Disembodiment of Itch Sensation by Implementing Sensory Stimuli and the Rubber Hand Illusion

Chronic scratching can damage the skin and lead to more itching, impeding the healing process. Even if not directly scratching the itchy areas, previous studies have approached itch relief by stimulating the skin itself. In contrast, our research pioneers the exploration of itch disembodiment. We attempted to disembody the itch sensation by implementing the Rubber Hand Illusion and investigated the feasibility of itch reduction by scratching a rubber hand using sensory stimuli (visual, tactile, and auditory). Participants scratched a rubber hand under three conditions: without auditory stimuli, with auditory stimuli using scratching sounds, and listening to their favorite song. Scratching the rubber hand significantly reduced itch intensity in all conditions (P-value < 0.001, Wilcoxon signed-rank test). Furthermore, participants consistently reported pleasant sensations from scratching the rubber hand as measured by a self-reported score. A significant correlation was found between pleasant sensation and ownership scores, particularly in the condition accompanied by scratching sounds (P-value < 0.01, correlation: 0.61, Spearman's rank correlation coefficient).