[Development of the sense of agency scale and its factor structure]

A "sense of agency" involves a contemporaneous experience that the "self" causes the actions performed by the "self" (i.e., "I am the one who causes my actions"). This may comprise the main component of self-consciousness. The present research focuses on the development of a questionnaire to investigate the subjective aspects of a sense of agency. We selected items from the extant relevant measures and from previous empirical studies, and conducted four longitudinal surveys with additional scales. Statistical computations confirmed the validity and reliability of the Sense of Agency Scale (SOAS), consisting of seventeen items involving three factors. Furthermore, the results indicated that these three factors might be organized hierarchically, with each factor showing a unique relationship with emotional or social traits. This novel finding, emerging from the Sense of Agency Scale, would have been difficult to obtain via traditional empirical studies.