Stereotypes as Judgmental Heuristics: Evidence of Circadian Variations in Discrimination

The question of when people rely on stereotypic preconceptions in judging others was investigated in two studies. As a person's motivation or ability to process information systematically is diminished, the person may rely to an increasing extent on stereotypes, when available, as a way of simplifying the task of generating a response. It was hypothesized that circadian variations in arousal levels would be related to social perceivers' propensity to stereotype others by virtue of their effects on motivation and processing capacity. In support of this hypothesis, subjects exhibited stereotypic biases in their judgments to a much greater extent when the judgments were rendered at a nonoptimal time of day (i.e., in the morning for “night people” and in the evening for “morning people”). In Study One, this pattern was found in probability judgments concerning personal characteristics; in Study Two, the pattern was obtained in perceptions of guilt in allegations of student misbehavior. Results generalized over a range of different types of social stereotypes and suggest that biological processes should be considered in attempts to conceptualize the determinants of stereotyping.