Longer Saccades Research Articles

Analysis of Eye Movements Reveals Longer Visual Saccades and Abnormal Preference for Social Images in Autism Spectrum Disorder: Longer Saccades and Fewer Fixations on Social Stimuli in Autism

Analysis of Eye Movements Reveals Longer Visual Saccades and Abnormal Preference for Social Images in Autism Spectrum Disorder: Longer Saccades and Fewer Fixations on Social Stimuli in Autism

Changes in oculo‐motor activity during a cognitive challenge can distinguish clinical stages of early Alzheimer’s disease

AbstractBackgroundThe eye adapts to the demands of our behavior [1], its motor activity has proven to be a feasible method for measuring cognition in both health and disease [2]. This study assessed the sensitivity of oculo‐motor features in a benign cognitive challenge model with the purpose of identifying objective efficacy readouts for clinical drug trials in early Alzheimer’s disease (AD).MethodFifty participants, aged 60 to 80 years, performed a reading task in two sessions conducted the same day, morning and evening (i.e. the “cognitive challenge”), with an average inter‐session period of 9.28h, during which participants were not allowed to take naps or consume stimulating beverages. Participants were distributed across four cohorts corresponding to progressive stages of early AD [3]: 1) amyloid negative, cognitively healthy (control group), 2) amyloid positive pre‐symptomatic AD, 3) Mild Cognitive Impairment (MCI) due to AD (pre‐dementia group) and 4) mild AD (mild‐dementia group). ViewMind technology was used to track the oculo‐motor activity [4].ResultNone of the four cohorts reported increased levels of sleepiness during the challenge. However, cohorts showed significantly different oculo‐motor responses during the cognitive challenge (Table 1). The control group showed evidence of learning effects on the reading during the challenge reflected in no change in pupil size, longer saccades, less fixations and shorter gaze. Within the pre‐symptomatic group, however, a negative impact of the challenge was observed in a decrease in pupil size and increase in fixations. However, some learning effects were nevertheless seen in this cohort, in shorter gaze and longer saccades. In pre‐dementia group the learning effects were lost and participants demonstrated difficulty performing the task reflected in decreased pupil size and longer gaze. Finally, the mild‐AD participants showed an increase in fixations, longer gaze and no change in pupil size indicating a pattern of poor reading performance during the challenge.ConclusionOur preliminary results demonstrate that oculo‐motor activity may reflect changes in cognitive resources induced by a benign challenge in progressive clinical stages of early AD. These promising results support continued investigation into the potential of eye‐tracking during reading as a sensitive and objective measure .

Titles and Semantic Violations Affect Eye Movements When Viewing Contemporary Paintings

The role of titles in perception of visual art is a topic of interesting discussions that brings together artists, curators, and researchers. Titles provide contextual cues and guide perception. They can be particularly useful when paintings include semantic violations that make them challenging for viewers, especially viewers lacking expert knowledge. The aim of this study is to investigate the effects of titles and semantic violations on eye movements. A total of 127 participants without expertise in visual art viewed 40 paintings with and without semantic violations (20 each) in one of three conditions: untitled, consistent titles and inconsistent titles. After each painting was viewed participants also rated liking and understanding. Our results suggest that titles affect the way paintings are viewed: both titled conditions were associated with shorter first fixation duration, longer saccade durations, and amplitudes and higher dynamic entropy than the untitled conditions. Titles were fixated on more frequently (but only in the time window between 1,200 and 2,800 ms) when presented alongside paintings with semantic violations than paintings without violations, and the percentage of fixations to titles was particularly high in the case of paintings with double inconsistencies (inconsistent titles and semantic violations). Also, we found that semantic violations attracted attention early on (300–900 ms), whereas titles received attention later (average first fixation on title was at 936.28 ms) and inconsistencies in titles were processed even later (after 4,000 ms). Finally, semantic violations were associated with higher dynamic entropy than paintings without violations. Our results demonstrate the importance of titles for processing of artworks, especially artworks that present a challenge for the viewers.

