Visual Search Patterns Research Articles

Tracking eye gaze during interpretation of endoluminal three-dimensional CT colonography: visual perception of experienced and inexperienced readers.

To identify and compare key stages of the visual process in experienced and inexperienced readers and to examine how these processes are used to search a moving three-dimensional ( 3D three-dimensional ) image and their relationship to false-negative errors. Institutional review board research ethics approval was granted to use anonymized computed tomographic (CT) colonographic data from previous studies and to obtain eye-tracking data from volunteers. Sixty-five radiologists (27 experienced, 38 inexperienced) interpreted 23 endoluminal 3D three-dimensional CT colonographic videos. Eye movements were recorded by using eye tracking with a desk-mounted tracker. Readers indicated when they saw a polyp by clicking a computer mouse. Polyp location and boundary on each video frame were quantified and gaze data were related to the polyp boundary for each individual reader and case. Predefined metrics were quantified and used to describe and compare visual search patterns between experienced and inexperienced readers by using multilevel modeling. Time to first pursuit was significantly shorter in experienced readers (hazard ratio, 1.22 [95% confidence interval: 1.04, 1.44]; P = .017) but other metrics were not significantly different. Regardless of expertise, metrics such as assessment, identification period, and pursuit times were extended in videos where polyps were visible on screen for longer periods of time. In 97% (760 of 787) of observations, readers correctly pursued polyps. Experienced readers had shorter time to first eye pursuit, but many other characteristics of eye tracking were similar between experienced and inexperienced readers. Readers pursued polyps in 97% of observations, which indicated that errors during interpretation of 3D three-dimensional CT colonography in this study occurred in either the discovery or the recognition phase, but rarely in the scanning phase of radiologic image inspection.

Understanding visual search patterns of dermatologists assessing pigmented skin lesions before and after online training.

The goal of this investigation was to explore the feasibility of characterizing the visual search characteristics of dermatologists evaluating images corresponding to single pigmented skin lesions (PSLs) (close-ups and dermoscopy) as a venue to improve training programs for dermoscopy. Two Board-certified dermatologists and two dermatology residents participated in a phased study. In phase I, they viewed a series of 20 PSL cases ranging from benign nevi to melanoma. The close-up and dermoscopy images of the PSL were evaluated sequentially and rated individually as benign or malignant, while eye position was recorded. Subsequently, the participating subjects completed an online dermoscopy training module that included a pre- and post-test assessing their dermoscopy skills (phase 2). Three months later, the subjects repeated their assessment on the 20 PSLs presented during phase I of the study. Significant differences in viewing time and eye-position parameters were observed as a function of level of expertise. Dermatologists overall have more efficient search than residents generating fewer fixations with shorter dwells. Fixations and dwells associated with decisions changing from benign to malignant or vice versa from photo to dermatoscopic viewing were longer than any other decision, indicating increased visual processing for those decisions. These differences in visual search may have implications for developing tools to teach dermatologists and residents about how to better utilize dermoscopy in clinical practice.

Gaze and visual search strategies of children with Asperger syndrome/high functioning autism viewing a magic trick

Objective: To examine visual search patterns and strategies used by children with and without Asperger syndrome/high functioning autism (AS/HFA) while watching a magic trick. Limited responsivity to gaze cues is hypothesised to contribute to social deficits in children with AS/HFA. Methods: Twenty-one children with AS/HFA and 31 matched peers viewed a video of a gaze-cued magic trick twice. Between the viewings, they were informed about how the trick was performed. Participants’ eye movements were recorded using a head-mounted eye-tracker. Results: Children with AS/HFA looked less frequently and had shorter fixation on the magician’s direct and averted gazes during both viewings and more frequently at not gaze-cued objects and on areas outside the magician’s face. After being informed of how the trick was conducted, both groups made fewer fixations on gaze-cued objects and direct gaze. Conclusions: Information may enhance effective visual strategies in children with and without AS/HFA.

