The human pupil and the use of video-based eyetrackers

Wyatt, Harry J.

doi:10.1016/j.visres.2010.07.008

Cited by 72 publications

(85 citation statements)

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“…The absolute magnitude of fixation disparity was significantly greater in the EyeLink data set than in the DPI data set and, therefore, fewer fixations were classed as aligned. Wyatt (2010) demonstrated that changes in pupil size can affect the accuracy of camera-based eyetrackers. Drewes, Masson, and Montagnine (2012) demonstrated a method to compensate for this artifact by calibrating during constricted and dilated pupil conditions, using pupil size as an index to weight the calibrations.…”

Section: Discussionmentioning

confidence: 99%

Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

et al. 2013

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Previous studies examining binocular coordination during reading have reported conflicting results in terms of the nature of disparity (e.g. Kliegl, Nuthmann, & Engbert (Journal of Experimental Psychology General 135:12-35, 2006); Liversedge, White, Findlay, & Rayner (Vision Research 46:2363-2374. One potential cause of this inconsistency is differences in acquisition devices and associated analysis technologies. We tested this by directly comparing binocular eye movement recordings made using SR Research EyeLink 1000 and the Fourward Technologies Inc. DPI binocular eyetracking systems. Participants read sentences or scanned horizontal rows of dot strings; for each participant, half the data were recorded with the EyeLink, and the other half with the DPIs. The viewing conditions in both testing laboratories were set to be very similar. Monocular calibrations were used. The majority of fixations recorded using either system were aligned, although data from the EyeLink system showed greater disparity magnitudes. Critically, for unaligned fixations, the data from both systems showed a majority of uncrossed fixations. These results suggest that variability in previous reports of binocular fixation alignment is attributable to the specific viewing conditions associated with a particular experiment (variables such as luminance and viewing distance), rather than acquisition and analysis software and hardware.

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Section: Discussionmentioning

confidence: 99%

Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

et al. 2013

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“…The signals coming from PD recordings have been analyzed in both the time and frequency domains: State-of-the art is briefly reviewed in this section. Regardless of the method employed for the analysis, eye-blink artifacts represent a common problem in video-pupillography: Most systems measure pupil size upon eye image processing (see Holmqvist et al, 2010;Wyatt, 2010). During eye-blinks the lid covers the eye, and the camera cannot detect the pupil.…”

Section: Methods For Pd Data Analysismentioning

confidence: 99%

Automatic Stress Classification With Pupil Diameter Analysis

Pedrotti

Mirzaei

Tedesco³

et al. 2014

International Journal of Human-Computer Interaction

155

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. This article proposes a method based on wavelet transform and neural networks for relating pupillary behavior to psychological stress. The proposed method was tested by recording pupil diameter and electrodermal activity during a simulated driving task. Self-report measures were also collected. Participants performed a baseline run with the driving task only, followed by three stress runs where they were required to perform the driving task along with sound alerts, the presence of two human evaluators, and both. Self-reports and pupil diameter successfully indexed stress manipulation, and significant correlations were found between these measures. However, electrodermal activity did not vary accordingly. After training, the four-way parallel neural network classifier could guess whether a given unknown pupil diameter signal came from one of the four experimental trials with 79.2% precision. The present study shows that pupil diameter signal has good discriminating power for stress detection.

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“…However, the spatial error in eye position measuring can vary greatly within trials depending on physiological and cognitive factors, as well as the participant's compliance during the task. For example, it has been shown that the measured gaze position using video-based eyetrackers is influenced by the size of the pupil (Drewes, Masson, & Montagnini, 2012;Wyatt, 2010), which, in turn, depends on the stimulus luminance, which might vary between and within trials but can also be influenced by task difficulty or cognitive load (e.g., Beatty, 1982;Granholm, Asarnow, Sarkin, & Dykes, 1996;Hess & Polt, 1964). The radius of the scotoma should thus be increased by the averaged spatial error of the eye-tracking system, which should be separately measured-for example, via fixation validation, as in our experiment.…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

A behavioral task for the validation of a gaze-contingent simulated scotoma

2013

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Gaze-contingent displays provide a valuable method in visual research for controlling visual input and investigating its visual and cognitive processing. Although the body of research using gaze-contingent retinal stabilization techniques has grown considerably during the last decade, only few studies have been concerned with the reliability of the specific real-time simulations applied. Using a Landolt ring discrimination task, we present a behavioral validation of gaze-contingent central scotoma simulation in healthy observers. Importantly, behavioral testing is necessary to show whether the simulation impairs foveal processing of visual information. This test becomes even more crucial when researchers are faced with null results in a task performed with the scotoma, as compared with a control condition. It must be ruled out that the lack of behavioral effects results from a type II error caused by improper implementation before conclusions about foveal contributions to the given task may be drawn. In our experiment, the scotoma effectively prevented foveal processing of the visual stimuli, leading to significantly reduced response accuracies, as compared with unimpaired vision.Moreover, the final fixation at the time of the participants' responses was placed close to the target position in the unimpaired condition, whereas the distance to the target was enhanced with the scotoma, indicating that the observers were not able to discriminate visual target stimuli from distractors, due to the scotoma. The present work presents a validated behavioral testing method for the efficiency of gaze-contingent scotoma simulations, including code for implementation. In addition, solutions for common methodological problems are discussed.

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The human pupil and the use of video-based eyetrackers

Cited by 72 publications

References 1 publication

Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

Investigating eye movement acquisition and analysis technologies as a causal factor in differential prevalence of crossed and uncrossed fixation disparity during reading and dot scanning

Automatic Stress Classification With Pupil Diameter Analysis

A behavioral task for the validation of a gaze-contingent simulated scotoma

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