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How could you confuse a rubber hand for your own hand?


A 2011 study led by Vanderbilt professor Sohee Park studied the rubber hand illusion in the context of schizophrenia, unexpectedly triggering an out-of-body experience in the lab.
A 2011 study led by Vanderbilt professor Sohee Park studied the rubber hand illusion in the context of schizophrenia, unexpectedly triggering an out-of-body experience in the lab.
Photo courtesy of Vanderbilt University

Stroke patients have been known to disown body parts, not recognizing, say, their right arm as their own [source: Science Daily]. Schizophrenics, too, can experience blips in "body ownership," and evidence also points to this phenomenon playing a role in out-of-body experiences [source: Thakkar].

Body ownership is a term used to describe the sense of our physical selves as being ours, distinct from our surroundings. It contributes to humans' knowledge that the hammer we see and feel in our hands is not a part of our bodies, and, in lower-order animals, that this leg belongs to me, so I shouldn't eat it.

A trick known as the rubber hand illusion plays with this sense of body ownership. In this illusion, a subject is made to believe a rubber hand is in fact his own hand, which is hidden from view, to the point of pulling his own hand away if the rubber hand is attacked.

And so it seems our minds can be tricked not only into disowning parts of our bodies, but also into owning parts that don't actually belong to us -- in this case, a rubber hand. Scientists have been studying the illusion for years to learn about brain-body connections. In 2004, researchers pinpointed the premotor cortex as guiding the misperception [source: Science Daily]. In 2008, it was shown the temperature of the hidden hand actually drops during the illusion [source: Keim]. A rubber-hand experiment conducted at Vanderbilt lab in 2011 produced an observable, repeatable out-of-body experience [source: Salisbury].

The trick's usefulness in neuroscience research belies its simplicity: If you've got a relatively lifelike rubber hand lying around, along with a couple of helpers, you can create the illusion right now.


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