Eye movements during information processing tasks: individual differences and cultural effects

Task-Related Differences in Eye Movements in Individuals With Aphasia

Background: Neurotypical young adults show task-based modulation and stability of their eye movements across tasks. This study aimed to determine whether persons with aphasia (PWA) modulate their eye movements and show stability across tasks similarly to control participants.

Methods: Forty-eight PWA and age-matched control participants completed four eye-tracking tasks: scene search, scene memorization, text-reading, and pseudo-reading.

Results: Main effects of task emerged for mean fixation duration, saccade amplitude, and standard deviations of each, demonstrating task-based modulation of eye movements. Group by task interactions indicated that PWA produced shorter fixations relative to controls. This effect was most pronounced for scene memorization and for individuals who recently suffered a stroke. PWA produced longer fixations, shorter saccades, and less variable eye movements in reading tasks compared to controls. Three-way interactions of group, aphasia subtype, and task also emerged. Text-reading and scene memorization were particularly effective at distinguishing aphasia subtype. Persons with anomic aphasia showed a reduction in reading saccade amplitudes relative to their respective control group and other PWA. Persons with conduction/Wernicke’s aphasia produced shorter scene memorization fixations relative to controls or PWA of other subtypes, suggesting a memorization specific effect. Positive correlations across most tasks emerged for fixation duration and did not significantly differ between controls and PWA.

Conclusion: PWA generally produced shorter fixations and smaller saccades relative to controls particularly in scene memorization and text-reading, respectively. The effect was most pronounced recently after a stroke. Selectively in reading tasks, PWA produced longer fixations and shorter saccades relative to controls, consistent with reading difficulty. PWA showed task-based modulation of eye movements, though the pattern of results was somewhat abnormal relative to controls. All subtypes of PWA also demonstrated task-based modulation of eye movements. However, persons with anomic aphasia showed reduced modulation of saccade amplitude and smaller reading saccades, possibly to improve reading comprehension. Controls and PWA generally produced stabile fixation durations across tasks and did not differ in their relationship across tasks. Overall, these results suggest there is potential to differentiate among PWA with varying subtypes and from controls using eye movement measures of task-based modulation, especially reading and scene memorization tasks.

Contributions of reader- and text-level characteristics to eye-movement patterns during passage reading

The present research presents a novel method for investigating how characteristics of texts (words, sentences, and passages) and individuals (verbal and general cognitive skills) jointly influence eye-movement patterns over the time-course of reading, as well as comprehension accuracy. Fifty-one proficient readers read passages of varying complexity from the Gray Oral Reading Test, while their eye-movements were recorded. Participants also completed a large battery of tests assessing various components of reading comprehension ability (vocabulary size, decoding, phonological awareness, and experience with print), as well as general cognitive and executive skills. We used the Random Forests nonparametric regression technique to simultaneously estimate relative importance of all predictors. This method enabled us to trace the temporal engagement of individual predictors and entire predictor groups on eye-movements during reading, while avoiding the problems of model overfitting and collinearity, typical of parametric regression methods. Our findings both confirmed well-established results of prior research and pointed to a space of hypotheses that is as yet unexplored. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Investigation of eye movement pattern parameters of individuals with different fluid intelligence

Eye movement studies are subject of interest in human cognition. Cortical activity and cognitive load impress eye movement influentially. Here, we investigated whether fluid intelligence (FI) has any effect on eye movement pattern in a comparative visual search (CVS) task. FI of individuals was measured using the Cattell test, and participants were divided into three groups: low FI, middle FI, and high FI. Eye movements of individuals were then recorded during the CVS task. Eye movement patterns were extracted and compared statistically among the three groups. Our experiment demonstrated that eye movement patterns were significantly different among the three groups. Pearson correlation coefficients between FI and eye movement parameters were also calculated to assess which of the eye movement parameters were most affected by FI. Our findings illustrate that saccade peak velocity had the greatest positive correlation with FI score and the ratio of total fixation duration to total saccade duration had the greatest negative correlation with FI. Next, we extracted 24 features from eye movement patterns and designed: (1) a classifier to categorize individuals and (2) a regression analysis to predict the FI score of individuals. In the best case examined, the classifier categorized subjects with 68.3% accuracy, and the regression predicted FI of individuals with a 0.54 correlation between observed FI and predicted FI. In our investigation, the results have emphasized that imposed loads on low FI individuals is greater than that of high FI individuals in the cognitive load tasks.

