A Study on the Trade-off Relation between Numbness Illusion and Self-touch Illusion

Abstract

Sense of numbness arises when one person holds the palm of one hand against another person’s opposite palm and strokes with his other hand the two joined index fingers (double-touch). While the numbness is thought to be a side effect from ownership distortion, no study has investigated direct relationship between ownership and numbness. In this study, we examined the effect of angles between two fingers in the double-touch situation on sense of ownership, numbness and transform for the experimenter’s finger. The result showed that opening and closing both fingers enhances the sense of ownership, numbness and transform in a strongly correlated manner.