Scientists Simulate Out-of-Body Experiences | Mind Cafe

Wednesday, August 29, 2007

Scientists Simulate Out-of-Body Experiences

Get ready to see yourself in a new light. Two papers released this week by the journal Science describe what seem to be the first lab-induced out-of-body experiences in healthy people.

Using goggles hooked up to video cameras, and sticks to poke and stroke, researchers subjected study participants to a variety of visual and physical cues to confuse their brain about their body's location.

Sound a bit impractical? Consider, then, how the studies relate to humankind's most enduring question: what makes us ourselves in the first place?

"I'm not really interested in out-of-body experiences," says Henrik Ehrsson, one of the study's authors and an assistant professor at the Karolinska Institute in Sweden. "I'm really interested in in-body experiences: how the brain keeps and updates a model of the world and the body. To have a perception of your own body is the foundation of self-consciousness."

That is, of course, why out-of-body experiences have always been, well, out-of-body. People report such experiences after returning from the "brink of death," or being under the influence of mind-altering drugs — no doubt why the sensation has long been equated with spiritual awakening (and with crackpots).

But, today, with new advances in neurology, scientists are better able than ever to locate the physical roots of these bizarre perceptions of self. For example, neurologists have studied amputees who can feel sensation where their missing limbs used to be; researchers think this phantom limb phenomenon has to do with rewiring in the brain's somatosensory cortex. And, in the lab, researchers have been able to make people feel that fake rubber hands are attached to their own bodies. (This was done simply enough, by touching the participants' real hands while having them watch the rubber hands be touched in the same way and the same time.)

Now, there are the current Science experiments: the first where volunteers have relocated their entire "selves" — their minds, as it were — outside of their bodies.

In both studies, participants wore goggles hooked up to cameras planted behind them, so that participants had a view of their own backs. Then they were physically stimulated in ways that would enhance or reduce the feeling that their selves were located outside their bodies. For his paper, Ehrsson used a stick to poke the chest of each participant (out of view of the person being poked) while also poking the area below the camera where a chest would have been (which the person could see through the goggles). Sure enough, the participants reported that it felt like their vantage point was exactly the same as that of the camera.

"You feel quite clearly that you are sitting in the corner of the room, and you see yourself sitting elsewhere. But it's not you," Ehrsson says. To be certain — and to get some harder data — he hooked up his participants to stress-monitoring devices, and then swung a hammer at the space where the illusory chest would have been. The readings showed signs of stress all right. Many participants also visibly flinched.

The second experiment was conducted at Ecole Polytechnique Federale de Lausanne in Switzerland, by a team including neurologist Olaf Blanke, whose work with out-of-body experiences suggests that their neural underpinnings reside in the brain's temporo-parietal junction. Blanke and his colleagues had participants watch their own backs being stroked — either through a video feed coming live to their eyes or through one coming slightly out of synch. Afterward, the participants were blindfolded and asked to return to their original place in the room; on average, those who had had the in-sync physical stimuli — and, thus, the real feeling of an out-of-body experience — "drifted" toward where the illusion had been.

So, do these lab experiments really feel like a true out-of-body experience? "It's very vivid," says Ehrsson of his test. Participants say they really did feel like they were outside of their bodies. People in both sets of studies found the experience "weird." Some of Ehrsson's subjects described the experiment as "cool" and giggled, while some in Blanke's study called it "irritating." But the extent to which the experiments succeeded "depends what you mean by the full-blown out-of-body experience," says Ehrsson. "Of course you know that it's not real, that it's all due to the goggles. But you can't just think it away."

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