Active self-touch restores bodily self-awareness following disruption by "rubber hand illusion"

Abstract

Bodily self-awareness relies on a constant integration of visual, tactile, proprioceptive, and motor signals. In the "Rubber Hand Illusion" (RHI), conflicting visuo-tactile stimuli lead to changes in self- awareness. It remains unclear whether other, somatic signals could compensate for the alterations in self-awareness caused by visual information about the body. Here, we used the RHI in combination with robot-mediated self-touch to systematically investigate the role of tactile, proprioceptive, and motor signals in protecting and restoring bodily self-awareness. Participants moved the handle of a leader robot with their right hand and simultaneously received corresponding tactile feedback on their left hand from a follower robot. This self-touch stimulation was performed either before or after the induction of a classical RHI. Across three experiments, active self-touch delivered after - but not before - the RHI, significantly reduced the proprioceptive drift caused by RHI, supporting a restorative role of active self-touch on bodily self-awareness. The effect was not present during involuntary self-touch, where the participants hand was passively moved, suggesting that the restorative effect depends on the presence of a voluntary motor command, and that synchrony of bilateral sensory events is insufficient. Unimodal control conditions confirmed that the coordination of both tactile and motor components of self-touch was necessary to restore bodily self-awareness. These results suggest that voluntary self-touch can restore an intrinsic representation of the body following visual capture during RHI.