Dissecting Sense of Agency in Schizophrenia: A Predictive Coding Perspective.

Background and hypothesis: A large body of literature suggests that neurocognitive processes underlying the sense of agency are disrupted in schizophrenia. We here tested the sense of agency in schizophrenia patients, by controlling for the potential confounding effect of temporal perception biases, antipsychotics, attentional-executive functioning, and illness duration. We also analyze the role of symptoms such as delusions, hallucinations, and passivity experiences.

Study design: We capitalized on the intentional binding phenomenon, an implicit measure of the sense of agency. 30 schizophrenia patients and 30 healthy controls completed 2 tasks. Experimental task participants pressed a switch to turn a light bulb on (active condition) or let their finger be moved by an automated switch (passive condition). They then judged the interval between the action (active or passive) and the lighting of the bulb. Control task participants estimated the time interval between two light flashes presented in sequence. All participants underwent a comprehensive neuropsychological assessment, while schizophrenia patients were also evaluated for positive, negative symptoms, and passivity symptoms.

Study results: Control participants showed the expected intentional binding effect, particularly at shorter action-outcome delays. In contrast, the effect was absent in schizophrenia patients. The alteration was significantly moderated by temporal perception biases, hallucinations, and delusions.

Conclusions: The study provides the first evidence in favor of the relationship between agency disturbances, symptomatology, and temporal perception biases in schizophrenia while excluding putative confounding factors like neuroleptics. Results are discussed in the light of a recent predictive coding model of the sense of agency.