Background. Frith & Done (1988) have proposed that the experience of alien control symptoms in schizophrenia is related to a failure by such individuals to monitor effectively their own willed intentions, actions and thoughts.

Method. To examine this hypothesis, a heterogeneous group of 35 patients, all carrying a DSM-III-R diagnosis of schizophrenia (or schizophreniform psychosis) and 24 non-patient controls, completed a battery of neuropsychological and cognitive tests, which inter alia, included four putative measures of self-monitoring. Patients took part in a detailed clinical interview to assess current levels of symptomatology.

Results. Patients generally performed at a lower level on most components of the test battery, including the four self-monitoring tests. Moreover, patients currently experiencing symptoms of alien control tended to experience greater difficulty with each of the self-monitoring tests; an effect that was relatively independent of neuropsychological or general cognitive function.

Conclusions. The relationship between poor self-monitoring and the presence of alien control symptoms provides support for Frith & Done's account of the origins of these symptoms in schizophrenia.