-dimensional (2D) images, there is mixed evidence about the importance of memory. Because the stimulus context in laboratory experiments and daily behaviors differs extensively, we investigated the role of memory in visual search, in both two-dimensional (2D) and three-dimensional (3D) environments. A 3D immersive virtual apartment composed of two rooms was created, and a parallel 2D visual search experiment composed of snapshots from the 3D environment was developed. Eye movements were tracked in both experiments. Repeated searches for geometric objects were performed to assess the role of spatial memory. Subsequently, subjects searched for realistic context objects to test for incidental learning. Our results show that subjects learned the room-target associations in 3D but less so in 2D. Gaze was increasingly restricted to relevant regions of the room with experience in both settings. Search for local contextual objects, however, was not facilitated by early experience. Incidental fixations to context objects do not necessarily benefit search performance. Together, these results demonstrate that memory for global aspects of the environment guides search by restricting allocation of attention to likely regions, whereas task relevance determines what is learned from the active search experience. Behaviors in 2D and 3D environments are comparable, although there is greater use of memory in 3D. |
Viorica Marian; Henrike K. Blumenfeld; Max R. Freeman; Scott R. Schroeder; Susan C. Bobb Auditory word recognition across the lifespan: Links between linguistic and nonlinguistic inhibitory control in bilinguals and monolinguals Journal Article In: Linguistic Approaches to Bilingualism, vol. 6, no. 1-2, pp. 119–146, 2016. @article{Marian2016,Recent research suggests that bilingual experience reconfigures linguistic and nonlinguistic cognitive processes. We examined the relationship between linguistic competition resolution and nonlinguistic cognitive control in younger and older adults who were either bilingual or monolingual. Participants heard words in English and identified the referent among four pictures while eye-movements were recorded. Target pictures (e.g., cab ) appeared with a phonological competitor picture (e.g., cat ) and two filler pictures. After each eye-tracking trial, priming probes assessed residual activation and inhibition of target and competitor words. When accounting for processing speed, results revealed that age-related changes in activation and inhibition are smaller in bilinguals than in monolinguals. Moreover, younger and older bilinguals, but not monolinguals, recruited similar inhibition mechanisms during word identification and during a nonlinguistic Stroop task. Results suggest that, during lexical access, bilinguals show more consistent competition resolution and recruitment of cognitive control across the lifespan than monolinguals. |
Jacob L. Orquin; Nathaniel J. S. Ashby; Alasdair D. F. Clarke Areas of interest as a signal detection problem in behavioral eye-tracking research Journal Article In: Journal of Behavioral Decision Making, vol. 29, no. 2-3, pp. 103–115, 2016. @article{Orquin2016,Decision researchers frequently analyze attention to individual objects to test hypotheses about underlying cognitive processes. Generally, fixations are assigned to objects using a method known as area of interest (AOI). Ideally, an AOI includes all fixations belonging to an object while fixations to other objects are excluded. Unfortunately, due to measurement inaccuracy and insufficient distance between objects, the distributions of fixations to objects may overlap, resulting in a signal detection problem. If the AOI is to include all fixations to an object, it will also likely include fixations belonging to other objects (false positives). In a survey, we find that many researchers report testing multiple AOI sizes when performing analyses, presumably trying to balance the proportion of true and false positive fixations. To test whether AOI size influences the measurement of object attention and conclusions drawn about cognitive processes, we reanalyze four published studies and conduct a fifth tailored to our purpose. We find that in studies in which we expected overlapping fixation distributions, analyses benefited from smaller AOI sizes (0° visual angle margin). In studies where we expected no overlap, analyses benefited from larger AOI sizes (>.5° visual angle margins). We conclude with a guideline for the use of AOIs in behavioral eye-tracking research. |
Hak Soo Choi; Shinjung Kim; Donghoon Lee; Chang Seok Kim; Myung Yung Jeong Synchronized tracking of brain cognitive processing using EEG and vision signals Journal Article In: Applied Spectroscopy Reviews, vol. 51, no. 7-9, pp. 592–602, 2016. @article{Choi2016,Many efforts have been made to understand the neural mechanisms of the human brain. However, visualization of human brain processing has been a main challenge in the field. It is still largely unknown how the human brain allocates attention to target objects while excluding unrelated information in a complex visual environment. Using simultaneous electroencephalogram and eye tracking measurements, in this study, we analyzed two brain regions separately to detect the brain wave activity during visual information processing. We observed an activation difference between sensory (P100) and cognitive (P300) processing, and the behavioral response was improved by providing valid cue-target location information. Furthermore, neural processing was evaluated according to the specific area of brain activation and eye movements during cognitive processing. Our results demonstrate the correlation between behavior performance and visual stimuli and suggest an advantage of combined paradigms for efficient visual information processing. |
Ben M. Harvey; Serge O. Dumoulin Visual motion transforms visual space representations similarly throughout the human visual hierarchy Journal Article In: NeuroImage, vol. 127, pp. 173–185, 2016. @article{Harvey2016,Several studies demonstrate that visual stimulus motion affects neural receptive fields and fMRI response amplitudes. Here we unite results of these two approaches and extend them by examining the effects of visual motion on neural position preferences throughout the hierarchy of human visual field maps. We measured population receptive field (pRF) properties using high-field fMRI (7. T), characterizing position preferences simultaneously over large regions of the visual cortex. We measured pRFs properties using sine wave gratings in stationary apertures, moving at various speeds in either the direction of pRF measurement or the orthogonal direction. We find direction- and speed-dependent changes in pRF preferred position and size in all visual field maps examined, including V1, V3A, and the MT. + map TO1. These effects on pRF properties increase up the hierarchy of visual field maps. However, both within and between visual field maps the extent of pRF changes was approximately proportional to pRF size. This suggests that visual motion transforms the representation of visual space similarly throughout the visual hierarchy. Visual motion can also produce an illusory displacement of perceived stimulus position. We demonstrate perceptual displacements using the same stimulus configuration. In contrast to effects on pRF properties, perceptual displacements show only weak effects of motion speed, with far larger speed-independent effects. We describe a model where low-level mechanisms could underlie the observed effects on neural position preferences. We conclude that visual motion induces similar transformations of visuo-spatial representations throughout the visual hierarchy, which may arise through low-level mechanisms. |
Hossein Karimi; Fernanda Ferreira Informativity renders a referent more accessible: Evidence from eyetracking Journal Article In: Psychonomic Bulletin & Review, vol. 23, no. 2, pp. 507–525, 2016. @article{Karimi2016,The amount of information attached to a noun phrase (henceforth, NP) has been shown to enhance accessibility and increase pronominal reference in language production. However, both the effect of information quantity on the comprehension of ambiguous pronouns and the time course of any informativity effect have been left unexplored. In two eyetracking experiments, we investigated how additional information on the part of NP referents influenced the resolution of following ambiguous pronouns. The results of the first experiment revealed an informativity effect, with more looks to the informationally richer referent than to the competitor. However, the effect of additional information emerged late in time when the referent was the object of the verb. The second experiment replicated the results of the first and also showed that, consistent with the online results, an ambiguous pronoun is interpreted as referring to the informationally richer NP in an offline, explicit pronoun resolution tas k. The results lend support to theories of language processing that assume that explicit information increases the accessibility of the associated concept, in contrast to approaches that assume that accessibility is associated with givenness. |
Laura Piccardi; Maria De Luca; Raffaella Nori; Liana Palermo; Fabiana Iachini; Cecilia Guariglia Navigational style influences eye movement pattern during exploration and learning of an environmental map Journal Article In: Frontiers in Behavioral Neuroscience, vol. 10, pp. 140, 2016. @article{Piccardi2016,During navigation people may adopt three different spatial styles (i.e., Landmark, Route, and Survey). Landmark style (LS) people are able to recall familiar landmarks but cannot combine them with directional information; Route style (RS) people connect landmarks to each other using egocentric information about direction; Survey style (SS) people use a map-like representation of the environment. SS individuals generally navigate better than LS and RS people. Fifty-one college students (20 LS; 17 RS, and 14 SS) took part in the experiment. The spatial cognitive style (SCS) was assessed by means of the SCS test; participants then had to learn a schematic map of a city, and after 5 min had to recall the path depicted on it. During the learning and delayed recall phases, eye-movements were recorded. Our intent was to investigate whether there is a peculiar way to explore an environmental map related to the individual's spatial style. Results support the presence of differences in the strategy used by the three spatial styles for learning the path and its delayed recall. Specifically, LS individuals produced a greater number of fixations of short duration, while the opposite eye movement pattern characterized SS individuals. Moreover, SS individuals showed a more spread and comprehensive explorative pattern of the map, while LS individuals focused their exploration on the path and related targets. RS individuals showed a pattern of exploration at a level of proficiency between LS and SS individuals. We discuss the clinical and anatomical implications of our data. |
