Overconfidence or resolution in psychosis: a Bayesian reanalysis.

Abstract

Introduction: People with psychosis place greater confidence in errors and less confidence in accurate judgements relative to controls. This overconfidence in errors bias is theorised to contribute to the formation and maintenance of delusions. However, no research has examined whether people with psychosis have an impaired ability to judge whether they are confident or not, known as resolution. This study aimed to establish whether psychosis populations show a resolution deficit.

Method: We used hierarchical Bayesian modelling and Type 2 Signal Detection Theory to explore whether participants with schizophrenia (n = 25) had poorer resolution and higher overconfidence than high delusion-prone (n = 25) and low delusion-prone participants (n = 25) when making confidence judgements. A discrimination index and over/underconfidence statistic examined resolution and overconfidence, respectively.

Results: While all participants showed a low discrimination index, schizophrenia participants had a meaningfully lower discrimination index than low delusion-prone participants, indicating poorer resolution. All groups were overconfident, with schizophrenia participants showing the greatest level of overconfidence.

Conclusions: Results suggest schizophrenia patients show impairments in using confidence judgements to discriminate between correct and incorrect judgements. Resolution deficits in psychosis could have theoretical and clinical implications for our approach towards delusions.