Abstract
The dominant cognitive model that accounts for the persistence of delusional beliefs in schizophrenia postulates that patients suffer from a general deficit in belief revision. It is generally assumed that this deficit is a consequence of impaired reasoning skills. However, the possibility that such inflexibility affects the entire system of a patient's beliefs has rarely been empirically tested. Using delusion-neutral material in a well-documented advice-taking task, the present study reports that patients with schizophrenia: 1) revise their beliefs, 2) take into account socially provided information to do so, 3) are not overconfident about their judgments, and 4) show less egocentric advice-discounting than controls. This study thus shows that delusional patients' difficulty in revising beliefs is more selective than had been previously assumed. The specificities of the task and the implications for a theory of delusion formation are discussed.
Highlights
Belief change is a complex process by which rational agents shift from one belief state to another as a way to improve their knowledge [1]
They admit that perceptual aberrations, potentially coupled with attributional biases, strongly contribute to generate the content of bizarre delusions. They emphasize that such factors are not sufficient to explain why delusional beliefs are deeply entrenched instead of being ephemeral hypotheses doomed to disappear. In particular they argue that having an anomalous experience should not prevent individuals from accepting the possibility that some dysfunction arises in their mind and that their experience is inaccurate
Consistent with this view they provide numerous examples of brain dysfunctions that result in anomalous experiences without resulting in delusional beliefs
Summary
Belief change is a complex process by which rational agents shift from one belief state to another as a way to improve their knowledge [1]. One can reasonably assume that a dysfunction in such a mechanism would prevent an individual from correctly assessing her/his beliefs and eliminating those that are patently false in light of compelling counter-evidence This could lead her/him to hold ill-founded, irrational or even delusional beliefs. Deficit in belief revision will not cause the abnormal or unrealistic content of these beliefs by itself, but it could make these beliefs hard to assess and reject This idea has been largely developed by Langdon and Coltheart [4] (see [5,6]). They emphasize that such factors are not sufficient to explain why delusional beliefs are deeply entrenched instead of being ephemeral hypotheses doomed to disappear In particular they argue that having an anomalous experience should not prevent individuals from accepting the possibility that some dysfunction arises in their mind and that their experience is inaccurate. It is not the case that experiencing a serious perceptual anomaly leads to delusion
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