Eugene McSorley; Rachel McCloy; Louis Williams The concurrent programming of saccades Journal Article In: PLoS ONE, vol. 11, no. 12, pp. e0168724, 2016. @article{McSorley2016,Sequences of saccades have been shown to be prepared concurrently however it remains unclear exactly what aspects of those saccades are programmed in parallel. To examine this participants were asked to make one or two target-driven saccades: a reflexive sac- cade; a voluntary saccade; a reflexive then a voluntary saccade; or vice versa. During the first response the position of a second target was manipulated. The new location of the sec- ond saccade target was found to impact on second saccade latencies and second saccade accuracy showing that some aspects of the second saccade program are prepared in paral- lel with the first. However, differences were found in the specific pattern of effects for each sequence type. These differences fit well within a general framework for saccade control in which a common priority map for saccade control is computed and the influence of saccade programs on one another depends not so much on the types of saccade being produced but rather on the rate at which their programs develop. |
Andrey R. Nikolaev; Radha Nila Meghanathan; Cees Leeuwen Combining EEG and eye movement recording in free viewing: Pitfalls and possibilities Journal Article In: Brain and Cognition, vol. 107, pp. 55–83, 2016. @article{Nikolaev2016,Co-registration of EEG and eye movement has promise for investigating perceptual processes in free viewing conditions, provided certain methodological challenges can be addressed. Most of these arise from the self-paced character of eye movements in free viewing conditions. Successive eye movements occur within short time intervals. Their evoked activity is likely to distort the EEG signal during fixation. Due to the non-uniform distribution of fixation durations, these distortions are systematic, survive across-trials averaging, and can become a source of confounding. We illustrate this problem with effects of sequential eye movements on the evoked potentials and time-frequency components of EEG and propose a solution based on matching of eye movement characteristics between experimental conditions. The proposal leads to a discussion of which eye movement characteristics are to be matched, depending on the EEG activity of interest. We also compare segmentation of EEG into saccade-related epochs relative to saccade and fixation onsets and discuss the problem of baseline selection and its solution. Further recommendations are given for implementing EEG-eye movement co-registration in free viewing conditions. By resolving some of the methodological problems involved, we aim to facilitate the transition from the traditional stimulus-response paradigm to the study of visual perception in more naturalistic conditions. |
Yi Xia; Yusuke Morimoto; Yasuki Noguchi Retrospective triggering of conscious perception by an interstimulus interaction Journal Article In: Journal of Vision, vol. 16, pp. 1–8, 2016. @article{Xia2016,Attention facilitates conscious perception of a visual stimulus at an attended location. Interestingly, a recent study (using the Posner spatial-cueing task) reported that attention facilitated conscious perception even when it was cued after a stimulus was gone (postcued- attention or retroperception effect). Here, we show that this effect can be induced without any contribution of attention. Contrary to previous situations, we fixed a position of a target (Gabor patch) and cue (luminance change of a circle encompassing the target) across trials so that subjects always could allocate their full attention to the target position. The cue (luminance change) improved objective and subjective visibility of the nearby target even when it was given ;200 ms after the target's offset. This retrospective improvement was diminished when a shape of the cue was changed from a circle to a dot pattern, suggesting that the improvement emerged from a visual interaction (combinations of shapes) between the circular cue and target. Those results indicated that a local visual interaction between the target and cue is sufficient to trigger consciousness of the target, revealing a new type of retroperception effect mediated by sensory (nonattentional) mechanisms. |
Akiko Ikkai; Sangita Dandekar; Clayton E. Curtis Lateralization in alpha-band oscillations predicts the locus and spatial distribution of attention Journal Article In: PLoS ONE, vol. 11, no. 5, pp. e0154796, 2016. @article{Ikkai2016,Attending to a task-relevant location changes how neural activity oscillates in the alpha band (8-13Hz) in posterior visual cortical areas. However, a clear understanding of the relationships between top-down attention, changes in alpha oscillations in visual cortex, and attention performance are still poorly understood. Here, we tested the degree to which the posterior alpha power tracked the locus of attention, the distribution of attention, and how well the topography of alpha could predict the locus of attention. We recorded magnetoencephalographic (MEG) data while subjects performed an attention demanding visual discrimination task that dissociated the direction of attention from the direction of a saccade to indicate choice. On some trials, an endogenous cue predicted the target's location, while on others it contained no spatial information. When the target's location was cued, alpha power decreased in sensors over occipital cortex contralateral to the attended visual field. When the cue did not predict the target's location, alpha power again decreased in sensors over occipital cortex, but bilaterally, and increased in sensors over frontal cortex. Thus, the distribution and the topography of alpha reliably indicated the locus of covert attention. Together, these results suggest that alpha synchronization reflects changes in the excitability of populations of neurons whose receptive fields match the locus of attention. This is consistent with the hypothesis that alpha oscillations reflect the neural mechanisms by which top-down control of attention biases information processing and modulate the activity of neurons in visual cortex. |
Rong Liu; MiYoung Kwon Integrating oculomotor and perceptual training to induce a pseudofovea: A model system for studying central vision loss Journal Article In: Journal of Vision, vol. 16, no. 6, pp. 1–21, 2016. @article{Liu2016b,People with a central scotoma often adopt an eccentric retinal location (Preferred Retinal Locus, PRL) for fixation. Here, we proposed a novel training paradigm as a model system to study the nature of the PRL formation and its impacts on visual function. The training paradigm was designed to effectively induce a PRL at any intended retinal location by integrating oculomotor control and pattern recognition. Using a gaze-contingent display, a simulated central scotoma was induced in eight normally sighted subjects. A subject's entire peripheral visual field was blurred, except for a small circular aperture with location randomly assigned to each subject (to the left, right, above, or below the scotoma). Under this viewing condition, subjects performed a demanding oculomotor and visual recognition task. Various visual functions were tested before and after training at both PRL and nonPRL locations. After 6-10 hr of the training, all subjects formed their PRL within the clear window. Both oculomotor control and visual recognition performance significantly improved. Moreover, there was considerable improvement at PRL location in high-level function, such as trigram letter-recognition, reading, and spatial attention, but not in low-level function, such as acuity and contrast sensitivity. Our results demonstrated that within a relatively short time, a PRL could be induced at any intended retinal location in normally-sighted subjects with a simulated scotoma. Our training paradigm might not only hold promise as a model system to study the dynamic nature of the PRL formation, but also serve as a rehabilitation regimen for individuals with central vision loss. |
Sameer Saproo; Victor Shih; David C. Jangraw; Paul Sajda Neural mechanisms underlying catastrophic failure in human-machine interaction during aerial navigation Journal Article In: Journal of Neural Engineering, vol. 13, pp. 1–12, 2016. @article{ssjs16,Objective. We investigated the neural correlates of workload buildup in a fine visuomotor task called the boundary avoidance task (BAT). The BAT has been known to induce naturally occurring failures of human–machine coupling in high performance aircraft that can potentially lead to a crash—these failures are termed pilot induced oscillations (PIOs). Approach. We recorded EEG and pupillometry data from human subjects engaged in a flight BAT simulated within a virtual 3D environment. Main results. We find that workload buildup in a BAT can be successfully decoded from oscillatory features in the electroencephalogram (EEG). Information in delta, theta, alpha, beta, and gamma spectral bands of the EEG all contribute to successful decoding, however gamma band activity with a lateralized somatosensory topography has the highest contribution, while theta band activity with a fronto-central topography has the most robust contribution in terms of real-world usability. We show that the output of the spectral decoder can be used to predict PIO susceptibility. We also find that workload buildup in the task induces pupil dilation, the magnitude of which is significantly correlated with the magnitude of the decoded EEG signals. These results suggest that PIOs may result from the dysregulation of cortical networks such as the locus coeruleus (LC)—anterior cingulate cortex (ACC) circuit. Significance. Our findings may generalize to similar control failures in other cases of tight manmachine coupling where gains and latencies in the control system must be inferred and compensated for by the human operators. A closed-loop intervention using neurophysiological decoding of workload buildup that targets the LC-ACC circuit may positively impact operator performance in such situations. |
