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2018 |
Marta Suárez-Pinilla; Anil K. Seth; Warrick Roseboom The illusion of uniformity does not depend on the primary visual cortex: Evidence from sensory adaptation Journal Article In: i-Perception, vol. 9, no. 5, pp. 1–13, 2018. @article{SuarezPinilla2018a, Visual experience appears richly detailed despite the poor resolution of the majority of the visual field, thanks to foveal-peripheral integration. The recently described Uniformity Illusion (UI), in which peripheral elements of a pattern seem to take on the properties of foveal elements, may shed light on this integration. We examined the basis of UI by generating adaptation to a pattern of Gabors suitable for producing UI on orientation. After removing the pattern, participants reported the tilt of a single peripheral Gabor. The tilt after-effect (TAE) followed the physical adapting orientation rather than the global orientation perceived under UI, even when the illusion had been reported for a long time. Conversely, a control experiment replacing illusory for physical uniformity for the same durations did produce an after-effect to the global orientation. Our results indicate that the UI is not associated with changes in sensory encoding, but likely depends on high-level processes. |
Aditi Subramaniam; Vijay Danivas; Sri Mahavir Agarwal; Sunil Kalmady; Venkataram Shivakumar; Anekal C. Amaresha; Anushree Bose; Janardhanan C. Narayanaswamy; Shivarama Varambally; Samuel B. Hutton; Ganesan Venkatasubramanian; Bangalore N. Gangadhar Clinical correlates of saccadic eye movement in antipsychotic-naïve schizophrenia Journal Article In: Psychiatry Research, vol. 259, pp. 154–159, 2018. @article{Subramaniam2018, Some aspects of saccadic performance have been found to be abnormal in chronic schizophrenia. The majority of this research has, however, been performed on patients treated with long-term antipsychotic medication. Very few studies have examined saccadic performance in antipsychotic-naïve/free patients. There are also very few studies describing the relationship between saccadic performance and clinical symptoms, particularly in antipsychotic free patients. In this study, we compared pro and antisaccade performance in a large sample of antipsychotic-naïve/free schizophrenia patients (N = 45) with healthy controls (N = 57). Clinical symptoms were assessed using Scale for Assessment of Positive Symptoms (SAPS) and Negative Symptoms (SANS). In the antisaccade task, patients made significantly more errors, and their correct antisaccades had smaller amplitudes in comparison to healthy controls. Higher error rates were associated with increased severity of hallucinations. In the prosaccade task, patients had less accurate final eye positions, and made saccades with slower latency and reduced amplitude compared to the healthy controls. These observations in schizophrenia patients without the potential confounds of antipsychotic treatment suggest intrinsic link between saccadic deficits and schizophrenia pathogenesis. The relationship between antisaccade errors and hallucination severity supports the potential link between hallucinations and deficits in inhibitory control. |
Emma Sumner; Hayley C. Leonard; Elisabeth L. Hill Comparing attention to socially-relevant stimuli in autism spectrum disorder and developmental coordination disorder Journal Article In: Journal of Abnormal Child Psychology, vol. 46, no. 8, pp. 1717–1729, 2018. @article{Sumner2018, Difficulties with social interaction have been reported in both children with an autism spectrum disorder (ASD) and children with developmental coordination disorder (DCD), although these disorders have very different diagnostic characteristics. To date, assessment of social skills in a DCD population has been limited to paper-based assessment or parent report. The present study employed eye tracking methodology to examine how children attend to socially-relevant stimuli, comparing 28 children with DCD, 28 children with ASD and 26 typically-developing (TD) age-matched controls (aged 7-10). Eye movements were recorded while children viewed 30 images, half of which were classed as 'Individual' (one person in the scene, direct gaze) and the other half were 'Social' (more naturalistic scenes showing an interaction). Children with ASD spent significantly less time looking at the face/eye regions in the images than TD children, but children with DCD performed between the ASD and TD groups in this respect. Children with DCD demonstrated a reduced tendency to follow gaze, in comparison to the ASD group. Our findings confirm that social atypicalities are present in both ASD and to a lesser extent DCD, but follow a different pattern. Future research would benefit from considering the developmental nature of the observed findings and their implications for support. |
Ayuko Suzuki; Jun Shinozaki; Shogo Yazawa; Yoshino Ueki; Noriyuki Matsukawa; Shun Shimohama; Takashi Nagamine In: Journal of Alzheimer's Disease, vol. 61, no. 4, pp. 1653–1665, 2018. @article{Suzuki2018, Background: The mental rotation task is well-known for the assessment of visuospatial function; however, it has not been used for screening of dementia patients. Objective: The aim of this study was to create a simple screening test for patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) by focusing on non-amnestic symptoms. Methods: Age-matched healthy controls (age 75.3+/-6.8), patients with MCI (76.5+/-5.5), and AD (78.2+/-5.0) participated in this study. They carried out mental rotation tasks targeting geometric graphics or alphabetical characters with three rotating angles (0degree, 90degree, and 180degree) and indicated the correct answer. Response accuracy and reaction time were recorded along with their eye movements using an eye tracker. To quantify their visual processing strategy, the run count ratio (RC ratio) was calculated by dividing the mean number of fixations in incorrect answers by that in correct answers. Results: AD patients showed lower accuracy and longer reaction time than controls. They also showed a significantly greater number of fixation and smaller saccade amplitude than controls, while fixation duration did not differ significantly. The RC ratio was higher for AD, followed by MCI and control groups. By setting the cut-off value to 0.47 in the 180degree rotating angle task, we could differentiate MCI patients from controls with a probability of 80.0%. Conclusions: We established a new screening system for dementia patients by evaluating visuospatial function. The RC ratio during a mental rotation task is useful for discriminating MCI patients from controls. |
Yuta Suzuki; Tetsuto Minami; Shigeki Nakauchi Association between pupil dilation and implicit processing prior to object recognition via insight Journal Article In: Scientific Reports, vol. 8, pp. 6874, 2018. @article{Suzuki2018a, Insight refers to the sudden conscious shift in the perception of a situation following a period of unconscious processing. The present study aimed to investigate the implicit neural mechanisms underlying insight-based recognition, and to determine the association between these mechanisms and the extent of pupil dilation. Participants were presented with ambiguous, transforming images comprised of dots, following which they were asked to state whether they recognized the object and their level of confidence in this statement. Changes in pupil dilation were not only characterized by the recognition state into the ambiguous object but were also associated with prior awareness of object recognition, regardless of meta-cognitive confidence. Our findings indicate that pupil dilation may represent the level of implicit integration between memory and visual processing, despite the lack of object awareness, and that this association may involve noradrenergic activity within the locus coeruleus-noradrenergic (LC-NA) system. |
Martin Szinte; Donatas Jonikaitis; Dragan Rangelov; Heiner Deubel Pre-saccadic remapping relies on dynamics of spatial attention Journal Article In: eLife, vol. 7, pp. 1–16, 2018. @article{Szinte2018, Each saccade shifts the projections of the visual scene on the retina. It has been proposed that the receptive fields of neurons in oculomotor areas are predictively remapped to account for these shifts. While remapping of the whole visual scene seems prohibitively complex, selection by attention may limit these processes to a subset of attended locations. Because attentional selection consumes time, remapping of attended locations should evolve in time, too. In our study, we cued a spatial location by presenting an attention-capturing cue at different times before a saccade and constructed maps of attentional allocation across the visual field. We observed no remapping of attention when the cue appeared shortly before saccade. In contrast, when the cue appeared sufficiently early before saccade, attentional resources were reallocated precisely to the remapped location. Our results show that pre-saccadic remapping takes time to develop suggesting that it relies on the spatial and temporal dynamics of spatial attention. |
Tobias Talanow; Ulrich Ettinger Effects of task repetition but no transfer of inhibitory control training in healthy adults Journal Article In: Acta Psychologica, vol. 187, pp. 37–53, 2018. @article{Talanow2018, Executive functions (EFs) comprise the updating, shifting and inhibition dimensions. According to the Unity and Diversity Model, the inhibition dimension is fully accounted for by a general EFs factor. This suggests that training of inhibition should transfer, in part, to updating and shifting. Therefore, we tested the effectiveness of a three-week inhibition training (high-conflict Stroop task) and explored near transfer effects to an untrained inhibition task (antisaccade task) and far transfer effects to untrained tasks demanding task-set shifting (number-letter-task), working memory updating (n-back task) and planning abilities (Stockings of Cambridge task). We employed a randomized pretest/treatment/posttest study design in n = 102 healthy young adults, assigned to an intensive Stroop training (n = 38), an active control condition (n = 34) or no training intervention (n = 30). In the Stroop training group, Stroop performance improved with practice, while performance in the active control group remained unchanged. The Stroop training group showed improvements in overall Stroop task performance from pretest to posttest, but we observed neither near nor far transfer effects. Additionally, specifically stronger gains on incongruent Stroop trials compared to congruent trials were observed in the Stroop training group when color bar trials were excluded from the pretest-posttest-analysis. Generally, there were substantial improvements from pretest to posttest independent of training condition in all transfer tasks. In sum, our data do not support the existence of transfer effects from inhibition training in healthy young adults. |
Jessica Taubert; Goedele Van Belle; Rufin Vogels; Bruno Rossion The impact of stimulus size and orientation on individual face coding in monkey face-selective cortex Journal Article In: Scientific Reports, vol. 8, pp. 10339, 2018. @article{Taubert2018, Face-selective neurons in the monkey temporal cortex discharge at different rates in response to pictures of different individual faces. Here we tested whether this pattern of response across single neurons in the face-selective area ML (located in the middle Superior Temporal Sulcus) tolerates two affine transformations; picture-plane inversion, known to decrease the average response of face- selective neurons and the other, stimulus size. We recorded the response of 57 ML neurons in two awake and fixating monkeys. Face stimuli were presented at two sizes (10 and 5 degrees of visual angle) and two orientations (upright and inverted). Different faces elicited distinct patterns of activity across ML neurons that were reliable (i.e., predictable with a classifier) within a specific size and orientation condition. Despite observing a reduction in the average response magnitude of face-selective neurons to inverted faces, compared to upright faces, classifier performance was above chance for both upright and inverted faces. While decoding was largely preserved across changes in stimulus size, a classifier trained with one orientation condition and tested on the other did not lead to performance above chance level. We conclude that different individual faces can be decoded from patterns of responses in the monkey area ML regardless of orientation or size, but with qualitatively different patterns of responses for upright and inverted faces. |
Robert Taylor; Paul M. Bays Efficient coding in visual working memory accounts for stimulus-specific variations in recall Journal Article In: Journal of Neuroscience, vol. 38, no. 32, pp. 7132–7142, 2018. @article{Taylor2018, Recall of visual features from working memory varies in both bias and precision depending on stimulus parameters. Whereas a number of models can approximate the average distribution of recall error across target stimuli, attempts to model how error varies with the choice of target have been ad hoc Here we adapt a neural model of working memory to provide a principled account of these stimulus-specific effects, by allowing each neuron's tuning function to vary according to the principle of efficient coding, which states that neural responses should be optimized with respect to the frequency of stimuli in nature. For orientation, this means incorporating a prior that favors cardinal over oblique orientations. While continuing to capture the changes in error distribution with set size, the resulting model accurately described stimulus-specific variations as well, better than a slot-based competitor. Efficient coding produces a repulsive bias away from cardinal orientations, a bias that ought to be sensitive to changes in the environmental statistics. We subsequently tested whether shifts in the stimulus distribution influenced response bias to uniformly sampled target orientations in human subjects (of either sex). Across adaptation blocks, we manipulated the distribution of nontarget items by sampling from a bimodal congruent (incongruent) distribution with peaks centered on cardinal (oblique) orientations. Preadaptation responses were repulsed away from the cardinal axes. However, exposure to the incongruent distribution produced systematic decreases in repulsion that persisted after adaptation. This result confirms the role of prior expectation in generating stimulus-specific effects and validates the neural framework. |
Nina N. Thigpen; L. Forest Gruss; Steven Garcia; David R. Herring; Andreas Keil What does the dot-probe task measure? A reverse correlation analysis of electrocortical activity Journal Article In: Psychophysiology, vol. 55, no. 6, pp. e13058, 2018. @article{Thigpen2018, The dot-probe task is considered a gold standard for assessing the intrinsic attentive selection of one of two lateralized visual cues, measured by the response time to a subsequent, lateralized response probe. However, this task has recently been associated with poor reliability and conflicting results. To resolve these discrepancies, we tested the underlying assumption of the dot-probe task-that fast probe responses index heightened cue selection-using an electrophysiological measure of selective attention. Specifically, we used a reverse correlation approach in combination with frequency-tagged steady-state visual potentials (ssVEPs). Twenty-one participants completed a modified dot-probe task in which each member of a pair of lateralized face cues, varying in emotional expression (angry-angry, neutral-angry, neutral-neutral), flickered at one of two frequencies (15 or 20 Hz), to evoke ssVEPs. One cue was then replaced by a response probe, and participants indicated the probe orientation (0° or 90°). We analyzed the ssVEP evoked by the cues as a function of response speed to the subsequent probe (i.e., a reverse correlation analysis). Electrophysiological measures of cue processing varied with probe hemifield location: Faster responses to left probes were associated with weak amplification of the preceding left cue, apparent only in a median split analysis. By contrast, faster responses to right probes were systematically and parametrically predicted by diminished visuocortical selection of the preceding right cue. Together, these findings highlight the poor validity of the dot-probe task, in terms of quantifying intrinsic, nondirected attentive selection irrespective of probe/cue location. |
Grace Anne Thompson; Larry Allen Abel Fostering spontaneous visual attention in children on the autism spectrum: A proof-of-concept study comparing singing and speech Journal Article In: Autism Research, vol. 11, no. 5, pp. 732–737, 2018. @article{Thompson2018, Children on the autism spectrum are reported to have lower rates of social gaze as early as toddlerhood, and this pattern persists across the lifespan. Finding ways to promote more natural and spontaneous engagement in social interactions may help to boost developmental opportunities in the child's home and community settings. This proof-of-concept study hypothesized that a video of a singer would elicit more attention to the performer, particularly to her face, than a video of her reading a story, and that the child's familiarity with the material would enhance attention. Sixteen children on the autism spectrum (7-10 years old) watched 4 videos 1 min long comprising a favorite song or story, and an unfamiliar song and story. Eye movements were recorded, and three-way repeated measures ANOVAs examined the proportion of total valid visual dwell time and fixations, in each trial and each target area. For proportion of both dwell time and fixation counts, children were significantly more likely to look at the performer's face and body and less at the prop during singing than story-telling and when familiar rather than unfamiliar material was presented. These findings raise important issues for supporting children to naturally initiate looking toward a person's face. |
Malathi Thothathiri; Christine T. Asaro; Nina S. Hsu; Jared M. Novick Who did what? A causal role for cognitive control in thematic role assignment during sentence comprehension Journal Article In: Cognition, vol. 178, pp. 162–177, 2018. @article{Thothathiri2018, Thematic role assignment – generally, figuring out who did what to whom – is a critical component of sentence comprehension, which is influenced by both syntactic and semantic cues. Conflict between these cues can result in temporary consideration of multiple incompatible interpretations during real-time sentence processing. We tested whether the resolution of syntax-semantics conflict can be expedited by the online engagement of cognitive control processes that are routinely used to regulate behavior across domains. In this study, cognitive control deployment from a previous Stroop trial influenced eye movements during subsequent sentence comprehension. Specifically, when syntactic and semantic cues competed for influence on interpretation, dynamic cognitive control engagement led to (a) fewer overall looks to a picture illustrating the competing but incorrect interpretation (Experiment 1), or (b) steeper growth in looks to a picture illustrating the correct interpretation (Experiment 2). Thus, prior cognitive control engagement facilitated the resolution of syntax-semantics conflict by biasing processing towards the intended analysis. This conflict adaptation effect demonstrates a causal connection between cognitive control and real-time thematic role assignment. Broader patterns demonstrated that prior cognitive control engagement also modulated sentence processing irrespective of the presence of conflict, reflecting increased integration of newly arriving cues with prior sentential content. Together, the results suggest that cognitive control helps listeners determine correct event roles during real-time comprehension. |
Shira Tkacz-Domb; Yaffa Yeshurun The size of the attentional window when measured by the pupillary response to light Journal Article In: Scientific Reports, vol. 8, pp. 11878, 2018. @article{TkaczDomb2018, This study measured the size of the attentional window when attention is narrowly focused, using attentional modulation of the pupillary light response – pupillary constriction when covertly attending a brighter than darker area. This allowed us to avoid confounds and biases involved in relying on observers' response (e.g., RT), which contaminated previous measurements of this window. We presented letters to the right and left of fixation, each surrounded by task-irrelevant disks with varying distances. The disks were bright on one side and dark on the other. A central cue indicated which letter to attend. Luminance levels were identical across trials. We found that pupil size was modulated by the disks' luminance when they were 1° away from the attended letter, but not when this distance was larger. This suggests that the diameter of the attentional window is at least 2°, which is twice as large as that established with behavioral measurements. |
