The sense of agency and its disturbances in schizophrenia: a reappraisal.

How it happens that one can recognise oneself as the source of one's own actions? This process of self-recognition is in fact far from trivial: although it operates covertly and effortlessly, it depends upon a set of mechanisms involving the processing of specific neural signals, from sensory as well as from central origin. In this paper, experimental situations where these signals can be dissociated from each other and where self-recognition becomes ambiguous will be used in healthy subjects and in schizophrenic patients. These situations will reveal that there are two levels of self-recognition, an automatic level for action identification, and a conscious level for the sense of agency, which both rely on the same principle of congruence of the action-related signals. The automatic level provides an immediate signal for controlling and adapting actions to their goal, whereas the conscious level provides information about the intentions, plans and desires of the author of these actions. The contribution of schizophrenic patients is to show that these two levels can be dissociated from each other. Whereas the automatic self-identification is functional in these patients, their sense of agency is deeply impaired: the first rank symptoms, which represent one of the major features of the disease, testify to the loss of the ability of schizophrenic patients to attribute their own thoughts, internal speech, covert or overt actions to themselves.