Farahnaz A. Wick; Tyler W. Garaas; Marc Pomplun Saccadic adaptation alters the attentional field Journal Article In: Frontiers in Human Neuroscience, vol. 10, pp. 568, 2016. @article{Wick2016,It is currently unknown whether changes to the oculomotor system can induce changes to the distribution of spatial attention around a fixated target. Previous studies have used perceptual performance tasks to show that adaptation of saccadic eye movements affects dynamic properties of visual attention, in particular, attentional shifts to a cued location. In this study, we examined the effects of saccadic adaptation on the static distribution of visual attention around fixation (attentional field). We used the classic double step adaptation procedure and a flanker task to test for differences in the attentional field after forward and backward adaptation. RT measures revealed that the shape of the attentional field changed significantly after backward adaptation as shown through altered interference from distracters at different eccentricities but not after forward adaptation. This finding reveals that modification of saccadic amplitudes can affect metrics of not only dynamic properties of attention but also its static properties. A major implication is that the neural mechanisms underlying fundamental selection mechanisms and the oculomotor system can reweight each other. |
Yingyi Luo; Ming Yan; Shaorong Yan; Xiaolin Zhou; Albrecht W. Inhoff In: Cognitive, Affective, & Behavioral Neuroscience, vol. 16, no. 1, pp. 72–92, 2016. @article{Luo2016,In two experiments, we examined the contribution of articulation-specific features to visual word recognition during the reading of Chinese. In spoken Standard Chinese, a syllable with a full tone can be tone-neutralized through sound weakening and pitch contour change, and there are two types of two-character compound words with respect to their articulation variation. One type requires articulation of a full tone for each constituent character, and the other requires a full- and a neutral-tone articulation for the first and second characters, respectively. Words of these two types with identical first characters were selected and embedded in sentences. Native speakers of Standard Chinese were recruited to read the sentences. In Experiment 1, the individual words of a sentence were presented serially at a fixed pace while event-related potentials were recorded. This resulted in less-negative N100 and anterior N250 amplitudes and in more-negative N400 amplitudes when targets contained a neutral tone. Complete sentences were visible in Experiment 2, and eye movements were recorded while participants read. Analyses of oculomotor activity revealed shorter viewing durations and fewer refixations on—and fewer regressive saccades to—target words when their second syllable was articulated with a neutral rather than a full tone. Together, the results indicate that readers represent articulation-specific word properties, that these representations are routinely activated early during the silent reading of Chinese sentences, and that the representations are also used during later stages of word processing. |
Jason C. Coronel; Kara D. Federmeier In: Communication Research, vol. 43, no. 7, pp. 922–944, 2016. @article{Coronel2016,Gender-based political stereotypes pervade the media environment in the United States, and this may cause voters to automatically activate these stereotypes while evaluating politicians. In the research reported here, we investigate whether voters are able to reduce the automatic activation of unwanted stereotypes and how political sophistication influences this capacity. The current experiment uses self-reports to measure controlled stereotyping, and we develop a new eye movement metric to measure automatic stereotyping. We find that political sophisticates are more effective than novices at reducing unwanted gender-based political stereotypes. This study has two main implications for communication research. First, the results suggest that the effects of gender-based automatic stereotyping—induced by the information environment—on political judgments may not be as powerful as some of the current literature portrays them to be. Second, this study adds eye movements to the arsenal of tools available to communication scholars interested in measuring covert forms of stereotyping. |
Martha M. Shiell; François Champoux; Robert J. Zatorre The right hemisphere planum temporale supports enhanced visual motion detection ability in deaf people: Evidence from cortical thickness Journal Article In: Neural Plasticity, vol. 2016, pp. 7217630, 2016. @article{Shiell2016,After sensory loss, the deprived cortex can reorganize to process information from the remaining modalities, a phenomenon known as cross-modal reorganization. In blind people this cross-modal processing supports compensatory behavioural enhancements in the nondeprived modalities. Deaf people also show some compensatory visual enhancements, but a direct relationship between these abilities and cross-modally reorganized auditory cortex has only been established in an animal model, the congenitally deaf cat, and not in humans. Using T1-weighted magnetic resonance imaging, we measured cortical thickness in the planum temporale, Heschl's gyrus and sulcus, the middle temporal area MT+, and the calcarine sulcus, in early-deaf persons. We tested for a correlation between this measure and visual motion detection thresholds, a visual function where deaf people show enhancements as compared to hearing. We found that the cortical thickness of a region in the right hemisphere planum temporale, typically an auditory region, was greater in deaf individuals with better visual motion detection thresholds. This same region has previously been implicated in functional imaging studies as important for functional reorganization. The structure-behaviour correlation observed here demonstrates this area's involvement in compensatory vision and indicates an anatomical correlate, increased cortical thickness, of cross-modal plasticity. |
Ivan Koychev; Dan Joyce; E. Barkus; Ulrich Ettinger; Anne Schmechtig; Colin T. Dourish; G. R. Dawson; Kevin J. Craig; J. F. William Deakin Cognitive and oculomotor performance in subjects with low and high schizotypy: Implications for translational drug development studies Journal Article In: Translational Psychiatry, vol. 6, pp. e811, 2016. @article{Koychev2016,The development of drugs to improve cognition in patients with schizophrenia is a major unmet clinical need. A number of promising compounds failed in recent clinical trials, a pattern linked to poor translation between preclinical and clinical stages of drug development. Seeking proof of efficacy in early Phase 1 studies in surrogate patient populations (for example, high schizotypy individuals where subtle cognitive impairment is present) has been suggested as a strategy to reduce attrition in the later stages of drug development. However, there is little agreement regarding the pattern of distribution of schizotypal features in the general population, creating uncertainty regarding the optimal control group that should be included in prospective trials. We aimed to address this question by comparing the performance of groups derived from the general population with low, average and high schizotypy scores over a range of cognitive and oculomotor tasks. We found that tasks dependent on frontal inhibitory mechanisms (N-Back working memory and anti-saccade oculomotor tasks), as well as a smooth-pursuit oculomotor task were sensitive to differences in the schizotypy phenotype. In these tasks the cognitive performance of 'low schizotypes' was significantly different from 'high schizotypes' with 'average schizotypes' having an intermediate performance. These results indicate that for evaluating putative cognition enhancers for treating schizophrenia in early-drug development studies the maximum schizotypy effect would be achieved using a design that compares low and high schizotypes. |
John Kingston; Joshua Levy; Amanda Rysling; Adrian Staub Eye movement evidence for an immediate Ganong effect Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 12, pp. 1969–1988, 2016. @article{Kingston2016,Listeners tend to categorize an ambiguous speech sound so that it forms a word with its context (Ganong, 1980). This effect could reflect feedback from the lexicon to phonemic activation (McClelland & Elman, 1986), or the operation of a task-specific phonemic decision system (Norris, McQueen, & Cutler, 2000). Because the former account involves feedback between lexical and phonemic levels, it predicts that the lexicon's influence on phonemic decisions should be delayed and should gradually increase in strength. Previous response time experiments have not delivered a clear verdict as to whether this is the case, however. In 2 experiments, listeners' eye movements were tracked as they categorized phonemes using visually displayed response options. Lexically relevant information in the signal, the timing of which was confirmed by separate gating experiments, immediately increased eye movements toward the lexically supported response. This effect on eye movements then diminished over the course of the trial rather than continuing to increase. These results challenge the lexical feedback account. The present work also introduces a novel method for analyzing data from ‘visual-world' type tasks, designed to assess when an experimental manipulation influences the probability of an eye movement toward the target. |
