Human brain is taken in by scientists’ body swap illusion
A “body-swap” effect that convinces people they inhabit a different body from their own has been induced by scientists for the first time.
In the study, published in the journal Public Library of Science One, the scientists used special goggles to change the perspective from which volunteers see the world. A stereo camera was mounted on a mannequin where the eyes would be and its images were projected on screens inside the goggles worn by the volunteers.
When the volunteers looked down at their bodies, the camera pointed down too and they saw the mannequin’s torso. When each body was stroked simultaneously in the stomach area, they felt that the mannequin’s body was their own.
The scientists then induced a “full-blown body swap”, in which people experienced another body as their own. The camera was put on an experimenter’s head instead of a mannequin’s, and experimenter and volunteer shook hands. Again, the subjects perceived the experimenter’s hand, not their own, as part of their body.
The effect suggests that the brain builds its sense of which body belongs to it less from signals from the muscles, joints and skin, and more from to what it sees. Split-second body awareness is important to co-ordination and to physical survival, and so the brain uses a short-cut that is almost always correct. The body we see as ours through our eyes is usually ours, and so changing the visual input can easily trick our perception.
“You can see the possibilities, putting a male in a female body, young in old, white in black and vice versa,” Dr Ehrsson said.
“It could lead to the next generation of virtual reality applications in games, where people have the full-blown experience of being the avatar,” he said. It could also have military applications, such as robotic soldiers.