Leah N. Tobin; Christopher R. Sears; Alicia S. Zumbusch; Kristin M. Von Ranson Attention to fat- and thin-related words in body-satisfied and body-dissatisfied women before and after thin model priming Journal Article In: PLoS ONE, vol. 13, no. 2, pp. e0192914, 2018. @article{Tobin2018, Understanding the cognitive processes underlying body dissatisfaction provides important information on the development and perpetuation of eating pathology. Previous research suggests that body-dissatisfied women process weight-related information differently than body-satisfied women, but the precise nature of these processing differences is not yet understood. In this study, eye-gaze tracking was used to measure attention to weight-related words in body-dissatisfied (n = 40) and body-satisfied (n = 38) women, before and after exposure to images of thin fashion models. Participants viewed 8-second displays containing fat-related, thin-related, and neutral words while their eye fixations were tracked and recorded. Based on previous research and theory, we predicted that body-dissatisfied women would attend to fat-related words more than body-satisfied women and would attend to thin-related words less. It was also predicted that exposure to thin model images would increase self-rated body dissatisfaction and heighten group differences in attention. The results indicated that body-dissatisfied women attended to both fat- and thin-related words more than body-satisfied women and that exposure to thin models did not increase this effect. Implications for cognitive models of eating disorders are discussed. |
Shin-ichi Tokushige; Shun-ichi Matsuda; Genko Oyama; Yasushi Shimo; Atsushi Umemura; Takuya Sasaki; Satomi Inomata-Terada; Akihiro Yugeta; Masashi Hamada; Yoshikazu Ugawa; Shoji Tsuji; Nobutaka Hattori; Yasuo Terao Effect of subthalamic nucleus deep brain stimulation on visual scanning Journal Article In: Clinical Neurophysiology, vol. 129, no. 11, pp. 2421–2432, 2018. @article{Tokushige2018, Objective: Deep brain stimulation (DBS) can provide insights into the workings of the basal ganglia (BG) by interfering with their function. In patients with Parkinson's disease (PD) treated with DBS of the subthalamic nucleus, we studied the effect of DBS on scanning eye movements. Methods: In the visual memory task, subjects viewed images of various complexities for later recall. In visual search tasks, subjects looked for and fixated one odd target ring, embedded among 48 Landolt rings, which either stood out or not from the distractors. We compared the parameters of scanning saccades when DBS was on and off. Results: In the visual memory task, DBS increased the amplitude of saccades scanning simple but not complex drawings. In the visual search tasks, DBS showed no effect on saccade amplitude or frequency. Conclusions: Saccades when viewing simple images were affected by DBS since they are internally guided saccades, for which the involvement of BG is large. In contrast, saccades when viewing complex images or during visual search, made with the help of visual cues in the images (externally guided saccades) and less dependent on BG, were resistant to the effect of DBS. Significance: DBS affects saccades differentially depending on the task. |
Gregor Torkar; Manja Veldin; Saša Aleksej Glažar; Anja Podlesek In: EURASIA Journal of Mathematics, Science and Technology Education, vol. 14, no. 6, pp. 2265–2276, 2018. @article{Torkar2018, In order to understand water balance in plants, students must understand the relation between external representations at the macroscopic, microscopic, and submicroscopic levels. This study investigated how Slovenian students (N = 79) at the primary, secondary, and undergraduate tertiary levels understand water balance in plants. The science problem consisted of a text describing the setting, visualizations of the process occurring in a wilted plant stem, and five tasks. To determine students' visual attention to the various elements of the tasks, we used eye tracking and focused on the total fixation duration in particular areas of interest. As expected, primary school students showed less knowledge and understanding of the process than the secondary school and university students did. Students with correct answers spent less time observing the biological phenomena displayed at the macroscopic and submicroscopic levels than those with incorrect answers, and more often provided responses that combined the macro-, micro-, and submicroscopic levels of thought. Learning about difficult scientific topics, such as the water balance in plants, with representations at the macroscopic and submicroscopic levels can be either helpful or confusing for learners, depending on their expertise in using multiple external representations, which is important to consider in biology and science education. |
Ralph S. Redden; Matthew D. Hilchey; Raymond M. Klein Oculomotor inhibition of return: Evidence against object-centered representation Journal Article In: Visual Cognition, vol. 26, no. 9, pp. 719–733, 2018. @article{Redden2018, Intermixing central, directional arrow targets with the peripheral targets typically used in the Posnerian spatial cueing paradigm offers a useful diagnostic for ascertaining the relative contributions of output and input processes to oculomotor inhibition of return (IOR). Here, we use this diagnostic to determine whether object-based oculomotor IOR comprises output and/or input processes. One of two placeholder objects in peripheral vision was cued, then both objects rotated smoothly either 90 or 180 degrees around the circumference of an imaginary circle. After this movement, a saccade was made to the location marked by a peripheral onset target or indicated by the central arrow. In our first three experiments, whereas there was evidence for IOR when measured by central arrow or peripheral onset targets at cued locations, there was little trace of IOR at the cued object. We thereafter precisely replicated the seminal experiment for object-based oculomotor IOR (Abrams, R. A., & Dobkin, R. S. (1994). Inhibition of return: Effects of attentional cuing on eye movement latencies. Journal of Experimental Psychology: Human Perception and Performance, 20(3), 467–477; Experiment 4) but again found little evidence of an object-based IOR effect. Finally, we ran a paradigm with only peripheral targets and with motion and stationary trials randomly intermixed. Here we again showed IOR at the cued location but not at the cued object. Together, the findings suggest that object-based representation of oculomotor IOR is much more tenuous than implied by the literature. |
Thomas R. Reppert; Ioannis Rigas; David J. Herzfeld; Ehsan Sedaghat-Nejad; Oleg V. Komogortsev; Reza Shadmehr Movement vigor as a traitlike attribute of individuality Journal Article In: Journal of Neurophysiology, vol. 120, no. 2, pp. 741–757, 2018. @article{Reppert2018a, A common aspect of individuality is our subjective preferences in evaluation of reward and effort. The neural circuits that evaluate these commodities influence circuits that control our movements, raising the possibility that vigor differences between individuals may also be a trait of individuality, reflecting a willingness to expend effort. In contrast, classic theories in motor control suggest that vigor differences reflect a speed-accuracy trade-off, predicting that those who move fast are sacrificing accuracy for speed. Here we tested these contrasting hypotheses. We measured motion of the eyes, head, and arm in healthy humans during various elementary movements (saccades, head-free gaze shifts, and reaching). For each person we characterized their vigor, i.e., the speed with which they moved a body part (peak velocity) with respect to the population mean. Some moved with low vigor, while others moved with high vigor. Those with high vigor tended to react sooner to a visual stimulus, moving both their eyes and arm with a shorter reaction time. Arm and head vigor were tightly linked: individuals who moved their head with high vigor also moved their arm with high vigor. However, eye vigor did not correspond strongly with arm or head vigor. In all modalities, vigor had no impact on end-point accuracy, demonstrating that differences in vigor were not due to a speed-accuracy trade-off. Our results suggest that movement vigor may be a trait of individuality, not reflecting a willingness to accept inaccuracy but demonstrating a propensity to expend effort. |
Thomas R. Reppert; Mathieu Servant; Richard P. Heitz; Jeffrey D. Schall In: Journal of Neurophysiology, vol. 120, no. 1, pp. 372–384, 2018. @article{Reppert2018, Balancing the speed-accuracy tradeoff (SAT) is necessary for successful behavior. Using a visual search task with interleaved cues emphasizing speed or accuracy, we recently reported diverse contributions of frontal eye field (FEF) neurons instantiating salience evidence and response preparation. Here, we report replication of visual search SAT performance in two macaque monkeys, new information about variation of saccade dynamics with SAT, extension of the neurophysiological investigation to describe processes in the superior colliculus (SC), and a description of the origin of search errors in this task. Saccade vigor varied idiosyncratically across SAT conditions and monkeys but tended to decrease with response time. As observed in the FEF, speed-accuracy tradeoff was accomplished through several distinct adjustments in the superior colliculus. In “Accurate” relative to “Fast” trials, visually responsive neurons in SC as in FEF had lower baseline firing rates and later target selection. The magnitude of these adjustments in SC was indistinguishable from that in FEF. Search errors occurred when visual salience neurons in the FEF and the SC treated distractors as targets, even in the Accurate condition. Unlike FEF, the magnitude of visual responses in the SC did not vary across SAT conditions. Also unlike FEF, the activity of SC movement neurons when saccades were initiated was equivalent in Fast and Accurate trials. Saccade-related neural activity in SC, but not FEF, varied with saccade peak velocity. These results extend our understanding of the cortical and subcortical contributions to SAT. |
Leon C. Reteig; Tomas Knapen; Floris J. F. W. Roelofs; K. Richard Ridderinkhof; Heleen A. Slagter No evidence that frontal eye field tDCS affects latency or accuracy of prosaccades Journal Article In: Frontiers in Neuroscience, vol. 12, pp. 617, 2018. @article{Reteig2018, Transcranial direct current stimulation (tDCS) may be used to directly affect neural activity from outside of the skull. However, its exact physiological mechanisms remain elusive, particularly when applied to new brain areas. The frontal eye field (FEF) has rarely been targeted with tDCS, even though it plays a crucial role in control of overt and covert spatial attention. Here we investigate whether tDCS over the FEF can affect the latency and accuracy of saccadic eye movements. 26 participants performed a prosaccade task in which they made eye movements to a sudden-onset eccentric visual target (lateral saccades). After each lateral saccade, they made an eye movement back to the center (center saccades). The task was administered before, during and after anodal or cathodal tDCS over the FEF, in a randomized, double-blind, within-subject design. One previous study (Kanai et al., 2012) found that anodal tDCS over the FEF decreased the latency of saccades contralateral to the stimulated hemisphere. We did not find the same effect: neither anodal nor cathodal tDCS influenced the latency of lateral saccades. tDCS also did not affect accuracy of lateral saccades (saccade endpoint deviation and saccade endpoint variability). For center saccades, we found some differences between the anodal and cathodal sessions, but these were not consistent across analyses (latency, endpoint variability), or were already present before tDCS onset (endpoint deviation). We tried to improve on the design of Kanai et al. (2012) in several ways, including the tDCS duration and electrode montage, which could explain the discrepant results. Our findings add to a growing number of null results, which have sparked concerns that tDCS outcomes are highly variable. Future studies should aim to establish the boundary conditions for frontal eye field tDCS to be effective, in addition to increasing sample size and adding additional controls such as a sham condition. At present, we conclude that it is unclear whether eye movements or other aspects of spatial attention can be affected through tDCS of the frontal eye fields. |
Reuben Rideaux; Andrew E. Welchman Proscription supports robust perceptual integration by suppression in human visual cortex Journal Article In: Nature Communications, vol. 9, pp. 1502, 2018. @article{Rideaux2018, Perception relies on integrating information within and between the senses, but how does the brain decide which pieces of information should be integrated and which kept separate? Here we demonstrate how proscription can be used to solve this problem: certain neurons respond best to unrealistic combinations of features to provide ‘what not' information that drives suppression of unlikely perceptual interpretations. First, we present a model that captures both improved perception when signals are consistent (and thus should be integrated) and robust estimation when signals are conflicting. Second, we test for signatures of proscription in the human brain. We show that concentrations of inhibitory neurotransmitter GABA in a brain region intricately involved in integrating cues (V3B/KO) correlate with robust integration. Finally, we show that perturbing excitation/inhibition impairs integration. These results highlight the role of proscription in robust perception and demonstrate the functional purpose of ‘what not' sensors in supporting sensory estimation. |
Andrew T. Rider; Antoine Coutrot; Elizabeth Pellicano; Steven C. Dakin; Isabelle Mareschal Semantic content outweighs low-level saliency in determining children's and adults' fixation of movies Journal Article In: Journal of Experimental Child Psychology, vol. 166, pp. 293–309, 2018. @article{Rider2018, To make sense of the visual world, we need to move our eyes to focus regions of interest on the high-resolution fovea. Eye movements, therefore, give us a way to infer mechanisms of visual processing and attention allocation. Here, we examined age-related differences in visual processing by recording eye movements from 37 children (aged 6–14 years) and 10 adults while viewing three 5-min dynamic video clips taken from child-friendly movies. The data were analyzed in two complementary ways: (a) gaze based and (b) content based. First, similarity of scanpaths within and across age groups was examined using three different measures of variance (dispersion, clusters, and distance from center). Second, content-based models of fixation were compared to determine which of these provided the best account of our dynamic data. We found that the variance in eye movements decreased as a function of age, suggesting common attentional orienting. Comparison of the different models revealed that a model that relies on faces generally performed better than the other models tested, even for the youngest age group (<10 years). However, the best predictor of a given participant's eye movements was the average of all other participants' eye movements both within the same age group and in different age groups. These findings have implications for understanding how children attend to visual information and highlight similarities in viewing strategies across development. |
Abigail R. Riemer; Michelle Haikalis; Molly R. Franz; Michael D. Dodd; David DiLillo; Sarah J. Gervais In: Sex Roles, vol. 79, no. 7-8, pp. 449–463, 2018. @article{Riemer2018, Despite literature revealing the adverse consequences of objectifying gazes for women, little work has empirically examined origins of objectifying gazes by perceivers. Integrating alcohol myopia and objectification theories, we examined the effects of alcohol as well as perceived female attractiveness, warmth, and competence on objectifying gazes. Specifically, male undergraduates (n = 49) from a large U.S. Midwestern university were administered either an alcoholic or placebo beverage. After consumption, participants were asked to focus on the appearance or personality (counterbalanced) of pictured women who were previously rated as high, average, or low in attractiveness, warmth, and competence. Replicating previous work, appearance focus increased objectifying gazes as measured by decreased visual dwell time on women's faces and increased dwell time on women's bodies. Additionally, alcohol increased objectifying gazes. Whereas greater perceived attractiveness increased objectifying gazes, more perceived warmth and perceived competence decreased objectifying gazes. Furthermore, the effects of warmth and competence perceptions on objectifying gazes were moderated by alcohol condition; intoxicated participants objectified women low in warmth and competence to a greater extent than did sober participants. Implications for understanding men's objectifying perceptions of women are addressed, shedding light on potential interventions for clinicians and policymakers to reduce alcohol-involved objectification and related sexual aggression. |
Anthony J. Ries; David Slayback; Jon Touryan The fixation-related lambda response: Effects of saccade magnitude, spatial frequency, and ocular artifact removal Journal Article In: International Journal of Psychophysiology, vol. 134, pp. 1–8, 2018. @article{Ries2018, Fixation-related potentials (FRPs) enable examination of electrophysiological signatures of visual perception under naturalistic conditions, providing a neural snapshot of the fixated scene. The most prominent FRP component, commonly referred to as the lambda response, is a large deflection over occipital electrodes (O1, Oz, O2) peaking 80–100 ms post fixation, reflecting afferent input to visual cortex. The lambda response is affected by bottom-up stimulus features and the size of the preceding saccade; however, prior research has not adequately controlled for these influences in free viewing paradigms. The current experiment (N = 16, 1 female) addresses these concerns by systematically manipulating spatial frequency in a free-viewing task requiring a range of saccade sizes. Given the close temporal proximity between saccade related activity and the onset of the lambda response, we evaluate how removing independent components (IC) associated with ocular motion artifacts affects lambda response amplitude. Our results indicate that removing ocular artifact ICs based on the covariance with gaze position did not significantly affect the amplitude of this occipital potential. Moreover, the results showed that spatial frequency and saccade magnitude each produce significant effects on lambda amplitude, where amplitude decreased with increasing spatial frequency and increased as a function of saccade size for small and medium-sized saccades. The amplitude differences between spatial frequencies were maintained across all saccade magnitudes suggesting these effects are produced from distinctly different and uncorrelated mechanisms. The current results will inform future analyses of the lambda potential in natural scenes where saccade magnitudes and spatial frequencies ultimately vary. |
Samy Rima; Mylène Poujade; Marcello Maniglia; Jean-Baptiste Durand Rewarding objects appear larger but not brighter Journal Article In: Journal of Vision, vol. 18, no. 7, pp. 1–10, 2018. @article{Rima2018, Whether reward can accentuate the perception of visual objects, that is, makes them appear larger than they really are, is a long-standing and controversial question. Here, we revisit this issue with a novel two alternative forced-choice paradigm combining asymmetric reward schedule and task reversal. In a first experiment, participants (n = 27) choose the larger of two unequally rewarded objects in some sessions and the smaller one in other sessions. Response biases toward the most rewarding object differ significantly between the reversed tasks, revealing an influence of reward on perceived sizes. In a second experiment, participants (n = 27) indicate either the brighter or darker object. In contrast with the first experiment, response biases are similar between those reversed tasks, indicating that the perceived luminance is immune to reward manipulation. Together, these results reveal that if two objects are associated with different amounts of reward, participants will perceive the more rewarded object to be slightly larger, but not brighter, than the less rewarded one. |
