The effects of categorization on social judgement

Abstract

The effects of categorization on judgement have been of considerable importance in recent social psychology. The two principal effects of categorization on judgement are the accentuation of judged similarities within classes and of judged differences between classes. While there is good evidence for each effect independently, specific experiments tend to show one effect or the other but not both. The variables examined here were classification, social influence and information about the classification. In two experiments ( N = 96 and N = 103) both categorization effects were observed as a result of explicit classification (the interclass effect in Expt 1 being significant only with moderate extremity information). Furthermore, in Expt 1 social influence had powerful effects. Interestingly, it was found that providing information per se did not increase the strength of categorization effects. It is concluded that both categorization effects are reliable in a social judgement task under appropriate conditions. The findings are used to argue that accessible categories generally become salient where they provide a meaningful fit to stimulus information and are implicitly normative.