Pain During Illusory Own Arm Movement: A Study in Immersive Virtual Reality

Previous studies have demonstrated that the vision of one’s own body, or of external embodied limbs, can lead to pain relieving outcomes. Analgesic effects have also been related to the vision of illusory limb movements. Nonetheless, whether these two processes can be put together to obtain a summatory analgesic effect is not yet clear. The aim of this work was to investigate if it is possible to combine the analgesic effects of looking at one’s own body with those deriving from the illusion that one’s own limb is moving. Thirty-eight healthy participants underwent four visual conditions in immersive virtual reality while their heat pain thresholds were measured. In different conditions the subject watched from a first-person perspective: i) a still virtual arm, ii) a moving virtual arm, iii) a still non-corporeal object, and iv) a moving non-corporeal object. All participants were asked to keep their arms completely still during the visual exposures. After each condition, participants answered questions about their illusory experience. Our results show that the vision of the ‘own’ body significantly increased participants’ pain threshold as compared to the vision of the non-corporeal object. However, no statistically significant analgesic effect of vision of the virtual arm movement was found. The implications and limitations of this study are discussed.

The authors are thankful to Cameron Magrath and Jackson Davies for their help with data collection.