Hierarchical analysis of the sense of agency in schizophrenia: motor control, control detection, and self-attribution

The sense of agency refers to the feeling of initiating and controlling one's actions and their resulting effects on the external environment. Previous studies have uncovered behavioral evidence of excessive self-attribution and, conversely, a reduction in the sense of agency in patients with schizophrenia. We hypothesize that this apparent paradox is likely to result from impairment in lower-level processes underlying the sense of agency, combined with a higher-level compensational bias. The present study employed three behavioral tasks utilizing the same stimuli and experimental design to systematically evaluate multiple factors that influence the sense of agency, including motor control, sensorimotor processing, and self-attribution. Participants' real-time mouse movements were combined with prerecorded motions of others in ratios of 30/70, 55/45, or 80/20, with an additional angular bias of either 0° or 90°. Twenty-six patients with schizophrenia and 27 health control volunteers participated in the three tasks. Patients with schizophrenia performed significantly worse in the reaching and control detection tasks than healthy controls. However, their self-attribution in the control judgment task was comparable to that of the healthy controls. Patients with schizophrenia were impaired in motor control components and in the detection of control using sensorimotor information, but their evaluation of agency remained relatively less affected. This underscores the importance of distinguishing between different subcomponents when addressing the abnormal sense of agency in patients with schizophrenia. Subsequent cluster analysis revealed that the combined task performance accurately distinguished between the patients and healthy control participants.