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Evidence for two systems mediating perceived contrast

Published online by Cambridge University Press:  02 June 2009

Julie R. Brannan
Affiliation:
Departments of Neurology and Neurobiology, Mount Sinai Medical School of the City University of New York
Ivan Bodis
Affiliation:
Departments of Neurology and Ophthalmology, Mount Sinai Medical School of the City University of New York

Abstract

We report psychophysical evidence for a categorical dichotomy in the perception of contrast. Observers were required to rate the contrast of sinusoidal gratings (2.3 c/d) with contrast varying over a given range relative to two standards. One standard was designated “high” contrast and the other was designated “low.” There was a boundary effect: contrast judgment depended upon whether the tested ranges included 10–15% contrast and discrimination was sharpest at the boundary between 10 and 15% contrast. These results are consistent with the existence of two systems underlying perceived contrast; one primarily sensitive below 10%, and the other primarily sensitive above 15% contrast.

Information

Type
Research Articles
Copyright
Copyright © Cambridge University Press 1991

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