Sleights Of Mind Part 8

"Yes."

The arm remains motionless. Berti tries again.

"Are you raising your left arm?"

"Yes," says Carla. But still her arm does not move. "Can you clap your hands?"

Carla moves her right hand to the midline of her body and waves it in a clapping motion. The left hand is motionless.

"Are you sure you're clapping?"

"Yes."

"But I can't hear a sound."

Carla replies, "I never make noise when I do something."

Insistent denial of paralysis was long thought to be a psychological problem, Berti says. It was a reaction to a stroke: I am paralyzed, it is so horrible, I will deny it.

But it is not a Freudian dilemma. Rather, it is a form of so-called neglect syndrome in which a brain area involved in the mental simulation of movements, the supplementary motor area, is damaged. When you close your eyes and simply imagine a golf swing or skiing motion, you activate this part of your brain.

When Berti asks Carla to raise her left arm or clap her hands, the region that imagines such movements produces a familiar pattern of activity in her brain. But the regions that carry out those movements and also maintain awareness of making them are not working.

The conflict is overwhelming. Carla's sense of having moved via simulation is powerful. Awareness is absent. Paralysis is complete. Her brain's solution: confabulate.

If prodded, patients make up stories to explain their lack of action, Berti says. One woman said her arm "went for a walk." A man claimed that his motionless arm did not belong to him. When it was placed in his right visual field, he insisted it was not his.

"Whose arm is it?" Berti asked.

"Yours."

"Are you sure? Look here, I only have two hands."

The patient replied, "What can I say? You have three wrists. You should have three hands."

Neuroscientists can also unmask your confabulatory nature in the laboratory. Two young Swedish scientists have developed a new scientific method that uses magic techniques to examine the fascinating way in which confabulation operates in the intact, healthy, ostensibly rational brain.

We are in Benasque, Spain, nestled in the heart of the Pyrenees, at the Pedro Pascual Center for Science, a retreat designed to bring together scientists from every discipline to hash out ideas in hopes of inspiring new interdisciplinary approaches. Miguel Angel, the Spanish magician whom you met in chapter 5, has just completed his demonstration of change blindness. Now up on stage are two neuropsychologists from Sweden, Petter Johansson and Lars Hall, from Lund University. These two twentysomethings are today's fair-haired boys of cognitive science, and not just because they're Swedish. They have brought a veritable smorgasbord of methods to the discipline. One especially sweet meatball was featured in an October 7, 2005, article in Science magazine describing the invention of a new and powerful method for studying human cognition, rationalization, and decision making called choice blindness. And they did it using magic.

Johansson explains that their experiments were inspired by the so-called introspection illusion. Introspection, he says, does not provide a direct pipeline to your unconscious mental processes. Instead, it is a process whereby you use the contents of your conscious mind to construct a personal narrative that may or may not correspond to your unconscious state. When you are asked to say why you have a particular preference or how you arrived at that preference, your personal self-report of your internal mental processes is confabulated. To put it bluntly, you are unaware of your unawareness.

Johansson and Hall describe their incredible experiments in a fast-beat tag-team style. They show a short movie of themselves, made by the BBC the previous year, to ill.u.s.trate their new approach. It starts with one of them displaying two photographs of two young women to either male or female subjects. The images have been previously matched for attractiveness, so the women are more or less equally good-looking. When they hold up the photos, the subject, seated across the table, points to the one he or she deems more attractive. Next the photos are placed facedown on the table and the selected photo is pushed across the tabletop to the subject, ostensibly so that he or she can pick it up and examine it more closely. "Here, take a closer look and tell us why you chose it!" the researchers ask, entreating each subject to consider the reasons leading to their choice. Johansson and Hall run the experiment dozens of time on each subject and dutifully record the considered opinion of each beauty judge, each time with a new attractiveness-matched pair of photographs.

