Naive theory impairment in schizophrenia: is it domain-specific?

The ability to represent mental states of self and others to account for behavior is called theory of mind (ToM). This study examined whether ToM deficit in schizophrenia patients is a specific deficit in the cognitive component of interpersonal skills or a more global deficit, involving impaired information processing skills. Schizophrenia inpatients (N = 41) were compared with a control group of healthy subjects (N = 22) and to nonschizophrenia psychiatric patients (24 with affective disorders, seven with other psychosis) over a range of ToM tasks and another naive theory (theory of biology; ToB). Psychiatric inpatients as a whole showed significant deficit compared with the control group of healthy subjects in ToM tasks. The schizophrenia patients showed significantly larger deficits compared with patients suffering from affective disorder, while the performance of patients with nonschizophrenia psychosis was intermediate. In contrast, no difference was observed in the performance of the different groups on the ToB tasks. The fact that a deficit was found in ToM but not in ToB suggests a specific deficit in a cognitive component of interpersonal skills in schizophrenia rather than a general deficit in information processing skills. Naive theories deficits in schizophrenia seem to be domain-dependent.