An illusion known as the "disappearing hand trick" earned the top prize at the eighth annual Best Illusions of the Year contest, held May 14 at a meeting of the Vision Sciences Society in Florida. The newly discovered illusion fools the brain into thinking one's hand has vanished.
It works like this: A participant places both hands inside a box and tries to keep them still. Meanwhile, a video of her hands is projected on the top of the box, and the footage is manipulated so that the hands appear to drift slowly toward one other. Instructed to keep her hands from touching, the partcipant moves her hands apart to counteract this apparent drift. What seems like fractions of an inch in the video, however, are several inches in real life: She eventually moves them out of reach of one other without knowing it, because the video continues to display footage of her hands close together.
Next, the image of her right hand disappears, and the experimenter asks her to touch it with her left hand. She reaches toward it, but to her complete shock, her right hand isn't there! (It is farther to the right than she thought, of course.)
As seen in the video, the participant then pulls her hands out of the box, finds them both to be intact, and — in the case of the participant shown — breaks into hysterical laughter.
"It's the combined loss of vision and touch that creates an experience that the hand is missing," said Roger Newport, who discovered the trick with his colleagues Helen Gilpin and Catherine Preston, all of the University of Nottingham in the U.K. "It's very striking, and works for everybody who does it."
Newport said the discovery might have applications outside of the lab, such as for chronic pain sufferers. He told Nature News, "It could change the very way we perceive pain."