A clever camera setup in a Swedish neuroscience lab produces the sensation of swapping bodies with a mannequin or, perhaps even more uncannily, with a cognitive neuroscientist, according to a paper in PLOS One(press release).
This is not a major new finding, but rather – as Reuters notes – a high-tech extension of an old trick in which subjects are made to perceive a rubber hand is their own. The paper describes the technique:
Two CCTV cameras were positioned on a male mannequin such that each recorded events from the position corresponding to one of the mannequin’s eyes. A set of head mounted displays … connected to the cameras was worn by the participants, and connected in such a way that the images from the left and right video cameras were presented on the left and right eye displays, respectively, providing a true stereoscopic image. Participants were asked to tilt their heads downwards as if looking down at their bodies. Thus, the participants saw the mannequin’s body where they expected to see their own.
We used a short rod to repetitively stroke the participant’s abdomen, which was out of view, in synchrony with identical strokes being applied to the mannequin’s abdomen in full view of the participant.
Participants reportedly felt the mannequin’s body to be their own.
A second experiment had scientist and subject swapping bodies by shaking hands while watching each other’s point of view through the goggles.
Edging inexorably from brain science toward mad science, the researchers also confirmed the strength of the illusion by observing “stress reactions when a knife was held to the camera wearer’s arm but not when it was held to their own” (press release).
“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,” says project leader Henrik Ehrsson, of the Karolinska Institute in Stockholm (press release).
I see this stunt sweeping the slumber parties of researchers’ tween children. Other possible applications: the press release cites virtual reality and robotics, plausibly enough. The Telegraph has the researchers speculating further that the goggles could be turned into a treatment for anorexics and others with body-image problems.
The New York Times takes the ability to stand in another person’s shoes and runs with it, imagining the enhancement of existing virtual-reality scenarios shown to increase empathy for people of other races or ages. Reporter Benedict Carey goes so far as to quote a clinical psychologist about relationship problems and anger management in adolescents.
Reuters, along with the press release, more soberly notes the limits of the illusion: if you have always wanted to be a box or a chair, you’ll have to wait for the next breakthrough.
Image: Alamy