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Why do shape aftereffects increase with eccentricity?
Elena Gheorghiu1, Frederick A A Kingdom, Jason Bell
1Laboratory of Experimental Psychology, University of Leuven, Leuven, Belgium. elena.gheorghiu@psy.kuleuven.be
Journal of Vision
|December 22, 2011
Summary
Shape aftereffects, like shape-frequency and shape-amplitude aftereffects, intensify with visual field eccentricity. This perceptual shift is scale-independent and suggests eccentricity-dependent changes in visual processing mechanisms.
Area of Science:
- Visual perception
- Neuroscience
- Psychophysics
Background:
- Spatial aftereffects are known to increase with visual field eccentricity.
- Previous research has established eccentricity-dependent changes in visual processing.
Purpose of the Study:
- To investigate whether shape-frequency and shape-amplitude aftereffects also increase with eccentricity.
- To determine the influence of stimulus size and display structure on these aftereffects.
- To explore the underlying mechanisms contributing to eccentricity-dependent aftereffects.
Main Methods:
- Participants adapted to sinusoidal-shaped contours and then judged the shape of test stimuli.
- Stimulus size and distance between stimuli during adaptation and testing were systematically varied.
- Perceptual shifts and discrimination thresholds were measured at different eccentricities.
Main Results:
- Shape-frequency and shape-amplitude aftereffects significantly increase with eccentricity.
- The perceptual shifts were found to be scale-independent across different stimulus sizes.
- Adaptation effects showed similar temporal decline rates across the visual field, with higher thresholds in the periphery.
Conclusions:
- The findings support the hypothesis that visual processing mechanisms involved in shape perception become less sensitive with eccentricity.
- An eccentricity-dependent increase in the bandwidth of shape-selective mechanisms may explain the observed results.
- These results highlight the significant impact of visual field location on shape perception and adaptation.
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