ABSTRACT
Introduction Many of the symptoms of schizophrenia involve experiences that are outside the normal range. Yet they must be the consequence of impairments to normal psychological processes. We (Frith, 1987; Frith & Done, 1988) have recently proposed that symptoms such as delusions of control and thought interference are the consequence of failure in a system whereby we monitor our intended actions (see also Feinberg, 1978). This monitoring permits the distinction between internally generated (willed) and externally generated (stimulus elicited) actions. It is necessary if we are to know what we have just done and why. If thoughts and actions occurred in the absence of central monitoring they might be attributed to alien forces.