Active Sampling State Dynamically Enhances Olfactory Bulb Odor Representation

The olfactory bulb (OB) is the first site of synaptic odor information processing, yet a wealth of contextual and learned information has been described in its activity. To investigate the mechanistic basis of contextual modulation, we use whole-cell recordings to measure odor responses across rapid learning episodes in identified mitral/tufted cells (MTCs). Across these learning episodes, diverse response changes occur already during the first sniff cycle. Motivated mice develop active sniffing strategies across learning that robustly correspond to the odor response changes, resulting in enhanced odor representation. Evoking fast sniffing in different behavioral states demonstrates that response changes during active sampling exceed those predicted from feedforward input alone. Finally, response changes are highly correlated in tufted cells, but not mitral cells, indicating there are cell-type-specific effects on odor representation during active sampling. Altogether, we show that active sampling is strongly associated with enhanced OB responsiveness on rapid timescales.

Meaning guides attention in real-world scene images: Evidence from eye movements and meaning maps

We compared the influence of meaning and of salience on attentional guidance in scene images. Meaning was captured by "meaning maps" representing the spatial distribution of semantic information in scenes. Meaning maps were coded in a format that could be directly compared to maps of image salience generated from image features. We investigated the degree to which meaning versus image salience predicted human viewers' spatiotemporal distribution of attention over scenes. Extending previous work, here the distribution of attention was operationalized as duration-weighted fixation density. The results showed that both meaning and image salience predicted the duration-weighted distribution of attention, but that when the correlation between meaning and salience was statistically controlled, meaning accounted for unique variance in attention whereas salience did not. This pattern was observed in early as well as late fixations, fixations including and excluding the centers of the scenes, and fixations following short as well as long saccades. The results strongly suggest that meaning guides attention in real-world scenes. We discuss the results from the perspective of a cognitive-relevance theory of attentional guidance.

The Gaze-Cueing Effect in the United States and Japan: Influence of Cultural Differences in Cognitive Strategies on Control of Attention

The direction of gaze automatically and exogenously guides visual spatial attention, a phenomenon termed as the gaze-cueing effect. Although this effect arises when the duration of stimulus onset asynchrony (SOA) between a non-predictive gaze cue and the target is relatively long, no empirical research has examined the factors underlying this extended cueing effect. Two experiments compared the gaze-cueing effect at longer SOAs (700 ms) in Japanese and American participants. Cross-cultural studies on cognition suggest that Westerners tend to use a context-independent analytical strategy to process visual environments, whereas Asians use a context-dependent holistic approach. We hypothesized that Japanese participants would not demonstrate the gaze-cueing effect at longer SOAs because they are more sensitive to contextual information, such as the knowledge that the direction of a gaze is not predictive. Furthermore, we hypothesized that American participants would demonstrate the gaze-cueing effect at the long SOAs because they tend to follow gaze direction whether it is predictive or not. In Experiment 1, American participants demonstrated the gaze-cueing effect at the long SOA, indicating that their attention was driven by the central non-predictive gaze direction regardless of the SOAs. In Experiment 2, Japanese participants demonstrated no gaze-cueing effect at the long SOA, suggesting that the Japanese participants exercised voluntary control of their attention, which inhibited the gaze-cueing effect with the long SOA. Our findings suggest that the control of visual spatial attention elicited by social stimuli systematically differs between American and Japanese individuals.

Hidden Markov model analysis reveals the advantage of analytic eye movement patterns in face recognition across cultures

It remains controversial whether culture modulates eye movement behavior in face recognition. Inconsistent results have been reported regarding whether cultural differences in eye movement patterns exist, whether these differences affect recognition performance, and whether participants use similar eye movement patterns when viewing faces from different ethnicities. These inconsistencies may be due to substantial individual differences in eye movement patterns within a cultural group. Here we addressed this issue by conducting individual-level eye movement data analysis using hidden Markov models (HMMs). Each individual's eye movements were modeled with an HMM. We clustered the individual HMMs according to their similarities and discovered three common patterns in both Asian and Caucasian participants: holistic (looking mostly at the face center), left-eye-biased analytic (looking mostly at the two individual eyes in addition to the face center with a slight bias to the left eye), and right-eye-based analytic (looking mostly at the right eye in addition to the face center). The frequency of participants adopting the three patterns did not differ significantly between Asians and Caucasians, suggesting little modulation from culture. Significantly more participants (75%) showed similar eye movement patterns when viewing own- and other-race faces than different patterns. Most importantly, participants with left-eye-biased analytic patterns performed significantly better than those using either holistic or right-eye-biased analytic patterns. These results suggest that active retrieval of facial feature information through an analytic eye movement pattern may be optimal for face recognition regardless of culture.

Neural correlates of individual differences in fixation duration during natural reading

Reading requires integration of language and cognitive processes with attention and eye movement control. Individuals differ in their reading ability, but little is known about the neurocognitive processes associated with these individual differences. To investigate this issue, we combined eyetracking and fMRI, simultaneously recording eye movements and BOLD activity while subjects read text passages. We found that the variability and skew of fixation duration distributions across individuals, as assessed by ex-Gaussian analyses, decreased with increasing neural activity in regions associated with the cortical eye movement control network (Left FEF, Left IPS, Left IFG, and Right IFG). The results suggest that individual differences in fixation duration during reading are related to underlying neurocognitive processes associated with the eye movement control system and its relationship to language processing. The results also show that eye movements and fMRI can be combined to investigate the neural correlates of individual differences in natural reading.

