The Eyes have it

A bad pun indeed, but how do I know where I am? I wake up every morning and look around. I look down and see my arm – I see “me.” I have yet to wake up and find myself somewhere else in the room looking at my body lying on the bed. This fundamental question about the relationship between human consciousness and the physical body has long been the topic of discussion in philosophy, theology, psychology and the popular press, but has been rarely seen within controlled clinical settings with healthy subjects.

Dr. Henrik Ehrsson, University College London Institute of Neurology, devised a recent experimental method that allowed him to induce an out-of-body experience in healthy people under controlled conditions. By setting up separate video displays that feed live images of participants’ backs into each eye he provided the subjects a viewpoint in which they perceived that they were sitting behind their own bodies. Using two plastic rods to simultaneously touch points on both their real bodies and where the perceived bodies were located he was able to induce the test subjects to feel that they were indeed sitting behind their bodies and watching the action.

“This experiment suggests that the first-person visual perspective is critically important for the in-body experience. In other words, we feel that our self is located where the eyes are,” Ehrsson said.

The eyes’ perception “trumped” the actual feel of the plastic rod on the participant’s skin.

To try a simpler version of this yourself:

For a quicker, less powerful jaunt outside your bodily confines, try the double-mirror trick: Position two mirrors facing each other and then lean toward one so that two thirds of your face is reflected in it. Scratch your cheek and stare deep into the hall of mirrors you have created, past your original reflection, past the image of your back, and settle on the third reflection—your own face but slightly obscured. Within seconds, you won’t recognize that reflection as you, says neuroscientist Eric Altschuler of the University of Medicine & Dentistry of New Jersey in Newark, who reported the phenomenon in the April issue of Perception.

Links: Scientific American

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