EXPECTATION-BASED AND DATA-BASED ILLUSORY CORRELATION - THE EFFECTS OF CONFIRMING VERSUS DISCONFIRMING EVIDENCE

The present study (n = 154) examines the effects of expectations and s timulus information on the perception of illusory correlation. There h ave been few studies attempting to integrate expectation-based and dat a- (distinctiveness-) based processes. These studies suggest that data -based illusory correlation can be overruled by prior expectations, bu t it is nor clear whether this is a consequence of a confirmation bias . In the present study, where participants were not exposed to the spe cific stimulus information, expectation was manipulated by stating tha t group B behaved more negatively than group A. Moreover, participants were provided with information contained in a statement-rating task t hat allowed for the confirmation and disconfirmation of the prior expe ctations. Participants rated the desirability of these behaviours and also performed the standard illusory correlation tasks. Based on self- categorization theory and Alloy and Tabachnik (1984), we predicted tha t in the absence of prior expectations, completing the rating task bef ore the illusory correlation tasks would produce stronger illusory cor relation than the reverse order. However, in the presence of prior exp ectations we expected the rating task to undermine illusory correlatio n, because the information obtained in this task tends to disconfirm p rior expectations. Results support the predicted interaction between t ask order and expectation. We discuss some implications for research o n confirmation bias.