How do older drivers perceive visual information under increasing cognitive load? Significance of personality on-road safety

The ability to properly receive information and respond to stimuli is a prerequisite for road safety. The aim of this study was to determine the changes in oculomotor activity under conditions of increasing cognitive load depending on personality traits in older drivers (65 years and above). We assessed 44 male active drivers (M = 69, SD = 8.1) in a road traffic simulator in the dual-task paradigm: n-back reaction test (central task) and memory test (peripheral task). During the test in the simulator, oculomotor activity was recorded. Drivers’ personality traits were determined using the EPQ-R questionnaire. With the increase of cognitive load in drivers with high levels of neuroticism and extraversion, the time of saccades and fixation significantly increased. The decrease in the effectiveness of visual attention shifting in older drivers intensified as the difficulty of performing tasks increased and manifested itself in longer saccade and fixation times. A higher level of neuroticism and the resulting stress and emotional tension can translate into a greater tendency to make mistakes in older drivers.

The Contribution of Oculomotor Functions to Rates of Visual Information Processing in Younger and Older Adults

Oculomotor functions are established surrogate measures of visual attention shifting and rate of information processing, however, the temporal characteristics of saccades and fixations have seldom been compared in healthy educated samples of younger and older adults. Thus, the current study aimed to compare duration of eye movement components in younger (18–25 years) and older (50–81 years) adults during text reading and during object/alphanumeric Rapid Automatic Naming (RAN) tasks. The current study also aimed to examine the contribution of oculomotor functions to threshold time needed for accurate performance on visually-driven cognitive tasks (Inspection Time [IT] and Change Detection [CD]). Results showed that younger adults fixated on individual stimuli for significantly longer than the older participants, while older adults demonstrated significantly longer saccade durations than the younger group. Results also demonstrated that older adults required longer threshold durations (i.e., performed slower) on the visually-driven cognitive tasks, however, the age-group time difference on the CD task was eradicated when the effects of saccade duration were covaried. Thus, these results suggest that age-related cognitive decline is also related to increased duration of saccades and hence, highlights the need to dissociate the age-related motor constraints on the temporal aspects of oculomotor function from visuo-cognitive speed of processing.

Examining the effects of passive and active strategies on behavior during hybrid visual memory search: evidence from eye tracking

Hybrid search requires observers to search both through a visual display and through the contents of memory in order to find designated target items. Because professional hybrid searchers such as airport baggage screeners are required to look for many items simultaneously, it is important to explore any potential strategies that may beneficially impact performance during these societally important tasks. The aim of the current study was to investigate the role that cognitive strategies play in facilitating hybrid search. We hypothesized that observers in a hybrid search task would naturally adopt a strategy in which they remained somewhat passive, allowing targets to “pop out.” Alternatively, we considered the possibility that observers could adopt a strategy in which they more actively directed their attention around the visual display. In experiment 1, we compared behavioral responses during uninstructed, passive, and active hybrid search. We found that uninstructed search tended to be more active in nature, but that adopting a passive strategy led to above average performance as indicated by a combined measure of speed and accuracy called a balanced integration score (BIS). We replicated these findings in experiment 2. Additionally, we found that oculomotor behavior in passive hybrid search was characterized by longer saccades, improved attentional guidance, and an improved ability to identify items as targets or distractors (relative to active hybrid search). These results have implications for understanding hybrid visual search and the effect that strategy use has on performance and oculomotor behavior during this common, and at times societally important, task.

Behavioral and Physiological Responses to Visual Interest and Appraisals: Multimodal Analysis and Automatic Recognition

Interest drives our focus of attention and plays an important role in social communication. Given its relevance for many activities (e.g., learning, entertainment) a system able to automatically detect someone's interest has several potential applications. In this paper, we analyze the physiological and behavioral patterns associated with visual interest and present a method for the automatic recognition of interest, curiosity and their most relevant appraisals, namely, coping potential, novelty and complexity. We conducted an experiment in which participants watched images and micro-videos while multimodal signals were recorded - facial expressions, galvanic skin response (GSR), and eye gaze. After watching each stimulus, participants self-reported their level of interest, curiosity, coping potential, perceived novelty, and complexity. Results showed that interest was associated with other facial Action Units than smiling when dynamics was taken into consideration, especially inner brow raiser and eye lid tightener. Longer saccades were also present when participants watched interesting stimuli. However, correlations of appraisals with specific facial Action Units and eye gaze were in general stronger than those we found for interest. We trained random forests regression models to detect the level of interest, curiosity, and appraisals from multimodal features. The recognition models - unimodal and multimodal - for appraisals generally outperformed those for interest, in particular for static images. In summary, our study suggests that automatic appraisal detection may be a suitable way to detect subtle emotions like interest for which prototypical expressions do not exist.

