Abstract
PURPOSE: How are separate neural representations of color (red) and form (an oriented grating) bound together to give a unified percept (a red grating)? Dichoptic presentation of rivalrous chromatic gratings reveals perceptual mis-binding of color and form, which implies (1) color and form rivalry are resolved separately and (2) resolution of color rivalry goes beyond just color dominance and color mixture. METHODS AND RESULTS: An equiluminant square-wave red/gray grating was presented to the left eye and an equiluminant blue/gray grating to the right eye. After an initial period of rivalry (less than a minute), these stimuli resulted in a perceived red/blue grating. This two-color perceived grating is not consistent with previous studies of dichoptic presentation of two chromaticities, which report either binocular color rivalry or binocular color mixture. Instead, the percept is accounted for by mis-binding of the color presented to each eye with the perceived form. In experiments, observers dichoptically viewed two rivalrous stimuli for 1 minute. The visibility time was measured for three percepts: left-eye stimulus, right-eye stimulus, or two-color grating. The chromaticities of the gratings were varied to exclude opponent chromatic induction as an explanation. Three types of spatial configurations were tested to exclude optical misalignment (eye vergence) as an explanation. All three configurations gave rise to the percept of a two-color grating, regardless of the chromaticities. CONCLUSIONS: The experiments showed that neither classical chromatic contrast nor misalignment of the two eyes could explain the percept of a grating with both eyes' rivalrous chromaticities (e.g., a red/blue grating). These results show that color rivalry is resolved independently of form rivalry and, further, that two rivalrous colors can both be represented simultaneously but separately. “Resolution” of color rivalry is not restricted to color dominance or color mixture.
This research was supported by PHS grant EY-04802.