Mariel Roberts; Brandon K. Ashinoff; F. Xavier Castellanos; Marisa Carrasco When attention is intact in adults with ADHD Journal Article In: Psychonomic Bulletin & Review, vol. 25, no. 4, pp. 1423–1434, 2018. @article{Roberts2018, Is covert visuospatial attention—selective processing of information in the absence of eye movements—preserved in adults with attention-deficit/hyperactivity disorder (ADHD)? Previous findings are inconclusive due to inconsistent terminology and suboptimal methodology. To settle this question, we used well-established spatial cueing protocols to investigate the perceptual effects of voluntary and involuntary attention on an orientation discrimination task for a group of adults with ADHD and their neurotypical age-matched and gender-matched controls. In both groups, voluntary attention significantly improved accuracy and decreased reaction times at the relevant location, but impaired accuracy and slowed reaction times at irrelevant locations, relative to a distributed attention condition. Likewise, involuntary attention improved accuracy and speeded responses. Critically, the magnitudes of all these orienting and reorienting attention effects were indistinguishable between groups. Thus, these counterintuitive findings indicate that spatial covert attention remains functionally intact in adults with ADHD. |
Marie Rogers; Anna Franklin; Kenneth Knoblauch A novel method to investigate how dimensions interact to inform perceptual salience in infancy Journal Article In: Infancy, vol. 23, no. 6, pp. 833–856, 2018. @article{Rogers2018, How physical dimensions govern children's perception, language acquisition, and cognition is an important question in developmental science. Here, we use the psychophysical technique of maximum likelihood conjoint measurement (MLCM) as a novel approach to investigate how infants combine information distributed along two or more dimensions. MLCM is based on a signal detection model of decision that allows testing of several models of how observers integrate information to make choices. We tested 6‐month‐old infants' preferential looking to "green" stimuli that covaried in lightness and chroma and analyzed infant preferences using MLCM. The findings show that infant looking is driven primarily by lightness, with darker stimuli having a greater preference than lighter, plus a small but significant positive contribution of chroma. This study demonstrates that the technique of MLCM can be used in conjunction with preferential looking to investigate the salience of physical dimensions during development. The technique could now be applied to investigate the role of physical dimensions in key aspects of perceptual and cognitive development such as face recognition, language acquisition, and object recognition. |
Christiane S. Rohr; Anish Arora; Ivy Y. K. Cho; Prayash Katlariwala; Dennis Dimond; Deborah Dewey; Signe Bray Functional network integration and attention skills in young children Journal Article In: Developmental Cognitive Neuroscience, vol. 30, pp. 200–211, 2018. @article{Rohr2018, Children acquire attention skills rapidly during early childhood as their brains undergo vast neural development. Attention is well studied in the adult brain, yet due to the challenges associated with scanning young children, investigations in early childhood are sparse. Here, we examined the relationship between age, attention and functional connectivity (FC) during passive viewing in multiple intrinsic connectivity networks (ICNs) in 60 typically developing girls between 4 and 7 years whose sustained, selective and executive attention skills were assessed. Visual, auditory, sensorimotor, default mode (DMN), dorsal attention (DAN), ventral attention (VAN), salience, and frontoparietal ICNs were identified via Independent Component Analysis and subjected to a dual regression. Individual spatial maps were regressed against age and attention skills, controlling for age. All ICNs except the VAN showed regions of increasing FC with age. Attention skills were associated with FC in distinct networks after controlling for age: selective attention positively related to FC in the DAN; sustained attention positively related to FC in visual and auditory ICNs; and executive attention positively related to FC in the DMN and visual ICN. These findings suggest distributed network integration across this age range and highlight how multiple ICNs contribute to attention skills in early childhood. |
Martin Rolfs; Nicholas Murray-Smith; Marisa Carrasco Perceptual learning while preparing saccades Journal Article In: Vision Research, vol. 152, pp. 126–138, 2018. @article{Rolfs2018, Traditional perceptual learning protocols rely almost exclusively on long periods of uninterrupted fixation. Taking a first step towards understanding perceptual learning in natural vision, we had observers report the orientation of a briefly flashed stimulus (clockwise or counterclockwise from a reference orientation) presented strictly during saccade preparation at a location offset from the saccade target. For each observer, the saccade direction, stimulus location, and orientation remained the same throughout training. Subsequently, we assessed performance during fixation in three transfer sessions, either at the trained or at an untrained location, and either using an untrained (Experiment 1) or the trained (Experiment 2) stimulus orientation. We modeled the evolution of contrast thresholds (i.e., the stimulus contrast necessary to discriminate its orientation correctly 75% of the time) as an exponential learning curve, and quantified departures from this curve in transfer sessions using two new, complementary measures of transfer costs (i.e., performance decrements after the transition into the Transfer phase). We observed robust perceptual learning and associated transfer costs for untrained locations and orientations. We also assessed if spatial transfer costs were reduced for the remapped location of the pre-saccadic stimulus—the location the stimulus would have had (but never had) after the saccade. Although the pattern of results at that location differed somewhat from that at the control location, we found no clear evidence for perceptual learning at remapped locations. Using novel, model-based ways to assess learning and transfer costs, our results show that location and feature specificity, hallmarks of perceptual learning, subsist if the target stimulus is presented strictly during saccade preparation throughout training. |
Steven W. Savage; Douglas D. Potter; Benjamin W. Tatler The effects of array structure and secondary cognitive task demand on processes of visual search Journal Article In: Vision Research, vol. 153, pp. 37–46, 2018. @article{Savage2018, Many aspects of our everyday behaviour require that we search for objects. However, in real situations search is often conducted while internal and external factors compete for our attention resources. Cognitive distraction interferes with our ability to search for targets, increasing search times. Here we consider whether effects of cognitive distraction interfere differentially with three distinct phases of search: initiating search, overtly scanning through items in the display, and verifying that the object is indeed the target of search once it has been fixated. Furthermore, we consider whether strategic components of visual search that emerge when searching items organized into structured arrays are susceptible to cognitive distraction or not. We used Gilchrist & Harvey's (2006) structured and unstructured visual search paradigm with the addition of Savage, Potter, and Tatler's (2013) secondary puzzle task. Cognitive load influenced two phases of search: 1) scanning times and 2) verification times. Under high load, fixation durations were longer and refixations of distracters were more common. In terms of scanning strategy, we replicated Gilchrist and Harvey's (2006) findings of more systematic search for structured arrays than unstructured ones. We also found an effect of cognitive load on this aspect of search but only in structured arrays. Our findings suggest that our eyes, by default, produce an autonomous scanning pattern that is modulated but not completely eliminated by secondary cognitive load. |
Annett Schirmer; Tabitha Ng; Richard P. Ebstein Vicarious social touch biases gazing at faces and facial emotions Journal Article In: Emotion, vol. 18, no. 8, pp. 1097–1105, 2018. @article{Schirmer2018, Research has suggested that interpersonal touch promotes social processing and other-concern, and that women may respond to it more sensitively than men. In this study, we asked whether this phenomenon would extend to third-party observers who experience touch vicariously. In an eye-tracking experiment, participants (N ⫽ 64, 32 men and 32 women) viewed prime and target images with the intention of remembering them. Primes comprised line drawings of dyadic interactions with and without touch. Targets comprised two faces shown side-by-side, with one being neutral and the other being happy or sad. Analysis of prime fixations revealed that faces in touch interactions attracted longer gazing than faces in no-touch interactions. In addition, touch enhanced gazing at the area of touch in women but not men. Analysis of target fixations revealed that touch priming increased looking at both faces immediately after target onset, and subsequently, at the emotional face in the pair. Sex differences in target processing were nonsignificant. Together, the present results imply that vicarious touch biases visual attention to faces and promotes emotion sensitivity. In addition, they suggest that, compared with men, women are more aware of tactile exchanges in their environment. As such, vicarious touch appears to share important qualities with actual physical touch. |
Katharina Schmidt; Matthias Gamer; Katarina Forkmann; Ulrike Bingel Pain affects visual orientation: An eye-tracking study Journal Article In: Journal of Pain, vol. 19, no. 2, pp. 135–145, 2018. @article{Schmidt2018, Because of its unique evolutionary relevance, it is understood that pain automatically attracts attention. So far, such attentional bias has mainly been shown for pain-related stimuli whereas little is known about shifts in attentional focus after actual painful stimulation. This study investigated attentional shifts by assessing eye movements into the direction of painful stimulation. Healthy participants were presented either a blank screen or a picture showing a natural scene while painful electrical stimuli were applied to the left or right hand. In general, painful stimulation reduced exploratory behavior as reflected by less and slower saccades as well as fewer and longer fixations. Painful stimulation on the right hand induced a rightward bias (ie, increased initial saccades, total number and duration of fixations to the right hemifield of the screen). Pain applied to the left hand as well as no pain induced a leftward bias that was largest for the direction of first saccades. These findings are in line with previous observations of attentional biases toward pain-related information and highlight eye tracking as a valuable tool to assess involuntary attentional consequences of pain. Future studies are needed to investigate how the observed changes in eye movements relate to pain-induced changes in perception and cognition. Perspective The study investigated pain-induced attentional shifts in terms of reflexive eye movements. This attention-capturing quality of pain should be examined in chronic pain conditions because it might contribute to the cognitive impairments often observed in chronic pain patients. |
Sebastian Schneegans; Paul M. Bays Drift in neural opulation activity causes working memory to deteriorate over time Journal Article In: Journal of Neuroscience, vol. 38, no. 21, pp. 4859–4869, 2018. @article{Schneegans2018, Short-term memories are thought to be maintained in the form of sustained spiking activity in neural populations. Decreases in recall precision observed with increasing number of memorized items can be accounted for by a limit on total spiking activity, resulting in fewer spikes contributing to the representation of each individual item. Longer retention intervals likewise reduce recall precision, but it is unknown what changes in population activity produce this effect. One possibility is that spiking activity becomes attenuated over time, such that the same mechanism accounts for both effects of set size and retention duration. Alternatively, reduced performance may be caused by drift in the encoded value over time, without a decrease in overall spiking activity. Human participants of either sex performed a variable-delay cued recall task with a saccadic response, providing a precise measure of recall latency. Based on a spike integration model of decision making, if the effects of set size and retention duration are both caused by decreased spiking activity, we would predict a fixed relationship between recall precision and response latency across conditions. In contrast, the drift hypothesis predicts no systematic changes in latency with increasing delays. Our results show both an increase in latency with set size, and a decrease in response precision with longer delays within each set size, but no systematic increase in latency for increasing delay durations. These results were quantitatively reproduced by a model based on a limited neural resource in which working memories drift rather than decay with time. |
Max Schneider; Laura Leuchs; Michael Czisch; Philipp G. Sämann; Victor I. Spoormaker Disentangling reward anticipation with simultaneous pupillometry / fMRI Journal Article In: NeuroImage, vol. 178, pp. 11–22, 2018. @article{Schneider2018, The reward system may provide an interesting intermediate phenotype for anhedonia in affective disorders. Reward anticipation is characterized by an increase in arousal, and previous studies have linked the anterior cingulate cortex (ACC) to arousal responses such as dilation of the pupil. Here, we examined pupil dynamics during a reward anticipation task in forty-six healthy human subjects and evaluated its neural correlates using functional magnetic resonance imaging (fMRI). Pupil size showed a strong increase during monetary reward anticipation, a moderate increase during verbal reward anticipation and a decrease during control trials. For fMRI analyses, average pupil size and pupil change were computed in 1-s time bins during the anticipation phase. Activity in the ventral striatum was inversely related to the pupil size time course, indicating an early onset of activation and a role in reward prediction processing. Pupil dilations were linked to increased activity in the salience network (dorsal ACC and bilateral insula), which likely triggers an increase in arousal to enhance task performance. Finally, increased pupil size preceding the required motor response was associated with activity in the ventral attention network. In sum, pupillometry provides an effective tool for disentangling different phases of reward anticipation, with relevance for affective symptomatology. |
Chris Scholes; Paul V. McGraw; Neil W. Roach Selective modulation of visual sensitivity during fixation Journal Article In: Journal of Neurophysiology, vol. 119, no. 6, pp. 2059–2067, 2018. @article{Scholes2018, During periods of steady fixation, we make small-amplitude ocular movements, termed microsaccades, at a rate of 1–2 every second. Early studies provided evidence that visual sensitivity is reduced during microsaccades—akin to the well-established suppression associated with larger saccades. However, the results of more recent work suggest that microsaccades may alter retinal input in a manner that enhances visual sensitivity to some stimuli. Here we parametrically varied the spatial frequency of a stimulus during a detection task and tracked contrast sensitivity as a function of time relative to microsaccades. Our data reveal two distinct modulations of sensitivity: suppression during the eye movement itself and facilitation after the eye has stopped moving. The magnitude of suppression and facilitation of visual sensitivity is related to the spatial content of the stimulus: suppression is greatest for low spatial frequencies, while sensitivity is enhanced most for stimuli of 1–2 cycles/°, spatial frequencies at which we are already most sensitive in the absence of eye movements. We present a model in which the tuning of suppression and facilitation is explained by delayed lateral inhibition between spatial frequency channels. Our data show that eye movements actively modulate visual sensitivity even during fixation: the detectability of images at different spatial scales can be increased or decreased depending on when the image occurs relative to a microsaccade. |
Kai Schreiber; Michael Morgan Aperture synthesis shows perceptual integration of geometrical form across saccades Journal Article In: Perception, vol. 47, no. 3, pp. 239–253, 2018. @article{Schreiber2018, We investigated the perceptual bias in perceived relative lengths in the Brentano version of the Muller-Lyer arrowheads figure. The magnitude of the bias was measured both under normal whole-figure viewing condition and under an aperture viewing condition, where participants moved their gaze around the figure but could see only one arrowhead at a time through a Gaussian-weighted contrast window. The extent of the perceptual bias was similar under the two conditions. The stimuli were presented on a CRT in a light-proof room with room-lights off, but visual context was provided by a rectangular frame surrounding the figure. The frame was either stationary with respect to the figure or moved in such a manner that the bias would be counteracted if the observer were locating features with respect to the frame. Biases were reduced in the latter condition. We conclude that integration occurs over saccades, but largely in an external visual framework, rather than in a body-centered frame using an extraretinal signal. |
Martijn J. Schut; Nathan Van der Stoep; Stefan Van der Stigchel Auditory spatial attention is encoded in a retinotopic reference frame across eye-movements Journal Article In: PLoS ONE, vol. 13, no. 8, pp. e020414, 2018. @article{Schut2018a, The retinal location of visual information changes each time we move our eyes. Although it is now known that visual information is remapped in retinotopic coordinates across eye movements (saccades), it is currently unclear how head-centered auditory information is remapped across saccades. Keeping track of the location of a sound source in retinotopic coordinates requires a rapid multi-modal reference frame transformation when making saccades. To reveal this reference frame transformation, we designed an experiment where participants attended an auditory or visual cue and executed a saccade. After the saccade had landed, an auditory or visual target could be presented either at the prior retinotopic location or at an uncued location. We observed that both auditory and visual targets presented at prior retinotopic locations were reacted to faster than targets at other locations. In a second experiment, we observed that spatial attention pointers obtained via audition are available in retinotopic coordinates immediately after an eye-movement is made. In a third experiment, we found evidence for an asymmetric cross-modal facilitation of information that is presented at the retinotopic location. In line with prior single cell recording studies, this study provides the first behavioral evidence for immediate auditory and cross-modal transsaccadic updating of spatial attention. These results indicate that our brain has efficient solutions for solving the challenges in localizing sensory input that arise in a dynamic context. |