Yasuo Terao; Hideki Fukuda; Shinnichi Tokushuge; Yoshiko Nomura; Ritsuko Hanajima; Yoshikazu Ugawa Saccade abnormalities associated with focal cerebral lesions – How cortical and basal ganglia commands shape saccades in humans Journal Article In: Clinical Neurophysiology, vol. 127, no. 8, pp. 2953–2967, 2016. @article{Terao2016,Objective: To study saccade abnormalities associated with focal cerebral lesions, including the cerebral cortex and basal ganglia (BG). Methods: We studied the latency and amplitude of reflexive and voluntary saccades in 37 patients with focal lesions of the frontal and parietal cortices and BG (caudate and putamen), and 51 age-matched controls, along with the ability to inhibit unwanted reflexive saccades. Results: Latencies of reflexive saccades were prolonged in patients with parietal lesions involving the parietal eye field (PEF), whereas their amplitude was decreased with parietal or putaminal lesions. In contrast, latency of voluntary saccades was prolonged and their success rate reduced with frontal lesions including the frontal eye field (FEF) or its outflow tract as well as the dorsolateral/medial prefrontal cortex, and caudate lesions, whereas their amplitude was decreased with parietal lesions. Inhibitory control of reflexive saccades was impaired with frontal, caudate and, less prominently, parietal lesions. Conclusions: PEF is important in triggering reflexive saccades, also determining their amplitude. Whereas FEF and the caudate emit commands for initiating voluntary saccades, their amplitude is mainly determined by PEF. Commands not only from FEF and dorsolateral/medial prefrontal cortex but also from the caudate and PEF serve to inhibit unnecessary reflexive saccades. Significance: The findings suggested how cortical and BG commands shape reflexive and voluntary saccades in humans. |
Taosheng Liu Neural representation of object-specific attentional priority Journal Article In: NeuroImage, vol. 129, pp. 15–24, 2016. @article{Liu2016a,Humans can flexibly select locations, features, or objects in a visual scene for prioritized processing. Although it is relatively straightforward to manipulate location- and feature-based attention, it is difficult to isolate object-based selection. Because objects are always composed of features, studies of object-based selection can often be interpreted as the selection of a combination of locations and features. Here we examined the neural representation of attentional priority in a paradigm that isolated object-based selection. Participants viewed two superimposed gratings that continuously changed their color, orientation, and spatial frequency, such that the gratings traversed the same exact feature values within a trial. Participants were cued at the beginning of each trial to attend to one or the other grating to detect a brief luminance increment, while their brain activity was measured with fMRI. Using multi-voxel pattern analysis, we were able to decode the attended grating in a set of frontoparietal areas, including anterior intraparietal sulcus (IPS), frontal eye field (FEF), and inferior frontal junction (IFJ). Thus, a perceptually varying object can be represented by patterned neural activity in these frontoparietal areas. We suggest that these areas can encode attentional priority for abstract, high-level objects independent of their locations and features. |
Jonathan J. Marotta; Timothy J. Graham Cluttered environments: Differential effects of obstacle position on grasp and gaze locations Journal Article In: Canadian Journal of Experimental Psychology, vol. 70, no. 3, pp. 242–247, 2016. @article{Marotta2016,Previous research has investigated the effects of nontarget objects (NTOs) on reach trajectories, but their effects on eye-hand coordination remain to be determined. The current investigation utilized an eye-hand coordination paradigm, where a reaching and grasping task was performed in the presence of an NTO positioned exclusively in the right or left workspace of each right-handed participant. NTOs varied in their closeness to the subject and reach-path, between the starting location of the hand and the target-object of the reach. A control condition, where only the target was present, was also included. When an NTO was presented on the right (ipsilateral to the reaching hand), it pushed the final grasp and gaze locations on the target, shifting them to the left-away from the "obstacle." The impact of the ipsilateral NTO was increased as it was moved into positions closer to the participant that were of greater obstruction to the hand and arm. In contrast, when the NTO was contralateral, the risk of collision was low and participants developed a set reach plan that was repeated nearly identically for each contralateral NTO position. Our findings also indicate that the "invasiveness" of the NTO positions had a greater effect on grasp than it did on gaze position-demonstrating how the arrangement of clutter in an environment can differentially affect gaze and grasp when reaching for an object. |
Arup Sarma; Nicolas Y. Masse; Xiao-Jing Wang; David J. Freedman Task-specific versus generalized mnemonic representations in parietal and prefrontal cortices Journal Article In: Nature Neuroscience, vol. 19, no. 1, pp. 143–149, 2016. @article{Sarma2015,Our ability to learn a wide range of behavioral tasks is essential for responding appropriately to sensory stimuli according to behavioral demands, but the underlying neural mechanism has been rarely examined by neurophysiological recordings in the same subjects across learning. To understand how learning new behavioral tasks affects neuronal representations, we recorded from posterior parietal cortex (PPC) before and after training on a visual motion categorization task. We found that categorization training influenced cognitive encoding in PPC, with a marked enhancement of memory-related delay-period encoding during the categorization task that was absent during a motion discrimination task before categorization training. In contrast, the prefrontal cortex (PFC) exhibited strong delay-period encoding during both discrimination and categorization tasks. This reveals a dissociation between PFC's and PPC's roles in working memory, with general engagement of PFC across multiple tasks, in contrast with more task-specific mnemonic encoding in PPC. |
Yoshihito Shigihara; Hideyuki Hoshi; Semir Zeki Early visual cortical responses produced by checkerboard pattern stimulation Journal Article In: NeuroImage, vol. 134, pp. 532–539, 2016. @article{shz16,Visual evoked potentials have been traditionally triggered with flash or reversing checkerboard stimuli and recorded with electroencephalographic techniques, largely but not exclusively in clinical or clinically related settings. They have been crucial in determining the healthy functioning or otherwise of the visual pathways up to and including the cerebral cortex. They have typically given early response latencies of 100 ms, the source of which has been attributed to V1, with the prestriate cortex being secondarily activated somewhat later. On the other hand, magnetoencephalographic studies using stimuli better tailored to the physiology of individual, specialized, visual areas have given early latencies of <. 50 ms with the sources localized in both striate (V1) and prestriate cortex. In this study, we used the reversing checkerboard pattern as a stimulus and recorded cortical visual evoked magnetic fields with magnetoencephalography, to establish whether very early responses can be traced to (estimated) in both striate and prestriate cortex, since such a demonstration would enhance considerably the power of this classical approach in clinical investigations. Our results show that cortical responses evoked by checkerboard patterns can be detected before 50 ms post-stimulus onset and that their sources can be estimated in both striate and prestriate cortex, suggesting a strong parallel input from the sub-cortex to both striate and prestriate divisions of the visual cortex. |
Caroline Landelle; Anna Montagnini; Laurent Madelain; Frederic R. Danion Eye tracking a self-moved target with complex hand-target dynamics Journal Article In: Journal of Neurophysiology, vol. 116, no. 4, pp. 1859–1870, 2016. @article{Landelle2016,Previous work has shown that the ability to track with the eye a moving target is substantially improved when the target is self-moved by the subject's hand compared with when being externally moved. Here, we explored a situation in which the mapping between hand movement and target motion was perturbed by simulating an elastic relationship between the hand and target. Our objective was to determine whether the predictive mechanisms driving eye-hand coordination could be updated to accommodate this complex hand-target dynamics. To fully appreciate the behavioral effects of this perturbation, we compared eye tracking performance when self-moving a target with a rigid mapping (simple) and a spring mapping as well as when the subject tracked target trajectories that he/she had previously generated when using the rigid or spring mapping. Concerning the rigid mapping, our results confirmed that smooth pursuit was more accurate when the target was self-moved than externally moved. In contrast, with the spring map- ping, eye tracking had initially similar low spatial accuracy (though shorter temporal lag) in the self versus externally moved conditions. However, within ⬃5 min of practice, smooth pursuit improved in the self-moved spring condition, up to a level similar to the self-moved rigid condition. Subsequently, when the mapping unexpectedly switched from spring to rigid, the eye initially followed the expected target trajectory and not the real one, thereby suggesting that subjects used an internal representation of the new hand-target dynamics. Overall, these results emphasize the stunning adaptability of smooth pursuit when self-maneuvering objects with complex dynamics. |
