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Disappearing hand trick wins best illusion of 2012

Posted on behalf of Julian De Freitas.

Watch where you put your hands, because Roger Newport of the University of Nottingham knows how to fool a brain into thinking they have vanished. This sleight of mind is so compelling that it has officially been crowned the best illusion in the world.

“The illusions this year were particularly spectacular”, says Stephen Macknik, judge moderator for the 8thAnnual Best Illusion of the Year contest, which took place at the annual meeting of the Vision Sciences Society in Florida yesterday. The 10 best illusions from 59 entries were unveiled in a concert hall packed with vision scientists from across the globe, who voted for the final winners.

Newport’s was the only tactile illusion. As shown in the video, a participant places both hands into a closed box, and then tries to keep them still while being shown a video of them. The video is manipulated so that the hands appear to drift slowly toward each other; in an attempt to counteract this drift, the participant moves her hands further away from each other. Eventually, she has moved them a fair distance apart without even noticing having done so, since the video continues to display an image of her hands close to each other.

The image of her right hand then disappears completely, and the experimenter asks her to grab it with her left hand. To her astonishment, her right hand is no longer where she thought it was.

Newport explains, “We created this illusion by separating the different senses. It’s the combined loss of vision and touch that creates an experience that the hand is missing. It’s very striking, and works for everybody who does it.” Newport also thinks that the discovery might end up having applications outside of the lab, such as for sufferers of osteoarthritis: “It could change the very way we perceive pain.”

Newport was up against some tough competition. Second place was taken by an illusion that recently went viral on YouTube: ‘When pretty girls turn ugly: the flashed face distortion effect.’ In this video, pairs of different faces are sequentially flashed on the screen for brief periods. Although you don’t notice anything unusual if you stare at any individual face, a very strange effect occurs if you fix your eyes between the faces — they suddenly appear highly deformed and grotesque. At the competition yesterday, Matthew Thompson from the University of Queensland in Australia also unveiled a never-before-seen version of the illusion that uses celebrity faces, much to the delight of the audience.

The explanation for the flashed face distortion effect remains unclear, but that’s not uncommon according to Susanna Martinez-Conde, president of the Neural Correlate Society, which hosts the competition. “These are the best illusions of the year, so they’re very new by definition. You’re going to know the phenomenology first, and the neural underpinnings second. Typically, we don’t know why these illusions work in the brain. We may have theories, but the experiments have not been done, because it’s too early. This is really at the cutting edge.”

Video © 2012 Roger Newport, Helen Gilpin and Catherine Preston


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