Illusory self-identification with an avatar reduces arousal responses to painful stimuli
Looking at one's own body has been shown to induce analgesia. In the present work we investigated whether illusory self-identification with an avatar, as induced experimentally through visuo-tactile stimulation, modulates the response to painful stimuli. In 30 healthy volunteers, a robotic device was used to stroke the participants' back, while they viewed either the body of an avatar, a non-body object (control object), or a body avatar with scrambled body parts (control body). All were visually stimulated in either congruent or incongruent fashion with the participant's body. We collected physiological responses (skin conductance response: SCR) to painful stimuli delivered to the participant's hand and responses to a questionnaire inquiring about self-identification with the avatar. We expected reduced physiological responses to pain during the observation of a body avatar only during synchronous visuo-tactile stroking and no reduction for the control object and the control body. Results showed a reduced SCR to painful stimuli when participants observed the normal body avatar being stroked synchronously that was also associated with largest self-identification ratings recordable already during the pain anticipation. Moreover, a negative correlation between self-identification and SCR was observed, suggesting that a greater degree of self-identification with the avatar was associated with larger decreases in SCR. These results suggest that during states of illusory self-identification with the avatar, the vision of an alien body (anatomically compatible for the vision and congruently stroked for the touch) is effective in modulating physiological responses to painful stimuli. (C) 2014 Elsevier B.V. All rights reserved.