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Impaired Evidence Integration and Delusions in Schizophrenia

2012; SAGE Publishing; Volume: 3; Issue: 4 Linguagem: Inglês

10.5127/jep.018411

2043-8087

William J. Speechley, Elton T.C. Ngan, Steffen Moritz, Todd S. Woodward,

Health Systems, Economic Evaluations, Quality of Life

A bias against disconfirmatory evidence (BADE) appears to be related to delusions in schizophrenia. However, preliminary studies have either not used the most comprehensive version of the BADE task, not included a psychiatric control group, and/or have used difference score methodology instead of analyzing all available measures. In the current study a comprehensive version of the BADE task was administered to people with schizophrenia, bipolar disorder and a healthy control group. The BADE task required rating four interpretations of delusion-neutral scenarios three times (in sequence) as increasingly disambiguating information was presented. A principal component analysis (PCA) carried out on all measures determined that two independent cognitive processes appear to combine to determine all responses on the BADE task: Integration of Evidence and Conservatism, with only the former discriminating between the severely delusional schizophrenia group and all other groups. Thus, integration of evidence appears to be functioning sub-optimally in severely delusional schizophrenia patients, resulting in a bias against disconfirmatory evidence (BADE). The cognitive process theorized to be underlying this effect is hypersalience of evidence-hypothesis matches.