The influence of naive causal theories on lay concepts of mental illness

Two experiments, incorporating both real-life (Experiment 1) and artificial (Experiment 2) stimuli, demonstrated that lay concepts of mental disorders can be reliably predicted from subjects' naive causal theories about those disorders. Symptoms that are deeper causes (X, where X causes Y, which causes Z) are more important in lay concepts than intermediate causes (Y), which in turn are more important than terminal effects (Z). In addition, symptoms that cause or are caused by other symptoms are more important in lay concepts than symptoms not participating in any causal relationships. Implications of these results for current models of categorization and for research on lay theories of mental disorders are discussed, and future directions for research are suggested.