Asynchrony in the rubber hand paradigm: Unexpected illusions following stroke

The rubber hand paradigm (Botvinick & Cohen, 1998) elicits a striking multisensory illusion. The participant views a prosthetic hand being touched by the Examiner while the participant's own hand (hidden from view) receives synchronous touch from the Examiner. Because of the correspondence between what the participant sees and feels, most participants experience a compelling illusion. It may seem to the participant that the prosthetic hand is her own hand and that she is feeling touch at the location of the viewed prosthetic hand. When testing participants with the rubber hand paradigm, researchers typically use asynchronous stimulation as a control condition. With temporal mismatch between what the participant sees on the rubber hand and what the participant feels on her own hand, the rubber hand illusion is abolished. However, as we demonstrate, sensory impairments following stroke can lead to the participant experiencing the rubber hand illusion even when stimulation is asynchronous. This surprising finding will be of interest to researchers working on body awareness and representation, and clinicians treating patients with impaired sensation