Immo Schütz; Johanna Elisabeth Busch; Lukas Gorka; Wolfgang Einhäuser Visual awareness in binocular rivalry modulates induced pupil fluctuations Journal Article In: Journal of Cognition, vol. 1, no. 1, pp. 1–10, 2018. @article{Schuetz2018, When a visual stimulus oscillates in luminance, pupil size follows this oscillation. Recently, it has been demonstrated that such induced pupil oscillations can be used to tag which stimulus is covertly attended. Here we ask whether this “pupil frequency tagging” approach can be extended to visual awareness, specifically to inferring perceptual dominance in Binocular Rivalry between complex stimuli. We presented two distinct stimuli, a face and a house, to each eye and modulated their luminance at 1.7 Hz either in counter-phase (180° phase shift), with a 90° phase shift or in phase (0° control). In some conditions, we additionally asked observers to attend either of the stimuli. The luminance modulation was sufficiently subtle that rivalry dynamics did not differ among these conditions, and was also indistinguishable from unmodulated presentation of the stimuli. For the 180° and the 90° phase-shifted stimuli, we found that the phase of the pupil response relative to the stimuli was modulated by perceptual dominance; that is, the relative phase depended on the stimulus the observer was aware of. In turn, this perceptually dominant stimulus could be decoded from the phase of the pupil response significantly above chance. Neither percept dependence of the phase nor significant decoding was found for the 0° control condition. Our results show that visual awareness modulates pupil responses and provide proof of principle that dominance in rivalry for complex stimuli can be inferred from induced pupil fluctuations. |
Luke A. Rosedahl; Miguel P. Eckstein; F. Gregory Ashby Retinal-specific category learning Journal Article In: Nature Human Behaviour, vol. 2, no. 7, pp. 500–506, 2018. @article{Rosedahl2018, Virtually all cognitive theories of category learning (such as prototype theory1–5 and exemplar theory6–8) view this important skill as a high-level process that uses abstract representations of objects in the world. Because these representations are removed from visual characteristics of the display, such theories suggest that category learning occurs in higher-level (such as association) areas and therefore should be immune to the visual field dependencies that characterize processing of objects mediated by representations in low-level visual areas. Here we challenge that view by describing a fully controlled demonstration of visual-field dependence in category learning. Eye-tracking was used to control gaze while participants either learned rule-based categories known to recruit prefrontal-based explicit reasoning, or information-integration categories known to depend on basal-ganglia-mediated procedural learning9. Results showed that learning was visual-field dependent with information-integration categories, but we found no evidence of visual-field dependence with rule-based categories. A theoretical interpretation of this difference is offered in terms of the underlying neurobiology. Finally, these results are situated within the broad perceptual-learning literature in an attempt to motivate further research on the similarities and differences between category and perceptual learning. |
Maya L. Rosen; Chantal E. Stern; Kathryn J. Devaney; David C. Somers Cortical and subcortical contributions to long-term memory-guided visuospatial attention Journal Article In: Cerebral Cortex, vol. 28, no. 8, pp. 2935–2947, 2018. @article{Rosen2018, Long-term memory (LTM) helps to efficiently direct and deploy the scarce resources of the attentional system; however, the neural substrates that support LTM-guidance of visual attention are not well understood. Here, we present results from fMRI experiments that demonstrate that cortical and subcortical regions of a network defined by resting-state functional connectivity are selectively recruited for LTM-guided attention, relative to a similarly demanding stimulus-guided attention paradigm that lacks memory retrieval and relative to a memory retrieval paradigm that lacks covert deployment of attention. Memory-guided visuospatial attention recruited posterior callosal sulcus, posterior precuneus, and lateral intraparietal sulcus bilaterally. Additionally, 3 subcortical regions defined by intrinsic functional connectivity were recruited: the caudate head, mediodorsal thalamus, and cerebellar lobule VI/Crus I. Although the broad resting-state network to which these nodes belong has been referred to as a cognitive control network, the posterior cortical regions activated in the present study are not typically identified with supporting standard cognitive control tasks. We propose that these regions form a Memory-Attention Network that is recruited for processes that integrate mnemonic and stimulus-based representations to guide attention. These findings may have important implications for understanding the mechanisms by which memory retrieval influences attentional deployment. |
Alasdair I. Ross; Thomas Schenk; Jutta Billino; Mary J. Macleod; Constanze Hesse Avoiding unseen obstacles: Subcortical vision is not sufficient to maintain normal obstacle avoidance behaviour during reaching Journal Article In: Cortex, vol. 98, pp. 177–193, 2018. @article{Ross2018, Previous research found that a patient with cortical blindness (homonymous hemianopia) was able to successfully avoid an obstacle placed in his blind field, despite reporting no conscious awareness of it [Striemer, C. L., Chapman, C. S., & Goodale, M. A., 2009, PNAS, 106(37), 15996–16001]. This finding led to the suggestion that dorsal stream areas, that are assumed to mediate obstacle avoidance behaviour, may obtain their visual input primarily from subcortical pathways. Hence, it was suggested that normal obstacle avoidance behaviour can proceed without input from the primary visual cortex. Here we tried to replicate this finding in a group of patients (N = 6) that suffered from highly circumscribed lesions in the occipital lobe (including V1) that spared the subcortical structures that have been associated with action-blindsight. We also tested if obstacle avoidance behaviour differs depending on whether obstacles are placed only in the blind field or in both the blind and intact visual field of the patients simultaneously. As expected, all patients successfully avoided obstacles placed in their intact visual field. However, none of them showed reliable avoidance behaviour – as indicated by adjustments in the hand trajectory in response to obstacle position – for obstacles placed in their blind visual field. The effects were not dependent on whether one or two obstacles were present. These findings suggest that behaviour in complex visuomotor tasks relies on visual input from occipital areas. |
Jason F. Rubinstein; Eileen Kowler The role of implicit perceptual-motor costs in the integration of information across graph and text Journal Article In: Journal of Vision, vol. 18, no. 13, pp. 1–18, 2018. @article{Rubinstein2018, Strategies used to gather visual information are typically viewed as depending solely on the value of information gained from each action. A different approach may be required when actions entail cognitive effort or deliberate control. Integration of information across a graph and text is a resource-intensive task in which decisions to switch between graph and text may take into account the resources required to plan or execute the switches. Participants viewed a graph and text depicting attributes of two fictitious products and were asked to select the preferred product. Graph and text were presented: (1) simultaneously, side by side; (2) sequentially, where the appearance of graph or text was triggered by a button press, or (3) sequentially, where the appearance of graph or text was triggered by a saccade, thus requiring cognitive effort, memory, or controlled processing to access regions out of immediate view. Switches between graph and text were rare during initial readings, consistent with prior observations of perceptual ‘‘switch costs.'' Switches became more frequent during re-inspections (80% of time). Switches were twice as frequent in the simultaneous condition than in either sequential condition (button press or saccade-contingent), showing the importance of perceptual availability. These results show that strategies used to gather information while reading a graph and text are not based solely on information value, but also on implicit costs of switching, such as effort level, working memory load, or demand on controlled processing. Taking implicit costs into account is important for a complete understanding of strategies used to gather visual information. |
Marius Rubo; Matthias Gamer Social content and emotional valence modulate gaze fixations in dynamic scenes Journal Article In: Scientific Reports, vol. 8, pp. 3804, 2018. @article{Rubo2018, Previous research has shown that low-level visual features (i.e., low-level visual saliency) as well as socially relevant information predict gaze allocation in free viewing conditions. However, these studies mainly used static and highly controlled stimulus material, thus revealing little about the robustness of attentional processes across diverging situations. Secondly, the influence of affective stimulus characteristics on visual exploration patterns remains poorly understood. Participants in the present study freely viewed a set of naturalistic, contextually rich video clips from a variety of settings that were capable of eliciting different moods. Using recordings of eye movements, we quantified to what degree social information, emotional valence and low-level visual features influenced gaze allocation using generalized linear mixed models. We found substantial and similarly large regression weights for low-level saliency and social information, affirming the importance of both predictor classes under ecologically more valid dynamic stimulation conditions. Differences in predictor strength between individuals were large and highly stable across videos. Additionally, low-level saliency was less important for fixation selection in videos containing persons than in videos not containing persons, and less important for videos perceived as negative. We discuss the generalizability of these findings and the feasibility of applying this research paradigm to patient groups. |
Douglas A. Ruff; David H. Brainard; Marlene R. Cohen Neuronal population mechanisms of lightness perception Journal Article In: Journal of Neurophysiology, vol. 120, no. 5, pp. 2296–2310, 2018. @article{Ruff2018, The way that humans and animals perceive the lightness of an object depends on its physical luminance as well as its surrounding context. While neuronal responses throughout the visual pathway are modulated by context, the relationship between neuronal responses and lightness perception is poorly understood. We searched for a neuronal mechanism of lightness by recording responses of neuronal populations in monkey primary visual cortex (V1) and area V4 to stimuli that produce a lightness illusion in humans, in which the lightness of a disk depends on the context in which it is embedded. We found that the way individual units encode the luminance (or equivalently for our stimuli, contrast) of the disk and its context is extremely heterogeneous. This motivated us to ask whether the population representation in either V1 or V4 satisfies three criteria: 1) disk luminance is represented with high fidelity, 2) the context surrounding the disk is also represented, and 3) the representations of disk luminance and context interact to create a representation of lightness that depends on these factors in a manner consistent with human psychophysical judgments of disk lightness. We found that populations of units in both V1 and V4 fulfill the first two criteria, but that we cannot conclude that the two types of information in either area interact in a manner that clearly predicts human psychophysical measurements: the interpretation of our population measurements depends on how subsequent areas read out lightness from the population responses. |
Donghyun Ryu; Bruce Abernethy; So Hyun Park; David L. Mann The perception of deceptive information can be enhanced by training that removes superficial visual information Journal Article In: Frontiers in Psychology, vol. 9, pp. 1132, 2018. @article{Ryu2018, The ability to detect deceptive intent within actions is a crucial element of skill across many tasks. Evidence suggests that deceptive actions may rely on the use of superficial visual information to hide the basic kinematic information which specifies the actor's intent. The purpose of this study was to determine whether the ability of observers to anticipate deceptive actions could be enhanced by training which removes superficial visual information. Novice badminton players (n = 36) were allocated to one of three groups who performed perceptual training over 3 days, with the efficacy of training assessed using tests of anticipatory skill conducted at pre-test, post-test, and a 1-week retention test. During training, participants watched a series of non-deceptive badminton shots performed by actors, with the footage manipulated to display either (i) low spatial-frequency information only (low-SF training group; blurring to remove superficial information); (ii) high spatial-frequency information only (high-SF training group; an 'edge detector' to highlight superficial information); or (iii) normal vision (normal-SF group). Participants were asked to anticipate the direction of the shuttle when footage was occluded at the moment of racquet-shuttle contact. In the post-test, response accuracy (RA) when viewing deceptive trials was higher for the low-SF training group when compared to the normal-SF (control) training group (p = 0.005), with the difference retained in the retention test (p = 0.020). High-SF training resulted in greater performance at post-test (p = 0.038) but not retention (p = 0.956). The analysis of gaze provided some explanation for the findings, with the low-SF training group spending more time after training fixating on the location of racquet-shuttle contact than did the normal training group (p = 0.028). The findings demonstrate that training which conveys only the basic kinematic movements visible in low-SF information may be effective in learning to 'see-through' deceptive intent. |
Marina Saito; Kentaro Miyamoto; Yusuke Uchiyama; Ikuya Murakami Invisible light inside the natural blind spot alters brightness at a remote location Journal Article In: Scientific Reports, vol. 8, pp. 7540, 2018. @article{Saito2018, The natural blind spot in the visual field has been known as a large oval region that cannot receive any optical input because it corresponds to the retinal optic disk containing no rod/cone-photoreceptors. Recently, stimulation inside the blind spot was found to enhance, but not trigger, the pupillary light reflex. However, it is unknown whether blind-spot stimulation also affects visual perception. We addressed this question using psychophysical brightness-matching experiments. We found that a test stimulus outside the blind spot was judged as darker when it was accompanied by a consciously unexperienced blue oval inside the blind spot; moreover, the pupillary light reflex was enhanced. These findings suggested that a photo-sensitive mechanism inside the optic disk, presumably involving the photopigment melanopsin, contributes to our image-forming vision and provides a ‘reference' for calibrating the perceived brightness of visual objects. |
Nikita A. Salovich; Roger W. Remington; Yuhong V. Jiang Acquisition of habitual visual attention and transfer to related tasks Journal Article In: Psychonomic Bulletin & Review, vol. 25, no. 3, pp. 1052–1058, 2018. @article{Salovich2018, Extensive research has shown that statistical learning affects perception, attention, and action control; however, few studies have directly linked statistical learning with the formation of habits. Evidence that learning can induce a search habit has come from location probability learning, in which people prioritize locations frequently attended to in the past. Here, using an alternating training–testing procedure, we demonstrated that the initial attentional bias arises from short-term intertrial priming, whereas probability learning takes longer to emerge, first reaching significance in covert orienting (measured by reaction times) after about 48 training trials, and in overt orienting (measured by eye movements) after about 96 training trials. We further showed that location probability learning is persistent after training is discontinued, by transferring from a letter search task to a scene search task—emulating another characteristic feature of habits. By identifying the onset of probability learning and investigating its task specificity, this study provides evidence that probability cuing can induce habitual spatial attention. |
Jason M. Samonds; Wilson S. Geisler; Nicholas J. Priebe Natural image and receptive field statistics predict saccade sizes Journal Article In: Nature Neuroscience, vol. 21, no. 11, pp. 1591–1599, 2018. @article{Samonds2018, Humans and other primates sample the visual environment using saccadic eye movements that shift a high-resolution fovea toward regions of interest to create a clear perception of a scene across fixations. Many mammals, however, like mice, lack a fovea, which raises the question of why they make saccades. Here we describe and test the hypothesis that saccades are matched to natural scene statistics and to the receptive field sizes and adaptive properties of neural populations. Specifically, we determined the minimum amplitude of saccades in natural scenes necessary to provide uncorrelated inputs to model neural populations. This analysis predicts the distributions of observed saccade sizes during passive viewing for nonhuman primates, cats, and mice. Furthermore, disrupting the development of receptive field properties by monocular deprivation changed saccade sizes consistent with this hypothesis. Therefore, natural-scene statistics and the neural representation of natural images appear to be critical factors guiding saccadic eye movements. |
Leandro R. D. Sanz; Patrik Vuilleumier; Alexia Bourgeois Cross-modal integration during value-driven attentional capture Journal Article In: Neuropsychologia, vol. 120, pp. 105–112, 2018. @article{Sanz2018, A growing body of evidence suggests that reward may be a powerful determinant of attentional selection. To date, the study of value-based attentional capture has been mainly focused on the visual sensory modality. It is yet unknown how reward information is communicated and integrated across the different senses in order to resolve between competing choices during selective attention. Our study investigated the interference produced by an auditory reward-associated distractor when a semantically-related visual target was concurrently presented. We measured both manual and saccadic response times towards a target image (drum or trumpet), while an irrelevant sound (congruent or incongruent instrument) was heard. Each sound was previously associated with either a high or a low reward. We found that manual responses were slowed by a high-reward auditory distractor when sound and image were semantically congruent. A similar effect was observed for saccadic responses, but only for participants aware of the past reward contingencies. Auditory events associated with reward value were thus capable of involuntarily capturing attention in the visual modality. This reward effect can mitigate cross-modal semantic integration and appears to be differentially modulated by awareness for saccadic vs. manual responses. Together, our results extend previous work on value-driven attentional biases in perception by showing that these may operate across sensory modalities and override cross-modal integration for semantically-related stimuli. This study sheds new light on the potential implication of brain regions underlying value-driven attention across sensory modalities. |
Caspar M. Schwiedrzik; Lucia Melloni; Aaron Schurger Mooney face stimuli for visual perception research Journal Article In: PLoS ONE, vol. 13, no. 7, pp. e0200106, 2018. @article{Schwiedrzik2018, In 1957, Craig Mooney published a set of human face stimuli to study perceptual closure: the formation of a coherent percept on the basis of minimal visual information. Images of this type, now known as “Mooney faces”, are widely used in cognitive psychology and neuroscience because they offer a means of inducing variable perception with constant visuo-spatial characteristics (they are often not perceived as faces if viewed upside down). Mooney's original set of 40 stimuli has been employed in several studies. However, it is often necessary to use a much larger stimulus set. We created a new set of over 500 Mooney faces and tested them on a cohort of human observers. We present the results of our tests here, and make the stimuli freely available via the internet. Our test results can be used to select subsets of the stimuli that are most suited for a given experimental purpose. |
