Belief inflexibility in schizophrenia.
BACKGROUND
Previous studies using delusion-neutral material have demonstrated that patients with schizophrenia, particularly those with delusions, display a bias against disconfirmatory evidence (BADE). In the current study we investigated the moderating impact of belief strength on this effect.


METHODS
Thirty-three schizophrenia patients, 18 patients with obsessive compulsive disorder, and 25 healthy control participants, were consecutively presented with delusion-neutral statements that provided increasingly detailed information about a scenario. They were asked to re-rate the plausibility of four descriptions of the scenario. The correct ("true") interpretation appeared poor on the first statement and then increasingly gained plausibility, whereas "lure" interpretations appeared plausible initially to varying degrees, but became implausible once all information was presented.


RESULTS
Schizophrenia patients displayed a BADE for strong beliefs, in that they were biased against revising their ratings of lure items in light of new disconfirming evidence compared to the mixed control group. However, like controls, patients with schizophrenia were willing to revise weak beliefs.


CONCLUSIONS
This confirms that schizophrenia patients are generally impaired in their ability to integrate disconfirmatory evidence, even for material that does not touch on delusional themes. This response pattern was more pronounced for strong beliefs, and this may contribute to the fixation of false ideas (i.e., delusions).
Woodward
Todd S
TS
Department of Psychiatry, University of British Columbia, and BC Mental Health and Addictions Research Institute, PHSA Research & Networks, Vancouver, BC, Canada. Todd.S.Woodward@gmail.com
Moritz
Steffen
S
Menon
Mahesh
M
Klinge
Ruth
R
D000328:Adult; D001290:Attitude; D016022:Case-Control Studies; D003071:Cognition; D003702:Delusions / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder; D012565:Schizophrenic Psychology