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Pupil diameter measurement errors as a function of gaze direction in corneal reflection eyetrackers
Julie Brisson1, Marc Mainville, Dominique Mailloux
1Université du Québec à Trois-Rivières, Psychologie, Trois-Rivieres, QC, Canada, julie_brisson@yahoo.fr.
Behavior Research Methods
|March 8, 2013
Summary
Pupil dilation, a measure of cognitive load, can be affected by gaze position. Three common eye-tracking systems showed systematic errors in pupil size estimation during object pursuit tasks.
Area of Science:
- Cognitive psychology
- Human-computer interaction
- Neuroscience
Background:
- Pupil dilation is a noninvasive indicator of cognitive load.
- It is particularly valuable for preverbal or nonverbal participants.
- Corneal reflection eye-tracking is a common method for measuring pupil dilation.
Purpose of the Study:
- To investigate the impact of gaze position on pupil size estimation.
- To evaluate the accuracy of three common eye-tracking systems.
Main Methods:
- Participants engaged in an object pursuit task with a rotating sphere.
- Pupil size was estimated using three different corneal reflection eye-tracking systems.
- Systematic gaze positions were analyzed for their effect on pupil size measurements.
Main Results:
- All three eye-tracking systems exhibited systematic errors in pupil size estimation.
- These errors were dependent on the gaze position during the object pursuit task.
Conclusions:
- Gaze position significantly influences pupil size estimation accuracy in eye-tracking systems.
- Findings have implications for task-elicited pupillometry, especially in gaze-contingent studies.
- Researchers should consider gaze position effects when using pupil dilation to measure cognitive load.
