Mentalising, schizotypy, and schizophrenia

Despite accumulating evidence that patients with schizophrenia perform poor ly in mentalising tasks, doubts remain about the primacy of the role played by defective mentalising in schizophrenia. This study investigated the rel ationship between mentalising ability and self-reported schizotypal traits in non-clinical adults who reported no history of psychiatric illness in or der to test two counter-proposals: (1) defective mentalising is a primary c ause of psychotic symptoms in schizophrenia; and (2) defective mentalising in schizophrenia is a secondary consequence of the chronic asociality that is typical of general psychiatric illness. Mentalising ability was tested u sing a false-belief picture sequencing task that has been used elsewhere to demonstrate poor mentalising in patients with schizophrenia. Evidence of s elective mentalising deficits in high schizotypal non-clinical subjects dis counted the view that defective mentalising is restricted to psychiatric il lness and strengthened the case for continuity models of psychosis-pronenes s. Furthermore, evidence that poor mentalisers in the normal population are more likely to self-report psychotic-like traits, as well as asocial or id iosyncratic behaviours, refuted suggestions that defective mentalising is l inked solely to asocial symptomatology and supported the view that defectiv e mentalising may have a fundamental role to play in the explanation of psy chotic symptoms. In order to specify what that role might be, alternative t heoretical accounts of defective mentalising were tested. Neither executive planning deficits nor failure to inhibit cognitively salient inappropriate information could adequately explain the pattern of selective mentalising deficits found in high schizotypal non-clinical subjects. Our findings sugg est that there exists a domain-specific cognitive module that is dedicated to inferring and representing mental states which, when dysfunctional, caus es defective mentalising that manifests phenomenologically in psychotic-lik e traits and impoverished social awareness of variable expression and rangi ng severity. (C) 1999 Elsevier Science B.V. All rights reserved.