Drifting into the mannequin

Sandra Blakeslee at the Times on a new study about the out-of-body experience:

The out-of-body experiments were conducted by two research groups using slightly different methods intended to expand the so-called rubber hand illusion.

In that illusion, people hide one hand in their lap and look at a rubber hand set on a table in front of them. As a researcher strokes the real hand and the rubber hand simultaneously with a stick, people have the vivid sense that the rubber hand is their own. When the rubber hand is whacked with a hammer, they wince and sometimes cry out.

The illusion shows that body parts can be “separated” from the whole body by manipulating a mismatch between touch and vision. That is, when a person’s brain sees the fake hand being stroked and feels the same sensation, the sense of being touched is misattributed to the fake.

The new experiments were designed to create a whole-body illusion with similar manipulations.

In Switzerland, Dr. Olaf Blanke, a neuroscientist at the École Polytechnique Fédérale in Lausanne, asked people to don virtual-reality goggles while standing in an empty room. A camera projected an image of each person taken from the back and displayed that image as if it were six feet in front of the subject, who thus saw an illusory image of himself.

Then Dr. Blanke stroked each person’s back for one minute with a stick while simultaneously projecting the image of the stick onto the illusory body.

When the strokes were synchronous, people reported the sensation of being momentarily within the illusory body. When the strokes were not synchronous, the illusion did not occur.

In another variation, Dr. Blanke projected a “rubber body” — a cheap mannequin bought on eBay and dressed in the same clothes as the subject — into the virtual-reality goggles. With synchronous strokes of the stick, people’s sense of self drifted into the mannequin.

The book that really stunned me around this sort of topic was V. S. Ramachandran's excellent Phantoms in the Brain (co-authored, I now remember, with Blakeslee). Another book recommendation, on an associated topic: Matt Ruff's wonderful Set This House In Order: A Romance of Souls.