Explaining The Science Behind Penn & Teller's Ball And Cups Magic Routine
February 12, 2013

Explaining The Science Behind Penn & Teller’s Ball And Cups Magic Routine

Michael Harper for redOrbit.com — Your Universe Online

Scientists: They just can´t leave well enough alone. It´s difficult for them to let certain things about life go unexplained and allow themselves to be amazed from time to time. Instead, they have to dissect, to find the truth, no matter how elusive it may be. For instance, scientists from the Barrow Neurological Institute have dug deep into neuroscience in order to explain how a certain magic trick performed by famous magicians “Penn & Teller” works.

Anyone who has ever seen Penn & Teller´s cups and balls routine already knows how the trick is done, of course. The way they do it, the trick is less of an illusion and more of an impeccably timed act, with tin foil balls of varying sizes moving seamlessly between pockets as Penn Jillette plainly yet rapidly explains the trick and Teller provides claps of distraction.

While we may “know” how the trick is done, Dr. Stephen Macknik, Director of the Laboratory of Behavioral Neurophysiology at Barrow Neurological Institute, and colleagues set out to explain why our brains are still somehow fooled by the illusion. The resulting report has been published today in PeerJ, a new peer reviewed journal with free and open access to everyone.

“We still don´t know how (the trick) really works in the brain,” said Dr. Macknik, “because this is the first, long overdue, neuroscientific study of the trick.”

As explained by Penn & Teller, the cups and balls trick is perhaps the earliest of all illusions and can be found everywhere from China to Egypt and India. Though there are different versions of the trick (with different materials used for the cups and the balls), the basic approach is the same. A magician or illusionist places 3 balls on top of 3 overturned cups. The magician then appears to make the balls pass through the cup, end up in other cups, and even turn into different objects. As in the case of Penn & Teller´s version, one of the balls can turn into a baseball or even a potato.

Normally, cups and balls is performed with brightly colored balls and dark, opaque cups. Penn & Teller do the trick twice, breaking the first rule of magic. Then, breaking a 4th an unspoken rule of magic, Penn & Teller use clear cups to perform the trick yet again, allowing the audience to see exactly how the trick is done. Our brains are still able to make complete sense of the trick at this point, yet we´re still not able to really “see” how the trick is done.

To complete their research, Dr. Macknik and team showed clips of different variations of this trick performed by Teller to 7 subjects. They then studied the way the subject´s eyes moved during the trick, tracking where the subjects were looking and presumably expecting the next ball to emerge.

They then asked these subjects to press button “1” whenever they thought a ball had been removed and button “2” when a ball had been placed on the table or under a cup.

According to their data, even though the subjects knew how the trick was being performed, they hit button 2 more often when balls had not been placed at all.

It did not matter if the trick was being performed with clear or opaque cups; the subjects were mostly unable to accurately tell when the balls had realistically been dropped into cups. Though these subjects eventually got better at identifying the trick the more they watched it, the neuroscientists say the fact a human was performing the trick created too many subtle variations to get a real and accurate result.

With this study complete, the scientists say these results could be used to better understand how people can be misdirected by sleight of hand as well as improve the technique of magicians such as Penn & Teller.