By Tanya Lewis via LiveScience
In virtual reality, a virtual arm can feel like a real one.
CREDIT: © Mel Slater
The brain’s perception of the body may seem set in stone, but a new study shows the mind can be tricked into taking an entire virtual body for its own.
In 1998, neuroscientists Matthew Botvinick and Jonathan Cohen performed an experiment where they showed people a rubber hand being stroked with a paintbrush, while applying the same strokes to each person’s own, hidden hand. This gave people the feeling that the dummy hand was their own.
Scientists have since demonstrated the so-called rubber hand illusion for other body parts — and even whole bodies. Often this is done by putting people in virtual reality settings.
“It seems the brain, under certain conditions, quite easily accepts the idea that [a virtual body] is your body,” said study author Mel Slater, a computer scientist at the University of Barcelona. [Eye Tricks: Gallery of Visual Illusions]
In the new study, Slater and his colleagues investigated whether taking ownership of a full virtual body resulted in neglect of the real body.
Head-mounted display
Study participants wore head-mounted displays in which they saw a virtual body when they looked down at their real body. Half of the participants experienced a realistic body illusion, where the virtual body’s posture and movements matched those of their real body, while the other half experienced an unrealistic one, where the posture and movements didn’t match their own.
The researchers had the participants place their hand on a cooling device, and measured participants’ sensitivity to small changes in temperature as they experienced a realistic virtual body illusion or an unrealistic one.
During the rubber hand illusion, the real hand has been shown to cool down, suggesting the brain pays more attention to the rubber hand. The researchers suspected that if people were neglecting their real body in favor of the virtual one, sensitivity to temperature changes on their real hand would diminish.
But the opposite was true: People remained sensitive to temperature changes when they experienced a strong illusion that the virtual body belonged to them, and became less sensitive when the illusion was unrealistic. In other words, the better the illusion, the more aware people were of temperature changes in their real hand.
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