Cultural Differences in Visual Search for Geometric Figures

While some studies suggest cultural differences in visual processing, others do not, possibly because the complexity of their tasks draws upon high-level factors that could obscure such effects. To control for this, we examined cultural differences in visual search for geometric figures, a relatively simple task for which the underlying mechanisms are reasonably well known. We replicated earlier results showing that North Americans had a reliable search asymmetry for line length: Search for long among short lines was faster than vice versa. In contrast, Japanese participants showed no asymmetry. This difference did not appear to be affected by stimulus density. Other kinds of stimuli resulted in other patterns of asymmetry differences, suggesting that these are not due to factors such as analytic/holistic processing but are based instead on the target-detection process. In particular, our results indicate that at least some cultural differences reflect different ways of processing early-level features, possibly in response to environmental factors.

Character-complexity effects in Chinese reading and visual search: A comparison and theoretical implications

Three eye-movement experiments were conducted to examine how the complexity of characters in Chinese words (i.e., number of strokes per character) influences their processing and eye-movement behaviour. In Experiment 1, English speakers with no significant knowledge of Chinese searched for specific low-, medium-, and high-complexity target characters in a multi-page narrative containing characters of varying complexity (3-16 strokes). Fixation durations and skipping rates were influenced by the visual complexity of both the target characters and the characters being searched even though participants had no knowledge of Chinese. In Experiment 2, native Chinese speakers performed the same character-search task, and a similar pattern of results was observed. Finally, in Experiment 3, a second sample of native Chinese speakers read the same text used in Experiments 1 and 2, with text characters again exhibiting complexity effects. These results collectively suggest that character-complexity effects on eye movements may not be due to lexical processing per se but may instead reflect whatever visual processing is required to know whether or not a character corresponds to an episodically represented target. The theoretical implications of this for our understanding of normal reading are discussed.

The categories, frequencies, and stability of idiosyncratic eye-movement patterns to faces

The spatial pattern of eye-movements to faces considered typical for neurologically healthy individuals is a roughly T-shaped distribution over the internal facial features with peak fixation density tending toward the left eye (observer's perspective). However, recent studies indicate that striking deviations from this classic pattern are common within the population and are highly stable over time. The classic pattern actually reflects the average of these various idiosyncratic eye-movement patterns across individuals. The natural categories and respective frequencies of different types of idiosyncratic eye-movement patterns have not been specifically investigated before, so here we analyzed the spatial patterns of eye-movements for 48 participants to estimate the frequency of different kinds of individual eye-movement patterns to faces in the normal healthy population. Four natural clusters were discovered such that approximately 25% of our participants' fixation density peaks clustered over the left eye region (observer's perspective), 23% over the right eye-region, 31% over the nasion/bridge region of the nose, and 20% over the region spanning the nose, philthrum, and upper lips. We did not find any relationship between particular idiosyncratic eye-movement patterns and recognition performance. Individuals' eye-movement patterns early in a trial were more stereotyped than later ones and idiosyncratic fixation patterns evolved with time into a trial. Finally, while face inversion strongly modulated eye-movement patterns, individual patterns did not become less distinct for inverted compared to upright faces. Group-averaged fixation patterns do not represent individual patterns well, so exploration of such individual patterns is of value for future studies of visual cognition.

Does Language Matter? Exploring Chinese-Korean Differences in Holistic Perception

Cross-cultural research suggests that East Asians display a holistic attentional bias by paying attention to the entire field and to relationships between objects, whereas Westerners pay attention primarily to salient objects, displaying an analytic attentional bias. The assumption of a universal pan-Asian holistic attentional bias has recently been challenged in experimental research involving Japanese and Chinese participants, which suggests that linguistic factors may contribute to the formation of East Asians' holistic attentional patterns. The present experimental research explores differences in attention and information processing styles between Korean and Chinese speakers, who have been assumed to display the same attentional bias due to cultural commonalities. We hypothesize that the specific structure of the Korean language predisposes speakers to pay more attention to ground information than to figure information, thus leading to a stronger holistic attentional bias compared to Chinese speakers. Findings of the present research comparing different groups of English, Chinese, and Korean speakers provide further evidence for differences in East Asians' holistic attentional bias, which may be due to the influence of language. Furthermore, we also extend prior theorizing by discussing the potential impact of other cultural factors. In line with critical voices calling for more research investigating differences between cultures that are assumed to be culturally similar, we highlight important avenues for future studies exploring the language-culture relationship.

