Scientists Use Virtual Reality to Bend the Body's Borders
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Reviewed By Louise Chang, MD
Aug. 23, 2007 -- Ever had an out-of-body experience, where you were wide awake and "saw" your body as if you were a bystander?
Scientists may have figured out how out-of-body experiences happen. Turns out, it's all about the eyes.
Two new studies -- both published in tomorrow's edition of the journal Science -- put a state-of-the-art spin on out-of-body research.
In one experiment, 14 healthy, young adults wore virtual-reality goggles as they stood in the researchers' lab. A few feet behind them, a video camera filmed their backs and projected that image, in real time, into a hologram a few feet in front of the participants.
The researchers stroked the participants' real and virtual back at the same time. Afterward, they only stroked the participants' virtual back -- but even so, participants said they had the sensation that their real backs were being touched.
Participants didn't lose all sense of themselves. They didn't report feeling like they had left their bodies.
But they did describe the sensation as weird or strange, according to Olaf Blanke, MD, PhD, and colleagues. Blanke directs the Laboratory of Cognitive Neuroscience at the Ecole Polytechnique Federale de Lausanne in Lausanne, Switzerland.
Blanke's team did similar tests on 14 other participants to confirm the findings.
The other study also used virtual reality and video cameras to simulate out-of-body experiences. But neuroscientist H. Henrik Ehrsson, MD, PhD, pushed the envelope a little farther.
Ehrsson works at University College London and the Karolinksa Institute in Stockholm, Sweden. In a series of experiments, Ehrsson found that participants "felt" touch applied to virtual-reality versions of their bodies.
What's more, when Ehrsson pretended to strike participants' virtual bodies -- not their true selves -- with a hammer, participants were scared for their actual flesh and blood, though they had been promised that they weren't in any danger whatsoever.
"This experiment suggests that the first-person visual perspective is critically important for the in-body experience," Ehrsson says in a news release. "In other words, we feel that our self is located where the eyes are."
SOURCES: Lenggenhager, B. Science, Aug. 24, 2007; vol 317: pp 1096-1099. Ehrsson, H. Science, Aug. 24, 2007; vol 317: p 1048. News release, American Association for the Advancement of Science.
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