By getting the audience to focus on one particular thing, magicians can cause them to not see what they don’t want them to see. This attentional blindness, as it’s called, is gold to a magician.

You can try this yourself, and if you really try to accurately count the passes, you probably won’t see the gorilla, even though you know to expect it. Roughly 50 percent of subjects failed see that while they’re counting passes, a person in a gorilla suit strolls across the center of the court, even stopping in the middle for a little theatrical chest-pounding.

In 1999, cognitive psychologists Christopher Chabris and Daniel Simons set up a now-famous experiment in which subjects are asked to watch a short video of a basketball game and count how many times the team wearing white shirts pass the ball. Here again, the brain helps the magician. Martinez-Conde, also a neuroscientist at SUNY Downstate, is a leading expert on the neuroscience of vision (and is married to Macknik). “What they do is direct attention very skillfully away from the secret method,” explains Susana Martinez-Conde. People often say that magicians use distraction to keep audiences from seeing how they do the trick. A good magician can basically control a good chunk of how your brain interprets things.” Pay Attention “A magician can turn that against an audience,” says Rensink, “and create a reality that's very very different from what's in front of them. Otherwise, we’d forever be walking into walls and tripping over the furniture. It's an estimation of what's actually happening out there.”

Or as Macknik, puts it, “Almost everything you see - 99 percent or more - is fabricated by your brain. That is to say, the brain fills in what’s missing based on previous experience and some logic, seeing basically what it expects to see. So how do we see the big picture? Our brains makes most of it up. 'That’s about the size of your thumbnail held at arm’s length. “Your visual system sees clearly only about 1/1000th of the entire visual field,' explains Stephen Macknik, a neuroscientist at SUNY Downstate Medical Center, also a pioneer of the scientific study of magic. One thing Rensink and others discovered when they started studying the science of magic is that magicians take advantage of the very odd (and maybe slightly creepy) fact that what we see is not actually what’s out there. This suggested that the effect is based on something central to the way human minds works. “Penn and Teller, say, can thousands of people at the same time the tricks are that reliable,” says Rensink. He specializes in visual attention and is one of the pioneers of scientific study of magic. Ronald Rensink is a professor of psychology at the University of British Columbia in Vancouver. Your grasp on reality is weaker than you think Because when you look closely at magic, you find neuroscience. The real magic is in the minds of the audience, and the art of the magician in manipulating those minds. Though magicians do use props, such as cabinets with hidden mirrors and stacked decks of cards, those things aren’t what make the tricks work.

Magic trick cut person in half