Illusory Correlations in Paranoid Schizophrenia: Another cognitive bias relevant to delusions?

Abstract

Enhanced Illusionary Correlations (IC) may predispose towards delusion formation. The present study examined the frequency and symptomatic correlates of IC in a sample of 25 schizophrenia patients and 40 healthy controls, using emotional cues from different categories (fear, delusion-relevant, neutral), which were presented to the participants followed by happy, neutral or negative affect faces. IC were assessed after the presentation of the emotional cues by asking the participants to judge the frequency with which each cue had previously been shown with each facial expression. As expected, schizophrenia patients exhibited more IC than controls. However, contrary to expectation, this bias was not enhanced for delusion-relevant compared to neutral cues. Furthermore, the expected positive correlation of IC and positive symptoms could not be found. These results suggest the presence of a novel cognitive bias in schizophrenia, occurring irrespective of the stimulus category, which is not directly linked to positive symptoms.