Visual and Motor Information in the Rubber Hand Illusion

The body schema, one’s sense of body part ownership, position and location, is informed by visual, proprioceptive, and tactile information. Under normal circumstances, these sources of information are consistent with one another in providing an accurate awareness of one’s own body. The rubber hand illusion (RHI), however, illustrates the flexibility of the body schema by creating conflict between visual and tactile information. In the RHI, when individuals watch the stimulation of a rubber hand while simultaneously feeling the stimulation of their own unseen hand, they often report feeling the touch on the rubber hand (Botvinick & Cohen, 1998). The current study builds upon this phenomenon by investigating the contribution of visual and kinesthetic information to the body schema. Two experiments employed the RHI to create a sense of ownership of a robot hand. In the first experiment, a toy robot hand was positioned in front of each participant, while the participant’s right hand was positioned inside a box where it could not be seen. On each trial, participants viewed the robot hand being stroked with a paintbrush while simultaneously feeling the stroking of their own unseen hand. After several moments, participants were asked to close their eyes and point with the left hand to the location in which they believed their unseen fingertips to be located. In the second experiment, we asked participants to flex the fingers on their unseen hand while viewing the robot hand flex its fingers in the same way. In both experiments we predicted that participants would judge their hand to be closer to the location of the robot hand than to the unseen hand’s actual location. These results suggest that the body schema incorporates prosthetic limbs when visual and movement information about the prosthetic are consistent with the body’s own movements.https://ecommons.udayton.edu/stander_posters/1538/thumbnail.jp