Scientists study out-of-body experiences
By RANDOLPH E. SCHMID, AP Science Writer
Thu Aug 23, 11:04 PM ET

WASHINGTON - The stories seem strange but riveting.
A heart attack victim recalls floating in the air, watching paramedics revive
him. A surgical patient remembers hovering, watching the doctors operate. Such
widely reported out-of-body experiences have long been the territory of
theology, philosophy and scary movies. Now scientists have turned their
attention to the topic.
Researchers in England and Switzerland have figured out ways to confuse the
sensory signals received by the brain, allowing people to seem to be standing
aside and watching themselves.
No, they're not using drugs, legal or otherwise.
The research is described in Friday's edition of the journal Science.
Dr. Henrik Ehrsson of University College London's Institute of Neurology and
the Karolinska Institute in Stockholm, explained that he was interested in a
person's perception of the "self."
"I'm interested in the question of why I feel that my self is located inside my
physical body. How does my brain know that I am standing right here," he said.
And what would happen to the self if a person could effectively move their eyes
to another part of the room and observe themselves from an outside perspective?
Would the self move with the eyes, or stay in the body, he wondered.
So seated volunteers were fitted with head-mounted video displays that allowed
them to view themselves from behind, using a pair of video cameras, one for each
eye.
A researcher would stand behind them and extend a plastic rod which they could
see toward the area just below the cameras. At the same time another plastic
rod, which they could not see, touched their chest.
The volunteers said they experienced the feeling of being behind their own body
watching. Many found it "weird" and seemingly real, though not scary.
They felt "that their center of awareness 'self' is located outside their
physical bodies and that they look at their bodies from the perspective of
another person," he reported.
"The idea is to change the visual input and its relationship to the tactile
information," he said. "The brain is always trying to interpret sensory
information. The brain can trick itself."
In a second test, Ehrsson connected sensors to the skin to measure electrical
conductance, which indicates emotional response.
He then allowed them to watch a hammer swing down to a point below the camera,
as though it were going to hurt an unseen portion of the virtual body.
Their skin conductance registered emotional responses including fear,
indicating they sensed their selves had left their physical bodies and moved to
the virtual bodies where the hammer was swung.
The research has applications in neuroscience and also potentially in
industrial applications involving virtual reality, he said.
Meanwhile, a team led by Olaf Blanke, a professor at the Laboratory of
Cognitive Neuroscience at Ecole Polytechnique Federale in Lausanne, Switzerland,
conducted a similar experiment using virtual reality goggles.
In these tests, the subjects could see a three-dimensional representation of
their body, the body of a dummy, or a simple object directly in front of them.
The subject then saw the back of the image being stroked with a paintbrush,
either in or out of sync with someone stroking his own back.
Then the participants were blindfolded and backed up, and then asked to return
to their original position.
Those whose backs were stroked synchronously with the virtual image of
themselves or the human dummy consistently overshot their position in the
direction of the image; but subjects who saw no virtual image or a simple object
did not.
The study aimed at determining how senses play a role in self consciousness,
Blanke said.
Ehrsson's research was funded by the Wellcome Trust, the Presence: Research
Encompassing Sensory Enhancement, Neuroscience, Cerebral-Computer Interfaces and
Applications Project, the Human Frontier Science Program, Swedish Medical
Research Council and the Swedish Foundation for Strategic Research. Blanke's
work was funded by the Cojito Foundation, Foundation de Familie Sandoz, the
Foundation Odier and the Swiss National Science Foundation.
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On the Net:
Science: http://www.sciencemag.org




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