Do Easterners and Westerners Differ in Visual Cognition? A Preregistered Examination of Three Visual Cognition Tasks

When performing cognitive tasks, Easterners often process information more holistically and contextually than Westerners. This is often taken as evidence for fundamental differences in basic cognition, including attention and perception. Yet, evidence for such basic cognitive differences is inconsistent, many studies are based on small samples, and few have been replicated. We report a preregistered replication of three prominent findings of cultural differences in visual cognition, testing a substantially larger sample than the original studies. Our comparisons of American and Asian International students living in the United States provided relatively little evidence for robust and consistent cultural differences in global/local biases, relative and absolute length judgments, or change detection performance. Although we observed some differences in change detection performance when comparing Chinese to American students, those differences were inconsistent across measures. We discuss the need for larger scale replications that adequately control for the testing context and demand characteristics.

When Does the Culturally Dominant Mode of Attention Appear or Disappear? Comparing Patterns of Eye Movement During the Visual Flicker Task Between European Canadians and Japanese

Previous findings in culture and attention reported mixed results. While some studies demonstrated systematic cultural variations in patterns of eye movement, other studies reported that the magnitude of the effects is minor. To further scrutinize when cultural variations in attention are attenuated or enhanced, we conducted a new series of visual flicker tasks while making changes in focal figures more salient than those in the background. European Canadian and Japanese participants searched for a change in a pair of quickly alternating still images. The task consisted of two parts: In the majority of trials, we set a change in part of either the focal object or the background (change trials), while in some trials, a pair of identical images was presented unbeknownst to participants (no-change trials), which resulted in forcing participants to search for a nonexistent change for 1 min. We then measured patterns of eye movement during each type of trial. The results of the change trials indicated that there were no cultural variations in change detection styles, nor were there cultural variations in eye movement patterns except for the total fixation duration, suggesting in general that both groups exhibited similar bottom-up patterns of attention. However, in the no-change trials, there were substantial cultural variations in eye movement patterns: European Canadians substantially attended to the focal figures longer and more frequently than to the backgrounds, whereas Japanese equally allocated their attention to both the focal figures and the backgrounds, suggesting that culturally unique top-down patterns were more evident.

Group-level differences in visual search asymmetry

East Asians and Westerners differ in various aspects of perception and cognition. For example, visual memory for East Asians is believed to be more influenced by the contextual aspects of a scene than is the case for Westerners (Masuda & Nisbett in Journal of Personality and Social Psychology, 81, 922-934, 2001). There are also differences in visual search: For Westerners, search is faster for a long line among short ones than for a short line among long ones, whereas this difference does not appear to hold for East Asians (Ueda et al., 2016). However, it is unclear how these group-level differences originate. To investigate the extent to which they depend upon environment, we tested visual search and visual memory in East Asian immigrants who had lived in Canada for different amounts of time. Recent immigrants were found to exhibit no search asymmetry, unlike Westerners who had spent their lives in Canada. However, immigrants who had lived in Canada for more than 2 years showed performance comparable to that of Westerners. These differences could not be explained by the general analytic/holistic processing distinction believed to differentiate Westerners and East Asians, since all observers showed a strong holistic tendency for visual recognition. The results instead support the suggestion that exposure to a new environment can significantly affect the particular processes used to perceive a given stimulus.

Differences in Sequential Eye Movement Behavior between Taiwanese and American Viewers

Knowledge of how information is sought in the visual world is useful for predicting and simulating human behavior. Taiwanese participants and American participants were instructed to judge the facial expression of a focal face that was flanked horizontally by other faces while their eye movements were monitored. The Taiwanese participants distributed their eye fixations more widely than American participants, started to look away from the focal face earlier than American participants, and spent a higher percentage of time looking at the flanking faces. Eye movement transition matrices also provided evidence that Taiwanese participants continually, and systematically shifted gaze between focal and flanking faces. Eye movement patterns were less systematic and less prevalent in American participants. This suggests that both cultures utilized different attention allocation strategies. The results highlight the importance of determining sequential eye movement statistics in cross-cultural research on the utilization of visual context.

The Influence of Content Meaningfulness on Eye Movements across Tasks: Evidence from Scene Viewing and Reading

The present study investigated the influence of content meaningfulness on eye-movement control in reading and scene viewing. Texts and scenes were manipulated to make them uninterpretable, and then eye-movements in reading and scene-viewing were compared to those in pseudo-reading and pseudo-scene viewing. Fixation durations and saccade amplitudes were greater for pseudo-stimuli. The effect of the removal of meaning was seen exclusively in the tail of the fixation duration distribution in both tasks, and the size of this effect was the same across tasks. These findings suggest that eye movements are controlled by a common mechanism in reading and scene viewing. They also indicate that not all eye movements are responsive to the meaningfulness of stimulus content. Implications for models of eye movement control are discussed.