K. Seeliger; Matthias Fritsche; U. Güçlü; S. Schoenmakers; J. M. Schoffelen; S. E. Bosch; Marcel A. J. Gerven Convolutional neural network-based encoding and decoding of visual object recognition in space and time Journal Article In: NeuroImage, vol. 180, pp. 253–266, 2018. @article{Seeliger2018, Representations learned by deep convolutional neural networks (CNNs) for object recognition are a widely investigated model of the processing hierarchy in the human visual system. Using functional magnetic resonance imaging, CNN representations of visual stimuli have previously been shown to correspond to processing stages in the ventral and dorsal streams of the visual system. Whether this correspondence between models and brain signals also holds for activity acquired at high temporal resolution has been explored less exhaustively. Here, we addressed this question by combining CNN-based encoding models with magnetoencephalography (MEG). Human participants passively viewed 1,000 images of objects while MEG signals were acquired. We modelled their high temporal resolution source-reconstructed cortical activity with CNNs, and observed a feed-forward sweep across the visual hierarchy between 75 and 200 ms after stimulus onset. This spatiotemporal cascade was captured by the network layer representations, where the increasingly abstract stimulus representation in the hierarchical network model was reflected in different parts of the visual cortex, following the visual ventral stream. We further validated the accuracy of our encoding model by decoding stimulus identity in a left-out validation set of viewed objects, achieving state-of-the-art decoding accuracy. |
Gün R. Semin; Tomás Palma; Cengiz Acartürk; Aleksandra Dziuba Gender is not simply a matter of black and white, or is it? Journal Article In: Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 373, pp. 1–9, 2018. @article{Semin2018, Based on research in physical anthropology, we argue that brightness marks the abstract category of gender, with light colours marking the female gender and dark colours marking the male gender. In a set of three experiments, we examine this hypothesis, first in a speeded gender classification experiment with male and female names presented in black and white. As expected, male names in black and female names in white are classified faster than the reverse gender-colour combinations. The second experiment relies on a gender classification task involving the disambiguation of very briefly appearing non-descript stimuli in the form of black and white ‘blobs'. The former are classified predominantly as male and the latter as female names. Finally, the processes driving light and dark object choices for males and females are examined by tracking the number of fixations and their duration in an eye-tracking experiment. The results reveal that when choosing for a male target, participants look longer and make more fixations on dark objects, and the same for light objects when choosing for a female target. The implications of these findings, which repeatedly reveal the same data patterns across experiments with Dutch, Portuguese and Turkish samples for the abstract category of gender, are discussed. The discussion attempts to enlarge the subject beyond mainstream models of embodied grounding. This article is part of the theme issue ‘Varieties of abstract concepts: development, use and representation in the brain'. |
Li Z. Sha; Roger W. Remington; Yuhong V. Jiang Statistical learning of anomalous regions in complex faux X-ray images does not transfer between detection and discrimination Journal Article In: Cognitive Research: Principles and Implications, vol. 3, pp. 1–16, 2018. @article{Sha2018, The visual environment contains predictable information - “statistical regularities” - that can be used to aid perception and attentional allocation. Here we investigate the role of statistical learning in facilitating search tasks that resemble medical-image perception. Using faux X-ray images, we employed two tasks that mimicked two problems in medical- image perception: detecting a target signal that is poorly segmented from the background; and discriminating a candidate anomaly from benign signals. In the first, participants searched a heavily camouflaged target embedded in cloud-like noise. In the second, the noise opacity was reduced, but the target appeared among visually similar distractors. We tested the hypothesis that learning may be task-specific. To this end, we introduced statistical regularities by presenting the target disproportionately more frequently in one region of the space. This manipulation successfully induced incidental learning of the target's location probability, producing faster search when the target appeared in the high-probability region. The learned attentional preference persisted through a testing phase in which the target's location was random. Supporting the task-specificity hypothesis, when the task changed between training and testing, the learned priority did not transfer. Eye tracking showed fewer, but longer, fixations in the detection than in the discrimination task. The observation of task-specificity of statistical learning has implications for theories of spatial attention and sheds light on the design of effective training tasks. |
Anna Shafer-Skelton; Julie D. Golomb Memory for retinotopic locations is more accurate than memory for spatiotopic locations, even for visually guided reaching Journal Article In: Psychonomic Bulletin & Review, vol. 25, pp. 1388–1398, 2018. @article{ShaferSkelton2018, To interact successfully with objects, we must maintain stable representations of their locations in the world. However, their images on the retina may be displaced several times per second by large, rapid eye movements. A number of studies have demonstrated that visual processing is heavily influenced by gaze-centered (retinotopic) information, including a recent finding that memory for an object's location is more accurate and precise in gaze-centered (retinotopic) than world-centered (spatiotopic) coordinates (Golomb & Kanwisher, 2012b). This effect is somewhat surprising, given our intuition that behavior is successfully guided by spatiotopic representations. In the present experiment, we asked whether the visual system may rely on a more spatiotopic memory store depending on the mode of responding. Specifically, we tested whether reaching toward and tapping directly on an object's location could improve memory for its spatiotopic location. Participants performed a spatial working memory task under four conditions: retinotopic vs. spatiotopic task, and computer mouse click vs. touchscreen reaching response. When participants responded by clicking with a mouse on the screen, we replicated Golomb & Kanwisher's original results, finding that memory was more accurate in retinotopic than spatiotopic coordinates and that the accuracy of spatiotopic memory deteriorated substantially more than retinotopic memory with additional eye movements during the memory delay. Critically, we found the same pattern of results when participants responded by using their finger to reach and tap the remembered location on the monitor. These results further support the hypothesis that spatial memory is natively retinotopic; we found no evidence that engaging the motor system improves spatiotopic memory across saccades. |
Lee Shalev; Rony Paz; Galia Avidan Visual aversive learning compromises sensory discrimination Journal Article In: Journal of Neuroscience, vol. 38, no. 11, pp. 2766–2779, 2018. @article{Shalev2018, Aversive learning is thought to modulate perceptual thresholds, which can lead to overgeneralization. However, it remains undetermined whether this modulation is domain specific or a general effect. Moreover, despite the unique role of the visual modality in human perception, it is unclear whether this aspect of aversive learning exists in this modality. The current study was designed to examine the effect of visual aversive outcomes on the perception of basic visual and auditory features. We tested the ability of healthy participants, both males and females, to discriminate between neutral stimuli, before and after visual learning. In each experiment, neutral stimuli were associated with aversive images in an experimental group and with neutral images in a control group. Participants demonstrated a deterioration in discrimination (higher discrimination thresholds) only after aversive learning. This deterioration was measured for both auditory (tone frequency) and visual (orientation and contrast) features. The effect was replicated in five different experiments and lasted for at least 24 h. fMRI neural responses and pupil size were also measured during learning. We showed an increase in neural activations in the anterior cingulate cortex, insula, and amygdala during aversive compared with neutral learning. Interestingly, the early visual cortex showed increased brain activity during aversive compared with neutral context trials, with identical visual information. Our findings imply the existence of a central multimodal mechanism, which modulates early perceptual properties, following exposure to negative situations. Such a mechanism could contribute to abnormal responses that underlie anxiety states, even in new and safe environments. |
Poppy Sharp; David Melcher; Clayton Hickey Endogenous attention modulates the temporal window of integration Journal Article In: Attention, Perception, and Psychophysics, vol. 80, no. 5, pp. 1214–1228, 2018. @article{Sharp2018, Constructing useful representations of our visual environment requires the ability to selectively pay attention to particular locations at specific moments. Whilst there has been much investigation on the influence of selective attention on spatial discrimination, less is known about its influence on temporal discrimination. In particular, little is known about how endogenous attention influences two fundamental and opposing temporal processes: segregation – the parsing of the visual scene over time into separate features, and integration – the binding together of related elements. In four experiments, we tested how endogenous cueing to a location influences each of these opposing processes. Results demonstrate a strong cueing effect on both segregation and integration. These results are consistent with the hypothesis that endogenous attention can influence both of these opposing processes in a flexible manner. The finding has implications for arbitrating between accounts of the multiple modulatory mechanisms comprising selective attention. |
Hannah R. Sheahan; James N. Ingram; Goda M. Žalalytė; Daniel M. Wolpert Imagery of movements immediately following performance allows learning of motor skills that interfere Journal Article In: Scientific Reports, vol. 8, pp. 14330, 2018. @article{Sheahan2018, Motor imagery, that is the mental rehearsal of a motor skill, can lead to improvements when performing the same skill. Here we show a powerful and complementary role, in which motor imagery of different movements after actually performing a skill allows learning that is not possible without imagery. We leverage a well-studied motor learning task in which subjects reach in the presence of a dynamic (force-field) perturbation. When two opposing perturbations are presented alternately for the same physical movement, there is substantial interference, preventing any learning. However, when the same physical movement is associated with follow-through movements that differ for each perturbation, both skills can be learned. Here we show that when subjects perform the skill and only imagine the follow-through, substantial learning occurs. In contrast, without such motor imagery there was no learning. Therefore, motor imagery can have a profound effect on skill acquisition even when the imagery is not of the skill itself. Our results suggest that motor imagery may evoke different neural states for the same physical state, thereby enhancing learning. |
Wei Shen; Qingqing Qu; Xiuhong Tong Visual attention shift to printed words during spoken word recognition in Chinese: The role of phonological information Journal Article In: Memory & Cognition, vol. 46, no. 4, pp. 642–654, 2018. @article{Shen2018a, The aim of this study was to investigate the extent to which phonological information mediates the visual attention shift to printed Chinese words in spoken word recognition by using an eye-movement technique with a printed-word paradigm. In this paradigm, participants are visually presented with four printed words on a computer screen, which include a target word, a phonological competitor, and two distractors. Participants are then required to select the target word using a computer mouse, and the eye movements are recorded. In Experiment 1, phonological information was manipulated at the full-phonological overlap; in Experiment 2, phonological information at the partial-phonological overlap was manipulated; and in Experiment 3, the phonological competitors were manipulated to share either fulloverlap or partial-overlap with targets directly. Results of the three experiments showed that the phonological competitor effects were observed at both the full-phonological overlap and partial-phonological overlap conditions. That is, phonological competitors attracted more fixations than distractors, which suggested that phonological information mediates the visual attention shift during spoken word recognition. More importantly, we found that the mediating role of phonological information varies as a function of the phonological similarity between target words and phonological competitors. |
Carlos Sillero-Rejon; Angela S. Attwood; Anna K. M. Blackwell; José Angel Ibáñez-Zapata; Marcus R. Munafò; Olivia M. Maynard Alcohol pictorial health warning labels: The impact of self-affirmation and health warning severity Journal Article In: BMC Public Health, vol. 18, pp. 1–9, 2018. @article{SilleroRejon2018, We examined whether enhancing self-affirmation among a population of drinkers, prior to viewing threatening alcohol pictorial health warning labels, would reduce defensive reactions and promote reactions related to behaviour change. We also examined how health warning severity influences these reactions and whether there is an interaction between self-affirmation and severity. In this experimental human laboratory study, participants (n = 128) were randomised to a self-affirmation or control group. After the self-affirmation manipulation was administered, we tracked participants' eye movements while they viewed images of six moderately-severe and six highly-severe pictorial health warning labels presented on large beer cans. Self-reported responses to the pictorial health warning labels were then measured, including avoidance, reactance, effectiveness, susceptibility and motivation to drink less. Finally, participants reported their self-efficacy to drink less and their alcohol use. There was no clear evidence that enhancing self-affirmation influenced any outcome. In comparison to moderately-severe health warnings, highly-severe health warnings increased avoidance and reactance and were perceived as more effective and increased motivation to drink less. These findings call into question the validity of the self-affirmation manipulation, which is purported to reduce defensive reactions to threatening warnings. We discuss possible explanations for this null effect, including the impact of participants' low perceived susceptibility to the risks shown on these pictorial health warning labels. Our finding that highly-severe health warnings increase avoidance and reactance but are also perceived as being more effective and more likely to motivate people to drink less will inform future health warning design and have implications for health warning label theory. |
Vivian Eng; Alfred Lim; Steve M. J. Janssen; Jason Satel Time course of inhibition of return in a spatial cueing paradigm with distractors Journal Article In: Acta Psychologica, vol. 183, pp. 51–57, 2018. @article{Eng2018, Studies of endogenous and exogenous attentional orienting in spatial cueing paradigms have been used to investigate inhibition of return, a behavioral phenomenon characterized by delayed reaction time in response to recently attended locations. When eye movements are suppressed, attention is covertly oriented to central or peripheral stimuli. Overt orienting, on the other hand, requires explicit eye movements to the stimuli. The present study examined the time course of slowed reaction times to previously attended locations when distractors are introduced into overt and covert orienting tasks. In a series of experiments, manual responses were required to targets following central and peripheral cues at three different cue-target intervals, with and without activated oculomotor systems. The results demonstrate that, when eye movements are suppressed, behavioral inhibition is reduced or delayed in magnitude by the presence of a distractor relative to conditions without distractors. However, the time course of behavioral inhibition when eye movements are required remains similar with or without distractors. |
Daniel Ernst; Gernot Horstmann Pure colour novelty captures the gaze Journal Article In: Visual Cognition, vol. 26, no. 5, pp. 366–381, 2018. @article{Ernst2018, While it is common wisdom that a salient visual event draws attention, experimental research provided mixed support for this hypothesis. The present experiment seeks evidence that a singleton draws attention to the degree that its feature is novel or unexpected. Two visual search experiments were conducted where an irrelevant colour singleton is presented on each pre-critical trial to familiarize participants with the presence of the singleton. In the critical trial of Experiment 1, the singleton was presented in a novel colour without prior announcement. The singleton was gazed at significantly earlier and longer in the critical trial, as compared to pre-critical trials. This result is consistent with predictions from the expectancy discrepancy hypothesis that colour novelty is sufficient to capture attention. Experiment 2 tested the alternative explanation that a surprising event mainly leads to a breakdown of the previously acquired attentional set, which in turn causes a reorientation towards perceptual salience. An unannounced change of the background colour in the critical trial while the singleton colour remained unchanged did not induce an attentional capture by the singleton like in Experiment 1. This result further confirms that surprising events capture attention in a spatial manner. |
Kris Evers; Goedele Van Belle; Jean Steyaert; Ilse Noens; Johan Wagemans Gaze-contingent display changes as new window on analytical and holistic face perception in children with Autism Spectrum Disorder Journal Article In: Child Development, vol. 89, no. 2, pp. 430–445, 2018. @article{Evers2018, The strength of holistic face perception in children with autism spectrum disorder (ASD) was evaluated byapplying the gaze-contingent mask and window technique to a face matching and discrimination task in 6- to14-year-old children with (n = 36) and without ASD (n = 47), and by examining fixation patterns. Behavioralresults suggested a slower and less efficient face processing in the ASD sample compared with the matchedcontrol group. Comparing the moving mask and window conditions revealed a reduced holistic face process-ing bias in the younger age group but not in the older sample. Preferential viewing patterns revealed bothsimilarities and differences between both participant groups. |
Marzieh Salehi Fadardi; Larry Allen Abel Saccades under mental load in infantile nystagmus syndrome and controls Journal Article In: Optometry and Vision Science, vol. 95, no. 4, pp. 373–383, 2018. @article{Fadardi2018, Significance: This study compares saccades and visual task performance in patients with infantile nystagmus syndrome (INS) with that in normally sighted individuals under mental load. The results highlighted that to more completely evaluate INS therapies recognition time should also be measured with mental load, resembling real-world conditions. Purpose: Patients with INS may complain of "being slow to see." Stress is reported to worsen nystagmus and to prolong visual recognition time. We hypothesized that the effects of mental load on timing indices of visual recognition, for example, saccade latency, target acquisition time, target viewing time, and subjects' reaction time, differ between the INS and control groups. Methods: Eye movements were recorded when participants (INS group |
