Journal of Eye Movement Research
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Oculomotor fatigue and neuropsychological assessments mirror multiple sclerosis fatigue
Fatigue is a major complaint in MS. Up to now no objective assessment tools have been established which hampers any treatment approach. Previous work has indicated an association of fatigue with cognitive measures of attention. Oculomotor tests have been established in healthy individuals as a read-out of fatigue, and to some extent in MS patients. Based on these observations we compared two groups of MS patients, one with fatigue (n=28) and one without fatigue (n=21) and a group of healthy subjects (n=15) with a stand- ardised computerised measure of alertness and an oculomotor stress test.
Patients with fatigue showed highly significant changes of their saccade dynamics as defined by the Main Sequence and Phase Plane plots: They showed slowing of saccades, the characteristical fatigue double peak, and an asymmetrical phase plane. Oculomotor tests differentiated significantly between fatigue and fatigabiliy in our MS patients.
They also showed significantly worse performance in the alertness test as well as in the oculomotor task. Significantly slower reaction times were observed for tonic alertness in 2 series without a cue (p=.025 and p=.037) but not in phasic alertness with a cue (p=.24 and p=.34). Performance was influenced by disability as well as by affective state. We conclude, when controlling for disability and depression, saccadic stress tests and alertness tests could be used as an objective read-out for fatigability and fatigue in MS patients
What makes a microsaccade? A review of 70 years research prompts a new detection method
We have developed a new method for detecting microsaccades in eye-movement data. The impetus was the review of the literature on microsaccades presented in this paper, which revealed (1) large changes in the size and speed of reported microsaccades over the last 70 years and (2) references to monocular microsaccades, which have recently been shown to be artefacts of analysis methods (Nyström et al, 2017; Fang et al, 2018). The changes in reported microsaccade characteristics, such as size and speed, must be due to experimental factors, such as methods of recording and analysis, and different levels of experience of the participants in the task: They cannot represent a change in the fundamental characteristics of microsaccades. In this paper we present a review of reported microsaccade properties between the 1940s and today and we determine the range within which certain physical parameters of microsaccades are thought to occur. These parameters drive our new microsaccade detection method. We have validated this method on two datasets of binocular eye-movements recorded using video-based systems: one from within our lab, and one from Nyström et al, 2017. We have additionally applied our method to eye-movement data collected using an adaptive optics scanning laser ophthalmoscope (AOSLO), to show its adaptability to a fundamentally different method of data capture. This confirmed that the microsaccade detection method produces microsaccade detection rates within expected limits across very different methods of recording. Our new microsaccade detection method is easy to implement and intuitive to understand, and affords researchers flexibility in adjusting it to their experimental set-up
The information gathering framework - a cognitive model of regressive eye movements during reading
In this article we present a new eye movement control framework that describes the interaction between fixation durations and regressive saccades during reading: The Information Gathering Framework (IGF).
Based on the FC model proposed by Bicknell and Levy (2010), the basic idea of the IGF is that a confidence level for each word is computed while being monitored by three independent thresholds. These thresholds shape eye movement behavior by increasing fixation duration, triggering a regression, or guiding regression target selection. In this way, the IGF does not only account for regressive eye movements but also provides a framework able to model eye movement control during reading across different scenarios. Importantly, within the IGF it is assumed that two different types of regressive eye movements exist which differ with regard to their releases (integrations difficulties vs. missing evidence) but also with regard to their time course.
We tested the predictions of the IGF by re-analyzing an experiment of Weiss et al. (2018) and found, inter alia, clear evidence for shorter fixation durations before regressive saccades relative to progressive saccades, with the exception of the last region. This clearly supports the assumptions of the IGF. In addition, we found evidence that there exists a window of about 15–20 characters to the left of the current fixation that plays an important role in target selection, probably indicating the perceptual span during a regressive saccade
Microsaccades in applied environments: Real-world applications of fixational eye movement measurements
Across a wide variety of research environments, the recording of microsaccades and other fixational eye movements has provided insight and solutions into practical problems. Here we review the literature on fixational eye movements—especially microsaccades—in applied and ecologically-valid scenarios. Recent technical advances allow noninvasive fixational eye movement recordings in real-world contexts, while observers perform a variety of tasks. Thus, fixational eye movement measures have been obtained in a host of real-world scenarios, such as in connection with driver fatigue, vestibular sensory deprivation in astronauts, and elite athletic training, among others. Here we present the state of the art in the practical applications of fixational eye movement research, examine its potential future uses, and discuss the benefits of including microsaccade measures in existing eye movement detection technologies. Current evidence supports the inclusion of fixational eye movement measures in real-world contexts, as part of the development of new or improved oculomotor assessment tools. The real-world applications of fixational eye movement measurements will only grow larger and wider as affordable high-speed and high-spatial resolution eye trackers become increasingly prevalent
Looking (for) patterns: Similarities and differences between infant and adult free scene-viewing patterns
Systematic tendencies such as the center and horizontal bias are known to have a large influence on how and where we move our eyes during static onscreen free scene viewing. However, it is unknown whether these tendencies are learned viewing strategies or are more default tendencies in the way we move our eyes. To gain insight into the origin of these tendencies we explore the systematic tendencies of infants (3 - 20-month-olds, N = 157) and adults (N = 88) in three different scene viewing data sets. We replicated common findings, such as longer fixation durations and shorter saccade amplitudes in infants compared to adults. The leftward bias was never studied in infants, and our results indicate that it is not present, while we did replicate the leftward bias in adults. The general pattern of the results highlights the similarity between infant and adult eye movements. Similar to adults, infants’ fixation durations increase with viewing time and the dependencies between successive fixations and saccades show very similar patterns. A straightforward conclusion to draw from this set of studies is that infant and adult eye movements are mainly driven by similar underlying basic processes