The “risky” reading strategy revisited: New simulations using E-Z Reader

Eye-movement studies have demonstrated that, relative to college-aged readers, older readers of alphabetic languages like English and German tend to read more slowly, making more frequent and longer fixations and longer saccades, and skipping more words, but also making more frequent regressions. These findings have led to suggestions that older readers either adopt a "risky" strategy of using context to "guess" words as a way of compensating for slower rates of lexical processing, or have a smaller and more asymmetrical perceptual span. Unfortunately, neither of these hypotheses seemingly explains more recent observations that older readers of Chinese seem to adopt a more "conservative" strategy, making shorter saccades and skipping less often. In this paper, we use the E-Z Reader model of eye-movement control to examine several possible accounts of the differences between college-aged and older readers of both alphabetic and non-alphabetic languages. These simulations re-confirm that the "risky" strategy may be sufficient to explain age-related differences in reader's eye movements, with older readers of English versus Chinese being, respectively, more versus less inclined to guess upcoming words. The implications of these results for aging, reading, and models of eye-movement control are discussed.

Comparative eye-tracking evaluation of scatterplots and parallel coordinates

We investigate task performance and reading characteristics for scatterplots (Cartesian coordinates) and parallel coordinates. In a controlled eye-tracking study, we asked 24 participants to assess the relative distance of points in multidimensional space, depending on the diagram type (parallel coordinates or a horizontal collection of scatterplots), the number of data dimensions (2, 4, 6, or 8), and the relative distance between points (15%, 20%, or 25%). For a given reference point and two target points, we instructed participants to choose the target point that was closer to the reference point in multidimensional space. We present a visual scanning model that describes different strategies to solve this retrieval task for both diagram types, and propose corresponding hypotheses that we test using task completion time, accuracy, and gaze positions as dependent variables. Our results show that scatterplots outperform parallel coordinates significantly in 2 dimensions, however, the task was solved more quickly and more accurately with parallel coordinates in 8 dimensions. The eye-tracking data further shows significant differences between Cartesian and parallel coordinates, as well as between different numbers of dimensions. For parallel coordinates, there is a clear trend toward shorter fixations and longer saccades with increasing number of dimensions. Using an area-of-interest (AOI) based approach, we identify different reading strategies for each diagram type: For parallel coordinates, the participants’ gaze frequently jumped back and forth between pairs of axes, while axes were rarely focused on when viewing Cartesian coordinates. We further found that participants’ attention is biased: toward the center of the whole plotfor parallel coordinates and skewed to the center/left side for Cartesian coordinates. We anticipate that these results may support the design of more effective visualizations for multidimensional data.

The effect of word frequency and parafoveal preview on saccade length during the reading of Chinese.

There are currently 2 theoretical accounts of how readers of Chinese select their saccade targets: (a) by moving their eyes to specific saccade targets (i.e., the default-targeting hypothesis) and (b) by adjusting their saccade lengths to accommodate lexical processing (i.e., the dynamic-adjustment hypothesis). In this article, we first report the results of an eye-movement experiment using a gaze-contingent boundary paradigm. This experiment demonstrates that both target-word frequency and its preview validity modulate the lengths of the saccades entering and exiting the target words, with longer saccades to/from high-frequency words when their preview was available. We then report the results of 2 simulations using computational models that instantiate the core theoretical assumptions of the default-targeting and dynamic-adjustment hypotheses. Comparisons of these simulations indicate that the dynamic-adjustment hypothesis provides a better quantitative account of the data from our experiment using fewer free parameters. We conclude by discussing evidence for dynamic saccade adjustment during the reading of alphabetic languages, and why such a heuristic may be necessary to fully explain eye-movement control during the reading of both alphabetic and nonalphabetic languages. (PsycINFO Database Record

Eye movements reveal distinct encoding patterns for number and cumulative surface area in random dot arrays.

