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Confirmation biases across the psychosis continuum: The contribution of hypersalient evidence-hypothesis matches

Authors


Correspondence should be addressed to Ryan Balzan, School of Psychology, Hughes Building, The University of Adelaide, Adelaide, SA 5005, Australia (e-mail: ryan.balzan@adelaide.edu.au).

Abstract

Objectives

Hypersalience of evidence-hypothesis matches has recently been proposed as the cognitive mechanism responsible for the cognitive biases, which, in turn, may contribute to the formation and maintenance of delusions. However, supporting evidence for this construct is still required. Using two tasks designed to elicit three core facets of the confirmation bias (i.e., biased search of confirming evidence; biased interpretation of confirming evidence; and biased recall of confirming evidence), this article investigated the possibility that individuals with delusions and those identified as delusion-prone are hypersalient to evidence-hypothesis matches.

Methods

A total of 75 participants (25 diagnosed with schizophrenia with a history of delusions; 25 non-clinical delusion-prone; 25 non-delusion-prone controls) completed both tasks.

Results

The results across both tasks showed that participants with schizophrenia and delusion-prone participants prefer: non-diagnostic or non-specific positive tests over diagnostic negative tests (biased search); rate confirming evidence as more important than disconfirming evidence (biased interpretation); and remember confirming evidence with greater ease than disconfirming evidence (biased recall). Participants with higher delusional ideation also failed to integrate disconfirmatory evidence to modify prior hypotheses.

Conclusions

These results suggest that delusional ideation is linked to a hypersalience of evidence-hypothesis matches. The theoretical implications of this cognitive mechanism on the formation and maintenance of delusions are discussed.

Practitioner Points

Clinical Implications

  • Evidence that people with delusions, and those identified as delusion-prone, are more susceptible to confirmation biases than non-delusion-prone controls.
  • Confirmation biases may therefore play a role in the formation and maintenance of delusional beliefs.
  • Further evidence that one of the underlying cognitive mechanisms behind many cognitive biases in people with delusions is a hypersalience of evidence-hypothesis matches. This has implications for psychotherapies that target delusion formation and maintenance, such as the metacognitive training (MCT) programme for people with schizophrenia.

Limitations

  • Heterogeneous delusional symptoms within patient group (i.e., consisted of individuals with mild to moderate active delusions and individuals with remitted delusions).
  • Delusion-prone group not consistently distinct from non-delusion-prone group across all tasks.
  • Set order of tasks across participants may have led to practice effects.
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