Illusory correlations and control across the psychosis continuum: The contribution of hypersalient evidence-hypothesis matches

It has recently been proposed that individuals with delusions may be hypersalient to evidence-hypothesis matches, which may contribute to the formation and the maintenance of delusions. However, empirical support for the construct is limited. Using cognitive tasks designed to elicit the illusory correlation bias (i.e., perception of a correlation in which none actually exists) and the illusion of control bias (i.e., overestimation of one's personal influence over an outcome), the current article investigates the possibility that individuals with delusions are hypersalient to evidence-hypothesis matches. It was hypothesized that this hypersalience may increase a person's propensity to rely on such illusory correlations and estimates of control. A total of 75 participants (25 participants diagnosed with schizophrenia with a history of delusions, 25 nonclinical participants with delusion proneness, and 25 controls without delusion proneness) completed computerized versions of the "fertilizer" illusory correlation task developed by Kao and Wasserman (J Exp Psychol Learn Mem Cogn 19:1363-1386; 1993) and the "light- onset" illusion of control task created by Alloy and Abramson (J Exp Psychol Gen 108:441-485; 1979). The results across both tasks showed that the participants with schizophrenia were more susceptible than the nonclinical groups to illusory correlations (i.e., higher estimates of covariation between unrelated events) and illusions of control (i.e., higher estimates of control and perceived connection between the responses and the outcome). These results suggest that delusional ideation is linked to a hypersalience of evidence-hypothesis matches. The theoretical implications of this cognitive mechanism on the formation and the maintenance of delusions are discussed.