Phantom touch illusion, an unexpected phenomenological effect of tactile gating in the absence of tactile stimulation

Abstract

We report the presence of a tingling sensation perceived during self touch without physical stimulation. We used immersive virtual reality scenarios in which subjects touched their body using a virtual object. This touch resulted in a tingling sensation corresponding to the location touched on the virtual body. We called it "phantom touch illusion" (PTI). Interestingly the illusion was also present when subjects touched invisible (inferred) parts of their limb. We reason that this PTI results from tactile gating process during self-touch. The reported PTI when touching invisible body parts indicates that tactile gating is not exclusively based on vision, but rather on multi-sensory, top-down input involving body schema. This finding shows that representations of own body are defined top-down, beyond the available sensory information.