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Appears in Collections:Psychology Journal Articles
Peer Review Status: Refereed
Title: Why do shape aftereffects increase with eccentricity?
Authors: Gheorghiu, Elena
Kingdom, Frederick A A
Bell, Jason
Gurnsey, Rick
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Keywords: eccentricity
Issue Date: Dec-2011
Publisher: Pion
Citation: Gheorghiu E, Kingdom FAA, Bell J & Gurnsey R (2011) Why do shape aftereffects increase with eccentricity?, Journal of Vision, 11 (14), Art. No.: 18.
Abstract: Studies have shown that spatial aftereffects increase with eccentricity. Here, we demonstrate that the shape-frequency and shape-amplitude aftereffects, which describe the perceived shifts in the shape of a sinusoidal-shaped contour following adaptation to a slightly different sinusoidal-shaped contour, also increase with eccentricity. Why does this happen? We first demonstrate that the perceptual shift increases with eccentricity for stimuli of fixed sizes. These shifts are not attenuated by variations in stimulus size; in fact, at each eccentricity the degree of perceptual shift is scale-independent. This scale independence is specific to the aftereffect because basic discrimination thresholds (in the absence of adaptation) decrease as size increases. Structural aspects of the displays were found to have a modest effect on the degree of perceptual shift; the degree of adaptation depends modestly on distance between stimuli during adaptation and post-adaptation testing. There were similar temporal rates of decline of adaptation across the visual field and higher post-adaptation discrimination thresholds in the periphery than in the center. The observed results are consistent with greater sensitivity reduction in adapted mechanisms following adaptation in the periphery or an eccentricity-dependent increase in the bandwidth of the shape-frequency- and shape-amplitude-selective mechanisms.
Type: Journal Article
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Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: Psychology
McGill University
McGill University
Concordia University

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