Automatic Mechanisms for Social Attention Are Culturally Penetrable

Are mechanisms for social attention influenced by culture? Evidence that social attention is triggered automatically by bottom-up gaze cues and is uninfluenced by top-down verbal instructions may suggest it operates in the same way everywhere. Yet considerations from evolutionary and cultural psychology suggest that specific aspects of one's cultural background may have consequence for the way mechanisms for social attention develop and operate. In more interdependent cultures, the scope of social attention may be broader, focusing on more individuals and relations between those individuals. We administered a multi-gaze cueing task requiring participants to fixate a foreground face flanked by background faces and measured shifts in attention using eye tracking. For European Americans, gaze cueing did not depend on the direction of background gaze cues, suggesting foreground gaze alone drives automatic attention shifting; for East Asians, cueing patterns differed depending on whether the foreground cue matched or mismatched background cues, suggesting foreground and background gaze information were integrated. These results demonstrate that cultural background influences the social attention system by shifting it into a narrow or broad mode of operation and, importantly, provides evidence challenging the assumption that mechanisms underlying automatic social attention are necessarily rigid and impenetrable to culture.

Initial eye movements during face identification are optimal and similar across cultures

Culture influences not only human high-level cognitive processes but also low-level perceptual operations. Some perceptual operations, such as initial eye movements to faces, are critical for extraction of information supporting evolutionarily important tasks such as face identification. The extent of cultural effects on these crucial perceptual processes is unknown. Here, we report that the first gaze location for face identification was similar across East Asian and Western Caucasian cultural groups: Both fixated a featureless point between the eyes and the nose, with smaller between-group than within-group differences and with a small horizontal difference across cultures (8% of the interocular distance). We also show that individuals of both cultural groups initially fixated at a slightly higher point on Asian faces than on Caucasian faces. The initial fixations were found to be both fundamental in acquiring the majority of information for face identification and optimal, as accuracy deteriorated when observers held their gaze away from their preferred fixations. An ideal observer that integrated facial information with the human visual system's varying spatial resolution across the visual field showed a similar information distribution across faces of both races and predicted initial human fixations. The model consistently replicated the small vertical difference between human fixations to Asian and Caucasian faces but did not predict the small horizontal leftward bias of Caucasian observers. Together, the results suggest that initial eye movements during face identification may be driven by brain mechanisms aimed at maximizing accuracy, and less influenced by culture. The findings increase our understanding of the interplay between the brain's aims to optimally accomplish basic perceptual functions and to respond to sociocultural influences.

Head-Eye Coordination Increases with Age and Varies across Countries

Purpose

Head movements in older people may contribute to their dizziness and equilibrium problems. Head gain is the ratio of head movement to total movement (head + eye) when executing a saccade to an eccentric target. Two studies have investigated the relationship between head gain and age but have provided conflicting results.

Methods

We report head gain data collected from research laboratories and optician stores. Our sample sizes are much larger (n = 657 for laboratory, n = 64,458 for optician stores), permitting more detailed analyses.

Results

The head-eye coefficient, expressed as 100 times the square root of head gain, was bimodal with one mode of primarily eye movers and one mode of eye-and-head movers. Head-eye coefficient increased with age and was invariant with eye correction and gender. We also found an effect of nation that seemed associated with gross domestic product or by latitude (in the northern hemisphere) and log population density.

Discussion

Assuming that head movements and visual distortions contribute to dizziness and equilibrium problems, our study suggests that customizing eyewear based on age and country may help in reducing the prevalence of problems associated with head and/or eye movements.

The Effects of Interdependent and Independent Priming on Western Participants’ Ability to Perceive Changes in Visual Scenes

The current study examined whether priming interdependent relative to independent self-knowledge would induce different thinking styles among Western participants, and whether this would, in turn, affect the speed of detecting changes in a change-blindness task. Based on predictions from the semantic–procedural interface model, we predicted that participants would attend more to the context following an interdependent self-construal priming manipulation than following an independent self-construal priming manipulation. Sixty individuals were asked to circle the pronouns we/us/our or I/me/my in a paragraph of text. Following this, all participants were shown alternating images in a change-blindness task. Reaction times and accuracy rates at identifying focal and contextual changes were measured. Though our Western participants were faster at identifying changes in focal objects relative to contextual objects, this difference in reaction times was reduced in half for participants who were primed with interdependency (we/us/our pronoun circling) relative to independence (I/me/my pronoun circling). This result is consistent with the claim that interdependent and independent self-construals are stored in a semantic network which is connected to different procedural modes of thinking and that by priming these different views of the self, participants activate a mode of thinking that influences attention.

Eye tracker based study: Perception of faces with a cleft lip and nose deformity

AIM

Quantification of visual attention directed towards cleft stigmata and its impact on the perception of selected personality traits.

METHODS

Forty observers were divided into two groups and their visual scan paths were recorded. Both groups observed a series of photographs displaying full frontal views of the faces of 18 adult patients with clefts, nine with residual cleft stigmata and nine with digitally-corrected stigmata (each patient only appeared once per series). Patients that appeared with residual stigmata in one series appeared digitally corrected in the other series and vice versa. Visual fixation times on the upper lip and nose were compared between the original and corrected photographs. Observers subsequently rated personality traits as perceived using visual analogue scales and the same photographs that they had observed in the series.