What Johansson and Hall don't tell their subjects, until after the experiment ends, is that they secretly swapped the photos on one-fifth of the trials, after each subject made their first choice but before they could expound on why they had made it. Most subjects didn't notice the swap. So instead of explaining why they chose the face they now held in their hands, each subject was in fact explaining why they picked the face they had actually just rejected. And boy oh boy, did they lie.

SPOILER ALERT! THE FOLLOWING SECTION DESCRIBES MAGIC SECRETS AND THEIR BRAIN MECHANISMS!.

Johansson and Hall pulled this off by using what magicians call Black Art (similar to that of Omar Pasha in chapter 1), but in this case instead of a black curtain they used a black tablecloth and black-backed photos. In order to fool subjects, they asked them to point to the preferred photo and laid it facedown on the table. That photo had a black back. On top of it they had hidden a second photo, this one of the rejected face. That photo had a red back. When it came time to move the photo toward the subject, the scientists slid the red-backed card (rejected face), leaving behind the black-backed card (preferred face), which was now invisible against the tablecloth. The subjects never saw the swap.

While each subject's brain made up a story for itself to rationalize the "choice," Johansson and Hall (they would take turns serving as experimenter on each sequential subject) surrept.i.tiously swept the actually chosen card off the table and into their laps. Meanwhile the subject a.s.sumed that the photo that had been pushed across the table was the same one he or she had chosen. This unspoken a.s.sumption served as a powerful method of duplicity.

END OF SPOILER ALERT.

The swaps were discovered less than a third of the time. On the successfully swapped trials, the subjects actually confabulated their reasons for having chosen the subst.i.tute photo.

One man said, "I preferred this one because I prefer blondes," when in fact he had first chosen a dark-haired woman. One woman chose a woman without earrings, and when the photo was secretly swapped for a woman with earrings, she said she had chosen that one because she liked earrings. Pants on fire! The subjects hadn't chosen the people whose photos they now held in their hands, but they thought they had. So what do you do when you are made to justify a choice you believe you made? Confabulate. Stick to your guns.

In a follow-up experiment, shoppers in a supermarket tasted two kinds of jam and then explained their choice while taking further spoonfuls from the "chosen" pot. The pots were rigged so that the subjects effusively praised jam they had previously rejected. A similar experiment was done with tea.

Currently, the researchers have begun to examine choice blindness for moral and political opinion. Using a new tool, a "magical questionnaire," they are able to manipulate people's answers to questions presented in a survey format. Partic.i.p.ants are asked to rate to what extent they agreed with a specific moral statement, e.g., "It is morally reprehensible to purchase s.e.xual services even in democratic societies where prost.i.tution is legal and regulated by the government," and then, at the end of the experiment, they are asked to explain why they agreed or disagreed with the statement. Again, the results show that a majority of the partic.i.p.ants are blind to the changes made, and that they often construct elaborate arguments supporting the opposite of their initial position.

These studies help us understand how we rationalize many of our decisions. It's not so much the nature of decision making but the repercussions of those decisions that affect our lives.

Choice Blindness as a Way of Life.

Choice blindness works havoc in your everyday life. Have you ever been the victim of the bait-and-switch, where you thought you were buying one thing but came home with something else?

If you truly had free will, advertising and salesmen's pitches would have no effect. For example, when Steve was a postdoctoral fellow splitting his time between two labs, he needed a car to drive between Harvard Medical School in Boston and Cold Spring Harbor Laboratory on Long Island. So he bought a s.h.i.+ny new black Dodge Intrepid ES with a moon roof, motorized leather seats, upgraded rims, Infiniti surround-sound system, and automatic air temperature controls. It was expensive for a postdoc's salary and put a drain on his resources, but he rationalized the decision because it was an incredibly safe car with side air bags (which were new at the time), traction control, an automatic braking system, and other advanced safety features. After all, the long drives between Ma.s.sachusetts and New York required an extra measure of safety, right?

Sure they did. His decision had nothing to do with thinking that chicks dig a cool car.

