Background. The present study investigated whether a failure of self-monitoring contributes to core syndromes of schizophrenia.

Method. Three groups of patients with a DSM-IV diagnosis of schizophrenia (n=27), with either prominent paranoid hallucinatory or disorganization syndrome, or without these symptoms, and a matched healthy control group (n=23) drew circles on a writing pad connected to a PC monitor. Subjects were instructed to continuously monitor the relationship between their hand movements and their visual consequences. They were asked to detect gain changes in the mapping. Self-monitoring ability and the ability to automatically correct movements were assessed.

Results. Patients with either paranoid-hallucinatory syndrome or formal thought disorder were selectively impaired in their ability to detect a mismatch between a self-generated movement and its consequences, but not impaired in their ability to automatically compensate for the gain change.

Conclusions. These results support the claim that a failure of self-monitoring may underlie the core symptoms of schizophrenia.