Illusory self-identification with an avatar reduces arousal responses to painful stimuli

Abstract

h i g h l i g h t s• We experimentally induced the full body illusion through a robotic device.• We collected SCRs and ratings following acute pain stimulation during bodily illusion.• Reduced arousal responses were detectable under illusory states of self-consciousness.• Reduced SCR was related to the degree of ownership experienced for the virtual body.• Virtual body must be in anatomical configuration to be effective. a r t i c l e i n f o b s t r a c tLooking 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.

Body ownership: When feeling and knowing diverge

“…These findings are further compatible with the notion that the sense of ownership for a limb tunes analgesic effects when a noxious stimulus is delivered to that body part (Longo, Betti, Aglioti, & Haggard, 2009;Romano et al, 2014c). Despite the interesting results from bodily illusion paradigms in healthy individuals, it is unquestionable that the sense of limb ownership disrupted by brain-damage is incomparably more disturbed.…”

“…The peak-to-base measures were then normalized within-subject and converted to Z-scores (Rhudy, McCabe, & Williams, 2007;Romano, Pfeiffer, Maravita, & Blanke, 2014c), to reduce the effect of the inter-subject variability of SCR, which is commonly large and also to reduce the effect of stimulations on different body districts in different participants.…”

Visuospatial viewpoint manipulation during full-body illusion modulates subjective first-person perspective

“…When stroking was applied in a synchronous fashion participants typically reported increased self-identification and a concomitant bias in self-location toward the virtual body (Lenggenhager et al 2007;Ehrsson 2007;Guterstam and Ehrsson 2012). These changes in self-identification and self-location were accompanied by changes in visuotactile and audiovisual integration (Aspell et al 2009(Aspell et al , 2010, mental imagery Pfeiffer et al 2013;Ionta et al 2011), physiological responses to threat (Petkova et al 2011;Petkova and Ehrsson 2008;Ehrsson 2007), body temperature (Salomon et al 2013), and pain responses (Romano et al 2014;Hänsel et al 2011). This shows that self-identification and self-location can be experimentally manipulated and that this manipulation modulates cognitive as well as physiological processes regarding the own body.…”

Right insular damage decreases heartbeat awareness and alters cardio-visual effects on bodily self-consciousness

“…Additionally, with respect to the results of the questionnaire, we have performed the single case Crawford tests using ipsatized scores, which are standard scores calculated with individual subject's mean and standard deviation. Statistical analyses using ipsatized scores allow both a comparison free of response biases and a proper use of parametric tests as the data are normalized (Broughton and Wasel, 1990;Cattell, 1944; see a previous use of ipsatized scores on questionnaire ratings in Romano et al, 2014). The significance (alpha) level used was 0.05.…”