Effect of a Body Part Action on Body Perception of the Other Inactive Body Part

The rubber hand illusion (RHI) is an illusory experience in which a fake rubber hand is felt as if it were one’s own hand when the visible fake and invisible real hands are stimulated synchronously. Although several studies have suggested contributions of action to body ownership using the RHI paradigm, the relationship between body ownership and agency has not yet been fully revealed. To better understand this relationship, the present study investigated the transfer of body ownership between body parts induced by a body part action. Using an RHI paradigm involving virtual reality, we tested whether a simple finger action of the dominant (active) hand can induce the embodiment of a virtual hand corresponding to the nondominant (inactive) hand. We evaluated the illusory experience, perceptual changes, and physiological changes during the experiment with a subjective questionnaire, crossmodal congruency effect measurement, and skin temperature measurement, respectively. The results demonstrated that the finger action induced the embodiment of both virtual hands, causing a significant increase in agency of the inactive hand. This suggests that the illusory experience induced by an active body part contributes to an increase in agency as well as body ownership over the virtual body of the other inactive body part.