24 August 2007

Out-of-body in the lab

Through the use of virtual reality goggles, a Swedish researcher has been able to induce an "out-of-body" experience.

Through the use of virtual reality goggles, a Swedish researcher has been able to induce an "out-of-body" experience, the perception that a person is viewing their own body from the outside.

The findings provide evidence that such experiences may have a real scientific basis and are not simply a figment of the imagination, according to the report in this week's issue of the journal Science.

How the study was done
Dr H. Henrik Ehrsson, from the Karolinska Institute in Stockholm, had healthy volunteers wear goggles connected to two video cameras placed 2 meters behind them. The right eye display of the goggles was connected to the right camera and the left eye display to the left camera. "Thus, the person would see his or her back with the perspective of a person sitting behind him or her with stereoscopic vision," the researcher explains.

While the subjects were viewing their own backs through the goggles, the technician, who stood beside them, touched either their real chest, which was not viewable on the cameras, or their illusionary chest with a plastic rod. The latter effect was achieved by having the technician move the rod to a position just below the cameras, while still being in view.

After the experiment, the subjects were asked 10 questions designed to determine if an out-of-body experience had occurred. The results confirmed that the subjects did indeed have an out-of-body experience. As Ehrsson puts it, he created "a perceptual illusion in which individuals experience that their centre of awareness, or "self," is located outside their physical bodies and that they look at their bodies from the perspective of another person."

As if they were outside their bodies
To objectively verify this finding, another experiment was performed in which the technician hit the illusionary body with a hammer and gauged the emotional response by measuring sweating with skin electrodes. The results showed that the subjects responded emotionally as if they were viewing their physical bodies from the outside.

These illusions show "that the sense of being localised within the physical body can be fully determined by perceptual processes, that is, by the visual perspective in conjunction with multisensory stimulation on the body," Ehrsson states.

The results represent "a fundamental advance because the natural 'in-body experience' forms the foundation of self-consciousness," he concludes.

SOURCE: Science, August 24, 2007. – (Reuters Health)

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Mind Centre

August 2007


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