As you read this story, perhaps you are sitting in a chair in your living room or on an airplane bound for Cancún. Now dig a little deeper, focus inward, and ask yourself this: What is the location of your internal being, your sense of self, that most essential I? Sure, you exist in your body, in your head presumably, itself ensconced someplace particular in the world. But what if all that were secondary? What if your perception could be altered so that you could be anyone and anyplace at all — leaving without traveling?
Those are real possibilities now posed by neuroscientists studying the locus of self- perception in the brain. The research suggests that our concept of self, along with a related quality called presence (the sense of being immersed in a location or environment), need not be tied to our physical bodies. Although most of the current research is still lab-based, scientists have already imbued test participants with the sense of moving from their own bodies into another form, such as a Barbie doll, or watching themselves from a distance in a willful out-of-body experience. The new body-swapping and teleportation techniques illustrate the incredible imaginative potential of the brain and the malleability of perception.
1. Raise Your Third Hand
Humans were long assumed to have an unshakable innate body plan, meaning that our brains and hard-wired sense of self could never accept having anything other than one head, two arms, and two legs. But in 1998, University of Pittsburgh psychiatrists Matthew Botvinick and Jonathan Cohen conducted the now-classic “rubber-hand illusion,” which showed the brain could feel ownership of a body part that was not truly its own. In that experiment, a research subject’s real hand was stroked while a prosthetic hand was also stroked in exactly the same way. In less than two minutes, most participants felt that the rubber limb was part of their own body, provided their own hand was hidden while the rubber one stayed in view.
Taking the findings further, cognitive neuroscientist Henrik Ehrsson, who heads the Karolinska Institute’s Brain, Body and Self Laboratory in Stockholm, showed the brain could fully accept ownership of three hands at once. To make his point, he again induced the illusion that his subjects had a third hand but this time threatened either the prosthetic hand or a real one with a kitchen knife. Next he measured the subjects’ degree of sweating, a stress reaction, in 154 test participants and controls. Ehrsson found that people exhibited the same fear-based physiological response regardless of whether a real or fake hand was threatened, suggesting the rubber hand felt almost as authentically their own as their flesh-and-blood appendages.
