The ownership of a virtual body induced by visuo-tactile stimulation indicates the alteration of self-boundaries

Watching a virtual body (avatar) being stroked while one’s own body is being synchronously stroked has been shown to elicit the experience of bodily ownership over the avatar in the viewer. Previously this has been interpreted such that individuals take exclusively ownership over the avatar. However, it should be considered that due to the sensory integration of visual and tactile percepts avatar ownership could be the result of a decrease of differentiation between (visual) non-self and (tactile) self-percepts. Hence, in this case individuals would incorporate an avatar, because the boundaries of what they experience as ‘‘themselves’’ get altered. We have used a head-mounted display based setup in which participants viewed an avatar from behind within a virtual city. We stroked the participants’ body while they watched the avatar getting synchronously stroked. Subsequently, we assessed their avatar and their spatial presence experience with a questionnaire, and then repeated the initial treatment. Finally, we rotated the participants’ perspective around their vertical axis for 1 min. During rotation the avatar was in the same location in front of the viewer. Participants were asked to indicate when they started to experience self-motion. They reported higher identification with the avatar and showed a later onset of visually induced self-motion perception after visuo-tactile stimulation. Overall, our results indicate that there was a decrease of differentiation between non-self and self-percepts. Hence, we propose that avatar ownership should not be understood as a ‘‘body swapping’’, but as an integration of the avatar within an individual’s multimodal self-boundaries