Distractor effect and saccade amplitudes: Further evidence on different modes of processing in free exploration of visual images

Ambient and focal attention during complex problem-solving: preliminary evidence from real-world eye movement data

Time course analysis of eye movements during free exploration of real-world scenes often reveals an increase in fixation durations together with a decrease in saccade amplitudes, which has been explained within the two visual systems approach, i.e., a transition from ambient to focal. Short fixations and long saccades during early viewing periods are classified as ambient mode of vision, which is concerned with spatial orientation and is related to simple visual properties such as motion, contrast, and location. Longer fixations and shorter saccades during later viewing periods are classified as focal mode of vision, which is concentrated in the foveal projection and is capable of object identification and its semantic categorization. While these findings are mainly obtained in the context of image exploration, the present study endeavors to investigate whether the same pattern of interplay between ambient and focal visual attention is deployed when people work on complex real-world tasks-and if so, when? Based on a re-analysis of existing data that integrates concurrent think aloud and eye tracking protocols, the present study correlated participants' internal thinking models to the parameters of their eye movements when they planned solutions to an open-ended design problem in a real-world setting. We hypothesize that switching between ambient and focal attentional processing is useful when solvers encounter difficulty compelling them to shift their conceptual direction to adjust the solution path. Individuals may prefer different attentional strategies for information-seeking behavior, such as ambient-to-focal or focal-to-ambient. The observed increase in fixation durations and decrease in saccade amplitudes during the periods around shifts in conceptual direction lends support to the postulation of the ambient-to-focal processing; however, focal-to-ambient processing is not evident. Furthermore, our data demonstrate that the beginning of a shift in conceptual direction is observable in eye movement behavior with a significant prolongation of fixation. Our findings add to the conclusions drawn from laboratory settings by providing preliminary evidence for ambient and focal processing characteristics in real-world problem-solving.

Modeling Eye Movements During Decision Making: A Review

This article reviews recent advances in the psychometric and econometric modeling of eye-movements during decision making. Eye movements offer a unique window on unobserved perceptual, cognitive, and evaluative processes of people who are engaged in decision making tasks. They provide new insights into these processes, which are not easily available otherwise, allow for explanations of fundamental search and choice phenomena, and enable predictions of future decisions. We propose a theoretical framework of the search and choice tasks that people commonly engage in and of the underlying cognitive processes involved in those tasks. We discuss how these processes drive specific eye-movement patterns. Our framework emphasizes the central role of task and strategy switching for complex goal attainment. We place the extant literature within that framework, highlight recent advances in modeling eye-movement behaviors during search and choice, discuss limitations, challenges, and open problems. An agenda for further psychometric modeling of eye movements during decision making concludes the review.

Bodily feelings and aesthetic experience of art

Humans all around the world are drawn to creating and consuming art due to its capability to evoke emotions, but the mechanisms underlying art-evoked feelings remain poorly characterised. Here we show how embodiement contributes to emotions evoked by a large database of visual art pieces (n = 336). In four experiments, we mapped the subjective feeling space of art-evoked emotions (n = 244), quantified "bodily fingerprints" of these emotions (n = 615), and recorded the subjects' interest annotations (n = 306) and eye movements (n = 21) while viewing the art. We show that art evokes a wide spectrum of feelings, and that the bodily fingerprints triggered by art are central to these feelings, especially in artworks where human figures are salient. Altogether these results support the model that bodily sensations are central to the aesthetic experience.

Eye tracking metrics of orthopedic surgeons with different competency levels who practice simulation-based hip arthroscopic procedures

Objective

This study aimed to investigate the feasibility of using eye tracking data to identify orthopedic trainees' technical proficiency in hip arthroscopic procedures during simulation-based training.

Design

A cross sectional study.

Setting

A simulation-based training session for hip arthroscopy was conducted. Eye tracking devices were used to record participants' eye movements while performing simulated operations. The NASA Task Load Index survey was then used to measure subjective opinions on the perceived workload of the training. Statistical analyses were performed to determine the significance of the eye metrics and survey data.

