Illusory body-ownership entails automatic compensative movement: for the unified representation between body and action.

The rubber hand illusion (RHI) makes people feel that a fake hand is their own when they see it stroked in sync with their own hidden hand. This illusion typically causes a sense that their real hand has shifted toward the fake hand (proprioceptive drift). Two experiments show that participants' actual hand, resting on a movable board, physically moved toward the rubber hand during synchronous stroking. Even when the board was fixed, participants unconsciously pushed force toward the rubber hand. These results suggest that awareness of one's body and one's actions are tightly linked, forming a unified sense of self as a single agent.

Study at a glance

Abstract

The sense of body-ownership involves the integration of vision and somatosensation. In the rubber hand illusion (RHI), watching a rubber hand being stroked for a short time synchronously as one's own unseen hand is also stroked causes the observers to attribute the rubber hand to their own body. The RHI may elicit proprioceptive drift: The observers' sense of their own hand's location drifts toward the external proxy hand. The current experiments examined the possibility of observing, not the proprioceptive drift, but the actual drift "movement" during RHI induction. The participants' hand, located on horizontally movable board, tended to move toward the rubber hand only while they observed synchronous visuo-tactile stimulation. Furthermore, even when the participants' hand was located on a fixed, unmovable board (that is, the conventional RHI paradigm), participants automatically administered the force toward the rubber hand. These findings suggest that since awareness of our own body and action are fundamental to self-consciousness, these components of "minimal self" are closely related and integrated into "one agent" with a unified awareness of the body and action.