Your body or mine?

Would it hurt you if someone poked a finger into your friend's eye? Well, according to the scientists at the Karolinska Institute in Sweden, if you were perceiving your friend's body to be your own, it would hurt! Body-swap, an ageless folk-lore is actually a scientific possibility.

After elaborate experiments conducted by the Swedish researchers, they could prove that by altering visual and tactile sensations, an individual can be tricked into feeling someone else's body as his/her own. The participants in this experiment were made to wear a set of head-mounted displays (HMDs) which were connected to cameras placed in either the place of eyes in a simple shop mannequins (all males) or atop a big rectangular box. This means that the field of vision of the participant was now the view of the cameras.

A series of tests were done using this set-up. In one experiment, the mannequin was threatened with a knife. The participant's body reacted as if the attack was on him. This clearly establishes that a kind of belonging was developed between the participant and the mannequin body. The participants perceived it to be their own. This sense of ownership was not affected by gender, considering that all the mannequins were male, but the rectangular box did not generate any of these feelings of ownership by the participant. The most exciting aspect of this experiment was when the researchers substituted the mannequins with real human beings. The participants were put face to face with other volunteers and their HMDs displayed a field of vision of the person in front of them. So, when these two individuals shook hands, they perceived that they were shaking a hand which was actually their own. Some participants later told each other that, "Your arm felt like it was my arm, and I was behind it". Twisted logic, eh?

The researchers conclude that the perception of presence of our own body is a continuous process. The body keeps signalling our brain about its position in the surroundings via sensory stimuli, physical movements and feeling of pain. All these might also be affected by past experiences as in the case of phantom limbs where victims of amputations of limbs are known to feel pain and other stimuli where the limb previously was.

The technique of evoking the feeling of being in another body is clinically important. It can be used to treat psychological disorders like poor body image. Research has shown that 8 out of 10 women are dissatisfied with their body image. In some cases, it can aggravate to depression, eating disorders and other related psychological conditions. The body-swap technique can be used to make the patient aware of the difference between the actual physical being and perception of it by us and would help cure these disorders. Another psychological disorder which can be treated using the body-swap illusion is identity crisis. Perceiving self through another individual might help in the treatment.

However, the gaming industry is the one which is likely to exploit this 'body-swap' illusion the most. Most modern games give the player of being in a different environment and using these body-swap techniques, the gaming experience could be more and more realistic. Beware, those game-loving boys you know, might be getting more addicted in the future. It also would be more enjoyable to have a go at being some power hungry dictator or a fearless warrior yourself in these body-swap games.

Philosophers, psychologists and now neuroscientists are pondering on the nature of perception of self. More research in this field will likely help us understand how the brain can differentiate between ourselves and others; and why we know who the person in the mirror is.