Feeling the burn

The current study investigated the impact of the Rubber Hand Illusion the experience of pain. Attributing a healthy fake limb may lead to increased pain tolerance. Attributing a wounded fake limb however, may increase pain sensitivity.

Body illusions, including the rubber hand illusion (RHI), have been used as an experimental tool for modulating pain. Apart from reducing pain, pain experience may also be increased when seeing painful injuries.

The first experiment used a ‘healthy’ and ‘wounded’ RHI to investigate changes in pain tolerance after asking participants to place their hands into a cold pressor ice bath.  After the RHI with a ‘healthy’ rubber hand, pain tolerance increased by 19% as opposed to the ‘wounded’ rubber hand, which resulted in a decrease of 11.5% in pain tolerance. The second experiment investigated the effects of the wounded rubber hand on pain intensity and unpleasantness during the wounded RHI (synchronous and asynchronous trials). No differences were found in pain experience or pain sensitivity. Pain sensitivity and unpleasantness was higher in the synchronous trials compared to the asynchronous trials.

Compared to no illusion or a wounded rubber hand, the RHI can result in an increase in pain tolerance. These effects were found despite relatively low ‘illusion strength’.  Awareness of self-attributed injuries seems to augment the intensity and unpleasantness of pain and may play a key role in both emotional en sensory appraisals of painful experiences.

> From: Giummarra et al., Conscious Cogn 36 (2015) 314-326. All rights reserved to Elsevier Inc. Click here for the Pubmed summary.