Assessment of the McCollough effect by a shift in psychometric function

Following adaptation to chromatic grids, we assessed the orientation-contingent color aftereffect with a new procedure—a shift in the psychometric function from the preadaptation level. With this procedure, the conditions that did and did not induce the aftereffect were the same as those previously reported with other measurement procedures. The psychometric function shift provides a new, simple, and objective technique for evaluation of illusory color.