Central monitoring deficiency and schizophrenic symptoms.

Twenty-five schizophrenic patients currently experiencing Schneiderian symptoms performed a series of tasks in which drawings had to be made in the absence of immediate visual feedback. In comparison to 10 normal controls and to 30 patients not experiencing Schneiderian symptoms, the target group had great difficulty in keeping track of their performance and remembering what actions they had made. These results are consistent with the hypothesis that Schneiderian symptoms (such as delusions of alien control) are associated with impairments in the central monitoring of action.