Movement and the rubber hand illusion.

When a participant views a rubber hand being stroked by a paintbrush while his/her real hand is unseen and similarly stroked by another paintbrush, a misperception known as the rubber hand illusion occurs whereby tactile sensations are falsely referred to the non-body part. The purpose of the current study was to further examine the rubber hand illusion with conditions of movement. An apparatus was devised that would synchronise visual with felt movement in an active condition and a passive condition. An asynchronous condition was included as a control in which visual and felt movement were purposely disconnected. The three movement conditions (active, passive, and asynchronous) were statistically compared in order to assess our prediction that synchronous conditions of movement (especially active) would generate more reports of the illusion. The performance of the movement conditions was evaluated against a visual-tactile condition, which is a known contributor to the rubber hand illusion. Not only significantly more robust reports of the illusion were obtained when visual movement and felt movement were synchronised but there was also a trend toward stronger reports in the active condition rather than the passive condition. Interestingly, the pattern of results differed according to the particular question on the self-report.