Knowledge‐based causal inference: Norms and the usefulness of distinctiveness

Research on Kelley's (1967, 1972) covariation model of causal attributions has typically overlooked the effects of subjects' prior knowledge of norms on causal judgements. The present studies were designed to show that such norms are important in part because they help govern the usefulness of distinctiveness information for making such attributions. Study 1 revealed that distinctiveness information is considered more useful for answering causal questions when it involves a low base rate event compared to when it involves a high base rate event. Study 2 showed that distinctiveness information involving a low base rate event makes dispositional attributions more likely. The results are discussed in terms of how they question the common belief that consensus information is underused in causal attributions and in terms of how various forms of social judgment appear affected by the inconspicuous yet influential presence of norms. 1992 The British Psychological Society