Levitating magician: How magicians use science to deceive
Levitating magician: A viral Pepsi ad shows an English magician apparently levitating alongside a double-decker bus. How are we so easily fooled by magic?
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This happens because of a human blind spot, the point at which the optic nerve attaches to the retina. There are no photoreceptors on that part of the eye. But most of us are never aware that we have a pair of empty spots hovering right in front of us. Your brain just fills in the gap with whatever is in the background. You see what you expect to see.Skip to next paragraph
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Magicians don't usually exploit this physiological blind spot, but they exploit our cognitive blind spots all the time. For instance, you watch as a conjurer appears to pass a coin from the right hand to the left. Your attention, honed by thousands of generations of your rock-throwing forbears, leads the target, missing the sleight. You're surprised when the magician reveals the left hand to be empty. Then, while you're looking at the left hand, you fail to notice the right hand slipping the coin into a pocket. The human mind naturally assumes that the background, that is, everything but the empty hand that you're staring at, remains static.
The other big reason that we are so easily fooled by magicians is that humans are intensely social animals. In 1969, the psychologist Stanley Milgram conducted an experiment in New York City that involved volunteers staring up at the sky, gazing at nothing in particular. With one person looking up, about one in 25 passers by also looked up. When five people looked up, about one in five followed suit. As the number of upward-gazing volunteers grew, so did the upward-gazing passers-by. Milgram described this behavior as a "contagion."
Magicians are masters of contagious attention. A paper published in the journal Current Biology in 2006 had subjects watch the Vanishing Ball illusion, a simple trick in which the magician tosses a ball in the air a few times, only to have it apparently vanish in midair:
In the final "toss," the ball actually remains in the magician's hand. But our attention follows the gaze of the magician. When the magician's gaze followed the trajectory of the toss, more than two thirds of the subjects said they saw a ball where there wasn't one. Most even suspected that there was someone at the top of the screen catching the ball. But when the magician looked straight ahead, only a third were fooled. It's the social cues, not the sleight-of-hand, that makes the trick work.
The subjects had cameras tracking their eyes. Interestingly, the researchers found that the observers eyes only followed the actual tosses, not the imaginary one. It wasn't their eyes that were fooled. It was their minds.
So the next time you attend a magic show, here's how to see through the illusions. First, keep an eye on the magician's other hand, the one that doesn't seem to be doing anything interesting. Second, never look where the magician is looking.
Or better still, don't. Just sit back enjoy the show. After all, you paid money to be entertained, not disillusioned.
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[Editor's note of full disclosure: The writer's mother is a magician, thus his reluctance to completely spill professional secrets].