Introduction to the special issue on cognition and delusions: What do we know, what do we guess, and what do we perhaps falsely believe?

Functional brain networks underlying probabilistic reasoning and delusions in schizophrenia

Delusions in schizophrenia are false beliefs that are assigned certainty and not afforded the scrutiny that normally gives rise to doubt, even under conditions of weak evidence. The goal of the current functional magnetic resonance imaging (fMRI) study is to identify the brain network(s) involved in gathering information under conditions of weak evidence, in people with schizophrenia experiencing delusions. fMRI activity during probabilistic reasoning in people with schizophrenia experiencing delusions (n = 29) compared to people with schizophrenia not experiencing delusions (n = 41) and healthy controls (n = 41) was observed when participants made judgments based on evidence that weakly or strongly matched (or mismatched) with the focal hypothesis. A brain network involved in visual attention was strongly elicited for conditions of weak evidence for healthy controls and patients not experiencing delusions, but this increase was absent for patients experiencing delusions. This suggests that the state associated with delusions manifests in fMRI as reduced activity in an early visual attentional process whereby weak evidence is incorrectly stamped as conclusive, manifestating as a feeling of fluency and misplaced certainty, short-circuiting the search for evidence, and providing a candidate neural process for 'seeding' delusions.

The simulation heuristic, paranoia, and social anxiety in a non-clinical sample

BACKGROUND AND OBJECTIVES

Quality of reasoning within non-clinical paranoia and mental simulation of future paranoia themed events was investigated by use of a simulation task to determine whether paranoid individuals would be restricted or more adept at reasoning about paranoia relevant material in comparison to a social anxiety group and a group with low paranoia and social anxiety.

METHOD

Participants (N = 63) were divided into the three groups based on paranoia and social anxiety scores. They were presented with the beginning and end of an imaginary situation and were asked to describe, step-by-step, what they imagined would happen between those two points. They were also administered a beads task to evaluate the jumping to conclusion decision making bias.

RESULTS

The prediction of more adept reasoning was not supported for paranoia. However, the social anxiety comparison group on average better simulated a scenario with congruent (socially anxious) thematic content compared to ones with non-congruent content. Further, in an exploratory analysis, jumping to conclusions bias was found to be positively related to goodness of simulation for paranoia themed scenarios within the paranoia group.

LIMITATIONS

Study groups were relatively small and so power was an issue.

CONCLUSION

The results are discussed in the context of the sometimes paradoxical findings in the area of cognitive biases and paranoia.

Self-Reported Cognitive Biases Are Equally Present in Patients Diagnosed With Psychotic Versus Nonpsychotic Disorders

We investigated the relation between subjective cognitive biases measured with the Dutch Davos Assessment of Cognitive Biases (DACOBS-NL) and (1) the presence of a psychotic versus nonpsychotic psychiatric disorder, (2) the current dose of antipsychotic medication and current psychotic symptoms, and (3) the Personality Inventory for the DSM-5 (PID-5) Psychoticism personality trait. Results showed that DACOBS-NL subjective cognitive biases (1) were equally present in patients diagnosed with nonpsychotic disorders compared with patients with a psychotic disorder, (2) could not be explained by the current dose of antipsychotic medication, nor by current psychotic symptoms, and (3) significantly correlated with all PID-5 Personality domains. Moreover, in predicting membership of the psychotic versus nonpsychotic psychiatric disorder group, the addition of the PID-5 domains in step 2 rendered the contribution of the DACOBS-NL subjective cognitive biases in step 1 nonsignificant. Further research is needed to clarify the interplay between cognitive biases and aberrant salience in the prediction of psychotic disorders.