Shiva Farashahi; Habiba Azab; Benjamin Y. Hayden; Alireza Soltani On the flexibility of basic risk attitudes in monkeys Journal Article In: Journal of Neuroscience, vol. 38, no. 18, pp. 4383–4398, 2018. @article{Farashahi2018, Monkeys and other animals appear to share with humans two risk attitudes predicted by prospect theory: an inverse-S-shaped probability weighting function and a steeper utility curve for losses than for gains. These findings suggest that such preferences are stable traits with common neural substrates. We hypothesized instead that animals tailor their preferences to subtle changes in task contexts, making risk attitudes flexible. Previous studies used a limited number of outcomes, trial types, and contexts. To gain a broader perspective, we examined two large datasets of male macaques' risky choices: one from a task with real (juice) gains and another from a token task with gains and losses. In contrast to previous findings, monkeys were risk-seeking for both gains and losses (i.e. lacked a reflection effect) and showed steeper gain than loss curves (loss-seeking). Utility curves for gains were substantially different in the two tasks. Monkeys showed nearly linear probability weightings in one task and S-shaped ones in the other; neither task produced a consistent inverse-S-shaped curve. To account for these observations, we developed and tested various computational models of the processes involved in the construction of reward value. We found that adaptive differential weighting of prospective gamble outcomes could partially account for the observed differences in the utility functions across the two experiments and thus, provide a plausible mechanism underlying flexible risk attitudes. Together, our results support the idea that risky choices are constructed flexibly at the time of elicitation and place important constraints on neural models of economic choice. |
Tobias Feldmann-Wüstefeld; Edward K. Vogel; Edward Awh Contralateral delay activity indexes working memory storage, not the current focus of spatial attention Journal Article In: Journal of Cognitive Neuroscience, vol. 30, no. 8, pp. 1185–1196, 2018. @article{FeldmannWuestefeld2018, Contralateral delay activity (CDA) has long been argued to track the number of items stored in visual working memory (WM). Recently, however, Berggren and Eimer [Berggren, N., & Eimer, M. Does contralateral delay activity reflect working memory storage or the current focus of spatial attention within visual working memory? Journal ofCognitive Neuroscience, 28, 2003–2020, 2016] proposed the alternative hypothesis that the CDA tracks the current focus of spatial attention instead of WM storage. This hypothesis was based on the finding that, when two successive arrays of memoranda were placed in opposite hemifields, CDA amplitude was primarily determined by the position and number of items in the second display, not the total memory load across both displays. Here, we considered the alternative interpretation that participants dropped the first array from WM when they encoded the second array because the format of the probe display was spatially incompatible with the initial sample display. In this case, even if the CDA indexes active storage rather than spatial attention, CDA activity would be determined by the second array. We tested this idea by directly manipulating the spatial compatibility of sample and probe displays. With spatially incompatible displays, we replicated Berggren and Eimer's findings. However, with spatially compatible displays, we found clear evidence that CDA activity tracked the full storage load across both arrays, in line with a WM storage account of CDA activity. We propose that expectations of display compatibility influenced whether participants viewed the arrays as parts of a single extended event or two independent episodes. Thus, these findings raise interesting new questions about how event boundaries may shape the interplay between passive and active representations of task-relevant information. |
Gerardo Fernández; David Orozco; Osvaldo Agamennoni; Marcela Schumacher; Silvana Sañudo; Juan Biondi; Mario A. Parra Visual processing during short-term memory binding in mild Alzheimer's disease Journal Article In: Journal of Alzheimer's Disease, vol. 63, no. 1, pp. 185–194, 2018. @article{Fernandez2018a, Patients with Alzheimer disease (AD) typically present with attentional and oculomotor abnormalities that can have an impact on visual processing and associated cognitive functions. Over the last few years, we have witnessed a shift towards the analyses of eye movement behaviors as a means to further our understanding of the pathophysiology of common disorders such as AD. However, little work has been done to unveil the link between eye moment abnormalities and poor performance on cognitive tasks known to be markers for AD patients, such as the short-term memory-binding task. This was the aim of the present study. We analyzed eye movement fixation behaviors of thirteen healthy older adults (Controls) and thirteen patients with probable mild AD while they performed the visual short-term memory binding task (Parra et al., 2011). The short-term memory binding task asks participants to detect changes across two consecutive arrays of two bicolored object whose features (i.e., colors) have to be remembered separately (i.e., Unbound Colors), or combined within integrated objects (i.e., Bound Colors). Patients with mild AD showed the well-known pattern of selective memory binding impairments. This was accompanied by significant impairments in their eye movements only when they processed Bound Colors. Patients with mild AD remarkably decreased their mean gaze duration during the encoding of color-color bindings. These findings open new windows of research into the pathophysiological mechanisms of memory deficits in AD patients and the link between its phenotypic expressions (i.e., oculomotor and cognitive disorders). We discuss these findings considering current trends regarding clinical assessment, neural correlates, and potential avenues for robust biomarkers. |
Jose A. Fernandez-Leon; Bryan J. Hansen; Valentin Dragoi Representation of rapid image sequences in V4 Networks Journal Article In: Cerebral Cortex, vol. 28, no. 8, pp. 2675–2684, 2018. @article{FernandezLeon2018, Natural viewing often consists of sequences of brief fixations to image patches of different structure. Whether and how briefly presented sequential stimuli are encoded in a temporal-position manner is poorly understood. Here, we performed multiple-electrode recordings in the visual cortex (area V4) of nonhuman primates (Macaca mulatta) viewing a sequence of 7 briefly flashed natural images, and measured correlations between the cue-triggered population response in the presence and absence of the stimulus. Surprisingly, we found significant correlations for images occurring at the beginning and the end of a sequence, but not for those in the middle. The correlation strength increased with stimulus exposure and favored the image position in the sequence rather than image identity. These results challenge the commonly held view that images are represented in visual cortex exclusively based on their informational content, and indicate that, in the absence of sensory information, neuronal populations exhibit reactivation of stimulus-evoked responses in a way that reflects temporal position within a stimulus sequence. |
Ian C. Fiebelkorn; Mark A. Pinsk; Sabine Kastner A dynamic interplay within the frontoparietal network underlies rhythmic spatial attention Journal Article In: Neuron, vol. 99, no. 4, pp. 842–853.e8, 2018. @article{Fiebelkorn2018, Classic studies of spatial attention assumed that its neural and behavioral effects were continuous over time. Recent behavioral studies have instead revealed that spatial attention leads to alternating periods of heightened or diminished perceptual sensitivity. Yet, the neural basis of these rhythmic fluctuations has remained largely unknown. We show that a dynamic interplay within the macaque frontoparietal network accounts for the rhythmic properties of spatial attention. Neural oscillations characterize functional interactions between the frontal eye fields (FEF) and the lateral intraparietal area (LIP), with theta phase (3–8 Hz) coordinating two rhythmically alternating states. The first is defined by FEF-dominated beta-band activity, associated with suppressed attentional shifts, and LIP-dominated gamma-band activity, associated with enhanced visual processing and better behavioral performance. The second is defined by LIP-specific alpha-band activity, associated with attenuated visual processing and worse behavioral performance. Our findings reveal how network-level interactions organize environmental sampling into rhythmic cycles. Fiebelkorn et al. use simultaneous recordings in two hubs of the macaque frontoparietal network to demonstrate a neural basis of rhythmic sampling during spatial attention. Theta-organized, alternating attentional states, characterized by different spatiotemporal dynamics, shape environmental sampling. |
Ian Donovan; Marisa Carrasco Endogenous spatial attention during perceptual learning facilitates location transfer Journal Article In: Journal of Vision, vol. 18, no. 11, pp. 1–16, 2018. @article{Donovan2018, Covert attention and perceptual learning enhance perceptual performance. The relation between these two mechanisms is largely unknown. Previously, we showed that manipulating involuntary, exogenous spatial attention during training improved performance at trained and untrained locations, thus overcoming the typical location specificity. Notably, attention-induced transfer only occurred for high stimulus contrasts, at the upper asymptote of the psychometric function (i.e., via response gain). Here, we investigated whether and how voluntary, endogenous attention, the top-down and goal-based type of covert visual attention, influences perceptual learning. Twenty-six participants trained in an orientation discrimination task at two locations: half of participants received valid endogenous spatial precues (attention group), while the other half received neutral precues (neutral group). Before and after training, all participants were tested with neutral precues at two trained and two untrained locations. Within each session, stimulus contrast varied on a trial basis from very low (2%) to very high (64%). Performance was fit by a Weibull psychometric function separately for each day and location. Performance improved for both groups at the trained location, and unlike training with exogenous attention, at the threshold level (i.e., via contrast gain). The neutral group exhibited location specificity: Thresholds decreased at the trained locations, but not at the untrained locations. In contrast, participants in the attention group showed significant location transfer: Thresholds decreased to the same extent at both trained and untrained locations. These results indicate that, similar to exogenous spatial attention, endogenous spatial attention induces location transfer, but influences contrast gain instead of response gain. |
Alessio Dragone; Stefano Lasaponara; Mario Pinto; Francesca Rotondaro; Maria De Luca; Fabrizio Doricchi Expectancy modulates pupil size during endogenous orienting of spatial attention Journal Article In: Cortex, vol. 102, pp. 57–66, 2018. @article{Dragone2018, fMRI investigations in healthy humans have documented phasic changes in the level of activation of the right temporal-parietal junction (TPJ) during cued voluntary orienting of spatial attention. Cues that correctly predict the position of upcoming targets in the majority of trials, i.e., predictive cues, produce higher deactivation of the right TPJ as compared with non-predictive cues. Since the right TPJ is the recipient of noradrenergic (NE) innervation, it has been hypothesised that changes in the level of TPJ activity are matched with changes in the level of NE activity. Based on aforementioned fMRI findings, this might imply that orienting with predictive cues is matched with different levels of NE activity as compared with non-predictive cues. To test this hypothesis, we measured changes in pupil dilation, an indirect index of NE activity, during voluntary orienting of attention with highly predictive (80% validity) or non-predictive (50% validity) cues. In agreement with current interpretations of the tonic/phasic activity of the Locus Coeruleus-Norepinephrinic system (LC-NE), we found that the steady level of cue predictiveness that characterised both the predictive and non-predictive conditions caused, across consecutive blocks of trials, a progressive decrement in pupil dilation during the baseline-fixation period that anticipated the cue period. With predictive cues we observed increased pupil dilation as compared with non-predictive cues. In addition, the relative reduction in pupil size observed with non-predictive cues increased as a function of cue-duration. These results show that changes in the predictiveness of cues that guide voluntary orienting of spatial attention are matched with changes in pupil dilation and, putatively, with corresponding changes in LC-NE activity. |
Laura Dugué; Elisha P. Merriam; David J. Heeger; Marisa Carrasco Specific visual subregions of TPJ mediate reorienting of spatial attention Journal Article In: Cerebral Cortex, vol. 28, no. 7, pp. 2375–2390, 2018. @article{Dugue2018, The temporo-parietal junction (TPJ) has been associated with various cognitive and social functions, and is critical for attentional reorienting. Attention affects early visual processing. Neuroimaging studies dealing with such processes have thus far concentrated on striate and extrastriate areas. Here, we investigated whether attention orienting or reorienting modulate activity in visually driven TPJ subregions. For each observer we identified 3 visually responsive subregions within TPJ: 2 bilateral (vTPJ ant and vTPJ post) and 1 right lateralized (vTPJ cent). Cortical activity in these subregions was measured using fMRI while observers performed a 2-alternative forced-choice orientation discrimination task. Covert spatial endogenous (voluntary) or exogenous (involuntary) attention was manipulated using either a central or a peripheral cue with task, stimuli and observers constant. Both endogenous and exogenous attention increased activity for invalidly cued trials in right vTPJ post ; only endogenous attention increased activity for invalidly cued trials in left vTPJ post and in right vTPJ cent ; and neither type of attention modulated either right or left vTPJ ant . These results demonstrate that vTPJ post and vTPJ cent mediate the reorientation of covert attention to task relevant stimuli, thus playing a critical role in visual attention. These findings reveal a differential reorienting cortical response after observers' attention has been oriented to a given location voluntarily or involuntarily. |
Katherine Duncan; Bradley B. Doll; Nathaniel D. Daw; Daphna Shohamy More than the sum of its parts: A role for the hippocampus in configural reinforcement learning Journal Article In: Neuron, vol. 98, no. 3, pp. 645–657.e6, 2018. @article{Duncan2018, People often perceive configurations rather than the elements they comprise, a bias that may emerge because configurations often predict outcomes. But how does the brain learn to associate configurations with outcomes and how does this learning differ from learning about individual elements? We combined behavior, reinforcement learning models, and functional imaging to understand how people learn to associate configurations of cues with outcomes. We found that configural learning depended on the relative predictive strength of elements versus configurations and was related to both the strength of BOLD activity and patterns of BOLD activity in the hippocampus. Configural learning was further related to functional connectivity between the hippocampus and nucleus accumbens. Moreover, configural learning was associated with flexible knowledge about associations and differential eye movements during choice. Together, this suggests that configural learning is associated with a distinct computational, cognitive, and neural profile that is well suited to support flexible and adaptive behavior. Duncan et al. investigate how people learn to predict outcomes using cue configurations. They show that configural learning is characterized by unique computational, behavioral, and neural signatures, including hippocampal activity, interactions between the hippocampus and striatum, and enhanced flexible knowledge. |
Stefan Duschek; Alexandra Hoffmann; Casandra I. Montoro; Gustavo A. Reyes del Paso; Daniel Schuepbach; Ulrich Ettinger Cerebral blood flow modulations during preparatory attention and proactive inhibition Journal Article In: Biological Psychology, vol. 137, pp. 65–72, 2018. @article{Duschek2018, This study investigated cerebral blood flow modulations during task preparation in a precued saccade paradigm. Bilateral blood flow velocities in the middle cerebral arteries were recorded in 48 subjects using functional transcranial Doppler sonography. Video-based eye-tracking was applied for ocular recording. Antisaccade and prosaccade trials were presented in both block-wise and interleaved order. A right dominant flow response arose during task preparation. While the response was stronger during antisaccade than prosaccade trials, the degree of lateralisation did not differ between the two trial types. Direction error rates were higher and latencies were longer for antisaccades than prosaccades. There were no differences between block-wise and interleaved trials in blood flow or performance. The stronger blood flow increases during antisaccade than prosaccade preparation reflects the complexity of the upcoming task demands as well as proactive inhibition. The right hemispheric lateralisation may be attributed to preparatory attention independent of demands on inhibitory control. |
Marianne Duyck; Mark Wexler; Eric Castet; Thérèse Collins Motion masking by stationary objects: A study of simulated saccades Journal Article In: i-Perception, vol. 9, no. 3, pp. 1–111, 2018. @article{Duyck2018, Saccades are crucial to visual information intake by re-orienting the fovea to regions of interest in the visual scene. However, they cause drastic disruptions of the retinal input by shifting the retinal image at very high speeds. The resulting motion and smear are barely noticed, a phenomenon known as saccadic omission. Here, we studied the perception of motion during simulated saccades while observers fixated, moving naturalistic visual scenes across the retina with saccadic speed profiles using a very high temporal frequency display. We found that the mere presence of static pre- and post-saccadic images significantly reduces the perceived amplitude of motion but does not eliminate it entirely. This masking of motion perception could make the intra-saccadic stimulus much less salient and thus easier to ignore. |
R. Becket Ebitz; Eddy Albarran; Tirin Moore Exploration disrupts choice-predictive signals and alters dynamics in prefrontal cortex Journal Article In: Neuron, vol. 97, no. 2, pp. 450–461.e9, 2018. @article{Ebitz2018, In uncertain environments, decision-makers must balance two goals: they must “exploit” rewarding options but also “explore” in order to discover rewarding alternatives. Exploring and exploiting necessarily change how the brain responds to identical stimuli, but little is known about how these states, and transitions between them, change how the brain transforms sensory information into action. To address this question, we recorded neural activity in a prefrontal sensorimotor area while monkeys naturally switched between exploring and exploiting rewarding options. We found that exploration profoundly reduced spatially selective, choice-predictive activity in single neurons and delayed choice-predictive population dynamics. At the same time, reward learning was increased in brain and behavior. These results indicate that exploration is related to sudden disruptions in prefrontal sensorimotor control and rapid, reward-dependent reorganization of control dynamics. This may facilitate discovery through trial and error. Exploratory choices permit the discovery of new rewarding options. Ebitz et al. report that spatially selective, choice-predictive neurons in the prefrontal cortex do not predict choice before exploratory decisions. Reduced prefrontal control may underlie flexible decision-making and trial-and-error discovery. |
