Illusion of That Shrinking Feeling

Was doing some research on the brain, when i came across this. So fun! haha.

The researchers, led by Dr. H. Henrik Ehrsson of University College London, fooled 17 people into feeling as if they were getting skinnier by outfitting them with gadgets that stimulated a tendon in each wrist to create the false sensation that both hands were moving inward.

The subjects wore blindfolds and placed their hands at their waists, and then the stimulators were turned on, while an M.R.I. scanner measured activity in different parts of the brain. For the subjects, the feeling that their wrists were flexing inward was so powerful that they felt their waists had to be getting smaller.

Dr. Ehrsson said he had tried the tricks on himself.
"It's a very funny sensation," he said. "The nose is my favorite. It really feels like your nose is getting longer. You start giggling."

The first time people feel the illusions, "they're very surprised and shocked," Dr. Ehrsson said.

"The illusion happens as a result of a conflict between senses," Dr. Ehrsson said, explaining that the wrists feel as if they are moving, but the palms of the hands, resting against the waist, do not. "The brain has to interpret the conflicting sensory information. The brain hates ambiguity. It always tries to come up with an explanation."

"It's a little bit of a forgotten sense," he said. "We know about touch, pain and position, but the sense of size of body parts has been a mystery. There are no receptors in skin or muscle that tell the brain the size of body parts, so the brain has to figure it out by comparing signals."

He said the research might shed light on anorexia, in which people can be wasting away, and yet still see themselves as fat. Shown body images on a screen and asked to adjust them to match their own size, people with anorexia often overestimate and create images that are way too large.
"They seem to have a perception deficit," Dr. Ehrsson said. "We don't know if it's the cause of anorexia, probably not, but it's clearly part of the problem."

Dr. Ehrsson's finding was not surprising, since other studies had shown that people with brain injuries in that area had sensations suggesting that the sizes and shapes of parts of their bodies had changed.
Also, in rare cases, people with migraine headaches suffer from the "Alice in Wonderland syndrome," in which they feel as if parts of their bodies are shrinking.

The full article is taken from the NY time here.