RESULTS

In faces depicting cleft stigmata observers spent more time looking at the oronasal region of interest, followed by the eyes (39.6%; SD 5.0 and 35.1%; SD 3.6, respectively, p = 0.0198). Observers spent more time looking at the cleft lip compared with the corrected lip (21.2%; SD 4.0 and 16.7%; SD 5.0, respectively, p = 0.006). The differences between questionnaire scores for faces with cleft stigmata compared with faces with corrected stigmata for withdrawn-sociable, discontent-content, lazy-assiduous, unimaginative-creative, unlikeable-likeable, and the sum of individual personality traits were not significant.

CONCLUSION

According to these findings, cleft lip and cleft nose have an attention-drawing potential with the cleft lip being the major attention drawing factor. These data do not provide supportive evidence for the notion reported in literature that patients with clefts are perceived as having negative personality traits.

Culture Wires the Brain: A Cognitive Neuroscience Perspective

There is clear evidence that sustained experiences may affect both brain structure and function. Thus, it is quite reasonable to posit that sustained exposure to a set of cultural experiences and behavioral practices will affect neural structure and function. The burgeoning field of cultural psychology has often demonstrated the subtle differences in the way individuals process information-differences that appear to be a product of cultural experiences. We review evidence that the collectivistic and individualistic biases of East Asian and Western cultures, respectively, affect neural structure and function. We conclude that there is limited evidence that cultural experiences affect brain structure and considerably more evidence that neural function is affected by culture, particularly activations in ventral visual cortex-areas associated with perceptual processing.

Individual Differences in Newborn Visual Attention Associate with Temperament and Behavioral Difficulties in Later Childhood

Recently it was shown that individual differences in attention style in infants are associated with childhood effortful control, surgency, and hyperactivity-inattention. Here we investigated whether effortful control, surgency and behavioral problems in childhood can be predicted even earlier, from individual differences in newborns’ average duration of gaze to stimuli. Eighty newborns participated in visual preference and habituation studies. Parents completed questionnaires at follow up (mean age = 7.5 years, SD = 1.0 year). Newborns’ average dwell time was negatively associated with childhood surgency (β = −.25, R² = .04, p = .02) and total behavioral difficulties (β = −.28, R² = .05, p = .04) but not with effortful control (β = .03, R² = .001, p = .76). Individual differences in newborn visual attention significantly associated with individual variation in childhood surgency and behavioral problems, showing that some of the factors responsible for this variation are present at birth.

ICAT: a computational model for the adaptive control of fixation durations

Eye movements depend on cognitive processes related to visual information processing. Much has been learned about the spatial selection of fixation locations, while the principles governing the temporal control (fixation durations) are less clear. Here, we review current theories for the control of fixation durations in tasks like visual search, scanning, scene perception, and reading and propose a new model for the control of fixation durations. We distinguish two local principles from one global principle of control. First, an autonomous saccade timer initiates saccades after random time intervals (local-I). Second, foveal inhibition permits immediate prolongation of fixation durations by ongoing processing (local-II). Third, saccade timing is adaptive, so that the mean timer value depends on task requirements and fixation history (Global). We demonstrate by numerical simulations that our model qualitatively reproduces patterns of mean fixation durations and fixation duration distributions observed in typical experiments. When combined with assumptions of saccade target selection and oculomotor control, the model accounts for both temporal and spatial aspects of eye movement control in two versions of a visual search task. We conclude that the model provides a promising framework for the control of fixation durations in saccadic tasks.

Are individual differences in reading speed related to extrafoveal visual acuity and crowding?

Readers differ considerably in their speed of self-paced reading. One factor known to influence fixation durations in reading is the preprocessing of words in parafoveal vision. Here we investigated whether individual differences in reading speed or the amount of information extracted from upcoming words (the preview benefit) can be explained by basic differences in extrafoveal vision—i.e., the ability to recognize peripheral letters with or without the presence of flanking letters. Forty participants were given an adaptive test to determine their eccentricity thresholds for the identification of letters presented either in isolation (extrafoveal acuity) or flanked by other letters (crowded letter recognition). In a separate eye-tracking experiment, the same participants read lists of words from left to right, while the preview of the upcoming words was manipulated with the gaze-contingent moving window technique. Relationships between dependent measures were analyzed on the observational level and with linear mixed models. We obtained highly reliable estimates both for extrafoveal letter identification (acuity and crowding) and measures of reading speed (overall reading speed, size of preview benefit). Reading speed was higher in participants with larger uncrowded windows. However, the strength of this relationship was moderate and it was only observed if other sources of variance in reading speed (e.g., the occurrence of regressive saccades) were eliminated. Moreover, the size of the preview benefit—an important factor in normal reading—was larger in participants with better extrafoveal acuity. Together, these results indicate a significant albeit moderate contribution of extrafoveal vision to individual differences in reading speed.

