Do microsaccades vary with discriminability around the visual field?
Simran Purokayastha1, Mariel Roberts1, Marisa Carrasco1,2
1Department of Psychology, New York University, New York, USA.
Biorxiv : the Preprint Server for Biology
|January 23, 2024
Summary
Microsaccades, tiny eye movements, do not adapt to varying visual task difficulty. Their directionality remained consistent across different locations and discriminability levels, suggesting limited flexibility in basic visual processing.
Area of Science:
- Neuroscience
- Vision Science
Background:
- Microsaccades (MS) are small, rapid eye movements crucial for high-acuity vision in the foveola.
- Their role in compensating for reduced visual performance in the perifovea, characterized by perceptual asymmetries like Horizontal-Vertical Anisotropy, is not well understood.
Approach:
- Investigated MS characteristics and directionality in relation to visual performance across different locations in the visual field.
- Utilized a two-alternative forced-choice orientation discrimination task under conditions of heterogeneous and homogeneous discriminability (Experiment 1 and 2).
Key Points:
- Visual performance was better on trials without MS compared to trials with MS.
- MS rate and directional patterns were consistent across various stimulus locations and discriminability levels.
- MS showed a bias towards the target location only during the response period, after stimulus offset.
Conclusions:
- Microsaccades do not flexibly adapt to varying stimulus discriminability in basic visual tasks.
- MS behavior appears largely independent of perceptual performance variations across the visual field, except during the response phase.
