How Neuroscientists and Magicians Are Conjuring Brain Insights

By Mariette DiChristina | May 14, 2012 | Scientific American

Seealso: http://worldtraining.net/BlindSpots.htm

“I see you have a watch with a buckle.” Standing at my side, Apollo Robbins held my wrist lightly as he turned my hand over and back. I knew exactly what was coming but I fell for it anyway. “Yes,” I said, trying to keep an eye on him, “that looks pretty easy for you to take off, but my rings would be harder.” He agreed, politely, while looking down at my hands and then up into my eyes: “Which one do you think would be hardest to remove?” While I considered the answer, he had already removed my watch and put it on his own wrist behind his back, unseen. He isn’t called the “The Gentleman Thief” for nothing.

Robbins had just skillfully managed my attentional spotlight—that is, the focus of awareness at any given moment. To conceal his pilfering, Robbins had employed what is generally called “misdirection”: he got me to attend to the wrong things, added to my brain’s cognitive load with his humorous patter, created a distracting internal dialogue in me by giving me a question to answer, and generally flummoxed me all the while by pressing here and there on a shoulder or wrist. Adding insult to injury, Robbins had just described what he does—and shown his techniques while swiftly lifting another watch and emptying the pockets of the amiable Flip Phillips of Skidmore College. Still, I never stood a chance. My response to being fooled so easily? I laughed out loud. (Watch Robbins work in this Scientific American video, “Magic and Science Together Again at Last” and learn more in this blog post. And here is another video of that I took of Robbins in action during Neuromagic 2012 in this blog post: “Neuroscience and Magic: the Science of Stealing a Watch.”)

Islands of Subjective Reality: We were at the Neuromagic 2012 conference held May 7 to 10, 2012, on San Simón, also appropriately named the Island of Thought, on the north Atlantic coast near Vigo, Spain. Organized by Susana Martinez-Conde and Stephen Macknik of the Barrow Neurological Institute, the talks were intended to advance an intriguing area of brain study that encompasses attention and awareness, aspects of perception, and, ultimately, consciousness research. More about this research area is in their book, Sleights of Mind, which came out in 2010. (An excerpt, “Mind Over Magic?“, by Martinez-Conde and Macknik, who are advisors for Scientific American Mind, appeared in that magazine’s November/December 2010 issue. They also wrote “Magic and the Brain: How Magicians ‘Trick’ the Mind” for Scientific American.)

Why are scientists working with sleight-of-hand artists? Their tricks, honed through the decades, have revealed that people respond to certain situations in specific ways. Like detectives looking for new leads to solve a mystery, scientists can mine magicians’ knowledge for ideas to test in the lab. And for the magicians, understanding principles about the brain—that is, why a trick works the way it does—can suggest new ways to advance their art as they develop new tricks or improve existing ones. (The article, “What Can Magicians Teach Us about the Brain?”, provides some more background and a November 2008 Nature Reviews Neuroscience paper coauthored by neuroscientists and magicians.)

The conference explored several aspects of attention. Macknik started things off by explaining how the brain constructs our experience of reality from a truly imperfect set of biophysical tools, resulting in a “grand simulation of everything around you.” For instance, “You have one megapixel eyeballs compared with your eight megapixel camera,” he said. In addition to collecting a relatively small amount of information from a scene, the eye itself has a large blind spot, where the optic nerve that ferries information to the brain pierces the light-collecting retina at the back of the eye; the brain fills in the visual gap to create the illusion of your vision acting like a seamless movie camera.

Our internally produced picture of reality is subjective—and subject to influence. “Magicians are the performance artists of attention and awareness,” Macknick said. They use a number of techniques, including misdirection, to manage attention. They also take advantage of the brain’s fallibility, including its inability to notice small alterations in a scene (“change blindness”), the multiple ways humans communicate, and more. Ultimately, says Macknik, “Magicians use the spotlight of attention to perform a kind of mental jujitsu.”

Windows of the Soul : An important aspect of human communication is tracking the eye movements of others. “One description of a magician is someone who controls people’s eyes,” said Macknik. In a recent study, for instance, Robbins helped scientists test the whys behind an observation he’d had: that his audience’s eyes followed a curved motion more intently than a straight one. (See the abstract from the journal Frontiers in Human Neuroscience, “Stronger Misdirection in Curved than in Straight Motion.”) When there are only two points in a motion—for instance, when a hand moves from left to right—the eye tends to jump from the start to the end point, and then snap back. That can be problematic for a magician who is trying to move something out of visual range. In contrast, as scientists have now documented in the lab, curves “are very special to the vision system. Curved motion makes the eye track more closely than straight,” said Martinez-Conde. As the magician moves one hand from left to right using a curved motion, the audience’s attention follows the arch and doesn’t snap back to the original point. “A lot of credit goes to Apollo for first bringing this to our attention,” said Martinez-Conde.

Visual perception is so important to survival that even if specific damage to the conscious visual pathways occurs, patients still can receive visual information. Speaker Beatrice de Gelder of Tilburg University in the Netherlands has worked with patients who have such “blindsight.” As you can see in this video, “Blindsight: Seeing Without Knowing It,” the patient can safely negotiate an obstacle course in a hallway without being aware of the objects. (For more on blindsight, see De Gelder’s Scientific American article, “Uncanny Sight in the Blind.”) Pursuing another line of research related to visual perception, studying gaze in infants could help reveal the onset of autism symptoms, which cause deficits in communication, said Jed Elison of the California Institute of Technology.

