Viewing touch improves tactile sensory threshold.

Previous research on multisensory integration has demonstrated that viewing the stimulated body part enhances discrimination ability. Participants in this experiment watched a video showing a hand being touched by a stick and a second video showing the stick touching the space beneath the hand. Sensory thresholds of the index fingers were tested with von Frey filaments. We found significant enhancements of the sensory threshold after showing the video with the touched hand but not after showing the video with no touch of the hand. This enhancement was specific for the index finger shown in the video. The results link the visuotactile enhancement of this study to the observation of touch rather than to the simple depiction of the body part.