Meghan B. Mitchell; Steven D. Shirk; Donald G. McLaren; Jessica S. Dodd; Ali Ezzati; Brandon A. Ally; Alireza Atri Recognition of faces and names: Multimodal physiological correlates of memory and executive function Journal Article In: Brain Imaging and Behavior, vol. 10, no. 2, pp. 408–423, 2016. @article{Mitchell2016,We sought to characterize electrophysiological, eye-tracking and behavioral correlates of face-name recognition memory in healthy younger adults using high-density electroencephalography (EEG), infrared eye-tracking (ET), and neuropsychological measures. Twenty-one participants first studied 40 face-name (FN) pairs; 20 were presented four times (4R) and 20 were shown once (1R). Recognition memory was assessed by asking participants to make old/new judgments for 80 FN pairs, of which half were previously studied items and half were novel FN pairs (N). Simultaneous EEG and ET recording were collected during recognition trials. Comparisons of event-related potentials (ERPs) for correctly identified FN pairs were compared across the three item types revealing classic ERP old/new effects including 1) relative positivity (1R > N) bi-frontally from 300 to 500 ms, reflecting enhanced familiarity, 2) relative positivity (4R > 1R and 4R > N) in parietal areas from 500 to 800 ms, reflecting enhanced recollection, and 3) late frontal effects (1R > N) from 1000 to 1800 ms in right frontal areas, reflecting post-retrieval monitoring. ET analysis also revealed significant differences in eye movements across conditions. Exploration of cross-modality relationships suggested associations between memory and executive function measures and the three ERP effects. Executive function measures were associated with several indicators of saccadic eye movements and fixations, which were also associated with all three ERP effects. This novel characterization of face-name recognition memory performance using simultaneous EEG and ET reproduced classic ERP and ET effects, supports the construct validity of the multimodal FN paradigm, and holds promise as an integrative tool to probe brain networks supporting memory and executive functioning. |
Florian Schwarz False but slow: Evaluating statements with Non-referring definites Journal Article In: Journal of Semantics, vol. 33, pp. 177–214, 2016. @article{Schwarz2016,One central debate in the analysis of definite descriptions concerns the truth-value of sentences where there is no entity that meets the description in the definite. Classical Russellian accounts predict them to be plain false, whereas presuppositional accounts predict them to be infelicitous. Recent discussions have homed in on the factors that affect actual judgment behaviour in relation to the underlying status posited by different accounts. This article presents experimental evidence for a presuppositional view based on response times for judging statements with non-referring definites to be ‘false', which were longer relative to control statements where existence was asserted. I discuss the theoretical implications ofthese results, as well as of other findings from the literature, arguing that they support a presuppositional view of definites that sees the existence presupposition as conventionally encoded. The article also makes a methodological contribution, as systematic evidence on speakers' judgments in these cases turns out to be hard to come by. Finally, the results inform the more general issue of the online processes involved in the interpretation of presupposed, as opposed to asserted, content. |
David Souto; Karl R. Gegenfurtner; Alexander C. Schütz Saccade adaptation and visual uncertainty Journal Article In: Frontiers in Human Neuroscience, vol. 10, pp. 227, 2016. @article{sgs16,Visual uncertainty may affect saccade adaptation in two complementary ways. First, an ideal adaptor should take into account the reliability of visual information for determining the amount of correction, predicting that increasing visual uncertainty should decrease adaptation rates. We tested this by comparing observers' direction discrimination and adaptation rates in an intra-saccadic-step paradigm. Second, clearly visible target steps may generate a slower adaptation rate since the error can be attributed to an external cause, instead of an internal change in the visuo-motor mapping that needs to be compensated. We tested this prediction by measuring saccade adaptation to different step sizes. Most remarkably, we found little correlation between estimates of visual uncertainty and adaptation rates and no slower adaptation rates with more visible step sizes. Additionally, we show that for low contrast targets backward steps are perceived as stationary after the saccade, but that adaptation rates are independent of contrast. We suggest that the saccadic system uses different position signals for adapting dysmetric saccades and for generating a trans-saccadic stable visual percept, explaining that saccade adaptation is found to be independent of visual uncertainty. |
Nathalie Van Humbeeck; Tom Putzeys; Johan Wagemans Apparent motion suppresses responses in early visual cortex: A population code model Journal Article In: PLoS Computational Biology, vol. 12, no. 10, pp. e1005155, 2016. @article{VanHumbeeck2016,Two stimuli alternately presented at different locations can evoke a percept of a stimulus continuously moving between the two locations. The neural mechanism underlying this apparent motion (AM) is thought to be increased activation of primary visual cortex (V1) neurons tuned to locations along the AM path, although evidence remains inconclusive. AM masking, which refers to the reduced detectability of stimuli along the AM path, has been taken as evidence for AM-related V1 activation. AM-induced neural responses are thought to interfere with responses to physical stimuli along the path and as such impair the perception of these stimuli. However, AM masking can also be explained by predictive coding models, predicting that responses to stimuli presented on the AM path are suppressed when they match the spatio-temporal prediction of a stimulus moving along the path. In the present study, we find that AM has a distinct effect on the detection of target gratings, limiting the maximum performance at high contrast levels. This masking is strongest when the target orientation is identical to the orientation of the inducers. We developed a V1-like population code model of early visual processing, based on a standard contrast normalization model. We find that AM-related activation in early visual cortex is too small to either cause masking or to be perceived as motion. Our model instead predicts strong suppression of early sensory responses during AM, consistent with the theoretical framework of predictive coding. |
Jeanne Bovet; Junpeng Lao; Océane Bartholomée; Roberto Caldara; Michel Raymond Mapping female bodily features of attractiveness Journal Article In: Scientific Reports, vol. 6, pp. 18551, 2016. @article{Bovet2016,"Beauty is bought by judgment of the eye" (Shakespeare, Love's Labour's Lost), but the bodily features governing this critical biological choice are still debated. Eye movement studies have demonstrated that males sample coarse body regions expanding from the face, the breasts and the midriff, while making female attractiveness judgements with natural vision. However, the visual system ubiquitously extracts diagnostic extra-foveal information in natural conditions, thus the visual information actually used by men is still unknown. We thus used a parametric gaze-contingent design while males rated attractiveness of female front- and back-view bodies. Males used extra-foveal information when available. Critically, when bodily features were only visible through restricted apertures, fixations strongly shifted to the hips, to potentially extract hip-width and curvature, then the breast and face. Our hierarchical mapping suggests that the visual system primary uses hip information to compute the waist-to-hip ratio and the body mass index, the crucial factors in determining sexual attractiveness and mate selection. |
Woo Young Choi; Jayalakshmi Viswanathan; Jason J. S. Barton The temporal dynamics of the distractor in the global effect Journal Article In: Experimental Brain Research, vol. 234, no. 9, pp. 2457–2463, 2016. @article{Choi2016a,In the global effect, saccades are displaced towards a distractor if the latter is near to the target, an effect thought to reflect spatial averaging in neurons of the superior colliculus. The temporal dynamics of the global effect have not been well studied, however. We had twelve subjects perform horizontal saccades to a target in trials in which there were either no distractor or a distractor stim- ulus located 20° above or below the target. The distractor appeared either simultaneously with the target or preceded it by an interval of between 100 and 800 ms, and was either flashed for only 100 ms or remained visible until the sub- ject responded with a saccade. Both flashed and persistent distractors reduced saccadic latency if they preceded target onset, indicating that subjects could use this cue to pre- pare saccades in advance. Saccadic endpoint was displaced towards a flashed distractor only if it was simultaneous with the target. However, persistent distractors produced a global effect for both simultaneous presentation and dis- tractor–target intervals of 100 ms, but not for longer inter- vals. We conclude that the global effect requires of the dis- tractor both a recent onset and persistence of the distractor, and that distractor-related activity decays rapidly within 300 ms. |
Jutta Billino; Jürgen Hennig; Karl R. Gegenfurtner The role of dopamine in anticipatory pursuit eye movements: Insights from genetic polymorphisms in healthy adults Journal Article In: eNeuro, vol. 3, no. 6, pp. 1–13, 2016. @article{Billino2016,There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val158Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3′-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients. |