Participants

A total of 12 arthroscopic trainees, including resident doctors, junior specialist surgeons, and consultant surgeons from the Department of Orthopedics in five hospitals, participated in this study. They were divided into three subgroups based on their prior clinical experience.

Results

Significant differences, including those for dwell time, number of fixations, number of saccades, saccade duration, peak velocity of the saccade, and pupil entropy, were observed among the three subgroups. Additionally, there were clear trends in the perceived workload of the simulation-based training based on feedback from the participants.

Conclusion

Based on this preliminary study, a correlation was identified between the eye tracking metrics and participants' experience levels. Hence, it is feasible to apply eye tracking data as a supplementary objective assessment tool to benchmark the technical proficiency of surgical trainees in hip arthroscopy, and enhance simulation-based training.

How central and peripheral vision influence focal and ambient processing during scene viewing

Central and peripheral vision carry out different functions during scene processing. The ambient mode of visual processing is more likely to involve peripheral visual processes, whereas the focal mode of visual processing is more likely to involve central visual processes. Although the ambient mode is responsible for navigating space and comprehending scene layout, the focal mode gathers detailed information as central vision is oriented to salient areas of the visual field. Previous work suggests that during the time course of scene viewing, there is a transition from ambient processing during the first few seconds to focal processing during later time intervals, characterized by longer fixations and shorter saccades. In this study, we identify the influence of central and peripheral vision on changes in eye movements and the transition from ambient to focal processing during the time course of scene processing. Using a gaze-contingent protocol, we restricted the visual field to central or peripheral vision while participants freely viewed scenes for 20 seconds. Results indicated that fixation durations are shorter when vision is restricted to central vision compared to normal vision. During late visual processing, fixations in peripheral vision were longer than those in central vision. We show that a transition from more ambient to more focal processing during scene viewing will occur even when vision is restricted to only central vision or peripheral vision.

Virtual reality boxing: Gaze-contingent manipulation of stimulus properties using blur

It has been reported that behavior of experts and novices in various sporting tasks is impervious to the introduction of blur. However, studies have used diverse methods of blurring the visual stimulus (i.e., dioptric blur and Gaussian blur), and tasks that did not always preserve the normal perception-action coupling. In the current study, we developed a novel experimental protocol to examine the effect of different levels of Gaussian blur on interception performance and eye gaze data using an immersive VR task. Importantly, this provided a realistic simulation of a real-world boxing scenario (e.g., the presence of a feint prior to the onset of different combinations of punches) in which expert combat athletes (n = 18) experienced a first-person, adaptive viewpoint of the visual environment, which could be blurred according to their gaze location (central blur, peripheral blur, no blur). We found that participants exhibited similar interception performance in the presence of central blur or peripheral blur compared to a control condition with no blur. However, interception performance was significantly better with a central blur compared to peripheral blur. Eye gaze data indicated that although participants fixated at similar areas of interest irrespective of the presence of blur, fixation duration was significantly longer with a strong level of blur in the peripheral viewing condition than all levels of central blur and the control condition. These findings can be explained by relocating attention to different areas of the environment, which thereby influenced the perception of salient information. Participants also performed better on the first punch of a sequence preceded by a foot feint compared to arm feint or no feint. Still, irrespective of feint type, performance was significantly better on the second and third punch compared to the first punch. These findings are consistent with participants using additional information from the opponent's body movements and situational probabilities to increase performance as the sequence of punches developed. Overall, these are the first evidence for the use of VR as a means to examine gaze-contingent manipulations of the environment, and hence highlight the potential for facilitating learning and transfer to a real sporting situations.

Visual search in neurodevelopmental disorders: evidence towards a continuum of impairment

Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses. N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.