Benedikt V. Ehinger; Lilli Kaufhold; Peter König Probing the temporal dynamics of the exploration–exploitation dilemma of eye movements Journal Article In: Journal of Vision, vol. 18, no. 3, pp. 1–24, 2018. @article{Ehinger2018, When scanning a visual scene, we are in a constant decision process regarding whether to further exploit the information content at the current fixation or to go on and explore the scene. The balance of these two processes determines the distribution of fixation durations. Using a gaze-contingent paradigm, we experimentally interrupt this process to probe its state. Here, we developed a guided-viewing task where only a single 3° aperture of an image ("bubble") is displayed. Subjects had to fixate the bubble for an experimentally controlled time (forced fixation time). Then, the previously fixated bubble disappeared, and one to five bubbles emerged at different locations. The subjects freely selected one of these by performing a saccade toward it. By repeating this procedure, the subjects explored the image. We modeled the resulting saccadic reaction times (choice times) from bubble offset to saccade onset using a Bayesian linear mixed model. We observed an exponential decay between the forced fixation time and the choice time: Short fixation durations elicited longer choice times. In trials with multiple bubbles, the choice time increased monotonically with the number of possible future targets. Additionally, we found only weak influences of the saccade amplitude, low-level stimulus properties, and saccade angle on the choice times. The exponential decay of the choice times suggests that the sampling and processing of the current stimulus were exhausted for long fixation durations, biasing toward faster exploration. This observation also shows that the decision process took into account processing demands at the current fixation location. |
Michelle L. Eisenberg; Jeffrey M. Zacks; Shaney Flores Dynamic prediction during perception of everyday events Journal Article In: Cognitive Research: Principles and Implications, vol. 3, no. 1, pp. 1–12, 2018. @article{Eisenberg2018, The ability to predict what is going to happen in the near future is integral for daily functioning. Previous research suggests that predictability varies over time, with increases in prediction error at those moments that people perceive as boundaries between meaningful events. These moments also tend to be points of rapid change in the environment. Eye tracking provides a method for noninterruptive measurement of prediction as participants watch a movie of an actor performing a series of actions. In two studies, we used eye tracking to study the time course of prediction around event boundaries. In both studies, viewers looked at objects that were about to be touched by the actor shortly before the objects were contacted, demonstrating predictive looking. However, this behavior was modulated by event boundaries: looks to to-be-contacted objects near event boundaries were less likely to be early and more likely to be late compared to looks to objects contacted within events. This result is consistent with theories proposing that event segmentation results from transient increases in prediction error. |
Yke Bauke Eisma; Christopher D. D. Cabrall; Joost C. F. Winter Visual sampling processes revisited: Replicating and extending senders (1983) using modern eye-tracking equipment Journal Article In: IEEE Transactions on Human-Machine Systems, vol. 48, no. 5, pp. 526–540, 2018. @article{Eisma2018, In pioneering work, Senders (1983) tasked five participants to watch a bank of six dials, and found that glance rates and times glanced at dials increase linearly as a function of the frequency bandwidth of the dial's pointer. Senders did not record the angle of the pointers synchronously with eye movements, and so could not assess participants' visual sampling behavior in regard to the pointer state. Because the study of Senders has been influential but never repeated, we replicated and extended it by assessing the relationship between visual sampling and pointer state, using modern eye-tracking equipment. Eye tracking was performed with 86 participants who watched seven 90-second videos, each video showing six dials with moving pointers. Participants had to press the spacebar when any of the six pointers crossed a threshold. Our results showed a close resemblance to Senders' original results. Additionally, we found that participants did not behave in accordance with a periodic sampling model, but rather were conditional samplers, in that the probability of looking at a dial was contingent on pointer angle and velocity. Finally, we found that participants sampled more in agreement with Nyquist sampling when the high bandwidth dials were placed in the middle of the bank rather than at its outer edges. We observed results consistent with the saliency, effort, expectancy, and value model and conclude that human sampling ofmultidegree offreedom systems should not only be modeled in terms of bandwidth but also in terms of saliency and effort. |
Eran Eldar; Gyung Jin Bae; Zeb Kurth-Nelson; Peter Dayan; Raymond J. Dolan Magnetoencephalography decoding reveals structural differences within integrative decision processes Journal Article In: Nature Human Behaviour, vol. 2, no. 9, pp. 670–681, 2018. @article{Eldar2018, When confronted with complex inputs consisting of multiple elements, humans use various strategies to integrate the elements quickly and accurately. For instance, accuracy may or over be improved by processing elements one at a time1–4 extended periods5–8 ; speed can increase if the internal rep- resentation of elements is accelerated9,10 . However, little is known about how humans actually approach these challenges because behavioural findings can be accounted for by mul- tiple alternative process models11 and neuroimaging investi-gations typically rely on haemodynamic signals that change too slowly. Consequently, to uncover the fast neural dynamics that support information integration, we decoded magnetoencephalographic signals that were recorded as human subjects performed a complex decision task. Our findings reveal three sources of individual differences in the temporal structure of the integration process—sequential representation, partial reinstatement and early computation—each having a dissociable effect on how subjects handled problem complexity and temporal constraints. Our findings shed new light on the structure and influence of self-determined neural integration processes. |
Ashleigh J. Filtness; Vanessa Beanland Sleep loss and change detection in driving scenes Journal Article In: Transportation Research Part F: Traffic Psychology and Behaviour, vol. 57, pp. 10–22, 2018. @article{Filtness2018, Driver sleepiness is a significant road safety problem. Sleep-related crashes occur on both urban and rural roads, yet to date driver-sleepiness research has focused on understanding impairment in rural and motorway driving. The ability to detect changes is an attention and awareness skill vital for everyday safe driving. Previous research has demonstrated that person states, such as age or motivation, influence susceptibility to change blindness (i.e., failure or delay in detecting changes). The current work considers whether sleepiness increases the likelihood of change blindness within urban and rural driving contexts. Twenty fully-licenced drivers completed a change detection ‘flicker' task twice in a counterbalanced design: once following a normal night of sleep (7–8 h) and once following sleep restriction (5 h). Change detection accuracy and response time were recorded while eye movements were continuously tracked. Accuracy was not significantly affected by sleep loss; however, following sleep loss there was some evidence of slowed change detection responses to urban images, but faster responses for rural images. Visual scanning across the images remained consistent between sleep conditions, resulting in no difference in the probability of fixating on the change target. Overall, the results suggest that sleep loss has minimal impact on change detection accuracy and visual scanning for changes in driving scenes. However, a subtle difference in response time to change detection between urban and rural images indicates that change blindness may have implications for sleep-related crashes in more visually complex urban environments. Further research is needed to confirm this finding. |
Lauren K. Fink; Brian K. Hurley; Joy J. Geng; Petr Janata A linear oscillator model predicts dynamic temporal attention and pupillary entrainment to rhythmic patterns Journal Article In: Journal of Eye Movement Research, vol. 11, no. 2, pp. 1–25, 2018. @article{Fink2018, Rhythm is a ubiquitous feature of music that induces specific neural modes of processing. In this paper, we assess the potential of a stimulus-driven linear oscillator model (Tomic & Janata, 2008) to predict dynamic attention to complex musical rhythms on an instant-by-instant basis. We use perceptual thresholds and pupillometry as attentional indices against which to test our model predictions. During a deviance detection task, participants listened to continuously looping, multi-instrument, rhythmic patterns, while being eye-tracked. Their task was to respond anytime they heard an increase in intensity (dB SPL). An adaptive thresholding algorithm adjusted deviant intensity at multiple probed temporal locations throughout each rhythmic stimulus. The oscillator model predicted participants' perceptual thresholds for detecting deviants at probed locations, with a low temporal salience prediction corresponding to a high perceptual threshold and vice versa. A pupil dilation response was observed for all deviants. Notably, the pupil dilated even when partic- ipants did not report hearing a deviant. Maximum pupil size and resonator model output were significant predictors of whether a deviant was detected or missed on any given trial. Besides the evoked pupillary response to deviants, we also assessed the continuous pupillary signal to the rhythmic patterns. The pupil exhibited entrainment at prominent periodicities present in the stimuli and followed each of the different rhythmic patterns in a unique way. Overall, these results replicate previous studies using the linear oscillator model to predict dynamic attention to complex auditory scenes and extend the utility of the model to the prediction of neurophysiological signals, in this case the pupillary time course; however, we note that the amplitude envelope of the acoustic patterns may serve as a similarly useful predictor. To our knowledge, this is the first paper to show entrainment of pupil dynamics by demonstrating a phase relationship between musical stimuli and the pupillary signal. |
Paula Fischer; Letizia Camba; Seok Hui Ooi; Nicolas Chevalier Supporting cognitive control through competition and cooperation in childhood Journal Article In: Journal of Experimental Child Psychology, vol. 173, pp. 28–40, 2018. @article{Fischer2018, Cognitive control is often engaged in social contexts where actions are socially relevant. Yet, little is known about the immediate influence of the social context on childhood cognitive control. To examine whether competition or cooperation can enhance cognitive control, preschool and school-age children completed the AX Continuous Performance Task (AX-CPT) in competitive, cooperative, and neutral contexts. Children made fewer errors, responded faster, and engaged more cognitive effort, as shown by greater pupil dilation, in the competitive and cooperative social contexts relative to the neutral context. Competition and cooperation yielded greater cognitive control engagement but did not change how control was engaged (reactively or proactively). Manipulating the social context can be a powerful tool to support cognitive control in childhood. |
Aleya Flechsenhar; Olivia Larson; Albert End; Matthias Gamer Investigating overt and covert shifts of attention within social naturalistic scenes Journal Article In: Journal of Vision, vol. 18, no. 12, pp. 1–22, 2018. @article{Flechsenhar2018, Eye-tracking studies on social attention have consistently shown that humans prefer to attend to other human beings. Much less is known about whether a similar preference is also evident in covert attentional processes. To enable a direct comparison, this study examined covert and overt attentional guidance within two different experimental setups using complex naturalistic scenes instead of isolated single features. In the first experiment, a modified version of the dot-probe paradigm served as a measure of covert reflexive attention toward briefly presented scenes containing a social feature in one half of the visual field compared to nonsocial elements in the other while controlling for low-level visual saliency. Participants showed a stable congruency effect with faster reaction times and fewer errors for probes presented on the social side of the scene. In a second experiment, we tracked eye movements for the same set of stimuli while manipulating the presentation time to allow for differentiating reflexive and more sustained aspects of overt attention. Supportive of the first results, analyses revealed a robust preference for social features concerning initial saccade direction as well as fixation allocation. Collectively, these experiments imply preferential processing of social features over visually salient aspects for automatic allocation of covert as well as overt attention. |
Aleya Flechsenhar; Lara Rösler; Matthias Gamer Attentional selection of social features persists despite restricted bottom-up information and affects temporal viewing dynamics Journal Article In: Scientific Reports, vol. 8, pp. 12555, 2018. @article{Flechsenhar2018a, Previous studies have shown an attentional bias towards social features during free-viewing of naturalistic scenes. This social attention seems to be reflexive and able to defy top-down demands in form of explicit search tasks. However, the question remains whether social features continue to be prioritized when peripheral information is limited, thereby reducing the influence of bottom-up image information on gaze orienting. Therefore, we established a gaze-contingent viewing paradigm, in which the visual field was constrained and updated in response to the viewer's eye movements. Participants viewed social and non-social images that were randomly allocated to a free and a gaze-contingent viewing condition while their eye movements were tracked. Our results revealed a strong attentional bias towards social features in both conditions. However, gaze-contingent viewing altered temporal and spatial dynamics of viewing behavior. Additionally, recurrent fixations were more frequent and closer together in time for social compared to non-social stimuli in both viewing conditions. Taken together, this study implies a predominant selection of social features when bottom-up influences are diminished and a general influence of social content on visual exploratory behavior, thus highlighting mechanisms of social attention. |
Rebecca M. Foerster “Looking-at-nothing” during sequential sensorimotor actions: Long-term memory-based eye scanning of remembered target locations Journal Article In: Vision Research, vol. 144, pp. 29–37, 2018. @article{Foerster2018a, Before acting humans saccade to a target object to extract relevant visual information. Even when acting on remembered objects, locations previously occupied by relevant objects are fixated during imagery and memory tasks – a phenomenon called “looking-at-nothing”. While looking-at-nothing was robustly found in tasks encouraging declarative memory built-up, results are mixed in the case of procedural sensorimotor tasks. Eye-guidance to manual targets in complete darkness was observed in a task practiced for days beforehand, while investigations using only a single session did not find fixations to remembered action targets. Here, it is asked whether looking-at-nothing can be found in a single sensorimotor session and thus independent from sleep consolidation, and how it progresses when visual information is repeatedly unavailable. Eye movements were investigated in a computerized version of the trail making test. Participants clicked on numbered circles in ascending sequence. Fifty trials were performed with the same spatial arrangement of 9 visual targets to enable long-term memory consolidation. During 50 consecutive trials, participants had to click the remembered target sequence on an empty screen. Participants scanned the visual targets and also the empty target locations sequentially with their eyes, however, the latter less precise than the former. Over the course of the memory trials, manual and oculomotor sequential target scanning became more similar to the visual trials. Results argue for robust looking-at-nothing during procedural sensorimotor tasks provided that long-term memory information is sufficient. |
Rebecca M. Foerster; Werner X. Schneider Involuntary top-down control by search-irrelevant features: Visual working memory biases attention in an object-based manner Journal Article In: Cognition, vol. 172, pp. 37–45, 2018. @article{Foerster2018, Many everyday tasks involve successive visual-search episodes with changing targets. Converging evidence suggests that these targets are retained in visual working memory (VWM) and bias attention from there. It is unknown whether all or only search-relevant features of a VWM template bias attention during search. Bias signals might be configured exclusively to task-relevant features so that only search-relevant features bias attention. Alternatively, VWM might maintain objects in the form of bound features. Then, all template features will bias attention in an object-based manner, so that biasing effects are ranked by feature relevance. Here, we investigated whether search-irrelevant VWM template features bias attention. Participants had to saccade to a target opposite a distractor. A colored cue depicted the target prior to each search trial. The target was predefined only by its identity, while its color was irrelevant. When target and cue matched not only in identity (search-relevant) but also in color (search-irrelevant), saccades went more often and faster directly to the target than without any color match (Experiment 1). When introducing a cue-distractor color match (Experiment 2), direct target saccades were most likely when target and cue matched in the search-irrelevant color and least likely in case of a cue-distractor color match. When cue and target were never colored the same (Experiment 3), cue-colored distractors still captured the eyes more often than different-colored distractors despite color being search-irrelevant. As participants were informed about the misleading color, the result argues against a strategical and voluntary usage of color. Instead, search-irrelevant features biased attention obligatorily arguing for involuntary top-down control by object-based VWM templates. |
Jolande Fooken; Kathryn M. Lalonde; Gurkiran K. Mann; Miriam Spering Eye movement training is most effective when it involves a task-relevant sensorimotor decision Journal Article In: Journal of Vision, vol. 18, no. 4, pp. 1–18, 2018. @article{Fooken2018, Eye and hand movements are closely linked when performing everyday actions. We conducted a perceptual-motor training study to investigate mutually beneficial effects of eye and hand movements, asking whether training in one modality benefits performance in the other. Observers had to predict the future trajectory of a briefly presented moving object, and intercept it at its assumed location as accurately as possible with their finger. Eye and hand movements were recorded simultaneously. Different training protocols either included eye movements or a combination of eye and hand movements with or without external performance feedback. Eye movement training did not transfer across modalities: Irrespective of feedback, finger interception accuracy and precision improved after training that involved the hand, but not after isolated eye movement training. Conversely, eye movements benefited from hand movement training or when external performance feedback was given, thus improving only when an active interceptive task component was involved. These findings indicate only limited transfer across modalities. However, they reveal the importance of creating a training task with an active sensorimotor decision to improve the accuracy and precision of eye and hand movements. |
Michele Fornaciai; Paola Binda; Guido Marco Cicchini Trans-saccadic integration of orientation information Journal Article In: Journal of Vision, vol. 18, no. 4, pp. 1–11, 2018. @article{Fornaciai2018, Does visual processing start anew after each eye movement, or is information integrated across saccades? Here we test a strong prediction of the integration hypothesis: that information acquired after a saccade interferes with the perception of images acquired before the saccade. We investigate perception of a basic visual feature, grating orientation, and we take advantage of a delayed interference phenomenon-in human participants, the reported orientation of a target grating, briefly presented at an eccentric location, is strongly biased toward the orientation of flanker gratings that are flashed shortly after the target. Crucially, we find that the effect is the same whether or not a saccade is made during the delay interval even though the eye movement produces a large retinotopic separation between target and flankers. However, the trans-saccadic effect nearly vanishes when flankers are displaced to a different screen location even when this location matches the retinotopic coordinates of the target. We conclude that information about grating orientation is integrated across saccades within a spatial region that is defined in external coordinates and thereby is stable in spite of the movement of the eyes. |