Carolyn M. Dunifon; Samuel Rivera; Christopher W. Robinson Auditory stimuli automatically grab attention: Evidence from eye tracking and attentional manipulations Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 12, pp. 1947–1958, 2016. @article{Dunifon2016,Simultaneously presenting auditory and visual stimuli can hinder performance for one modality while the other dominates. For approximately 40 years, research with adults has primarily indicated visual dominance, while recent research with infants and young children has revealed auditory dominance. The current study further investigates modality dominance with adults, finding evidence for both auditory and visual dominance across 3 experiments. Using a simple discrimination task, Experiment 1 revealed that cross-modal presentation attenuated discrimination of auditory input, while at the same time, also slowed down visual processing. Even when participants were instructed to only pay attention to the visual stimuli, both spoken nonsense words and nonlinguistic sounds slowed down visual processing (Exper- iment 2). Experiment 3 used a similar discrimination task while utilizing an eye tracker to examine how auditory input affects visual fixations. Cross-modal presentation attenuated auditory discrimination; however, it also slowed down visual response times. In addition, adults also made longer fixations and were slower to make their first fixation when images were paired with sounds. The latter finding is novel and consistent with a proposed mechanism of auditory dominance: auditory stimuli automatically engage attention and attenuate or delay visual processing. |
Aleksandra Mitrovic; Pablo P. L. Tinio; Helmut Leder In: Frontiers in Human Neuroscience, vol. 10, pp. 122, 2016. @article{Mitrovic2016,One of the key behavioral effects of attractiveness is increased visual attention to attractive people. This effect is often explained in terms of evolutionary adaptations, such as attractiveness being an indicator of good health. Other factors could influence this effect. In the present study, we explored the modulating role of sexual orientation on the effects of attractiveness on exploratory visual behavior. Heterosexual and homosexual men and women viewed natural-looking scenes that depicted either two women or two men who varied systematically in levels of attractiveness (based on a pre- study). Participants' eye movements and attractiveness ratings toward the faces of the depicted people were recorded. The results showed that although attractiveness had the largest influence on participants' behaviors, participants' sexual orientations strongly modulated the effects.With the exception of homosexual women, all participant groups looked longer and more often at attractive faces that corresponded with their sexual orientations. Interestingly, heterosexual and homosexual men and homosexual women looked longer and more often at the less attractive face of their non-preferred sex than the less attractive face of their preferred sex, evidence that less attractive faces of the preferred sex might have an aversive character. These findings provide evidence for the important role that sexual orientation plays in guiding visual exploratory behavior and evaluations of the attractiveness of others. |
Jordan E. Pierce; Jennifer E. McDowell Effects of preparation time and trial type probability on performance of anti- and pro-saccades Journal Article In: Acta Psychologica, vol. 164, pp. 188–194, 2016. @article{Pierce2016,Cognitive control optimizes responses to relevant task conditions by balancing bottom-up stimulus processing with top-down goal pursuit. It can be investigated using the ocular motor system by contrasting basic prosaccades (look toward a stimulus) with complex antisaccades (look away from a stimulus). Furthermore, the amount of time allotted between trials, the need to switch task sets, and the time allowed to prepare for an upcoming saccade all impact performance. In this study the relative probabilities of anti- and pro-saccades were manipulated across five blocks of interleaved trials, while the inter-trial interval and trial type cue duration were varied across subjects. Results indicated that inter-trial interval had no significant effect on error rates or reaction times (RTs), while a shorter trial type cue led to more antisaccade errors and faster overall RTs. Responses following a shorter cue duration also showed a stronger effect of trial type probability, with more antisaccade errors in blocks with a low antisaccade probability and slower RTs for each saccade task when its trial type was unlikely. A longer cue duration yielded fewer errors and slower RTs, with a larger switch cost for errors compared to a short cue duration. Findings demonstrated that when the trial type cue duration was shorter, visual motor responsiveness was faster and subjects relied upon the implicit trial probability context to improve performance. When the cue duration was longer, increased fixation-related activity may have delayed saccade motor preparation and slowed responses, guiding subjects to respond in a controlled manner regardless of trial type probability. |
Nina S. Hsu; Jared M. Novick Dynamic engagement of cognitive control modulates recovery from misinterpretation during real-time language processing Journal Article In: Psychological Science, vol. 27, no. 4, pp. 572–582, 2016. @article{Hsu2016,Speech unfolds swiftly, yet listeners keep pace by rapidly assigning meaning to what they hear. Sometimes, though, initial interpretations turn out to be wrong. How do listeners revise misinterpretations of language input moment by moment to avoid comprehension errors? Cognitive control may play a role by detecting when processing has gone awry and then initiating behavioral adjustments accordingly. However, no research to date has investigated a cause-and-effect interplay between cognitive-control engagement and the overriding of erroneous interpretations in real time. Using a novel cross-task paradigm, we showed that Stroop-conflict detection, which mobilizes cognitive-control procedures, subsequently facilitates listeners' incremental processing of temporarily ambiguous spoken instructions that induce brief misinterpretation. When instructions followed incongruent Stroop items, compared with congruent Stroop items, listeners' eye movements to objects in a scene reflected more transient consideration of the false interpretation and earlier recovery of the correct one. Comprehension errors also decreased. Cognitive-control engagement therefore accelerates sentence-reinterpretation processes, even as linguistic input is still unfolding. |
Tom R. Marshall; Sophie Esterer; Jim D. Herring; Til O. Bergmann; Ole Jensen On the relationship between cortical excitability and visual oscillatory responses-A concurrent tDCS-MEG study Journal Article In: NeuroImage, vol. 140, pp. 41–49, 2016. @article{Marshall2016,Neuronal oscillations in the alpha band (8–12 Hz) in visual cortex are considered to instantiate ‘attentional gating' via the inhibition of activity in regions representing task-irrelevant parts of space. In contrast, visual gamma-band activity (40–100 Hz) is regarded as representing a bottom-up drive from incoming visual information, with increased synchronisation producing a stronger feedforward impulse for relevant information. However, little is known about the direct relationship between excitability of the visual cortex and these oscillatory mechanisms. In this study we used transcranial direct current stimulation (tDCS) in an Oz–Cz montage in order to stimulate visual cortex, concurrently recording whole-brain oscillatory activity using magnetoencephalography (MEG) whilst participants performed a visual task known to produce strong modulations of alpha- and gamma-band activity. We found that visual stimuli produced expected modulations of alpha and gamma – presenting a moving annulus stimulus led to a strong gamma increase and alpha decrease – and that this pattern was observable both during active (anodal and cathodal) tDCS and sham tDCS. However, tDCS did not seem to produce systematic alterations of these oscillatory responses. The present study thus demonstrates that concurrent tDCS/MEG of the visual system is a feasible tool for investigating visual neuronal oscillations, and we discuss potential reasons for the apparent inability of tDCS to effectively change the amplitude of visual stimulus induced oscillatory responses in the current study. |
F. Pieruccini-Faria; J. A. Jones; Q. J. Almeida Insight into dopamine-dependent planning deficits in Parkinson's disease: A sharing of cognitive & sensory resources Journal Article In: Neuroscience, vol. 318, pp. 219–229, 2016. @article{PierucciniFaria2016,Cognitive and sensorimotor processes are both needed for successful planning of footsteps during complex gait situations, but the interaction between these factors during motor planning, as well as their response to dopaminergic treatment is poorly understood in Parkinson's disease (PD). In the current study, we evaluated walking and gaze behaviors of individuals with PD while planning an approach toward an obstacle to be stepped over. The obstacle clearance task was completed both ON and OFF dopaminergic medication by individuals with Parkinson's disease (n = 20) and compared to healthy age-matched control participants (n = 19), as well as with and without an auditory digit monitoring dual task. In this novel protocol of synchronized gaze and gait data collection, each trial was split into an early and late phase prior to the obstacle, providing a unique opportunity to examine dopamine-dependent planning deficits in PD. Interestingly, only patients in the OFF medication state showed greater deceleration in the late phase (i.e., just before the obstacle) (F(1,37) = 45.42, p < 0.001), as well as an increase in step time variability (also in this late phase) with the additional demands of a dual task (F(2,74) = 3.49 |
Maria Solé Puig; Josep Marco Pallarés; Laura Perez Zapata; Laura Puigcerver; Josep Cañete; Hans Supèr Attentional selection accompanied by eye vergence as revealed by event-related brain potentials Journal Article In: PLoS ONE, vol. 11, no. 12, pp. e0167646, 2016. @article{Puig2016,Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention is conveyed by cortical feedback connections from frontal regions to lower sensory areas modulating late stimulus responses. A recent study reported the occurrence of small eye vergence during orienting top-down attention. Here we assessed a possible link between vergence and attention by comparing visual event related potentials (vERPs) to a cue stimulus that induced attention to shift towards the target location to the vERPs to a no-cue stimulus that did not trigger orienting attention. The results replicate the findings of eye vergence responses during orienting attention and show that the strength and time of eye vergence coincide with the onset and strength of the vERPs when subjects oriented attention. Our findings therefore support the idea that eye vergence relates to and possibly has a role in attentional selection. |