Similarities and Differences Between Eye and Mouse Dynamics During Web Pages Exploration

The study of eye movements is a common way to non-invasively understand and analyze human behavior. However, eye-tracking techniques are very hard to scale, and require expensive equipment and extensive expertise. In the context of web browsing, these issues could be overcome by studying the link between the eye and the computer mouse. Here, we propose new analysis methods, and a more advanced characterization of this link. To this end, we recorded the eye, mouse, and scroll movements of 151 participants exploring 18 dynamic web pages while performing free viewing and visual search tasks for 20 s. The data revealed significant differences of eye, mouse, and scroll parameters over time which stabilize at the end of exploration. This suggests the existence of a task-independent relationship between eye, mouse, and scroll parameters, which are characterized by two distinct patterns: one common pattern for movement parameters and a second for dwelling/fixation parameters. Within these patterns, mouse and eye movements remained consistent with each other, while the scrolling behaved the opposite way.

Revealing the dynamics of prospective memory processes in children with eye movements

Prospective memory (PM), the memory for delayed intentions, develops during childhood. The current study examined PM processes, such as monitoring, PM cue identification and intention retrieval with particular focus on their temporal dynamics and interrelations during successful and unsuccessful PM performance. We analysed eye movements of 6-7 and 9-10 year olds during the inspection of movie stills while they completed one of three different tasks: scene viewing followed by a snippet allocation task, a PM task and a visual search task. We also tested children's executive functions of inhibition, flexibility and working memory. We found that older children outperformed younger children in all tasks but neither age group showed variations in monitoring behaviour during the course of the PM task. In fact, neither age group monitored. According to our data, initial processes necessary for PM success take place during the first fixation on the PM cue. In PM hit trials we found prolonged fixations after the first fixation on the PM cue, and older children showed a greater efficiency in PM processes following this first PM cue fixation. Regarding executive functions, only working memory had a significant effect on children's PM performance. Across both age groups children with better working memory scores needed less time to react to the PM cue. Our data support the notion that children rely on spontaneous processes to notice the PM cue, followed by a resource intensive search for the intended action.

Effects of Transient Loss of Vision on Head and Eye Movements during Visual Search in a Virtual Environment

Central and peripheral fields of view extract information of different quality and serve different roles during visual tasks. Past research has studied this dichotomy on-screen in conditions remote from natural situations where the scene would be omnidirectional and the entire field of view could be of use. In this study, we had participants looking for objects in simulated everyday rooms in virtual reality. By implementing a gaze-contingent protocol we masked central or peripheral vision (masks of 6 deg. of radius) during trials. We analyzed the impact of vision loss on visuo-motor variables related to fixation (duration) and saccades (amplitude and relative directions). An important novelty is that we segregated eye, head and the general gaze movements in our analyses. Additionally, we studied these measures after separating trials into two search phases (scanning and verification). Our results generally replicate past on-screen literature and teach about the role of eye and head movements. We showed that the scanning phase is dominated by short fixations and long saccades to explore, and the verification phase by long fixations and short saccades to analyze. One finding indicates that eye movements are strongly driven by visual stimulation, while head movements serve a higher behavioral goal of exploring omnidirectional scenes. Moreover, losing central vision has a smaller impact than reported on-screen, hinting at the importance of peripheral scene processing for visual search with an extended field of view. Our findings provide more information concerning how knowledge gathered on-screen may transfer to more natural conditions, and attest to the experimental usefulness of eye tracking in virtual reality.

Graph-Based Analysis of Visual Scanning Patterns: A Developmental Study on Green and Normal Images

The present study investigated the visual scanning pattern of children with typical development in three different age groups(4-6,6-8,8-10 years old). We used a data set from one related research, which included images with different low-level features: Green and Normal. This study analyzed age-associated inter-individual differences and was intended to show that graph profiling combined with a fixation time approach could help us to better understand the developmental visual pattern. Thus, degree centrality as one of the graph theory measures was implied to analyze gaze distribution. We explored the influence of bottom-up features, comparing the first 2 s (early phase) with the interval from 4 to 6 s (late phase) of scene exploration during age development. Our results indicated that degree centrality and fixation time increased with age. Furthermore, it was found that the effects of saliency are short-lived but significant. Moreover, we found that Green images during the early phase play an important role in visual anchoring, and the children's performance was significantly different between 4-6 y and 6-8y-group. This comparative study underscores the ability of degree centrality as a developing innovative measure to perform eye-tracking data analyses.

