title: Evidence for two systems mediating perceived contrast.
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.
authors.affiliation: Department of Neurology, Mount Sinai Medical School, City University of New York, NY 10029.
authors.forename: J R
authors.initials: JR
authors.lastname: Brannan
authors.forename: I
authors.initials: I
authors.lastname: Bodis-Wollner
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011601:Psychophysics; D014795:Visual Pathways / Q000502:physiology*