Gloria Chamorro; Antonella Sorace; Patrick Sturt What is the source of L1 attrition? the effect of recent L1 re-exposure on Spanish speakers under L1 attrition Journal Article In: Bilingualism: Language and Cognition, vol. 19, no. 3, pp. 520–532, 2016. @article{Chamorro2016,The recent hypothesis that L1 attrition affects the ability to process interface structures but not knowledge representations (Sorace, 2011) is tested by investigating the effects of recent L1 re-exposure on antecedent preferences for Spanish pronominal subjects, using offline judgements and online eye-tracking measures. Participants included a group of native Spanish speakers experiencing L1 attrition ('attriters'), a second group of attriters exposed exclusively to Spanish before they were tested ('re-exposed'), and a control group of Spanish monolinguals. The judgement data shows no significant differences between the groups. Moreover, the monolingual and re-exposed groups are not significantly different from each other in the eye-tracking data. The results of this novel manipulation indicate that attrition effects decrease due to L1 re-exposure, and that bilinguals are sensitive to input changes. Taken together, the findings suggest that attrition affects online sensitivity with interface structures rather than causing a permanent change in speakers' L1 knowledge representations. |
Annegret Meermeier; Svenja Gremmler; Markus Lappe The influence of image content on oculomotor plasticity Journal Article In: Journal of Vision, vol. 16, no. 8, pp. 1–12, 2016. @article{Meermeier2016,When we observe a scene, we shift our gaze to different points of interest via saccadic eye movements. Saccades provide high resolution views of objects and are essential for vision. The successful view of an interesting target might constitute a rewarding experience to the oculomotor system. We measured the influence of image content on learning efficiency in saccade control. We compared meaningful pictures to luminance and spatial frequency-matched random noise images in a saccadic adaptation paradigm. In this paradigm a shift of the target during the saccades results in a gradual increase of saccade amplitude. Stimuli were masked at different times after saccade onset. For immediate masking of the stimuli, as well as for their permanent visibility, saccadic adaptation was similar for both types of targets. However, when stimuli were masked 200 ms after saccade onset, adaptation of saccades directed toward the meaningful target stimuli was significantly greater than that of saccades directed toward noise targets. Thus, the percept of a meaningful image at the saccade landing position facilitates learning of the appropriate parameters for saccadic motor control when time constraints exist. We conclude that oculomotor learning, which is traditionally considered a low-level and highly automatized process, is modulated by the visual content of the image. |
Jeffrey S. Bowers; Ivan I. Vankov; Casimir J. H. Ludwig The visual system supports online translation invariance for object identification Journal Article In: Psychonomic Bulletin & Review, vol. 23, no. 2, pp. 432–438, 2016. @article{Bowers2016,The ability to recognize the same image projected to different retinal locations is critical for visual object recognition in natural contexts. According to many theories, the translation invariance for objects extends only to trained retinal locations, so that a familiar object projected to a nontrained location should not be identified. In another approach, invariance is achieved "online," such that learning to identify an object in one location immediately affords generalization to other locations. We trained participants to name novel objects at one retinal location using eyetracking technology and then tested their ability to name the same images presented at novel retinal locations. Across three experiments, we found robust generalization. These findings provide a strong constraint for theories of vision. |
Gloria Chamorro; Patrick Sturt; Antonella Sorace Selectivity in L1 attrition: Differential object marking in Spanish near-native speakers of English Journal Article In: Journal of Psycholinguistic Research, vol. 45, no. 3, pp. 697–715, 2016. @article{Chamorro2016a,Previous research has shown L1 attrition to be restricted to structures at the interfaces between syntax and pragmatics, but not to occur with syntactic properties that do not involve such interfaces ('Interface Hypothesis', Sorace and Filiaci in Anaphora resolution in near-native speakers of Italian. Second Lang Res 22: 339-368, 2006). The present study tested possible L1 attrition effects on a syntax-semantics interface structure [Differential Object Marking (DOM) using the Spanish personal preposition] as well as the effects of recent L1 re-exposure on the potential attrition of these structures, using offline and eye-tracking measures. Participants included a group of native Spanish speakers experiencing attrition ('attriters'), a second group of attriters exposed exclusively to Spanish before they were tested, and a control group of Spanish monolinguals. The eye-tracking results showed very early sensitivity to DOM violations, which was of an equal magnitude across all groups. The off-line results also showed an equal sensitivity across groups. These results reveal that structures involving 'internal' interfaces like the DOM do not undergo attrition either at the processing or representational level. |
Heeyoung Choo; Dirk B. Walther In: NeuroImage, vol. 135, pp. 32–44, 2016. @article{Choo2016,Humans efficiently grasp complex visual environments, making highly consistent judgments of entry-level category despite their high variability in visual appearance. How does the human brain arrive at the invariant neural representations underlying categorization of real-world environments? We here show that the neural representation of visual environments in scene-selective human visual cortex relies on statistics of contour junctions, which provide cues for the three-dimensional arrangement of surfaces in a scene. We manipulated line drawings of real-world environments such that statistics of contour orientations or junctions were disrupted. Manipulated and intact line drawings were presented to participants in an fMRI experiment. Scene categories were decoded from neural activity patterns in the parahippocampal place area (PPA), the occipital place area (OPA) and other visual brain regions. Disruption of junctions but not orientations led to a drastic decrease in decoding accuracy in the PPA and OPA, indicating the reliance of these areas on intact junction statistics. Accuracy of decoding from early visual cortex, on the other hand, was unaffected by either image manipulation. We further show that the correlation of error patterns between decoding from the scene-selective brain areas and behavioral experiments is contingent on intact contour junctions. Finally, a searchlight analysis exposes the reliance of visually active brain regions on different sets of contour properties. Statistics of contour length and curvature dominate neural representations of scene categories in early visual areas and contour junctions in high-level scene-selective brain regions. |
Sarah C. Krall; Lukas J. Volz; Eileen Oberwelland; Christian Grefkes; Gereon R. Fink; Kerstin Konrad The right temporoparietal junction in attention and social interaction: A transcranial magnetic stimulation study Journal Article In: Human Brain Mapping, vol. 37, no. 2, pp. 796–807, 2016. @article{Krall2016,The right temporoparietal junction (rTPJ) has been associated with the ability to reorient attention to unexpected stimuli and the capacity to understand others' mental states (theory of mind [ToM]/false belief). Using activation likelihood estimation meta-analysis we previously unraveled that the anterior rTPJ is involved in both, reorienting of attention and ToM, possibly indicating a more general role in attention shifting. Here, we used neuronavigated transcranial magnetic stimulation to directly probe the role of the rTPJ across attentional reorienting and false belief. Task performance in a visual cueing paradigm and false belief cartoon task was investigated after application of continuous theta burst stimulation (cTBS) over anterior rTPJ (versus vertex, for control). We found that attentional reorienting was significantly impaired after rTPJ cTBS compared with control. For the false belief task, error rates in trials demanding a shift in mental state significantly increased. Of note, a significant positive correlation indicated a close relation between the stimulation effect on attentional reorienting and false belief trials. Our findings extend previous neuroimaging evidence by indicating an essential overarching role of the anterior rTPJ for both cognitive functions, reorienting of attention and ToM. |
Philipp Schwedhelm; B. Suresh Krishna; Stefan Treue An extended normalization model of attention accounts for feature-based attentional enhancement of both response and coherence gain Journal Article In: PLoS Computational Biology, vol. 12, no. 12, pp. e1005225, 2016. @article{skt16,Paying attention to a sensory feature improves its perception and impairs that of others. Recent work has shown that a Normalization Model of Attention (NMoA) can account for a wide range of physiological findings and the influence of different attentional manipulations on visual performance. A key prediction of the NMoA is that attention to a visual feature like an orientation or a motion direction will increase the response of neurons preferring the attended feature (response gain) rather than increase the sensory input strength of the attended stimulus (input gain). This effect of feature-based attention on neuronal responses should translate to similar patterns of improvement in behavioral performance, with psychometric functions showing response gain rather than input gain when attention is directed to the task-relevant feature. In contrast, we report here that when human subjects are cued to attend to one of two motion directions in a transparent motion display, attentional effects manifest as a combination of input and response gain. Further, the impact on input gain is greater when attention is directed towards a narrow range of motion directions than when it is directed towards a broad range. These results are captured by an extended NMoA, which either includes a stimulus-independent attentional contribution to normalization or utilizes direction-tuned normalization. The proposed extensions are consistent with the feature-similarity gain model of attention and the attentional modulation in extrastriate area MT, where neuronal responses are enhanced and suppressed by attention to preferred and non-preferred motion directions respectively. |