Humans can quickly and intuitively represent the number of objects in a scene using visual evidence through the Approximate Number System (ANS). But the computations that support the encoding of visual number-the transformation from the retinal input into ANS representations-remain controversial. Two types of number encoding theories have been proposed: those arguing that number is encoded through a dedicated, enumeration computation, and those arguing that visual number is inferred from nonnumber specific visual features, such as surface area, density, convex hull, etc. Here, we attempt to adjudicate between these two theories by testing participants on both a number and a cumulative area task while also tracking their eye-movements. We hypothesize that if approximate number and surface area depend on distinct encoding computations, saccadic signatures should be distinct for the two tasks, even if the visual stimuli are identical. Consistent with this hypothesis, we find that discriminating number versus cumulative area modulates both where participants look (i.e., participants spend more time looking at the more numerous set in the number task and the larger set in the cumulative area task), and how participants look (i.e., cumulative area encoding shows fewer, longer saccades, while number encoding shows many short saccades and many switches between targets). We further identify several saccadic signatures that are associated with task difficulty and correct versus incorrect trials for both dimensions. These results suggest distinct encoding algorithms for number and cumulative area extraction, and thereby distinct representations of these dimensions.

Human occipital cortices differentially exert saccadic suppression: Intracranial recording in children

By repeating saccades unconsciously, humans explore the surrounding world every day. Saccades inevitably move external visual images across the retina at high velocity; nonetheless, healthy humans don't perceive transient blurring of the visual scene during saccades. This perceptual stability is referred to as saccadic suppression. Functional suppression is believed to take place transiently in the visual systems, but it remains unknown how commonly or differentially the human occipital lobe activities are suppressed at the large-scale cortical network level. We determined the spatial–temporal dynamics of intracranially-recorded gamma activity at 80–150Hz around spontaneous saccades under no-task conditions during wakefulness and those in darkness during REM sleep. Regardless of wakefulness or REM sleep, a small degree of attenuation of gamma activity was noted in the occipital regions during saccades, most extensively in the polar and least in the medial portions. Longer saccades were associated with more intense gamma-attenuation. Gamma-attenuation was subsequently followed by gamma-augmentation most extensively involving the medial and least involving the polar occipital region. Such gamma-augmentation was more intense during wakefulness and temporally locked to the offset of saccades. The polarities of initial peaks of perisaccadic event-related potentials (ERPs) were frequently positive in the medial and negative in the polar occipital regions. The present study, for the first time, provided the electrophysiological evidence that human occipital cortices differentially exert perisaccadic modulation. Transiently suppressed sensitivity of the primary visual cortex in the polar region may be an important neural basis for saccadic suppression. Presence of occipital gamma-attenuation even during REM sleep suggests that saccadic suppression might be exerted even without external visual inputs. The primary visual cortex in the medial region, compared to the polar region, may be more sensitive to an upcoming visual scene provided at the offset of each saccade.

Expertise Differences in the Comprehension of Visualizations: a Meta-Analysis of Eye-Tracking Research in Professional Domains

This meta-analysis integrates 296 effect sizes reported in eye-tracking research on expertise differences in the comprehension of visualizations. Three theories were evaluated: Ericsson and Kintsch’s (Psychol Rev 102:211–245, 1995) theory of long-term working memory, Haider and Frensch’s (J Exp Psychol Learn Mem Cognit 25:172–190, 1999) information-reduction hypothesis, and the holistic model of image perception of Kundel et al. (Radiology 242:396–402, 2007). Eye movement and performance data were cumulated from 819 experts, 187 intermediates, and 893 novices. In support of the evaluated theories, experts, when compared with non-experts, had shorter fixation durations, more fixations on task-relevant areas, and fewer fixations on task-redundant areas; experts also had longer saccades and shorter times to first fixate relevant information, owing to superiority in parafoveal processing and selective attention allocation. Eye movements, reaction time, and performance accuracy were moderated by characteristics of visualization (dynamics, realism, dimensionality, modality, and text annotation), task (complexity, time-on-task, and task control), and domain (sports, medicine, transportation, other). These findings are discussed in terms of their implications for theories of visual expertise in professional domains and their significance for the design of learning environments.