Visual exploration of emotional faces in schizophrenia using masks from the Japanese Noh theatre

Studying eye movements during visual exploration is widely used to investigate visual information processing in schizophrenia. Here, we used masks from the Japanese Noh theatre to study visual exploration behavior during an emotional face recognition task and a brightness evaluation control task using the same stimuli. Eye movements were recorded in 25 patients with schizophrenia and 25 age-matched healthy controls while participants explored seven photos of Japanese Noh masks tilted to seven different angles. Additionally, participants were assessed on seven upright binary black and white pictures of these Noh masks (Mooney-like pictures), seven Upside-down pictures (180° upside-down turned Mooneys), and seven Neutral pictures. Participants either had to indicate whether they had recognized a face and its emotional expression, or they had to evaluate the brightness of the picture (total N = 56 trials). We observed a clear effect of inclination angle of Noh masks on emotional ratings (p < 0.001) and visual exploration behavior in both groups. Controls made larger saccades than patients when not being able to recognize a face in upside-down Mooney pictures (p < 0.01). Patients also made smaller saccades when exploring pictures for brightness (p < 0.05). Exploration behavior in patients was related to depressive symptom expression during emotional face recognition but not during brightness evaluation. Our findings suggest that visual exploration behavior in patients with schizophrenia is less flexible than in controls depending on the specific task requirements, specifically when exploring physical aspects of the environment.

The Changing Landscape: High-Level Influences on Eye Movement Guidance in Scenes

The use of eye movements to explore scene processing has exploded over the last decade. Eye movements provide distinct advantages when examining scene processing because they are both fast and spatially measurable. By using eye movements, researchers have investigated many questions about scene processing. Our review will focus on research performed in the last decade examining: (1) attention and eye movements; (2) where you look; (3) influence of task; (4) memory and scene representations; and (5) dynamic scenes and eye movements. Although typically addressed as separate issues, we argue that these distinctions are now holding back research progress. Instead, it is time to examine the intersections of these seemingly separate influences and examine the intersectionality of how these influences interact to more completely understand what eye movements can tell us about scene processing.

Distraction by deviant sounds during reading: An eye-movement study

Oddball studies have shown that sounds unexpectedly deviating from an otherwise repeated sequence capture attention away from the task at hand. While such distraction is typically regarded as potentially important in everyday life, previous work has so far not examined how deviant sounds affect performance on more complex daily tasks. In this study, we developed a new method to examine whether deviant sounds can disrupt reading performance by recording participants’ eye movements. Participants read single sentences in silence and while listening to task-irrelevant sounds. In the latter condition, a 50-ms sound was played contingent on the fixation of five target words in the sentence. On most occasions, the same tone was presented (standard sound), whereas on rare and unexpected occasions it was replaced by white noise (deviant sound). The deviant sound resulted in significantly longer fixation durations on the target words relative to the standard sound. A time-course analysis showed that the deviant sound began to affect fixation durations around 180 ms after fixation onset. Furthermore, deviance distraction was not modulated by the lexical frequency of target words. In summary, fixation durations on the target words were longer immediately after the presentation of the deviant sound, but there was no evidence that it interfered with the lexical processing of these words. The present results are in line with the recent proposition that deviant sounds yield a temporary motor suppression and suggest that deviant sounds likely inhibit the programming of the next saccade.

