Monocularly established the McCollough effect, an orientation-specific color effect, using the aftereffect inspection pattern of C. Blakemore and P. Sutton (see record) oriented vertically on a red ground, which alternated with the inspection pattern oriented horizontally on a green ground. 48 undergraduates were tested for the size aftereffect and the McCollough effect with neutral vertically and horizontally oriented test patterns presented either to the same eye used during inspection or to the opposite eye. The size aftereffect showed interocular transfer as it occurred in both conditions, while the McCollough effect was observed only in the same eye test condition. Results are interpreted to mean that the McCollough effect involves color adaptation at a visual locus separate from orientation-specific receptors. (PsycINFO Database Record (c) 2006 APA, all rights reserved)