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Distinct eccentricity-driven dynamics in foveal and extrafoveal visual crowding
Ashley M Clark1,2, Krishnamachari S Prahalad1,2, Martina Poletti1,2,3
1Department of Brain and Cognitive Sciences, University of Rochester, Meliora Hall, Rochester, NY 14627, USA.
Iscience
|March 20, 2026
Summary
Visual crowding, which impairs object recognition, surprisingly increases even in the central fovea. This study reveals that crowding zones change with eccentricity, even in the highest-acuity vision region.
Area of Science:
- Visual neuroscience
- Perception and cognition
Background:
- Visual crowding impairs object recognition, particularly in peripheral vision, and its spatial extent follows Bouma's law.
- Bouma's law predicts minimal crowding at fixation, but foveal crowding exists, challenging this prediction.
- The central fovea, with its high acuity and unique connectivity, is expected to have constant crowding, but this remains unverified.
Purpose of the Study:
- To investigate whether visual crowding varies within the foveola (central 1 degree).
- To precisely measure crowding thresholds at different foveolar eccentricities using advanced eye-tracking technology.
Main Methods:
- Employed high-resolution eye tracking to monitor gaze precisely.
- Utilized gaze-contingent display control to measure crowding thresholds at specific foveolar locations.
- Analyzed crowding variations across eccentricities within the central fovea.
Main Results:
- Visual crowding increased linearly within the foveola, contrary to expectations of constant crowding.
- The rate of crowding increase in the foveola was approximately 3.5 times shallower than in the extrafovea.
- These findings were consistent across different participants and fixation criteria.
Conclusions:
- Integration zones in human vision change with eccentricity even within the high-acuity central fovea.
- The central fovea is not uniform regarding crowding, suggesting a distinct crowding regime.
- These results challenge the assumption of a uniform central fovea and refine our understanding of visual crowding.
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