The Effect of Art Expertise on Eye Fixation-Related Potentials During Aesthetic Judgment Task in Focal and Ambient Modes

This study aimed to determine the effect of expertise on the eye fixation-related potentials (EFRPs) during the aesthetic evaluation of images, independently in focal and ambient modes of visual processing. Focal and ambient modes were identified by averaging EFRP waveforms about the beginning of long eye fixations followed by short saccades and short fixations followed by long saccades, respectively. Thirty experts with formal training in visual arts and thirty-two non-experts freely viewed 150 figurative paintings presented for 20 s, each. After viewing the painting, the participant answered the question: “Is this painting beautiful?” Differences were found between the group of experts and non-experts due to the amplitude of EFRPs but only in focal mode, which is related to top-down, focused attention on the objects. Long fixations of experts had a higher amplitude of the parietal P2 recorded from right site than non-experts. In the group of experts, the frontal P2 was higher for long fixations on not beautiful paintings in comparison to long fixation on beautiful paintings. Moreover, in focal mode, there were higher occipital lambda response and N1-P2 complex for not beautiful than beautiful paintings. These results are discussed in the light of the results of studies on the effect of visual art expertise on event-related potentials (ERPs), ERP studies during aesthetic judgment task, and the knowledge of different modes of visual processing and EFRPs.

Perceptual enhancement as a result of a top-down attentional influence in a scene viewing task: Evidence from saccadic inhibition

Prior research has shown that task instructions influence the locations and durations of eye fixations during scene viewing. These task-related changes in gaze patterns are likely to be associated with a top-down influence of attention. Presently we applied a saccadic-inhibition manipulation in order to detect another expected manifestation of top-down attention: perceptual enhancement. Participants viewed eight-item arrays containing photographs from two categories of scenes. Four of the photos depicted natural landscapes ("nature") and the other four depicted urban environments ("buildings"). Participants were instructed to memorize scenes from one of the categories in preparation for a later recognition memory test. During eye fixations the border around the fixated scene flickered briefly from black to white with a random interval between flickers ranging from 400 to 600 ms. We computed the likelihood of a saccade being initiated in the period following the flicker. Consistent with prior research, we found a strong saccadic inhibition effect with maximum saccadic inhibition occurring approximately 97 ms following the flicker. Importantly, the saccadic inhibition effect was stronger and longer lasting when the subject's eyes were fixated on a relevant scene compared to an irrelevant scene. These findings are consistent with perceptual enhancement as a result of top-down attention.

Modeling eye movement patterns to characterize perceptual skill in image-based diagnostic reasoning processes

Experts have a remarkable capability of locating, perceptually organizing, identifying, and categorizing objects in images specific to their domains of expertise. In this article, we present a hierarchical probabilistic framework to discover the stereotypical and idiosyncratic viewing behaviors exhibited with expertise-specific groups. Through these patterned eye movement behaviors we are able to elicit the domain-specific knowledge and perceptual skills from the subjects whose eye movements are recorded during diagnostic reasoning processes on medical images. Analyzing experts' eye movement patterns provides us insight into cognitive strategies exploited to solve complex perceptual reasoning tasks. An experiment was conducted to collect both eye movement and verbal narrative data from three groups of subjects with different levels or no medical training (eleven board-certified dermatologists, four dermatologists in training and thirteen undergraduates) while they were examining and describing 50 photographic dermatological images. We use a hidden Markov model to describe each subject's eye movement sequence combined with hierarchical stochastic processes to capture and differentiate the discovered eye movement patterns shared by multiple subjects within and among the three groups. Independent experts' annotations of diagnostic conceptual units of thought in the transcribed verbal narratives are time-aligned with discovered eye movement patterns to help interpret the patterns' meanings. By mapping eye movement patterns to thought units, we uncover the relationships between visual and linguistic elements of their reasoning and perceptual processes, and show the manner in which these subjects varied their behaviors while parsing the images. We also show that inferred eye movement patterns characterize groups of similar temporal and spatial properties, and specify a subset of distinctive eye movement patterns which are commonly exhibited across multiple images. Based on the combinations of the occurrences of these eye movement patterns, we are able to categorize the images from the perspective of experts' viewing strategies in a novel way. In each category, images share similar lesion distributions and configurations. Our results show that modeling with multi-modal data, representative of physicians' diagnostic viewing behaviors and thought processes, is feasible and informative to gain insights into physicians' cognitive strategies, as well as medical image understanding.

