Visually Induced Analgesia: Seeing the Body Reduces Pain

Abstract

Given previous reports of strong interactions between vision and somatic senses, we investigated whether vision of the body modulates pain perception. Participants looked into a mirror aligned with their body midline at either the reflection of their own left hand (creating the illusion that they were looking directly at their own right hand) or the reflection of a neutral object. We induced pain using an infrared laser and recorded nociceptive laser-evoked potentials (LEPs). We also collected subjective ratings of pain intensity and unpleasantness. Vision of the body produced clear analgesic effects on both subjective ratings of pain and the N2/P2 complex of LEPs. Similar results were found during direct vision of the hand, without the mirror. Furthermore, these effects were specific to vision of one's own hand and were absent when viewing another person's hand. These results demonstrate a novel analgesic effect of non-informative vision of the body.

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

“…Looking at one's own body but not looking at a neutral object or at another person's body has been reported to induce analgesia for acute painful stimulation [22,20]. Here, we sought for a similar modulation of pain responses induced by the vision of a virtual body that also depended upon the level of illusory self-identification with that body during a full-body illusion [9] induced by controlled robotic stimulations [23][24][25].…”

“…Questionnaire ratings. During each condition run and immediately after the pain-stimulation phase, participants were asked to complete a questionnaire comprising items adapted from previous studies on bodily illusions [4,9] and pain [20] (Table 1). Responses were given through a 7 points visual analogue scale (VAS) and were automatically coded by the experimental software with a score ranging from −3 to +3.…”

“…Recent studies from cognitive neuroscience show that although pain is highly subjective, it is affected by certain bodily states and experimentally modulated multisensory signals [18][19][20]. Thus, although nociceptive stimuli are processed through specific sensory pathways [18,21], similar to non painful stimuli, pain can be critically modulated by vision.…”

“…Previous work has shown that looking at one's own body but not to an object or at another person's body, while receiving a painful stimulus, produces analgesic effects [22,20]. Starting from this observation, we aimed at investigating the relationship between pain processing and body ownership; here, we sought for evidence that reduced responses to nociceptive stimuli can be obtained not only by looking at one's own body [20] but also when looking at another person's body or avatar, especially under conditions of self-identification with the virtual body.…”

“…Starting from this observation, we aimed at investigating the relationship between pain processing and body ownership; here, we sought for evidence that reduced responses to nociceptive stimuli can be obtained not only by looking at one's own body [20] but also when looking at another person's body or avatar, especially under conditions of self-identification with the virtual body. Thus, we asked whether changes in illusory self-identification following the induction of an FBI would be associated with a reduction of pain responses.…”