Photo: Science
Doctors have long puzzled over why some people report what are known as "out-of-body experiences" -- not just art students hopped up on good grass, but real patients, often those suffering from epilepsy, stroke or other neurological conditions, say they sometimes feel dissociated from their bodies, as if they're not inhabiting their skin. It turns out they're not lying.
In next week's issue of the journal Science, two teams of neuroscientists present findings confirming such feelings; using head-mounted virtual-reality displays, they were able to induce out-of-body experiences in healthy people. The experiments, researchers say, provide a greater understanding of how our brains understand "selfhood" -- plus, they could make for some awesome virtual-reality games that feel completely real.
In one experiment, Henrik Ehrsson of the Karolinska Institute in Sweden had people sit in a chair just in front of two video cameras. The subjects donned virtual-reality goggles in which they saw a view of their own backs as recorded by the camera; a person would thus see "himself" as being just a bit removed from his actual position in the room, like you were sitting behind yourself at a movie theater. Then, using two plastic rods, Ehrsson lightly scratched each subject's chest at the same time that he moved his hand in the air at the spot where the person "thought" he was. People could feel that they were being scratched, but on the display they saw the experimenter scratching the person sitting a few meters away -- and at this point, folks felt literally out of their skin.
"You really feel that you are sitting in a different place in the room and you're looking at this thing in front of you that looks like yourself and you know it's yourself but it doesn't feel like yourself," Ehrsson, who tried the experiment on himself, told Science.
In a similar experiment, Bigna Lenggenhager and Olaf Blanke of the Swiss Federal Institute of Technology showed people a virtual-reality view of themselves being just a little off from their true position in the room. When the experimenters guided the subjects a few feet back, shut off the display, and then asked the participants to walk back to their original position in the room, they got lost -- they would walk back to the location they'd seen on their virtual displays, not where they'd actually been.
The experimenters note that they were not able to produce out-of-body sensations as intense as some clinical patients feel them. But these studies at least point to the brain regions that are important in how we perceive "self." If game creators find some way to manipulate these areas well -- to make us see and touch their landscapes -- virtual reality might really be something big. I can't wait to play Wii Tennis while inhabiting my Mii's body.
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