In Their Minds, Volunteers Swap Bodies with Woman, Mannequin: Illusion Could Help Scientists Study Self-Identity, Body Image

Article excerpt

It sounds like a lost episode of The Twilight Zone. A man enters a laboratory, dons a special headset and shakes hands with a woman sitting across from him. In a matter of seconds, he feels like he's inside the woman's skin, reaching out and grasping his own hand.

Strange as it sounds, neuroscientists have induced this phenomenon in volunteers. People can experience the illusion that another body is their own, says Valeria Petkova of the Karolinska Institute in Stockholm. She and Karolinska colleague Henrik Ehrsson call the feeling the "body-swap illusion."

"Our subjects experienced this illusion as being exciting and strange, and often said that they wanted to come back and try it again," says Petkova, who reported the findings.

Illusory body-swapping could provide a new tool for studying self-identity and psychiatric disorders that involve distortions of body image, she suggests. The phenomenon might also be tapped to enhance virtual reality experiences.

Volunteers in the body-swap experiments stood across from a male mannequin or a female experimenter and received simultaneous visual and motor input. A headset covering participants' eyes displayed a 3-D view of the other body's visual perspective, transmitted from a small camera on the other body's head.

In the mannequin situation, an experimenter simultaneously touched the participant's belly and the mannequin's belly with separate probes. So, the volunteers felt a poking in the abdomen but saw the poking as if they were the mannequin. …