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| 2. |
- Ahlström, Christer, et al.
(författare)
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Fit-for-duty test for estimation of drivers sleepiness level: Eye movements improve the sleep/wake predictor
- 2013
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 26, s. 20-32
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Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a drivers sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS andgt;= 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.
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| 3. |
- Andersson, Bodil, et al.
(författare)
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Combining Keystroke Logging with Eye Tracking
- 2006
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Ingår i: Writing and Digital Media. - 1572-6304. - 0080448631 ; 17, s. 166-172
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Bokkapitel (refereegranskat)abstract
- This chapter describes the successful development of a new methodology for studying on-line writing. The text-logging tool ScriptLog has been combined with the eyetracking technology iView X HED HT, in order to enhance the study of the interplay between writing, monitoring and revision. Data on the distribution of visual attention during writing help determining to what extent pauses are used for monitoring. The complexity of the experimental settings, and the expertise needed for interpreting the eye-tracking data make this a method suitable mainly for laboratory settings. The chapter also introduces an analysis tool that merges data from ScriptLog and iView and thus helps the researcher to organise and analyse the vast amount of data produced.
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| 4. |
- Andersson, Richard, et al.
(författare)
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One algorithm to rule them all? : An evaluation and discussion of ten eye movement event-detection algorithms
- 2017
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Ingår i: Behavior Research Methods. - : Springer Science and Business Media LLC. - 1554-3528. ; 49:2, s. 616-637
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Tidskriftsartikel (refereegranskat)abstract
- Almost all eye-movement researchers use algorithms to parse raw data and detect distinct types of eye movement events, such as fixations, saccades, and pursuit, and then base their results on these. Surprisingly, these algorithms are rarely evaluated. We evaluated the classifications of ten eye-movement event detection algorithms, on data from an SMI HiSpeed 1250 system, and compared them to manual ratings of two human experts. The evaluation focused on fixations, saccades, and post-saccadic oscillations. The evaluation used both event duration parameters, and sample-by-sample comparisons to rank the algorithms. The resulting event durations varied substantially as a function of what algorithm was used. This evaluation differed from previous evaluations by considering a relatively large set of algorithms, multiple events, and data from both static and dynamic stimuli. The main conclusion is that current detectors of only fixations and saccades work reasonably well for static stimuli, but barely better than chance for dynamic stimuli. Differing results across evaluation methods make it difficult to select one winner for fixation detection. For saccade detection, however, the algorithm by Larsson, Nyström and Stridh (IEEE Transaction on Biomedical Engineering, 60(9):2484–2493,2013) outperforms all algorithms in data from both static and dynamic stimuli. The data also show how improperly selected algorithms applied to dynamic data misestimate fixation and saccade properties.
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| 7. |
- Andersson, Richard, et al.
(författare)
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Sampling frequency and eye-tracking measures : how speed affects durations, latencies, and more
- 2010
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Ingår i: Journal of Eye Movement Research. - : University of Bern. - 1995-8692. ; 3:3:6, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- We use simulations to investigate the effect of sampling frequency on common dependent variables in eye-tracking. We identify two large groups of measures that behave differently, but consistently. The effect of sampling frequency on these two groups of measures are explored and simulations are performed to estimate how much data are required to overcome the uncertainty of a limited sampling frequency. Both simulated and real data are used to estimate the temporal uncertainty of data produced by low sampling frequencies. The aim is to provide easy-to-use heuristics for researchers using eye-tracking. For example, we show how to compensate the uncertainty of a low sampling frequency with more data and post-experiment adjustments of measures. These findings have implications primarily for researchers using naturalistic setups where sampling frequencies typically are low.
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| 11. |
- Andra, Chiara, et al.
(författare)
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Reading mathematics representations: an eye-tracking study
- 2015
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Ingår i: International Journal of Science and Mathematics Education. - : Springer Science and Business Media LLC. - 1571-0068 .- 1573-1774. ; 13:2, s. 237-259
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Tidskriftsartikel (refereegranskat)abstract
- We use eye tracking as a method to examine how different mathematical representations of the same mathematical object are attended to by students. The results of this study show that there is a meaningful difference in the eye movements between formulas and graphs. This difference can be understood in terms of the cultural and social shaping of human perception, as well as in terms of differences between the symbolic and graphical registers.
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| 12. |
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| 13. |
- Balslev, Thomas, et al.
(författare)
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Visual Expertise In Paediatric Neurology
- 2012
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Ingår i: European Journal of Paediatric Neurology. - : Elsevier BV. - 1090-3798. ; 16, s. 161-166
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Tidskriftsartikel (refereegranskat)abstract
- Objective Visual expertise relies on perceptive as well as cognitive processes. At present, knowledge of these processes when diagnosing clinical cases mainly stems from studies with still pictures. Patient video cases constitute a dynamic and authentic, diagnostic challenge that may simulate seeing and diagnosing a patient in person. This study investigates visual attention and the concomitant cognitive processes of clinicians diagnosing authentic pediatric video cases. Methods A total of 43 clinicians with varying levels of expertise took part in this cross-sectional study. They diagnosed four brief video recordings of children: two with seizures and two with disorders imitating seizures. We used eye tracking to investigate time looking at relevant areas in the video cases and a concurrent think-aloud procedure to explore the associated clinical reasoning processes. Results More experienced clinicians were more accurate in visual diagnosis and spent more of their time looking at relevant areas. At the same time, they explored data less, yet they built and evaluated more diagnostic hypotheses. Interpretation This study adds a new perspective on medical expertise. More experienced clinicians (experts) focus better on relevant areas allowing them to explore data less and at the same time to build and evaluate more diagnostic hypotheses. The combination of effective visual search and the ability to effectively monitor for and evaluate different diagnostic options seems to characterize the experts in visual domains.
