Expectancy-effects without expectancies: Illusory correlations based on cue-overlap

Expectancy-based illusory correlations have been observed in numerous exper iments. Simulations using the connectionist computer model BIAS (Fiedler, 1 996) show that such illusory correlations may not always reflect expectancy biases but influences of similarity via cue-overlap. Cue-overlap means tha t some of the probabilistic cues that indicate the presence of one variable are also indicative of another variable. In an experiment, participants le arned two novel concepts pertaining to a fictitious painter and a fictitiou s artistic style in separate runs. Both concepts were defined by multiple p robabilistic cues observable in paintings. For half the participants, the c ue systems underlying the perception of the two concepts overlapped whereas for the other half they did not. In addition, we manipulated whether or no t participants expected a positive contingency between artist and artistic style. In the second part of the experiment, a series of paintings was pres ented that constituted an objective zero correlation between artist and art istic style. Participants' subsequent contingency judgments were assessed b y direct and indirect measures. Data analyses revealed main effects for exp ectancy induction and cue-overlap but no interaction on the direct measure and nearly identical results on the indirect measure. Thus, cue-overlap and expectancy induction independently triggered the development of illusory c orrelations. Copyright (C) 2000 John Wiley & Sons, Ltd.