Morphology of Primary Visual Cortex Predicts Individual Differences in Fixation Duration during Text Reading

In skilled reading, fixations are brief periods of time in which the eyes settle on words. E-Z Reader, a computational model of dynamic reading, posits that fixation durations are under real-time control of lexical processing. Lexical processing, in turn, requires efficient visual encoding. Here we tested the hypothesis that individual differences in fixation durations are related to individual differences in the efficiency of early visual encoding. To test this hypothesis, we recorded participants' eye movements during reading. We then examined individual differences in fixation duration distributions as a function of individual differences in the morphology of primary visual cortex measured from MRI scans. The results showed that greater gray matter surface area and volume in visual cortex predicted shorter and less variable fixation durations in reading. These results suggest that individual differences in eye movements during skilled reading are related to initial visual encoding, consistent with models such as E-Z Reader that emphasize lexical control over fixation time.

Cultural differences in sensitivity to the relationship between objects and contexts: evidence from P3

Cross-cultural differences in Easterners and Westerners have been observed in different cognitive domains. Differential sensitivity to the relationship between objects and contexts might be an underlying cognitive mechanism for these differences. Twenty-one Chinese and 22 Germans participated in a three-stimulus event-related potential oddball task. They were instructed to monitor geometrical forms filled in black (targets) that were presented among a series of blank geometrical forms (standards). Novel stimuli were colored images of common objects. Robust novelty P3 and target P3 over the entire scalp were observed in both groups. As compared with the German group, Chinese participants showed larger amplitudes of novelty P3 and target P3 over frontal regions and earlier peak latency for target P3. This indicates a higher sensitivity to the relationship between contexts and objects in the Chinese as compared with the German group, which might be an underlying mechanism for cross-cultural differences reported in many cognitive domains.

Faces in the eye of the beholder: unique and stable eye scanning patterns of individual observers

Eye scanning patterns while viewing pictures have provided valuable information in many domains of visual cognition. Such patterns are determined by the type of image viewed (e.g., faces, scenes) as well as the task individuals are asked to perform (e.g., visual search, memory). Here we show that another key factor that significantly influences eye scanning patterns but has been mostly overlooked is the individual observer. During face viewing, we found that individuals showed diverse scanning patterns that, in many cases, were inconsistent with the typical triangular shape pattern that is commonly observed when eye scanning patterns are averaged across individuals. These idiosyncratic eye scanning patterns were not random but highly stable even when examined 18 months later. Interestingly, these eye-tracking patterns were not predictive of behavioral performance. Such stable and unique scanning patterns may represent a specific behavioral trait/signature and be formed early in development, reflecting idiosyncratic strategies for performing visual recognition tasks.

Individual Differences in Infant Fixation Duration Relate to Attention and Behavioral Control in Childhood

Individual differences in fixation duration are considered a reliable measure of attentional control in adults. However, the degree to which individual differences in fixation duration in infancy (0–12 months) relate to temperament and behavior in childhood is largely unknown. In the present study, data were examined from 120 infants (mean age = 7.69 months, SD = 1.90) who previously participated in an eye-tracking study. At follow-up, parents completed age-appropriate questionnaires about their child’s temperament and behavior (mean age of children = 41.59 months, SD = 9.83). Mean fixation duration in infancy was positively associated with effortful control (β = 0.20, R2 = .02, p = .04) and negatively with surgency (β = −0.37, R2 = .07, p = .003) and hyperactivity-inattention (β = −0.35, R2 = .06, p = .005) in childhood. These findings suggest that individual differences in mean fixation duration in infancy are linked to attentional and behavioral control in childhood.

It depends on how you look at it: scanpath comparison in multiple dimensions with MultiMatch, a vector-based approach

Eye movement sequences-or scanpaths-vary depending on the stimulus characteristics and the task (Foulsham & Underwood Journal of Vision, 8(2), 6:1-17, 2008; Land, Mennie, & Rusted, Perception, 28, 1311-1328, 1999). Common methods for comparing scanpaths, however, are limited in their ability to capture both the spatial and temporal properties of which a scanpath consists. Here, we validated a new method for scanpath comparison based on geometric vectors, which compares scanpaths over multiple dimensions while retaining positional and sequential information (Jarodzka, Holmqvist, & Nyström, Symposium on Eye-Tracking Research and Applications (pp. 211-218), 2010). "MultiMatch" was tested in two experiments and pitted against ScanMatch (Cristino, Mathôt, Theeuwes, & Gilchrist, Behavior Research Methods, 42, 692-700, 2010), the most comprehensive adaptation of the popular Levenshtein method. In Experiment 1, we used synthetic data, demonstrating the greater sensitivity of MultiMatch to variations in spatial position. In Experiment 2, real eye movement recordings were taken from participants viewing sequences of dots, designed to elicit scanpath pairs with commonalities known to be problematic for algorithms (e.g., when one scanpath is shifted in locus or when fixations fall on either side of an AOI boundary). The results illustrate the advantages of a multidimensional approach, revealing how two scanpaths differ. For instance, if one scanpath is the reverse copy of another, the difference is in the direction but not the positions of fixations; or if a scanpath is scaled down, the difference is in the length of the saccadic vectors but not in the overall shape. As well as having enormous potential for any task in which consistency in eye movements is important (e.g., learning), MultiMatch is particularly relevant for "eye movements to nothing" in mental imagery and embodiment-of-cognition research, where satisfactory scanpath comparison algorithms are lacking.

