Scientists Report Mental 'Body-Swapping'
Tuesday, December 2, 2008;
12:00 AM
TUESDAY, Dec. 2 (HealthDay News) -- The illusion of
body-swapping --
making people perceive the bodies of mannequins and other
people as
their own -- has been achieved by Swedish
neuroscientists.
In one experiment, the team fitted the head of a
mannequin with two
cameras connected to two small screens placed in front of
volunteers'
eyes, so that they had the same view as the
mannequin.
When the mannequin's camera eyes and a participant'
directed downwards, the participant saw the mannequin's body where
the person would normally have seen their own body.
The researchers
created the illusion of body-swapping by touching the
stomach of both the
mannequin and the volunteer with sticks. The
person saw the mannequin's
stomach being touched while feeling (but
not seeing) a similar sensation on
their own stomach. As a result,
the person developed a strong belief that
the mannequin's body was
actually their own.
"This shows how easy it
is to change the brain's perception of the
physical self. By manipulating
sensory impressions, it's possible to
fool the self not only out of its body
but into other bodies, too,"
project leader Henrik Ehrsson, of the
Karolinska Institute in
Stockholm, said in a news release.
In another
experiment, a camera was mounted on one person's head and
screens were
mounted in front of another person's eyes. When the
person with the camera
and the person with the screens turned towards
each other to shake hands,
the person with the screens perceived the
camera-wearer'
"The subjects see themselves shaking hands from the outside,
but
experience it as another person. The sensory impression from the
handshake is perceived as though coming from the new body, rather
than
the subject's own," study co-author Valeria Petkova said in the
news
release.
This illusion worked even when two people looked different or
were of
different sexes. It did not work when a non-humanoid object -- such
as a chair or large block -- was used.
The research, published online
Wednesday in the journal PLoS One,
could prove useful in virtual reality
applications and in robot
technology, the team said.
More
information
There's more on how the brain works at McGill
University.
SOURCE: Public Library of Science, news release, Dec. 2,
2008
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