CONTEXT AND THE INVERSE BASE-RATE EFFECT

Recent categorization research set in abstract medical diagnosis conte xts has demonstrated an 'inverse base rate effect', whereby subjects m ake diagnoses which are consistent with base rates when presented with some sets of symptoms, but inconsistent with base rates when presente d with other sets of symptoms. This paper reports three experiments wh ich demonstrate that whether or not the inverse base rate effect is ob served depends on the context in which categorization takes place. Inv erse base rate effects are replicated in the abstract medical diagnosi s context used in prior research, but not in a relatively realistic fi nancial auditing setting, a less realistic financial auditing setting, or a very abstract generic setting. These results indicate that the i nverse base rate effect may not generalize to applied settings, sugges ting that interventions designed to mitigate the inverse base rate eff ect should not be instituted without first determining the existence o f the effect in the particular setting in question.