Hierarchical Components of Sense of Agency in Schizophrenia: From Motor Control to 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. Abnormal sense of agency has been reported in patients with schizophrenia. Previous studies have uncovered behavioural evidence of excessive self-attribution and, conversely, a reduction in sense of agency. This apparent paradox has yet to be fully resolved. In the current study, we employed three behavioural tasks utilising the same stimuli and experimental design to systematically evaluate multiple factors that influence sense of agency. These tasks included motor control, sensorimotor processing, and self-attribution. In all three tasks, participants’ real-time mouse movements were combined with prerecorded other’s motions with an angular bias of either 0 or 90 degrees. In the reaching task, participants were asked to move a dot to touch a target on the screen as frequently as possible. The control detection task required participants to identify one target dot among three moving dots whose motion incorporated a certain level of real-time mouse movement. In the control judgement task, participants made a binary yes/no response to indicate whether they felt they had control over the direction of one moving dot on the screen. The results indicated that patients with schizophrenia performed significantly worse on reaching and control detection tasks than healthy controls. However, their self-attribution judgement in the control judgement task was comparable to that of the healthy controls. The patient group seemed to retain the ability to evaluate the contingency between sensory and motor information; however, their capacity to use this sensorimotor information as a cue to detect control in a noisy environment was compromised. Subsequent cluster analysis revealed that the combined performance results of the three tasks accurately distinguished patients from healthy controls. To understand the interplay between the hierarchical components of sense of agency, we propose that both top-down and bottom-up sensorimotor signals processing is involved. Patients with schizophrenia show notably stronger dysfunction in bottom-up processes than in top-down processes.