Causal Judgement from Information about Outcome Magnitude

Abstract

Information was presented in which a candidate cause was either present or absent, and the outcome variable (number of spots on a patient's skin) could take any of four nonzero values. It was found that cause-absent information carried greater weight than cause-present information. This is contrary to the usual finding for contingency information about binary outcome variables. Judgement was influenced more by extreme values of the outcome variable, and larger outcome values tended to have more effect on judgements than smaller outcome values. The hypothesis that participants compute linear correlation is disconfirmed by these results. Instead, the results show that participants focus disproportionate attention on some kinds of events and neglect others.