Towards a framework for analysis of eye-tracking studies in the three dimensional environment: a study of visual search by experienced readers of endoluminal CT colonography

Eye tracking in three dimensions is novel, but established descriptors derived from two-dimensional (2D) studies are not transferable. We aimed to develop metrics suitable for statistical comparison of eye-tracking data obtained from readers of three-dimensional (3D) "virtual" medical imaging, using CT colonography (CTC) as a typical example. Ten experienced radiologists were eye tracked while observing eight 3D endoluminal CTC videos. Subsequently, we developed metrics that described their visual search patterns based on concepts derived from 2D gaze studies. Statistical methods were developed to allow analysis of the metrics. Eye tracking was possible for all readers. Visual dwell on the moving region of interest (ROI) was defined as pursuit of the moving object across multiple frames. Using this concept of pursuit, five categories of metrics were defined that allowed characterization of reader gaze behaviour. These were time to first pursuit, identification and assessment time, pursuit duration, ROI size and pursuit frequency. Additional subcategories allowed us to further characterize visual search between readers in the test population. We propose metrics for the characterization of visual search of 3D moving medical images. These metrics can be used to compare readers' visual search patterns and provide a reproducible framework for the analysis of gaze tracking in the 3D environment. This article describes a novel set of metrics that can be used to describe gaze behaviour when eye tracking readers during interpretation of 3D medical images. These metrics build on those established for 2D eye tracking and are applicable to increasingly common 3D medical image displays.

Telling people where to look in a soccer-based decision task: A nomothetic approach

Research has shown that identifiable visual search patterns characterize skilled performance of anticipation and decision-making tasks in sport. However, to date, the use of experts’ gaze patterns to entrain novices’ performance has been confined to aiming activities. Accordingly, in a first experiment, 40 participants of varying soccer experience viewed static images of oncoming soccer players and attempted to predict the direction in which those players were about to move. Multiple regression analyses showed that the sole predictor of decision-making efficiency was the time taken to initiate a saccade to the ball. In a follow-up experiment, soccer novices undertook the same task as in Experiment 1. Two experimental groups were instructed to either look at the ball, or the player’s head, as quickly as possible; a control group received no instructions. The experimental groups were fastest to make a saccade to the ball or head, respectively, but decision-making efficiency was equivalent across all three groups. The fallibility of a nomothetic approach to training eye movements is discussed.

Horizontal visual search in a large field by patients with unilateral spatial neglect

In this study, we investigated the horizontal visual search ability and pattern of horizontal visual search in a large space performed by patients with unilateral spatial neglect (USN). Subjects included nine patients with right hemisphere damage caused by cerebrovascular disease showing left USN, nine patients with right hemisphere damage but no USN, and six healthy individuals with no history of brain damage who were age-matched to the groups with brain right hemisphere damage. The number of visual search tasks accomplished was recorded in the first experiment. Neck rotation angle was continuously measured during the task and quantitative data of the measurements were collected. There was a strong correlation between the number of visual search tasks accomplished and the total Behavioral Inattention Test Conventional Subtest (BITC) score in subjects with right hemisphere damage. In both USN and control groups, the head position during the visual search task showed a balanced bell-shaped distribution from the central point on the field to the left and right sides. Our results indicate that compensatory strategies, including cervical rotation, may improve visual search capability and achieve balance on the neglected side.

Can reputation biases influence the outcome and process of making competence judgments of a coach?

The present studies explored the effect of reputational biases on judgments made of coach competence and the visual search patterns adopted by individuals when generating initial impressions and expectations of a target. In study 1, participants (n = 326) observed footage of two coaches prior to making competence judgments of them. All participants viewed similar footage for the first coach (control) but reputational information was manipulated for the second coach (target). In study 2, participants (n = 22) followed the same procedure as study 1 but also wore a head-mounted eye-tracking system to enable visual search data to be collected. Study 1 broadly reported coaches with a "professional" reputation to be judged as being significantly more competent across varying competence measures compared to coaches with either an "in-training" reputation or "no reputation." Study 2 indicated limited differences across the reputational conditions in relation to visual fixations. The data indicate that expectations of coach competence can be influenced, and largely controlled, by the reputational information provided to athletes. While there were limited differences in visual search strategies across reputation conditions, suggestions for research are made to enable a fuller insight to the interpersonal interactions that may facilitate the working association between athletes and coaches.