Saccade plan overlap and cancellation during free viewing

In the current study, we examined how the saccadic system responds when visual information changes dynamically in our environment. Previous studies, using the double-step task, have shown that (a) saccade plans could overlap, such that saccade preparation to an object started even while the saccade preparation to another object was ongoing, and (b) saccade plans could be cancelled before they were completed. In these studies, saccade targets were restricted to a few, experimenter-defined locations. Here, we examined whether saccade plan overlap and cancellation mechanisms could be observed in free-viewing conditions. For each trial, we constructed sets of two images, each containing five objects. All objects have unique positions. Image 1 was presented for several fixations, before Image 2 was presented during a fixation, presumably while a saccade plan to an object in Image 1 was ongoing. There were two crucial findings: (a) First, the saccade immediately following the transition was sometimes executed towards objects in Image 2, and not an object in Image 1, suggesting that the earlier saccade plan to an Image 1 object had been cancelled. Second, analysis of the temporal data also suggested that preparation of the first post-transition saccade started before an earlier saccade plan to an Image 1 object was executed, implying that saccade plans overlapped.

Face recognition in schizophrenia disorder: A comprehensive review of behavioral, neuroimaging and neurophysiological studies

Facial emotion processing has been extensively studied in schizophrenia patients while general face processing has received less attention. The already published reviews do not address the current scientific literature in a complete manner. Therefore, here we tried to answer some questions that remain to be clarified, particularly: are the non-emotional aspects of facial processing in fact impaired in schizophrenia patients? At the behavioral level, our key conclusions are that visual perception deficit in schizophrenia patients: are not specific to faces; are most often present when the cognitive (e.g. attention) and perceptual demands of the tasks are important; and seems to worsen with the illness chronification. Although, currently evidence suggests impaired second order configural processing, more studies are necessary to determine whether or not holistic processing is impaired in schizophrenia patients. Neural and neurophysiological evidence suggests impaired earlier levels of visual processing, which might involve the deficits in interaction of the magnocellular and parvocellular pathways impacting on further processing. These deficits seem to be present even before the disorder out-set. Although evidence suggests that this deficit may be not specific to faces, further evidence on this question is necessary, in particularly more ecological studies including context and body processing.

Intrinsic motivations drive learning of eye movements: an experiment with human adults

Intrinsic motivations drive the acquisition of knowledge and skills on the basis of novel or surprising stimuli or the pleasure to learn new skills. In so doing, they are different from extrinsic motivations that are mainly linked to drives that promote survival and reproduction. Intrinsic motivations have been implicitly exploited in several psychological experiments but, due to the lack of proper paradigms, they are rarely a direct subject of investigation. This article investigates how different intrinsic motivation mechanisms can support the learning of visual skills, such as "foveate a particular object in space", using a gaze contingency paradigm. In the experiment participants could freely foveate objects shown in a computer screen. Foveating each of two "button" pictures caused different effects: one caused the appearance of a simple image (blue rectangle) in unexpected positions, while the other evoked the appearance of an always-novel picture (objects or animals). The experiment studied how two possible intrinsic motivation mechanisms might guide learning to foveate one or the other button picture. One mechanism is based on the sudden, surprising appearance of a familiar image at unpredicted locations, and a second one is based on the content novelty of the images. The results show the comparative effectiveness of the mechanism based on image novelty, whereas they do not support the operation of the mechanism based on the surprising location of the image appearance. Interestingly, these results were also obtained with participants that, according to a post experiment questionnaire, had not understood the functions of the different buttons suggesting that novelty-based intrinsic motivation mechanisms might operate even at an unconscious level.

