Rubber hand illusion
Stroke a rubber hand and a person's hidden real hand at the same time, and within a minute or two the brain adopts the rubber hand as its own. It shows that your sense of your body is built moment by moment from sight and touch.
How common
Does this happen to you?
How it works
Proprioception is the sense of where your body parts are without looking2. The brain combines it with sight and touch to build a running model of the body. Normally the three senses agree. The illusion makes them disagree, and sight wins.
The setup is simple. Your real hand is hidden behind a screen. A rubber hand lies in view, where your real hand would be. An experimenter strokes both hands with brushes, on the same spot, at the same time1. Within about a minute, the feeling of touch moves to the rubber hand4. The rubber hand starts to feel like yours1. Asked to point to your real hand with eyes closed, you point closer to the rubber one. This shift is called proprioceptive drift4. If someone then stabs at the rubber hand with a needle, you move your real hand away1. Stroking the two hands out of time breaks the illusion1. With virtual reality the same trick can work on the whole body3.
How common it is
Laboratory studies find that 60% to 80% of people feel it, depending on how a ‘yes’ is counted4. Botvinick and Cohen first reported the illusion in 19981. How strongly someone feels it varies between individuals, and the reason is not known4.
Try it
You need a friend and a fake hand. A rubber glove stuffed with paper or a cheap costume hand works.
- Sit at a table. Put your real left hand out of sight, behind a book or under a cloth.
- Place the fake hand where your left hand would be. Cover the wrist with a sleeve.
- Your friend strokes both hands with two paintbrushes or two fingers, same spot, same moment.
- Look at the fake hand for one to two minutes.
- Notice when the touch seems to come from the fake hand.
- Your friend taps the fake hand sharply with a pen. Watch for your own flinch.
The illusion is safe and fades soon after the stroking stops5.
Is it a problem?
No. Feeling ownership over a rubber hand for a minute in an experiment is a normal quirk of how the brain builds its body sense, not a disorder1. The feeling lasts for tens of seconds after the stroking stops, then fades5. There is nothing to see a doctor about. Researchers use the illusion to study phantom limb pain1.
History and culture
Researchers use the illusion to study phantom limbs1. It also helps them make prosthetic hands that feel like part of the body6.
Sources and further material
- Wikipedia Body transfer illusion The wider family of body-ownership illusions, including whole-body versions in virtual reality.
- NCBI The Onset Time of the Ownership Sensation in the Moving Rubber Hand Illusion Kalckert and Ehrsson, 2017, Frontiers in Psychology.
- NCBI Sustained rubber hand illusion after the end of visuotactile stimulation with a similar time course for the reduction of subjective ownership and proprioceptive drift Abdulkarim, Hayatou and Ehrsson, 2021, Experimental Brain Research.
- NCBI Upper limb amputees can be induced to experience a rubber hand as their own Ehrsson et al., 2008, Brain.
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Related oddities
Pinocchio illusion
Vibrate the biceps tendon while a person touches their own nose with their eyes closed, and their nose can feel as if it is growing. It shows how the brain works out where the body parts are.
Cutaneous rabbit illusion
A few quick taps at the wrist followed by taps at the elbow feel like a small animal hopping up the arm. The brain fills in taps between the two spots that never happened.
Mirror-touch synesthesia
About 1 in 60 people feel a touch on their own body when they watch someone else being touched. The brain system that mirrors other people's actions appears to be turned up too high.
Derealization and depersonalization
The world suddenly seems flat, distant, or like a film (derealization), or you feel like you are watching yourself from outside (depersonalization). Many people have a brief episode at some point, usually under stress.