Gaze behaviors and decision making accuracy of higher- and lower-level ice hockey referees

BackgroundGaze behaviors are often studied in athletes, but infrequently for sport officials. There is a need to better understand gaze behavior in refereeing in order to improve training and education related to visual search patterns, which have been argued to be related to decision making (Abernethy & Russell, 1987a). ObjectiveTo examine gaze behaviors, decision accuracy, and decision sensitivity (using signal detection analysis) of ice hockey referees of varying skill levels in a laboratory setting. DesignUsing an experimental design, we conducted multiple t-tests. MethodHigher-level (N = 15) and lower-level ice hockey referees (N = 15) wore a head-mounted eye movement recorder and made penalty/no penalty decisions related to ice hockey video clips on a computer screen. We recorded gaze behaviors, decision accuracy, and decision sensitivity for each participant. ResultsResults of the t-tests indicated no group differences in gaze behaviors; however, higher-level referees made significantly more accurate decisions (both accuracy and sensitivity) than lower-level referees. ConclusionHigher-level ice hockey referees are superior to lower-level referees on decision making, but referees do not differ on gaze behaviors. Possibly, higher-level referees process relevant decision making information more effectively.

Contralesional cross-over in chronic neglect: Visual search patterns reveal neglect of the ipsilesional hemispace

With neuropsychological rehabilitation approaches neglect patients can learn to compensate for the reduced awareness of the contralesional hemispace that is often observed after right brain damage. Here, we report contralesional "cross-over" deviations in line bisection that are hypothesized to be a result of focusing on the contralesional hemispace while the intact hemispace is "neglected". We investigate whether this unexpected pattern of deviation is related to defects in the visual field, motor intention/hypokinesia deficits or deficits in working memory. Neglect patients with and without homonymous field defects were screened for contralesional cross-over deviations in line bisection of long lines. During line bisection eye movements were recorded in two conditions with and without requiring hand movements in order to search for directional hypokinesia. Visual fields were tested with near-threshold perimetry and with supra-threshold campimetry. Of 53 chronic neglect patients only 8 showed cross-over in line bisection. Evidence for directional hypokinesia was found in only one patient. Patients with cross-over focused more often to the left than to the right of the objective line midpoint. Patients with and without visual field defects did not differ in the extent of cross-over deviations. Cross-over deviation and inconsistent stimulus detection in left hemispace were correlated irrespective of the presence of a visual field deficit. Larger cross-over deviations were associated with poorer verbal working memory span, and disorganized patterns of eye movement were related to reduced visuo-spatial working memory capacity. Increasing awareness of the disorder and the use of compensatory strategies may have led to a cross-over shift of visual search dominance towards the neglected side resulting in an exploration deficit of the ipsilesional side.

Visual Search Patterns and Reaction Movement in Taekwondo According to Expertise

Visual Search Patterns and Reaction Movement in Taekwondo According to Expertise

Greater Sparing of Visual Search Abilities in Children After Congenital Rather Than Acquired Focal Brain Damage

Background. Visual search refers to the capacity of an individual to find a target among simultaneously presented distracters and is based on visual abilities such as a fast visual processing and an accurate control of ballistic eye movements (saccades) that guide the fovea to the target location. Objective. In adults, visual field defects caused by brain damage are often associated with visual search disorders; in children, little is known about the effects of early brain lesions on visual search abilities. Methods. To test the presence of visual search defects and to investigate the role of cortical plasticity after early brain lesions, 29 children with congenital or acquired cerebral lesions, with and without visual field defects, underwent a visual search test battery. Results. The children with acquired lesions and visual field defects had longer reaction times (RTs) in the contralesional visual field compared with the ipsilesional, whereas those with congenital lesions and visual field defects did not have differences in RTs between the contralateral and ipsilateral visual fields and had a visual search pattern similar to children without a visual field defect. Conclusions. These findings support the hypothesis of more effective mechanisms of functional compensation and reorganization of the visual system in children with very early brain lesions, as opposed to those with later damage.