Scrambled eyes? Disrupting scene structure impedes focal processing and increases bottom-up guidance

Previous research has demonstrated that search and memory for items within natural scenes can be disrupted by "scrambling" the images. In the present study, we asked how disrupting the structure of a scene through scrambling might affect the control of eye fixations in either a search task (Experiment 1) or a memory task (Experiment 2). We found that the search decrement in scrambled scenes was associated with poorer guidance of the eyes to the target. Across both tasks, scrambling led to shorter fixations and longer saccades, and more distributed, less selective overt attention, perhaps corresponding to an ambient mode of processing. These results confirm that scene structure has widespread effects on the guidance of eye movements in scenes. Furthermore, the results demonstrate the trade-off between scene structure and visual saliency, with saliency having more of an effect on eye guidance in scrambled scenes.

Cerebral hemispheric specialization for spatial attention: spatial distribution of search-related eye fixations in the absence of neglect

The “specialization” of the right hemisphere for spatial attention is widely accepted but poorly understood. While several theories have been supported by studies of patients with acute hemispatial neglect, generalizability beyond this population remains unclear. In this study, we compared the predictions of two attention models [Brain 119 (1996) 841; Trans. Am. Neurol. Assoc. 95 (1970) 143] when applied to data obtained from subjects with unilateral right- or left-cerebral lesions, but without clinical evidence of neglect during a visual search task. Both Left Lesion and Right Lesion subjects detected fewer targets in the contralesional hemispace. However, the Right Lesion subjects also made fewer visual fixations and longer saccades in the contralesional hemispace, suggesting a fundamental alteration in the architecture of visual search. The spatial distribution of fixations made by Right Lesion subjects more closely fits the prediction of a “salience” model than of the strict interpretation of a linear “gradient” model. These data support the long-standing notion of right hemisphere dominance for spatial attention, especially for the top–down processes entailed in self-directed visual search, and extend this to lesion patients without clinically evident neglect. A theoretical model based on the salience of extrapersonal space appears useful for understanding alterations of attentional allocation, particularly after recovery from stroke.

Evidence for cortical coding of saccade velocity in memory-guided saccades in patients with CADASIL

Saccadic eye movements were elicited in ten patients with CADASIL (an autosomal dominant cerebral angiopathy) and ten age-matched controls under six different conditions: 1) the gap paradigm, which tests visually guided, reflexive saccades; 2) the overlap paradigm; 3 and 4) the anti-gap and anti-overlap paradigms, which are thought to test especially the function of the frontal cortex; 5) the memory paradigm, which tests internally guided, intentional saccades; and 6) the sequential memory-guided saccades. Eye movements were recorded by means of DC electro-oculography, and the saccade latency, gain, duration, and peak eye velocity were estimated. The amplitude-to-duration as well as the amplitude-to-peak velocity ratios were calculated for both groups and conditions 1 and 5. There were no significant differences in the gains of the primary saccades in the gap, overlap, and memory paradigms. In general, the CADASIL patients showed a tendency toward longer saccade latencies and a larger number of unwanted saccades in the antitask saccade and memory saccade paradigms (suppression errors). Our main finding was that the patients had a highly significant reduction in peak velocity and a corresponding prolongation of the duration of the memory-guided saccades compared to the controls. In contrast, the duration and the peak velocity of the visually guided saccades did not differ between controls and patients. Thus, we observed a specific change in the dynamic properties of memory-guided saccades in CADASIL patients. The observed pattern of saccade abnormalities in the CADASIL patients does not allow localization to a specific cortical side; however, it might reflect the presence of a mostly frontal type of lesion. This finding contradicts the view that information passed from the cortex to the brainstem codes only the saccade vector and not saccade dynamics.

Word frequency effects and eye movements during two readings of a text.

The present study examined the influence of word frequency on rereading performance. Subjects read short passages, each twice in succession, while their eye movements were monitored. During first presentations, each passage contained a target word of low or high frequency; during second presentations, the targets were either repeated or replaced by synonyms. In general, during the second readings readers made shorter duration fixations, fewer fixations, and longer saccades. When fixation times on the target words were examined, results showed that fixation durations were shorter for high frequency words during both readings and that the decrease in fixation duration was similar in magnitude for low and high frequency words. This suggests that word frequency and repetition independently influenced reading time. In addition, replacing a target with a synonym did not increase processing time for the replacement word. This suggests that conceptual repetition was sufficient for obtaining repetition effects when reading text.