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| 16. |
- Brandão, Lenisa, et al.
(författare)
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Discourse intervention strategies in Alzheimer's disease : eye-tracking and the effect of visual cues in conversation
- 2014
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Ingår i: Dementia & Neuropsychologia. - 1980-5764. ; 8:3, s. 278-284
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The goal of this study was to investigate whether on-topic visual cues can serve as aids for the maintenance of discourse coherence and informativeness in autobiographical narratives of persons with Alzheimer's disease (AD). METHODS: The experiment consisted of three randomized conversation conditions: one without prompts, showing a blank computer screen; an on-topic condition, showing a picture and a sentence about the conversation; and an off-topic condition, showing a picture and a sentence which were unrelated to the conversation. Speech was recorded while visual attention was examined using eye tracking to measure how long participants looked at cues and the face of the listener. RESULTS: Results suggest that interventions using visual cues in the form of images and written information are useful to improve discourse informativeness in AD. CONCLUSION: This study demonstrated the potential of using images and short written messages as means of compensating for the cognitive deficits which underlie uninformative discourse in AD. Future studies should further investigate the efficacy of language interventions based in the use of these compensation strategies for AD patients and their family members and friends.
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| 17. |
- Breidegard, Björn, et al.
(författare)
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Enlightened: The art of finger reading
- 2008
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Ingår i: Studia Linguistica. - : Wiley. - 1467-9582 .- 0039-3193. ; 62:3, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- For some forty years the eye-tracking technology has facilitated the study of eye movement patterns for sighted people during reading and other visual activities. Today – a newly developed automatic finger tracking system makes it possible to reconstruct blind people’s tactile reading in real time and to automatically analyze finger movements during Braille text reading and tactile picture recognition. In this case study, the very first automatic finger tracking system is presented together with results indicating how Braille readers can increase awareness of their own reading styles. This opens up for future Braille education to become more evidence-based and, at the same time, for a new research field: contrastive studies of language in its auditory, visual and tactile manifestations.
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| 18. |
- Cardeña, Etzel, et al.
(författare)
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The "hypnotic state" and eye movements. Less there than meets the eye?
- 2017
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- Responsiveness to hypnotic procedures has been related to unusual eye behaviors for centuries. Kallio and collaborators claimed recently that they had found a reliable index for "the hypnotic state" through eye-tracking methods. Whether or not hypnotic responding involves a special state of consciousness has been part of a contentious debate in the field, so the potential validity of their claim would constitute a landmark. However, their conclusion was based on 1 highly hypnotizable individual compared with 14 controls who were not measured on hypnotizability. We sought to replicate their results with a sample screened for High (n = 16) or Low (n = 13) hypnotizability. We used a factorial 2 (high vs. low hypnotizability) x 2 (hypnosis vs. resting conditions) counterbalanced order design with these eye-tracking tasks: Fixation, Saccade, Optokinetic nystagmus (OKN), Smooth pursuit, and Antisaccade (the first three tasks has been used in Kallio et al.'s experiment). Highs reported being more deeply in hypnosis than Lows but only in the hypnotic condition, as expected. There were no significant main or interaction effects for the Fixation, OKN, or Smooth pursuit tasks. For the Saccade task both Highs and Lows had smaller saccades during hypnosis, and in the Antisaccade task both groups had slower Antisaccades during hypnosis. Although a couple of results suggest that a hypnotic condition may produce reduced eye motility, the lack of significant interactions (e.g., showing only Highs expressing a particular eye behavior during hypnosis) does not support the claim that eye behaviors (at least as measured with the techniques used) are an indicator of a "hypnotic state.” Our results do not preclude the possibility that in a more spontaneous or different setting the experience of being hypnotized might relate to specific eye behaviors.
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| 19. |
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| 20. |
- Děchtěrenko, Filip, et al.
(författare)
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Flipping the stimulus : effects on scanpath coherence?
- 2016
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Ingår i: Behavior Research Methods. - : Springer Science and Business Media LLC. - 1554-3528.
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Tidskriftsartikel (refereegranskat)abstract
- In experiments investigating dynamic tasks, it is often useful to examine eye movement scan patterns. We can present trials repeatedly and compute within-subjects/conditions similarity in order to distinguish between signal and noise in gaze data. To avoid obvious repetitions of trials, filler trials must be added to the experimental protocol, resulting in long experiments. Alternatively, trials can be modified to reduce the chances that the participant will notice the repetition, while avoiding significant changes in the scan patterns. In tasks in which the stimuli can be geometrically transformed without any loss of meaning, flipping the stimuli around either of the axes represents a candidate modification. In this study, we examined whether flipping of stimulus object trajectories around the x- and y-axes resulted in comparable scan patterns in a multiple object tracking task. We developed two new strategies for the statistical comparison of similarity between two groups of scan patterns, and then tested those strategies on artificial data. Our results suggest that although the scan patterns in flipped trials differ significantly from those in the original trials, this difference is small (as little as a 13 % increase of overall distance). Therefore, researchers could use geometric transformations to test more complex hypotheses regarding scan pattern coherence while retaining the same duration for experiments.
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| 21. |
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| 22. |
- 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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| 23. |
- 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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