Abstract
Illusory correlation means misperceived correlation between two variables which do not correlate. We examined the effects of skews of marginal distribution which is frequency distribution of each variable and joint distribution which is frequency distribution of combined items of two variables on illusory correlation. Participants were asked to predict targets (A or B) from predictors (square or circle). Targets were hidden on the half of trials. This made non-skewed conditions in which either the marginal distribution of the predictor or the joint distribution was not skewed. In skewed conditions and control condition both distributions were skewed, and targets were presented on all trials in the control condition. Illusory correlations were observed in the skewed conditions and the control condition whereas it was not observed in the non-skewed conditions. This suggests that both skews of marginal distribution and joint distribution play crucial roles for illusory correlation.