Synchronous brain activity across individuals underlies shared psychological perspectives

For successful communication, we need to understand the external world consistently with others. This task requires sufficiently similar cognitive schemas or psychological perspectives that act as filters to guide the selection, interpretation and storage of sensory information, perceptual objects and events. Here we show that when individuals adopt a similar psychological perspective during natural viewing, their brain activity becomes synchronized in specific brain regions. We measured brain activity with functional magnetic resonance imaging (fMRI) from 33 healthy participants who viewed a 10-min movie twice, assuming once a ‘social’ (detective) and once a ‘non-social’ (interior decorator) perspective to the movie events. Pearson's correlation coefficient was used to derive multisubject voxelwise similarity measures (inter-subject correlations; ISCs) of functional MRI data. We used k-nearest-neighbor and support vector machine classifiers as well as a Mantel test on the ISC matrices to reveal brain areas wherein ISC predicted the participants' current perspective. ISC was stronger in several brain regions—most robustly in the parahippocampal gyrus, posterior parietal cortex and lateral occipital cortex—when the participants viewed the movie with similar rather than different perspectives. Synchronization was not explained by differences in visual sampling of the movies, as estimated by eye gaze. We propose that synchronous brain activity across individuals adopting similar psychological perspectives could be an important neural mechanism supporting shared understanding of the environment.

Distractor effect at initial stages of recognition depends on visual image properties

In the present study, we describe a new method for estimation of distractor effect at image viewing. Dynamics of gaze fixation duration was compared at presentation of distractor during recognition of two types of target stimuli: fading-in contour images and black static cross. Circular blue distractor was applied to a target stimulus at some fixation points during initial stages of image recognition. All stimuli were presented in the center of computer screen inside the foveal part of the vision field. Subjects received the following instructions: to fixate their gaze on target image, recognize target stimulus as quick as possible and press the keyboard button to stop a trial. Our experiments have shown that (i) the median of the distractor effect (increase of fixation duration) was significantly less in trials with fading-in contour images, than in trials with cross image presentation (415 and 610 ms, p < 0.05); (ii) fixation duration without distractors had no significant difference between fading-in image trials (390 ± 10 ms) and cross image trials (438 ± 22 ms); (iii) mean recognition time for fading-in images was significantly more than for cross image (13.9 ± 4.3 s, and 2.47 ± 0.84 s). Possible prospective to use the presented method are discussed.

Saccadic context indicates information processing within visual fixations: evidence from event-related potentials and eye-movements analysis of the distractor effect

Attention, visual information processing, and oculomotor control are integrated functions of closely related brain mechanisms. Recently, it was shown that the processing of visual distractors appearing during a fixation is modulated by the amplitude of its preceding saccade (Pannasch & Velichkovsky, 2009). So far, this was demonstrated only at the behavioral level in terms of saccadic inhibition. The present study investigated distractor-related brain activity with cortical eye fixation-related potentials (EFRPs). Moreover, the following saccade was included as an additional classification criterion. Eye movements and EFRPs were recorded during free visual exploration of paintings. During some of the fixations, a visual distractor was shown as an annulus around the fixation position, 100 ms after the fixation onset. The saccadic context of a fixation was classified by its preceding and following saccade amplitudes with the cut-off criterion set to 4° of visual angle. The prolongation of fixation duration induced by distractors was largest for fixations preceded and followed by short saccades. EFRP data revealed a difference in distractor-related P2 amplitude between the saccadic context conditions, following the same trend as in eye movements. Furthermore, influences of the following saccade amplitude on the latency of the saccadic inhibition and on the N1 amplitude were found. The EFRP results cannot be explained by the influence of saccades per se since this bias was removed by subtracting the baseline from the distractor EFRP. Rather, the data suggest that saccadic context indicates differences in how information is processed within single visual fixations.