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| 2. |
- Dewhurst, Richard, et al.
(författare)
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How task demands influence scanpath similarity in a sequential number-search task
- 2018
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Ingår i: Vision Research. - : Elsevier BV. - 1878-5646 .- 0042-6989. ; , s. 9-23
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Tidskriftsartikel (refereegranskat)abstract
- More and more researchers are considering the omnibus eye movement sequence—the scanpath—in their studies of visual and cognitive processing (e.g. Hayes, Petrov, & Sederberg, 2011; Madsen, Larson, Loschky, & Rebello, 2012; Ni et al., 2011; von der Malsburg & Vasishth, 2011). However, it remains unclear how recent methods for comparing scanpaths perform in experiments producing variable scanpaths, and whether these methods supplement more traditional analyses of individual oculomotor statistics. We address this problem for MultiMatch (Jarodzka et al., 2010; Dewhurst et al., 2012), evaluating its performance with a visual search-like task in which participants must fixate a series of target numbers in a prescribed order. This task should produce predictable sequences of fixations and thus provide a testing ground for scanpath measures. Task difficulty was manipulated by making the targets more or less visible through changes in font and the presence of distractors or visual noise. These changes in task demands led to slower search and more fixations. Importantly, they also resulted in a reduction in the between-subjects scanpath similarity, demonstrating that participants’ gaze patterns became more heterogenous in terms of saccade length and angle, and fixation position. This implies a divergent strategy or random component to eye-movement behaviour which increases as the task becomes more difficult. Interestingly, the duration of fixations along aligned vectors showed the opposite pattern, becoming more similar between observers in 2 of the 3 difficulty manipulations. This provides important information for vision scientists who may wish to use scanpath metrics to quantify variations in gaze across a spectrum of perceptual and cognitive tasks. © 2018 Elsevier Ltd
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| 3. |
- Dewhurst, Richard, et al.
(författare)
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It depends on how you look at it: Scanpath comparison in multiple dimensions with MultiMatch, a vector-based approach
- 2012
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Ingår i: Behavior Research Methods. - : Springer Science and Business Media LLC. - 1554-3528.
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Tidskriftsartikel (refereegranskat)abstract
- Eye movement sequences---or scanpaths---vary depending on stimulus characteristics and task (Foulsham \& Underwood, 2008; Land, Mennie, \& Rusted, 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 validate a new method for scanpath comparison based on geometric vectors, which compares scanpaths over multiple dimensions retaining positional and sequential information (Jarodzka, Holmqvist, \& Nyström, 2010). `MultiMatch' was tested in two experiments and pitted against ScanMatch (Cristino, Mathôt, Theeuwes, \& Gilchrist, 2010), the most comprehensive adaptation of the popular Levenshtein method. Experiment 1 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 (for example, when one scanpath is shifted in locus, or fixations fall either side of an AOI boundary). Results illustrate the advantages of a multidimensional approach, revealing how two scanpath differ. For instance, if one scanpath is the reverse copy of another the difference is in direction but not the position of fixations; or if a scanpath is scaled down, the difference is in the length of saccadic vectors but not 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 research and embodiment of cognition, where satisfactory scanpath comparison algorithms are lacking.
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| 5. |
- Foulsham, Tom, et al.
(författare)
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Modeling eye movements in visual agnosia with a saliency map approach: Bottom–up guidance or top–down strategy?
- 2011
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Ingår i: Neural Networks. - : Elsevier BV. - 1879-2782 .- 0893-6080. ; 24:6, s. 665-677
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Tidskriftsartikel (refereegranskat)abstract
- Two recent papers (Foulsham, Barton, Kingstone, Dewhurst, & Underwood, 2009; Mannan, Kennard, & Husain, 2009) report that neuropsychological patients with a profound object recognition problem (visual agnosic subjects) show differences from healthy observers in the way their eye movements are controlled when looking at images. The interpretation of these papers is that eye movements can be modeled as the selection of points on a saliency map, and that agnosic subjects show an increased reliance on visual saliency, i.e., brightness and contrast in low-level stimulus features. Here we review this approach and present new data from our own experiments with an agnosic patient that quantifies the relationship between saliency and fixation location. In addition, we consider whether the perceptual difficulties of individual patients might be modeled by selectively weighting the different features involved in a saliency map. Our data indicate that saliency is not always a good predictor of fixation in agnosia: even for our agnosic subject, as for normal observers, the saliency–fixation relationship varied as a function of the task. This means that top–down processes still have a significant effect on the earliest stages of scanning in the setting of visual agnosia, indicating severe limitations for the saliency map model. Top–down, active strategies – which are the hallmark of our human visual system – play a vital role in eye movement control, whether we know what we are looking at or not.
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| 6. |
- Holmqvist, Kenneth, et al.
(författare)
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Eye tracking : empirical foundations for a minimal reporting guideline
- 2023
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Ingår i: Behavior Research Methods. - : Springer Science and Business Media LLC. - 1554-3528. ; 55:1, s. 364-416
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").
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| 7. |
- Strukelj, Alexander, et al.
(författare)
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Social context modulates basic properties of oculomotor control
- 2016
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Ingår i: Journal of Eye Movement Research. - : University of Bern. - 1995-8692. ; 9:2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Experiments performed in a lab are often considered generali- zable over both people and social settings. The problems with generalizing over different groups of people are well known, but it is only recently that changes in behavior depending on thesocial setting have been examined. Large changes in behavior can be seen in trivial cognitive tasks, depending on whether the participant is alone or if other people are present. However, there are very few studies which have measured eye move- ments in social settings. In this paper, we used the antisaccade task to test whether basic parameters of oculomotor control are sensitive to the size of an experimental group. 70 participants conducted 48 antisaccade trials in groups of one to seven people in a classroom equipped with multiple eye trackers. The results show that for horizontal saccades, but not for vertical saccades, participants make significantly more antisaccade errors when the group size become larger. The group size did however not significantly predict a change in antisaccade latency. These results are in line with a number of recent studies on social attention showing that the mere presence of other people in the room can modulate several aspects of performance, and show that behavior in a lab might not be easily generalizable to everyday life or social situations. Finally, from a methodological viewpoint, the results show that the group size should be considered when testing participants in a social setting.
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| 8. |
- Verghese, Preeti, et al.
(författare)
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Eye movements in visual impairment
- 2023
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Ingår i: Vision Research. - 0042-6989. ; 211
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Tidskriftsartikel (refereegranskat)abstract
- This Special Issue describes the impact of visual impairment on visuomotor function. It includes contributions that examine gaze control in conditions associated with abnormal visual development such as amblyopia, dyslexia and neurofibromatosis as well as disorders associated with field loss later in life, such as macular degeneration and stroke. Specifically, the papers address both gaze holding (fixation), and gaze-following behavior (single saccades, sequences of saccades and smooth-pursuit) that characterize active vision in daily life and evaluate the influence of both pathological and simulated field loss. Several papers address the challenges to reading and visual search; describing how the patterns of eye movements in these real-world tasks adapt to visual impairment and highlighting how they could serve as diagnostic markers of visuomotor function.
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