Superstitious perception: response-independent reinforcement and punishment as determinants of recurring eccentric interpretations.

This study provided controlled observations of a potential mechanism for the determination of the repetitive, aberrant perceptions or interpretations of everyday events that figure prominently in a range of psychological disorders: the adventitious reinforcement of acts of cognition by the actual consequences of concurrent motor acts. Adults made a series of two-choice brightness discriminations; on 60% of trials, choosing the brighter stimulus produced a "correct" signal while errors produced an aversive sound. On 40% of trials, the choice stimuli did not in fact differ in brightness; the consequences of responding on these "identical stimuli" trials differed across blocks of trials. Thus, on these trials perceptual judgments were directly followed by events that they did not produce. When all choices on identical stimuli trials were punished with the "error" sound, subjects showed little preference for the left-side or right-side identical stimuli, but when all choices of identical stimuli were reinforced with the "correct" light, individual preferences for the left-side or the right-side stimuli substantially increased. As the consequences of responding on identical stimuli trials were independent of the stimuli chosen, these findings provide evidence for superstitious perception, the reinforcement of perceptual acts by events that do not depend upon their occurrence.