title: Chromatic tuning of contour-shape mechanisms revealed through the shape-frequency and shape-amplitude after-effects.
abstract: We investigated whether contour-shape processing mechanisms are selective for color direction using the shape-frequency and shape-amplitude after-effects, or SFAE and SAAE [Gheorghiu, E. & Kingdom, F. A. A. (2006). Luminance-contrast properties of contour-shape processing revealed through the shape-frequency after-effect. Vision Research, 46(21), 3603-3615. Gheorghiu, E. & Kingdom, F. A. A. (2007). The spatial feature underlying the shape-frequency and shape-amplitude after-effects. Vision Research, 47(6), 834-844]. All contours were defined along the 'red-green', 'blue-yellow' and 'luminance' axes of cardinal color space. Adapting and test contours were defined along the same or along opposite polarities within a cardinal axis, and along the same or along different cardinal axes. We found (i) little transfer of the after-effects across different within-axis polarities, for all cardinal axes and for both even-symmetric and odd-symmetric contours; (ii) little transfer between the red-green and blue-yellow cardinal axes; (iii) little transfer between the chromatic and luminance cardinal directions for the SAAE; (iv) large transfer between the chromatic and luminance cardinal directions for the SFAE. We conclude that contour-shape mechanisms are selective for within-cardinal axis polarity and for the chromatic axes within the isoluminant plane. However for certain types of contour-shape processing they are poorly selective along the chromatic versus luminance dimension. Overall our results suggest that contour-shape encoding mechanisms are selective for color direction and that color is important for contour-shape processing.
authors.affiliation: McGill Vision Research, Department of Ophthalmology, McGill University, 687 Pine Avenue W., Montreal H3A 1A1, Que., Canada. elena.gheorghiu@mcgill.ca
authors.forename: Elena
authors.initials: E
authors.lastname: Gheorghiu
authors.forename: Frederick A A
authors.initials: FA
authors.lastname: Kingdom
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D003118:Color Perception / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology; D005366:Figural Aftereffect / Q000502:physiology; D006801:Humans; D008027:Light; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D014796:Visual Perception / Q000502:physiology*