Because the eyes reveal so much about our thoughts, poker players often mask them with glasses and hoods. Tournament veteran May Maceiras uses her peepers to spy on the “tells”—the physical actions that can accompany a poker move—of other players, later recording them in a logbook for future rounds. After all, “You don’t play with cards; you play with a person,” she said. “Just by observing, I can get a lot of information from my opponents.” Phillips of Skidmore studies deceptive biological motion: what we do to fake out an opponent in games, sports and magic, he said, “to divert attention or commit them to a biophysical motion they can’t get out of.” Software animations made from dots recorded on living subjects help the scientists break down the phases of a deceptive maneuver to find out where the performer might telegraph to an observer what he or she is about to do. For instance, in a move called the French drop, magicians create the illusion that a coin has switched hands when it hasn’t. In studies, Phillips and colleagues found that novices revealed their intentions with such factors as visible muscle tension in their forearms and exaggerated movements whereas experts were better at concealing their covert actions. “In a small amount of time, we get tons of visual information,” he added.

Communication is also influenced by who we are and with whom we’re interacting, said Ava Do, who worked in clinical psychology before moving to magic. (“From my perspective, it seemed that the two fields had a lot in common,” she said.) Certain go-to tricks for men are no guarantee for her. “I got to learn by the hard way that a lot of things that work for male magicians don’t necessarily work for me,” she said. Perhaps studies could reveal the differences at work.

Everybody Loves a Story: Narrative, which engages processing power in the brain by creating an interesting plot that the listener then follows, was effectively employed by attendee magicians such as American magician and debunker extraordinaire James “the Amazing” Randi and Spanish magician Kiko Pastur. Both demonstrated how they make heavy use of a storyline to misdirect, with delightful effect.

As he makes jokes with audience members, Robbins’ questions are also intended to create internal dialogue that eats up some of the brain’s bandwidth. He said he tries to engage what he calls the brain’s “two security guards.” The idea is to get the two talking to each other about what to watch out for, making thievery easier to conduct while the metaphorical guards are distracted. “We have only so many mental dollars that we get to spend,” he added. Once they’re consumed, the victim has no more left to focus on what is really happening. Presto! The wallet is gone.

Conscious expectations and built-in statistical assumptions can lead us astray as well. Amir Raz of McGill University, himself a neighborhood magician in his youth, explained that suggestive “expectation effects” produced by “top down” (or conscious) processes can cause us to think something is happening when it isn’t.

A magician’s knowledge about built-in assumptions and tendencies can be our undoing. Population stereotypes—patterns of behavior—come into play in the mentalist tricks used by Do. “We suffer a lot from our own cognitive biases,” she said. She did a trick with attendees that showed how easy it was, by constraining choices in specific ways, to steer the audience to certain choices and create the effect that she read their minds. (Yes, I fell for that, too.)

Two Sides of the Perception Coin: Probing the interface of science and magic has been yielding valuable insights for both disciplines. After last year’s Neuromagic conference, Miguel Angel Gea, a magician based in Spain, told attendees that he pondered the phenomenon of “filling in,” where the brain, seeing part of a pattern, will fill in the rest. He used that phenomenon in a wonderful card and coin trick. Gea said that one benefit of learning more about the brain is that he can push his magic further. For instance, he might be able to replace a trick deck, which would normally be used for a certain ploy, with real cards, because a better understanding of how the brain works would help him to create the same effect with a regular deck. In a recent study, Luis Martínez Otero of Institute of Neuroscience in Alicante, Spain, used a century-old ploy called the Princess Card Trick to test an observer’s ability to detect changes in a scene. As it turns out, “We are pretty bad at detecting discontinuities”—a perception flaw that can aid magicians. We experience the world as continuous, added Martínez, “but we do not perceive it that way.”

In the study, the researchers presented a set of cards; then the cards were presented again with one card removed. Although subjects weren’t consciously aware of which card had changed (“change blindness”), when asked to choose, they were right much of the time—showing that they had subconsciously processed the information. (Subjects even performed the task fairly successfully when the researchers replaced cards with pictures of faces.) Before making the second presentation of cards, the researchers also tested various options to see if they could interfere with that subconscious processing: asking the subject a question that was related to the topic at hand (“Have you ever played cards before?”); asking a question about a completely different topic (“Have you ever been to the Eiffel Tower?”); and asking the subject to “concentrate on” (instead of “think of”) a card. They found that any additional task depressed the subject’s accuracy. Macknik commented that this experiment was a great example of how magic can point neuroscientists in a new direction: “Neuroscientists can now look for what’s going on in neurons” during this trick. Magicians, too, are “kind of like researchers in labs,” said Do. But they have a lot of confounds working with audiences—there’s no way for them to isolate all the factors and focus on testing one variable. By revealing why something works the way it does in the lab, scientists can help magicians improve their illusions. “I’m turned on by this collaboration,” said D.J. Grothe, president of the James Randi Educational Foundation and a past magician, even though it is one that is not always comfortable in a world where secrecy is prized. “Magic is also the primary force to debunk pseudoscience,” added Macknik. Ultimately, added Robbins, “We’re working together to understand perception processes.” About the Author: Editor in Chief, Mariette DiChristina, oversees Scientific American, ScientificAmerican.com, Scientific American MIND and all newsstand special editions. Follow on Twitter @mdichristina.