Individuals exhibit idiosyncratic eye-movement behavior profiles across tasks

The purpose of this study was to examine individual differences in eye-movement behavior. Six metrics (Fixation Rate, Duration, and Size; Saccade Amplitude; Micro-Saccade Rate and Amplitude) were used to measure individuals' eye-movement behavior profiles (EmBP). We replicate previous research (Andrews & Coppola, 1999; Castelhano & Henderson, 2008) by finding consistent individual differences in fixation duration and saccade amplitude across tasks, and present new findings of stable idiosyncrasies in measures of fixational eye-movement (Fixation Size, Micro-Saccade Rate and Amplitude). Moreover, we observed consistent inter-metric correlations across tasks (e.g., individuals that exhibited relatively high Fixation Rates also presented relative low Micro-Saccade Rates and relatively high Micro-Saccade Amplitudes). Factor Analysis linked the six EmBP metrics together with a single factor, which we speculate might be related to the operational effectiveness of the attentional system, given that individual factor scores were correlated with scores on a self-report measure of attentional function. Normal subjects with relatively high scores on this attention-deficit measure exhibited relatively frequent fixations of short duration and large spatial extent, and relatively infrequent micro-saccades of large amplitude. This EmBP is similar to a general pattern of eye-movement behavior observed with ADHD individuals - difficulty controlling eye movements, maintaining fixation, and inhibiting intrusive saccades. Results of this study indicate that normal individuals exhibit idiosyncratic EmBPs that are quite stable across tasks and are related to attentional ability.

Culture, perception, and artistic visualization: a comparative study of children's drawings in three Siberian cultural groups

In a study of three indigenous and non-indigenous cultural groups in northwestern and northeastern Siberia, framed line tests and a landscape drawing task were used to examine the hypotheses that test-based assessments of context sensitivity and independence are correlated with the amount of contextual information contained in drawings, and with the order in which the focal and background objects are drawn. The results supported these hypotheses, and inspection of the regression relationships suggested that the intergroup variations in test performance were likely to result from differences in the attention accorded to contextual information, as revealed by the drawings. Social and environmental explanations for the group differences in context sensitivity are also discussed. The conclusions support the argument that cultural differences in artistic styles and perceptual tests reflect the same underlying perceptual tendencies, and they are consistent with the argument that these tendencies reflect corresponding differences in patterns of social and environmental interaction.

Individual differences in eye movements during face identification reflect observer-specific optimal points of fixation

In general, humans tend to first look just below the eyes when identifying another person. Does everybody look at the same place on a face during identification, and, if not, does this variability in fixation behavior lead to functional consequences? In two conditions, observers had their free eye movements recorded while they performed a face-identification task. In another condition, the same observers identified faces while their gaze was restricted to specific locations on each face. We found substantial differences, which persisted over time, in where individuals chose to first move their eyes. Observers' systematic departure from a canonical, theoretically optimal fixation point did not correlate with performance degradation. Instead, each individual's looking preference corresponded to an idiosyncratic performance-maximizing point of fixation: Those who looked lower on the face performed better when forced to fixate the lower part of the face. The results suggest an observer-specific synergy between the face-recognition and eye movement systems that optimizes face-identification performance.

Cultural influences on oculomotor inhibition of remote distractors: evidence from saccade trajectories

This study investigated whether low-level attentional processes as indicated by saccade trajectories are modulated by higher-order factors as indicated by participants' cultural background. We hypothesized that if the East Asian participants engage in context-dependent attentional processing to a greater extent than the Western participants, then the magnitude of the distractor effect on saccade trajectories (Doyle & Walker, 2001) should be larger with the East Asian participants than with the Western participants. Participants executed vertical saccades towards targets presented on the vertical meridian above or below fixation. Simultaneously with the target, a distractor appeared in one of the screen quadrants. Consistently with our hypothesis, we found evidence that the saccades of the Chinese participants tended to curve away from the distractors more strongly than the saccades of the German participants. However, this effect was restricted to the upper distractors and the lower targets. The findings are discussed in terms of cross-cultural differences in distractor-related activation and inhibition and functional specialization of hemifields.