Shorter fixation durations for up-directed saccades during saccadic exploration: A meta-analysis
Utilizing 23 datasets, we report a meta-analysis of an asymmetry in presaccadic fixation durations for saccades directed above and below eye fixation during saccadic exploration. For inclusion in the meta-analysis, saccadic exploration of complex visual displays had to have been made without gaze-contingent manipulations. Effect sizes for the asymmetry were quantified as Hedge’s g. Pooled effect sizes indicated significant asymmetries such that during saccadic exploration in a variety of tasks, presaccadic fixation durations for saccades directed into the upper visual field were reliably shorter than presaccadic fixation durations for saccades into the lower visual field. It is contended that the asymmetry is robust and important for efforts aimed at modelling when a saccade is initiated as a function of ensuing saccade direction
The closer, the better? Processing relations between picture elements in historical paintings
The present eye-tracking study investigated how audio explanations influence perception and the cognitive processing of historical paintings. Spatially close and distant pairs of picture elements and their semantic relations were named in an audio text either immediately after each other or with descriptions of other elements in between. It was assumed that the number of backward fixation counts on the first of the two mentioned related picture elements should be higher if they are spatially close rather than spatially distant. There should also be more backward fixation counts if the elements are named temporally close rather than temporally distant. Similar predictions were made for the retention of these picture elements and their relations. A 2x2x2 within-subject design (n=36) with spatial distance (close vs. distant), temporal distance (close vs. distant) and painting (Leutze vs. West) revealed more background fixation counts for spatially close compared to spatially distant elements but just for the Leutze painting. Accordingly, the relations between the spatially close pairs were retained better than between the spatially distant pairs in the Leutze painting but vice versa for the West painting. The results are discussed with regard to the spatial contiguity principle of multimedia learning and research on text coherence
Dog eye movements are slower than human eye movements
Eye movement of a species reflects the visual behavior strategy that it has adapted to during its evolution. What are eye movements of domestic dogs (Canis lupus familiaris) like? Investigations of dog eye movements per se have not been done, despite the increasing number of visuo-cognitive studies in dogs using eye-tracking systems. To fill this gap, we have recorded dog eye movements using a video-based eye-tracking system, and compared the dog data to that of humans. We found dog saccades follow the systematic relationships between saccade metrics previously shown in humans and other animal species. Yet, the details of the relationships, and the quantities of each metric of dog saccades and fixations differed from those of humans. Overall, dog saccades were slower and fixations were longer than those of humans. We hope our findings contribute to existing comparative analyses of eye movement across animal species, and also to improvement of algorithms used for classifying eye movement data of dogs
Pupillary and microsaccadic responses to cognitive effort and emotional arousal during complex decision making
A large body of literature documents the sensitivity of pupil response to cognitive load (e.g., Krejtz et al. 2018) and emotional arousal (Bradley et al., 2008). Recent empirical evidence also showed that microsaccade characteristics and dynamics can be modulated by mental fatigue and cognitive load (e.g., Dalmaso et al. 2017). Very little is known about the sensitivity of microsaccadic characteristics to emotional arousal. The present paper demonstrates in a controlled experiment pupillary and microsaccadic responses to information processing during multi-attribute decision making under affective priming. Twenty-one psychology students were randomly assigned into three affective priming conditions (neutral, aversive, and erotic). Participants were tasked to make several discriminative decisions based on acquired cues. In line with the expectations, results showed microsaccadic rate inhibition and pupillary dilation depending on cognitive effort (number of acquired cues) prior to decision. These effects were moderated by affective priming. Aversive priming strengthened pupillary and microsaccadic response to information processing effort. In general, results suggest that pupillary response is more biased by affective priming than microsaccadic rate. The results are discussed in the light of neuropsychological mechanisms of pupillary and microsaccadic behavior generation
Eye tracking for assessment of situational awareness in bridge resource management training
The purpose of this study is to experiment eye tracking in situational awareness assessment in Bridge Resource Management training of ship officers who play a critical role in maritime accidents. The maritime industry focuses on human factor developing and improving regulations including training requirements to prevent marine casualties. The mandatory Bridge Resource Management training as per international regulations includes assessment of situational awareness of trainees in full mission ship bridge simulators. The study involves capturing and analyzing eye movement data from maritime cadets and ship officers with sea experience in a simulation exercise. An eye tracking analysis software and eye tracking glasses are used for the study. Inferential and descriptive analyses were both used to validate the results. Significant differences were found between fixation duration measurements of novice cadets and experienced officers. Heat map visualizations also revealed differences in focuses of attention among participants. The evaluations of the certified simulator assessors are considered as the ground truth, and the results were compared to and discussed accordingly. The results show that the eye tracking technology is a valuable complementary tool for assessment of situational awareness in a simulator environment, utilized with the existing conventional observation and performance measurement methods. The study reveals that eye tracking provides the assessor with novel data in simulator based maritime training, such as focus of attention, which contributes to the evaluation of the situational awareness. The study, therefore, contributes to maritime education aiming to improve the effectiveness of Bridge Resource Management training. It also contributes to scientific research on eye movement in maritime field by proposing the integration of eye tracking in the Bridge Resource Management training