Internal source monitoring and thought disorder in schizophrenia.

A new task was developed to examine source monitoring in 52 patients with schizophrenia. Patients and nonpsychiatric controls were not found to differ on recognition memory, source discrimination, or attribution bias when the between group difference in IQ was controlled. However, among patients, source discrimination was significantly related to severity of thought disorder. After controlling for IQ and verbal working memory, thought-disordered patients were significantly poorer than nonthought-disordered patients at discriminating the source of previously presented information. Results suggest that internal source monitoring is specifically related to thought disorder in patients with schizophrenia.