Tom Foulsham; Emma Frost; Lilly Sage Stable individual differences predict eye movements to the left, but not handedness or line bisection Journal Article In: Vision Research, vol. 144, pp. 38–46, 2018. @article{Foulsham2018, When observers view an image, their initial eye movements are not equally distributed but instead are often biased to the left of the picture. This pattern has been linked to pseudoneglect, the spatial bias to the left that is observed in line bisection and a range of other perceptual and attentional tasks. Pseudoneglect is often explained according to the dominance of the right-hemisphere in the neural control of attention, a view bolstered by differences between left- and right-handed participants in both line bisection and eye movements. We re-examined this observation in eighty participants (half of whom reported being left handed) who completed a computerised line bisection task and viewed a series of images. We failed to replicate the previously-reported effect of handedness on eye movements in image viewing, with both groups showing a large average bias to the left on the first saccade. While there was a modest effect of handedness on line bisection, there was no correlation between the two tasks. Stable individual differences, as well as a shorter latency on the initial saccade, were robust predictors of an initial saccade to the left. Therefore, while there seems to be a reflexive and idiosyncratic drive to look to the left, it is not well accounted for by handedness and may have different mechanisms from other forms of pseudoneglect. |
Thomas Gallagher-Mitchell; Victoria Simms; Damien Litchfield Learning from where ‘eye' remotely look or point: Impact on number line estimation error in adults Journal Article In: Quarterly Journal of Experimental Psychology, vol. 71, no. 7, pp. 1526–1534, 2018. @article{GallagherMitchell2018, In this article, we present an investigation into the use of visual cues during number line estimation and their influence on cognitive processes for reducing number line estimation error. Participants completed a 0-1000 number line estimation task before and after a brief intervention in which they observed static-visual or dynamic-visual cues (control, anchor, gaze cursor, mouse cursor) and also made estimation marks to test effective number-target estimation. Results indicated that a significant pre-test to post-test reduction in estimation error was present for dynamic-visual cues of modelled eye-gaze and mouse cursor. However, there was no significant performance difference between pre- and post-test for the control or static anchor conditions. Findings are discussed in relation to the extent to which anchor points alone are meaningful in promoting successful segmentation of the number line and whether dynamic cues promote the utility of these locations in reducing error through attentional guidance. |
Kathleen A. Garrison; Stephanie S. O'malley; Ralitza Gueorguieva; Suchitra Krishnan-Sarin A fMRI study on the impact of advertising for flavored e-cigarettes on susceptible young adults Journal Article In: Drug and Alcohol Dependence, vol. 186, pp. 233–241, 2018. @article{Garrison2018, Background: E-cigarettes are sold in flavors such as "skittles," "strawberrylicious," and "juicy fruit," and no restrictions are in place on marketing e-cigarettes to youth. Sweets/fruits depicted in e-cigarette advertisements may increase their appeal to youth and interfere with health warnings. This study tested a brain biomarker of product preference for sweet/fruit versus tobacco flavor e-cigarettes, and whether advertising for flavors interfered with warning labels. Methods: Participants (N = 26) were college-age young adults who had tried an e-cigarette and were susceptible to future e-cigarette use. They viewed advertisements in fMRI for sweet/fruit and tobacco flavor e-cigarettes, menthol and regular cigarettes, and control images of sweets/fruits/mints with no tobacco product. Cue-reactivity was measured in the nucleus accumbens, a brain biomarker of product preference. Advertisements randomly contained warning labels, and recognition of health warnings was tested post-scan. Visual attention was measured using eye-tracking. Results: There was a significant effect of e-cigarette condition (sweet/tobacco/control) on nucleus accumbens activity, that was not found for cigarette condition (menthol/regular/control). Nucleus accumbens activity was greater for sweet/fruit versus tobacco flavor e-cigarette advertisements and did not differ compared with control images of sweets and fruits. Greater nucleus accumbens activity was correlated with poorer memory for health warnings. Conclusions: These and exploratory eye-tracking findings suggest that advertising for sweet/fruit flavors may increase positive associations with e-cigarettes and/or override negative associations with tobacco, and interfere with health warnings, suggesting that one way to reduce the appeal of e-cigarettes to youth and educate youth about e-cigarette health risks is to regulate advertising for flavors. |
Alexander Geiger; Axel Cleeremans; Gary Bente; Kai Vogeley Social cues alter implicit motor learning in a serial reaction time task Journal Article In: Frontiers in Human Neuroscience, vol. 12, pp. 197, 2018. @article{Geiger2018, Learning is a central ability for human development. Many skills we learn, such as language, are learned through observation or imitation in social contexts. Likewise, many skills are learned implicitly, that is, without an explicit intent to learn and without full awareness of the acquired knowledge. Here, we asked whether performance in a motor learning task is modulated by social vs. object cues of varying validity. To address this question, we asked participants to carry out a serial reaction time (SRT) task in which, on each trial, people have to respond as fast and as accurately as possible to the appearance of a stimulus at one of four possible locations. Unbeknownst to participants, the sequence of successive locations was sequentially structured, so that knowledge of the sequence facilitates anticipation of the next stimulus and hence faster motor responses. Crucially, each trial also contained a cue pointing to the next stimulus location. Participants could thus learn based on the cue, or on learning about the sequence of successive locations, or on a combination of both. Results show an interaction between cue type and cue validity for the motor responses: social cues (vs. object cues) led to faster responses in the low validity (LV) condition only. Concerning the extent to which learning was implicit, results show that in the cued blocks only, the highly valid social cue led to implicit learning. In the uncued blocks, participants showed no implicit learning in the highly valid social cue condition, but did in all other combinations of stimulus type and cueing validity. In conclusion, our results suggest that implicit learning is context-dependent and can be influenced by the cue type, e.g., social and object cues. |
Hagar Gelbard-Sagiv; Efrat Magidov; Haggai Sharon; Talma Hendler Noradrenaline modulates visual perception and late visually evoked activity Journal Article In: Current Biology, vol. 28, pp. 2239–2249, 2018. @article{GelbardSagiv2018, An identical sensory stimulus may or may not be incorporated into perceptual experience, depending on the behavioral and cognitive state of the organism. What determines whether a sensory stimulus will be perceived? While different behavioral and cognitive states may share a similar profile of electrophysiology, metabolism, and early sensory responses, neuromodulation is often different and therefore may constitute a key mechanism enabling perceptual awareness. Specifically, noradrenaline improves sensory responses, correlates with orienting toward behaviorally relevant stimuli, and is markedly reduced during sleep, while experience is largely ‘‘disconnected'' from external events. Despite correlative evidence hinting at a relationship between noradrenaline and perception, causal evidence remains absent. Here, we pharmacologically down- and upregulated noradrenaline signaling in healthy volunteers using clonidine and reboxetine in double-blind placebo-controlled experiments, testing the effects on perceptual abilities and visually evoked electroencephalography (EEG) and fMRI responses. We found that detection sensitivity, discrimination accuracy, and subjective visibility change in accordance with noradrenaline (NE) levels, whereas decision bias (criterion) is not affected. Similarly, noradrenaline increases the consistency of EEG visually evoked potentials, while lower noradrenaline levels delay response components around 200 ms. Furthermore, bloodoxygen-level-dependent (BOLD) fMRI activations in high-order visual cortex selectively vary along with noradrenaline signaling. Taken together, these results point to noradrenaline as a key factor causally linking visual awareness to external world events. |
Emily C. Gelfand; Gregory D. Horwitz Model of parafoveal chromatic and luminance temporal contrast sensitivity of humans and monkeys Journal Article In: Journal of Vision, vol. 18, no. 12, pp. 1–17, 2018. @article{Gelfand2018, Rhesus monkeys are a valuable model for studies of primate visual contrast sensitivity. Their visual systems are similar to that of humans, and they can be trained to perform detection tasks at threshold during neurophysiological recording. However, the stimulus dependence of rhesus monkey contrast sensitivity has not been well characterized. Temporal frequency, color, and retinal eccentricity affect the contrast sensitivity of humans in reasonably well-understood ways. To ask whether these factors affect monkey sensitivity similarly, we measured detection thresholds of two monkeys using a two-alternative, forced-choice task and compared them to thresholds of two human subjects who performed the same task. Stimuli were drifting Gabor patterns that varied in temporal frequency (1–60 Hz), L- and M-cone modulation ratio, and retinal eccentricity (28–148 from the fovea). Thresholds were fit by a model that assumed a pair of linear detection mechanisms: a luminance contrast detector and a red-green contrast detector. Analysis of model fits indicated that the sensitivity of these mechanisms varied across the visual field, but their temporal and spectral tuning did not. Human and monkey temporal contrast sensitivity was similar across the conditions tested, but monkeys were twofold less sensitive to low-frequency, luminance modulations. |
Anna C. Geuzebroek; Albert V. Berg Eccentricity scale independence for scene perception in the first tens of milliseconds Journal Article In: Journal of Vision, vol. 18, no. 9, pp. 1–14, 2018. @article{Geuzebroek2018, Visual processing of scenes in the first tens of milliseconds relies on global image summary statistics rather than localized processing. Although natural scenes typically involve our entire visual field, scenes are usually presented experimentally at limited eccentricity. Receptive-field size increases with foveal eccentricity while increasingly pooling activity from local receptive fields. Here, we asked to what extent an observer's performance on a scene-gist perception task depends on the contents of the scene as well as on the eccentricity of the scene. We manipulated the scene content by applying window and scotoma masks. In addition, we changed presentation eccentricity independent of image content by upscaling and downscaling the scenes. We find that discrimination is strongly affected when the scene is presented with a window of 58, showing only the central part rather than the whole scene. Performance is, however, eccentricity scale independent provided that the same scene content is presented and a comparable area of the surface of primary visual cortex is activated. We furthermore show that this eccentricity scale independence holds for shorter presentation times, down to 17 ms in some scene-discrimination tasks, but not for the naturalness-discrimination task. |
Saeideh Ghahghaei; Karina J. Linnell The effect of load on spatial attention depends on preview: Evidence from a reading study Journal Article In: Vision Research, vol. 149, pp. 115–123, 2018. @article{Ghahghaei2018, The spatio-temporal distribution of covert attention has usually been studied under unfamiliar tasks with static viewing. It is important to extend this work to familiar tasks such as reading where sequential eye movements are made. Our previous work with reading showed that covert spatial attention around the gaze location is affected by the fixated word frequency, or the processing load exerted by the word, as early as 40 ms into the fixation. Here, we hypothesised that this early effect of frequency is only possible when the word is previewed and thus pre-processed before being fixated. We tested this hypothesis by preventing preview. We investigated the dynamics of spatial attention around the gaze location while the observer read strings of random words. The words were either always exposed (normal preview) or only exposed while being fixated (masked preview). We probed spatial attention when a target word with either high or low printed frequency – or low or high load, respectively – was fixated. The results confirmed that, early in a fixation, allocation of spatial attention 6 characters from the gaze was affected by the word's frequency but only when the word was exposed before being fixated, so that processing of the word could start before it was fixated. Our results indicate that the ongoing processing load of a word is modulated by its pre-processing and affects the dynamics of covert spatial attention around the word once it is fixated. |
Delia A. Gheorghe; Muriel T. N. Panouillères; Nicholas D. Walsh Psychosocial stress affects the acquisition of cerebellar-dependent sensorimotor adaptation Journal Article In: Psychoneuroendocrinology, vol. 92, pp. 41–49, 2018. @article{Gheorghe2018, Despite being overlooked in theoretical models of stress-related disorders, differences in cerebellar structure and function are consistently reported in studies of individuals exposed to current and early-life stressors. However, the mediating processes through which stress impacts upon cerebellar function are currently unknown. The aim of the current experiment was to test the effects of experimentally-induced acute stress on cerebellar functioning, using a classic, forward saccadic adaptation paradigm in healthy, young men and women. Stress induction was achieved by employing the Montreal Imaging Stress Task (MIST), a task employing mental arithmetic and negative social feedback to generate significant physiological and endocrine stress responses. Saccadic adaptation was elicited using the double-step target paradigm. In the experiment, 48 participants matched for gender and age were exposed to either a stress (n = 25) or a control (n = 23) condition. Saliva for cortisol analysis was collected before, immediately after, and 10, and 30 min after the MIST. Saccadic adaptation was assessed approximately 10 min after stress induction, when cortisol levels peaked. Participants in the stress group reported significantly more stress symptoms and exhibited greater total cortisol output compared to controls. The stress manipulation was associated with slower learning rates in the stress group, while control participants acquired adaptation faster. Learning rates were negatively associated with cortisol output and mood disturbance. Results suggest that experimentally-induced stress slowed acquisition of cerebellar-dependent saccadic adaptation, related to increases in cortisol output. These ‘proof-of-principle' data demonstrate that stress modulates cerebellar-related functions. |
Marcello Giannini; David M. Alexander; Andrey R. Nikolaev; Cees Leeuwen Large-scale traveling waves in EEG activity following eye movement Journal Article In: Brain Topography, vol. 31, no. 4, pp. 608–622, 2018. @article{Giannini2018, In spontaneous, stimulus-evoked, and eye-movement evoked EEG, the oscillatory signal shows large scale, dynamically organized patterns of phase. We investigated eye-movement evoked patterns in free-viewing conditions. Participants viewed photographs of natural scenes in anticipation of a memory test. From 200 ms intervals following saccades, we estimated the EEG phase gradient over the entire scalp, and the wave activity, i.e. the goodness of fit of a wave model involving a phase gradient assumed to be smooth over the scalp. In frequencies centered at 6.5 Hz, large-scale phase organization occurred, peaking around 70 ms after fixation onset and taking the form of a traveling wave. According to the wave gradient, most of the times the wave spreads from the posterior-inferior to anterior–superior direction. In these directions, the gradients depended on the size and direction of the saccade. Wave propagation velocity decreased in the course of the fixation, particularly in the interval from 50 to 150 ms after fixation onset. This interval corresponds to the fixation-related lambda activity, which reflects early perceptual processes following fixation onset. We conclude that lambda activity has a prominent traveling wave component. This component consists of a short-term whole-head phase pattern of specific direction and velocity, which may reflect feedforward propagation of visual information at fixation. |
Esther S. Ginsberg; Nicole J. Rinehart; Joanne Fielding Exploration of gaze-arrow stimuli in a cued paradigm of overt attention Journal Article In: Psychology & Neuroscience, vol. 11, no. 3, pp. 266–279, 2018. @article{Ginsberg2018, Attentional shifts have been investigated extensively using gaze and arrow cues, but the spatiotemporal patterns of visual exploration of these stimuli—location and duration of fixations—has not been characterized. These patterns and the corresponding responses to gaze and arrow cues were examined using a saccade gap paradigm, with no constraints on central fixation, in 27 healthy adult males, aged 18–36. Mean relative dwell time, a measure of the duration of eye fixations on the stimuli relative to stimulus duration, was lower for gaze stimuli. In both stimulus conditions, responses were faster for validly cued targets at a stimulus-onset asynchrony of 400 ms, but slower at a stimulus-onset asynchrony of 800 ms. These effects were considered with reference to transient events at fixation (cue offset and gap). Foreperiod saccades—early idiosyncratic responses to the cue rather than to the target—occurred more frequently for arrow cues, were unrelated to attentional shifts, and moderately associated with readiness to respond. Asymmetries in saccade latencies, with faster responses either leftward or right-ward, were present in 37% of the sample across all conditions. |
Melita J. Giummarra; Govinda Poudel; P. Amanda Niu; Michael E. R. Nicholls; Joanne Fielding; Antonio Verdejo-Garcia; Izelle Labuschagne In: Laterality, vol. 23, no. 2, pp. 184–208, 2018. @article{Giummarra2018, We investigated emotional processing in vicarious pain (VP) responders. VP responders report an explicit sensory and emotional feeling of pain when they witness another in pain, which is greater in magnitude than the empathic processing of pain in the general population. In Study 1, 31 participants completed a chimeric faces task, judging whether emotional chimera in the left, or right, visual field was more intense. VP responders took longer to judge emotionality than non-responders, and fixated more on the angry hemiface in the right visual field, whereas non-responder controls had no lateralized fixation bias. In Study 2, blood-oxygen level-dependent signals were recorded during an emotional face matching task. VP intensity was correlated with increased insula activity and reduced middle frontal gyrus activity for angry faces, and with reduced activity in the inferior and middle frontal gyri for sad faces. Together, these findings suggest that VP responders are more reactive to negative emotional expressions. Specifically, emotional judgements involved altered left-hemisphere activity in VP responders, and reduced engagement of regions involved in emotion regulation. |