Beach lifeguards: visual search patterns, detection rates and the influence of experience

Lifeguard surveillance is critical to any water safety program. This study determined the rates of detection of a 'drowning' individual by beach lifeguards, and whether scanning patterns differed between groups of lifeguards (experienced/less experienced, male/females, surf/non-surf). It was hypothesized that (1) Experienced lifeguards would perform better and produce less fixations of longer duration than inexperienced; (2) A greater detection rate would be seen in a 'biased' compared to a 'non-biased' condition; (3) There would be no differences between the surf compared to non-surf lifeguards, and male compared to female lifeguards with regard to scanning patterns or detection rates. A mobile eye tracker was worn by each lifeguard (n = 69, 52 males, 17 females) as they watched 12 min of animated beach footage projected onto a screen in two conditions: a. 'Non-biased' (uniform scene). b. 'Biased' (uniform scene with presumed 'rip' on right side of screen). The lifeguards were informed that at any point during the 12 min a person may or may not disappear and to highlight if and where, a person disappeared. Unknown to the participants, a person always disappeared after 10 min at the same position within, but not between, conditions. Data were analysed using anova, t-tests and binary logistic regression. Experienced lifeguards were five times (p < 0.05) more likely to detect the drowning individual than inexperienced lifeguards. There were no significant differences between the visual search patterns of the groups between 2 and 10 min. The detection rates averaged 16% in the non-biased condition and 29% in biased conditions (p < 0.1), probably because lifeguards searched more on the right of the water. Furthermore, 40% (biased) and 42% (non-biased) did not detect the person disappearing, even though they fixated in the correct location in the 3.5 s before the person completely disappeared. This suggests that some lifeguards may have fixated on, but not processed, relevant visual data ('looked at but not seen'). 25% (biased) and 36% (non-biased) of the lifeguards did not fixate in the location of the person disappearing, but were able to identify their disappearance. Visual search patterns used by lifeguards can be altered by instruction and detection rates improve as a consequence. Peripheral vision is used effectively by some lifeguards, but cue extraction may be problematic for others.

Plans for the development of the journal

Plans for the development of the journal

Visual search patterns in semantic dementia show paradoxical facilitation of binding processes

While patients with Alzheimer's disease (AD) show deficits in attention, manifested by inefficient performance on visual search, new visual talents can emerge in patients with frontotemporal lobar degeneration (FTLD), suggesting that, at least in some of the patients, visual attention is spared, if not enhanced. To investigate the underlying mechanisms for visual talent in FTLD (behavioral variant FTD [bvFTD] and semantic dementia [SD]) patients, we measured performance on a visual search paradigm that includes both feature and conjunction search, while simultaneously monitoring saccadic eye movements. AD patients were impaired relative to healthy controls (NC) and FTLD patients on both feature and conjunction search. BvFTD patients showed less accurate performance only on the conjunction search task, but slower response times than NC on all three tasks. In contrast, SD patients were as accurate as controls and had faster response times when faced with the largest number of distracters in the conjunction search task. Measurement of saccades during visual search showed that AD patients explored more of the image, whereas SD patients explored less of the image before making a decision as to whether the target was present. Performance on the conjunction search task positively correlated with gray matter volume in the superior parietal lobe, precuneus, middle frontal gyrus and superior temporal gyrus. These data suggest that despite the presence of extensive temporal lobe degeneration, visual talent in SD may be facilitated by more efficient visual search under distracting conditions due to enhanced function in the dorsal frontoparietal attention network.