Micah Allen; Darya Frank; D. Samuel Schwarzkopf; Francesca Fardo; Joel S. Winston; Tobias U. Hauser; Geraint Rees Unexpected arousal modulates the influence of sensory noise on confidence Journal Article In: eLife, vol. 5, pp. 1–17, 2016. @article{Allen2016,Human perception is invariably accompanied by a graded feeling of confidence that guides metacognitive awareness and decision-making. It is often assumed that this arises solely from the feed-forward encoding of the strength or precision of sensory inputs. In contrast, interoceptive inference models suggest that confidence reflects a weighted integration of sensory precision and expectations about internal states, such as arousal. Here we test this hypothesis using a novel psychophysical paradigm, in which unseen disgust-cues induced unexpected, unconscious arousal just before participants discriminated motion signals of variable precision. Across measures of perceptual bias, uncertainty, and physiological arousal we found that arousing disgust cues modulated the encoding of sensory noise. Furthermore, the degree to which trial-by-trial pupil fluctuations encoded this nonlinear interaction correlated with trial level confidence. Our results suggest that unexpected arousal regulates perceptual precision, such that subjective confidence reflects the integration of both external sensory and internal, embodied states. |
Tal Golan; Ido Davidesco; Meir Meshulam; David M. Groppe; Pierre Mégevand; Erin M. Yeagle; Matthew S. Goldfinger; Michal Harel; Lucia Melloni; Charles E. Schroeder; D. L. Deouell; Ashesh D. Mehta; Rafael Malach Human intracranial recordings link suppressed transients rather than 'filling-in' to perceptual continuity across blinks Journal Article In: eLife, vol. 5, pp. 1–28, 2016. @article{Golan2016,We hardly notice our eye blinks, yet an externally generated retinal interruption of a similar duration is perceptually salient. We examined the neural correlates of this perceptual distinction using intracranially measured ECoG signals from human visual cortex in 14 patients. In early visual areas (V1 and V2), the disappearance of the stimulus due to either invisible blinks or salient blank video frames ('gaps') led to a similar drop in activity level, followed by a positive overshoot beyond baseline, triggered by stimulus reappearance. Ascending the visual hierarchy, the reappearance-related overshoot gradually subsided for blinks but not for gaps. By contrast, the disappearance-related drop did not follow the perceptual distinction - it was actually slightly more pronounced for blinks than for gaps. These findings suggest that blinks' limited visibility compared with gaps is correlated with suppression of blink-related visual activity transients, rather than with 'filling-in' of the occluded content during blinks. |
Benjawan Kasisopa; Ronan G. Reilly; Sudaporn Luksaneeyanawin; Denis Burnham Child readers' eye movements in reading Thai Journal Article In: Vision Research, vol. 123, pp. 8–19, 2016. @article{Kasisopa2016,It has recently been found that adult native readers of Thai, an alphabetic scriptio continua language, engage similar oculomotor patterns as readers of languages written with spaces between words; despite the lack of inter-word spaces, first and last characters of a word appear to guide optimal placement of Thai readers' eye movements, just to the left of word-centre. The issue addressed by the research described here is whether eye movements of Thai children also show these oculomotor patterns. Here the effect of first and last character frequency and word frequency on the eye movements of 18 Thai children when silently reading normal unspaced and spaced text was investigated. Linear mixed-effects model analyses of viewing time measures (first fixation duration, single fixation duration, and gaze duration) and of landing site location revealed that Thai children's eye movement patterns were similar to their adult counterparts. Both first character frequency and word frequency played important roles in Thai children's landing sites; children tended to land their eyes further into words, close to the word centre, if the word began with higher frequency first characters, and this effect was facilitated in higher frequency words. Spacing also facilitated more effective use of first character frequency and it also assisted in decreasing children's viewing time. The use of last-character frequency appeared to be a later development, affecting mainly single fixation duration and gaze duration. In general, Thai children use the same oculomotor control mechanisms in reading spaced and unspaced texts as Thai adults, who in turn have similar oculomotor control as readers of spaced texts. Thus, it appears that eye movements in reading converge on the optimal landing site using whatever cues are available to guide such placement. |
Minna Lyons; Urszula M. Marcinkowska; Victoria Moisey; Neil Harrison The effects of resource availability and relationship status on women's preference for facial masculinity in men: An eye-tracking study Journal Article In: Personality and Individual Differences, vol. 95, pp. 25–28, 2016. @article{Lyons2016,Previous research has demonstrated that perceived availability of environmental resources affects the mate choice of females. However, it is unclear whether women's partnership status influences the effects of environmental circumstances on masculinity preference. Further, the role of environmental scarcity on women's gaze patterns when evaluating male faces has not been investigated. The current study investigated how relationship status and environmental factors affected women's gaze patterns and preference towards masculinised and feminised male faces. Twenty-two participants in a long-term romantic relationship, and 26 who were single, were primed with either a high ('wealthy') or low ('scarcity') resource availability scenario. They then completed a facial masculinity/femininity preference task while eye-gaze behaviour was measured. Women in a relationship (but not single women) had an increased preference towards masculine faces in the scarcity condition, compared to the wealthy condition; this preference was also reflected in eye gaze behaviour. In contrast, single women had longer first fixations on feminine rather than masculine faces when evaluating them as long-term partners in the wealthy condition, but no overt preference for either face type. These findings reveal the importance of taking women's relationship status into account in investigations of the role of environmental influences on masculinity preferences. |
Gabriela Rosenblau; Dorit Kliemann; Benjamin Lemme; Henrik Walter; Hauke R. Heekeren; Isabel Dziobek The role of the amygdala in naturalistic mentalising in typical development and in autism spectrum disorder Journal Article In: British Journal of Psychiatry, vol. 208, no. 6, pp. 556–564, 2016. @article{Rosenblau2016,Background: The substantial discrepancy between mentalising in experimental settings v. real-life social interactions hinders the understanding of the neural basis of real-life social cognition and of social impairments in psychiatric disorders. Aims: To determine the neural mechanisms underlying naturalistic mentalising in individuals with and without autism spectrum disorder. Method: We investigated mentalising with a new video-based functional magnetic resonance imaging task in 20 individuals with autism spectrum disorder and 22 matched healthy controls. Results: Naturalistic mentalising implicated regions of the traditional mentalising network (medial prefrontal cortex, temporoparietal junction), and additionally the insula and amygdala. Moreover, amygdala activity predicted implicit mentalising performance on an independent behavioural task. Compared with controls, the autism spectrum disorder group did not show differences in neural activity within classical mentalising regions. They did, however, show reduced amygdala activity and a reduced correlation between amygdala activity and mentalising accuracy on the behavioural task, compared with controls. Conclusions: These findings highlight the crucial role of the amygdala in making accurate implicit mental state inferences in typical development and in the social cognitive impairments of individuals with autism spectrum disorder. |
Jue Xie; Camillo Padoa-Schioppa Neuronal remapping and circuit persistence in economic decisions Journal Article In: Nature Neuroscience, vol. 19, no. 6, pp. 855–861, 2016. @article{Xie2016,The orbitofrontal cortex plays a central role in good-based economic decisions. When subjects make choices, neurons in this region represent the identities and values of offered and chosen goods. Notably, choices in different behavioral contexts may involve a potentially infinite variety of goods. Thus a fundamental question concerns the stability versus flexibility of the decision circuit. Here we show in rhesus monkeys that neurons encoding the identity or the subjective value of particular goods in a given context 'remap' and become associated with different goods when the context changes. At the same time, the overall organization of the decision circuit and the function of individual cells remain stable across contexts. In particular, two neurons supporting the same decision in one context also support the same decision in different contexts. These results demonstrate how the same neural circuit can underlie economic decisions involving a large variety of goods. |