A mathematical model for social influences on perceptual judgments

A mathematical model based upon signal detection theory is developed that characterizes social influences upon judgments of a stimulus. A social influence cue and the physical aspects of the stimulus were assumed to have independent effects upon performance. A visual movement discrimination task was employed in which subjects could make their judgment either before or after a cue that they had been led to believe was the response of another subject. The accuracy of this “response” was varied. The model provided a good account of the data. A model-based estimate of the magnitude of the influence effect indicated that this effect was greater when the “other” was highly accurate. The model provided an interpretation of social influences on perceptual judgments in which influence pressures have their effects only when subjects' sensory impressions are ambiguous.