Rubber Hand Illusion

The rubber hand illusion is a perceptual illusion in which a person comes to feel that a visible artificial hand is actually part of their own body, and that their own real hand, hidden from view, belongs to someone else. In the classic experimental setup, a participant's real hand is concealed while a lifelike rubber hand is placed in view in a plausible position, and an experimenter then strokes both the hidden real hand and the visible rubber hand at the same time with a small paintbrush, matching the timing and direction of the strokes; after a short period of this synchronized stroking, most participants report feeling touch sensations as though they were coming from the rubber hand itself, and behavioral measures show they have started to treat the rubber hand as a genuine part of their own body, an effect that does not occur when the strokes on the two hands are desynchronized. The psychologists Matthew Botvinick and Jonathan Cohen first documented the effect in 1998, and Henrik Ehrsson, Charles Spence and Richard Passingham provided detailed neurological evidence for it in 2004 using brain imaging, showing that the parietal lobe first combines the visual and touch information before the premotor cortex generates the resulting feeling of ownership, and that the anterior cingulate cortex, an area normally involved in anticipating pain, becomes active when the false hand is threatened, indicating that the brain has genuinely incorporated the fake limb into its model of the body. The illusion is studied for what it reveals about how the brain constructs a sense of body ownership and self-location, and has informed clinical approaches such as mirror therapy and virtual reality treatments aimed at relieving phantom limb pain.