Drivers’ perception of vulnerable road users: A hazard perception approach

The present study examined how experienced and young-inexperienced drivers (either trained in hazard perception or not) respond to and identify pedestrians when they appear in residential roads within populated neighborhoods and in urban roads located outside neighborhoods and usually less populated. As part of a hazard perception test, participants were connected to an eye tracking system and were asked to observe 58 traffic scene movies and press a response button each time they detected a hazardous situation. Analyzing all pedestrian-related events revealed that, regardless of driving experience or training, drivers detect pedestrians less often when they appear in urban areas and more often when they appear in residential areas. Moreover, experienced drivers processed information more efficiently than young-inexperienced drivers (both trained and untrained) when pedestrians were identified. Visual search patterns in urban and residential traffic environments are discussed.

A Novel Framework for the Analysis of Eye Movements during Visual Search for Knowledge Gathering

In this article, a conceptual framework developed to acquire expert knowledge from eye-tracking data of skilled individuals is presented. Domain-specific knowledge is acquired from the visual behaviour of subjects whose eye movements are recorded while solving complex visual tasks. It is argued that relevant insights into the cognitive strategies followed by the observers to solve the visual search tasks may be gained by analysing the eye-tracking data in generic feature spaces, which are at the basis of the selected scheme for knowledge representation. In this context, a feature space is a domain in which each dimension is defined as a mathematical construct, which may correspond to perceptually meaningful visual cues and which can take either numerical or categorical values. A special case of such feature spaces is the spatial domain in which the spatial coordinates of the gaze points define the dimensions of such domain. In the proposed conceptual framework, the definition of similarities between visual search patterns is essential to characterise the stereotypical visual behaviour of a group of observers, and thus expert knowledge. Furthermore, since knowledge representation is closely related to the feature domain in which the search is analysed, feature relevance measures become central to knowledge gathering, and the main aspects regarding their definition are discussed in this work. Following a detailed presentation of the conceptual framework, a practical application dealing with expert knowledge gathering in lung radiology is shown both as a proof of concept and also to illustrate a particular functional implementation of the framework.

Rapid Adaptation of Visual Search in Simulated Hemianopia

Patients with homonymous hemianopia have altered visual search patterns, but it is unclear how rapidly this develops and whether it reflects a strategic adaptation to altered perception or plastic changes to tissue damage. To study the temporal dynamics of adaptation alone, we used a gaze-contingent display to simulate left or right hemianopia in 10 healthy individuals as they performed 25 visual search trials. Visual search was slower and less accurate in hemianopic than in full-field viewing. With full-field viewing, there were improvements in search speed, fixation density, and number of fixations over the first 9 trials, then stable performance. With hemianopic viewing, there was a rapid shift of fixation into the blind field over the first 5-7 trials, followed by continuing gradual improvements in completion time, number of fixations, and fixation density over all 25 trials. We conclude that in the first minutes after onset of hemianopia, there is a biphasic pattern of adaptation to altered perception: an early rapid qualitative change that shifts visual search into the blind side, followed by more gradual gains in the efficiency of using this new strategy, a pattern that has parallels in other studies of motor learning.

A real-time framework for eye detection and tracking

Epidemiological studies indicate that automobile drivers from varying demographics are confronted by difficult driving contexts such as negotiating intersections, yielding, merging and overtaking. We aim to detect and track the face and eyes of the driver during several driving scenarios, allowing for further understanding of a driver's visual search pattern behavior. Traditionally, detection and tracking of objects in visual media has been performed using specific techniques. These techniques vary in terms of their robustness and computational cost. This research proposes a real-time framework that is built upon a foundation synonymous to boosting, which we extend from learners to trackers and demonstrate that the idea of an integrated framework employing multiple trackers is advantageous in forming a globally strong tracking methodology. In order to model the effectiveness of trackers, a confidence parameter is introduced to help minimize the errors produced by incorrect matches and allow more effective trackers with a higher confidence value to correct the perceived position of the target.

Developmental differences in pedestrian visual search patterns

Measuring attention to traffic is common in pedestrian safety studies. However, little is known of how visual search patterns affect safe crossing decisions or to what pedestrians are actually attending....

61st Annual Meeting of the American Academy of Neurology Seattle, Washington April 25-May 2, 2009

61st Annual Meeting of the American Academy of Neurology Seattle, Washington April 25-May 2, 2009