The contribution of a cognitive bias against disconfirmatory evidence to delusions in first episode schizophrenia

Abstract

BACKGROUND: In previous work1 we observed, in chronic patients, that a generalized bias against disconfirmatory evidence (BADE) was associated with delusions in schizophrenia. In the present study we attempted to replicate this finding in first episode schizophrenia spectrum disorders. METHODS: Forty-three first-episode patients diagnosed with schizophrenia spectrum disorders (14 were acutely delusional) and 18 healthy control participants were presented with delusion-neutral scenarios (e.g., Jenny can’t fall asleep), and were asked to rate the plausibility of four causal interpretations (e.g., Jenny is nervous about the exam the next day, Jenny is excited about Christmas morning). Subsequently, two additional scenario descriptions that provided additional information (e.g., Jenny wonders how many presents she will find under the tree) were successively presented, and participants were requested to adjust their ratings after each. The degree to which participants were able to revise ratings of increasingly implausible interpretations in light of new evidence was the core variable of interest. RESULTS: In line with our previous study on chronic patients1, a BADE was observed for delusional compared to non-delusional patients and controls, but not for non-delusional patients compared to controls. CONCLUSION: These results strengthen our account holding that generalized impairment in the processing of disconfirmatory evidence, combined with impairments in metacognition2,3, may contribute to the formation and maintenance of delusions in schizophrenia. References: 1.Woodward, T. S., Moritz, S., Cuttler, C., & Whitman, J. (in press). The contribution of a cognitive bias against disconfirmatory evidence to delusions in schizophrenia. Journal of Clinical and Experimental Neuropsychology. 2. Moritz, S., & Woodward, T. S. (in press). The contribution of metamemory deficits to schizophrenia. Journal of Abnormal Psychology.