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Updated: Dec 7, 2025
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Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition
Published on: July 21, 2020
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Reduced fixation stability induced by peripheral viewing does not contribute to crowding.
Rajkumar Nallour Raveendran1,2,3, Arun Kumar Krishnan4,5, Benjamin Thompson2,6,7
1Envision Research Institute, Wichita, KS, USA.
Journal of Vision
|October 2, 2020
Summary
Peripheral viewing reduces fixation stability, but this instability does not explain crowding in peripheral vision. Eye movements during visual tasks are crucial for understanding visual perception.
Area of Science:
- Neuroscience
- Visual Perception
- Ophthalmology
Background:
- Covert attention to peripheral targets while maintaining central fixation decreases fixation stability.
- Peripheral crowding, a decline in visual performance with eccentricity, may be linked to increased positional uncertainty.
Purpose of the Study:
- To investigate if reduced fixation stability during peripheral viewing contributes to peripheral crowding.
- To determine the relationship between fixation stability and the magnitude of crowding.
Main Methods:
- Fourteen participants performed a tumbling E orientation discrimination task at 0°, 5°, and 10° eccentricity with and without flankers.
- Fixational eye movements were recorded using an infrared video-based eyetracker.
- Optotype size was scaled for each eccentricity.
Main Results:
- Peripheral viewing (crowded and uncrowded stimuli) reduced fixation stability, increased microsaccadic amplitude, and increased horizontal microsaccades compared to central viewing.
- Despite reduced fixation stability, the magnitude of crowding did not correlate with fixation stability.
- Visual discrimination of crowded stimuli deteriorated with eccentricity, even with scaled optotypes.
Conclusions:
- Reduced fixation stability during peripheral viewing does not appear to be a primary cause of peripheral crowding.
- Fixation stability is affected by peripheral viewing, but this effect is independent of crowding magnitude.
