Cue-contingent adaptation to color

The last of a series of drug administrations elicits a smaller response in the presence of drug-paired cues than in the presence of alternative cues. Such cue-contingent tolerance suggests that Pavlovian conditioning contributes to pharmacological adaptation. The present experiments evaluated the generality of the conditioning analysis of pharmacological adaptation to adaptation to a nonpharmacological stimulus—color. We demonstrated cue-contingent adaptation to color; chromatic adaptation is more pronounced (the color appears more desaturated) in the presence of orientation cues previously paired with the color than in the presence of other cues. Orientation-color pairings also result in complementary color aftereffects contingent on orientation (the McCollough effect). We hypothesize that the McCollough effect is the conditional response that mediates cue-contingent chromatic adaptation, much as we have hypothesized that drug-compensatory conditional responses mediate contingent adaptation to drugs, and other investigators have hypothesized that other compensatory conditional responses mediate contingent adaptation to other stimuli.