Belief Revision and Delusions: How Do Patients with Schizophrenia Take Advice?

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

Accuracy and confidence: patients and controls perform in a similar way.

<p>Accuracy (<b>A</b>): Mean number of years away from the correct date; Confidence (<b>B</b>): Mean level of confidence. Bars indicate standard error means.</p

The Weight of Advice predicts the severity of clinical symptoms.

<p>The linear regression lines derived from the linear regressions analyses between the Weight of Advice (explanatory factor) and patients’ symptoms are shown in red. The 95% confidence intervals for the regression lines are shown in grey. Note that the correlation is positive for SAPS subscores (<b>a, b, c</b>), and negative for the SANS subscore (<b>d</b>).</p

Example of the second part of the experimental procedure.

<p>Participants had to copy their initial answer and degree of confidence, read the advice presented and then give their final estimate along with a final confidence rating.</p

Patients put weight more on the advice than control participants.

<p>The dashed line represents equal weight ascribed to advice and initial opinions. Bars indicate standard error means.</p

Clinical and demographic characteristics of patients and controls.

<p>Clinical and demographic characteristics of patients and controls.</p

Proportions of choosing and averaging in the two groups.

<p>Proportions of choosing and averaging in the two groups.</p