To be fair, he did go to the car dealers.h.i.+p with a list of desired safety features. He arrived at the car lot driven by a strong sense of responsibility. The salesperson took one look at Steve's list, knew that the high-end models were the only ones that came with the features he wanted as standard, and then preyed on the fact that his customer was a single male with testosterone-driven needs. Steve could have ordered a cheaper, drabber, smaller model with the same safety equipment and then waited two to three months for the new car to arrive. But the salesman forced him (in the sense that magicians use the word) to buy the fancy car instead.

In the Western world we choose our own mates, right? Arranged marriages and professional matchmakers have joined siegecraft and alchemy in the dustbin of history, have they not? Perhaps. In theory, we can go forth and multiply with anybody we want, so long as there is mutual agreement. We are free, and our number of choices seems for all intents and purposes infinite.

But in practice most of us are no less restricted in our choice of mates than a tradition-bound Eastern youth heading toward an arranged marriage. Consider the fact that we must actually know and interact with the person with whom we pair. We are therefore restricted, in general, to the same geographic location, socioeconomic background, religion, age, current state of availability, and roughly the same level of attractiveness. In reality, it's hard to find a mate who matches all of these parameters, especially after you've completed high school and college. It's hardly a surprise that so many people marry either their high school or college sweethearts.

So how free are we really? Not very. Eastern practices of match-making seem fairly intelligent considering that the choices are made by people (usually parents) who care about the couple, who have hard-earned perspectives on the full course of life, careers, and parenthood, and take all of the issues listed above into account during their decision-making process. Further, with notable exceptions in certain isolated parts of the world, the "lovers" nowadays usually have veto power, at the very least.

Finding a great mate (and one whose baggage is lifetime-tolerable-heard any good mother-in-law jokes lately?) requires real luck in the West, and yet it feels completely free. "I make my own luck," say the enlightened, empowered ma.s.ses. "Believe you will get what you want," says the mega-bestselling self-help book The Secret, "and it will manifest." This ma.s.s enchantment is one of the grandest magic tricks ever devised.

Why do our choices feel so free and unlimited? One answer lies in a psychological principle called cognitive dissonance. This arises when two competing ideas, behaviors, facts, or beliefs are in conflict in your brain. A common way that your brain reconciles the conflict is to change its att.i.tude, beliefs, or behaviors to bring one of the competing ideas into prominence. Magicians love cognitive dissonance, since it leads spectators to feel as though they've made decisions freely for themselves.

An example of this comes from the 2009 Society for Neuroscience annual meeting in Chicago, where we organized a presentation to ill.u.s.trate the power of magic and its potential usefulness in the lab. Our colleagues Apollo Robbins the Gentleman Thief and the mentalist Eric Mead demonstrated various tricks and magic principles to more than seven thousand neuroscientists gathered in a huge ballroom.

The night before the big event, we saw cognitive dissonance in action when Mead performed a magic trick at a party hosted by the society's president, Tom Carew. Scores of world-famous neuroscientists were gathered in his opulent multiroom hotel suite overlooking Lake Michigan.

At one point, Mead had a scientist pick a card from a deck and then asked him to randomly spread out all the cards over a large area of the floor. Only the scientist knew which one was the chosen card. Then Mead took one end of a linen napkin, handed the other end to the scientist, and, pulling it tight, dragged the fellow around the strewn-out cards. Mead boasted that he would detect minute changes in the napkin's tension and thereby read unconscious signals from the scientist's mind to find the correct card. After a minute of this performance, Mead found the card.

The interesting thing about this trick37 is that after the party, when people were t.i.ttering to each other during the descent to street level in the elevator, the scientist who partic.i.p.ated in the trick opined that Mead must have known in advance which card he would choose. This was met by a quick denial from another scientist, a world expert in the field of motor control, who said it was no trick at all. To her mind, Mead had clearly used neuromuscular feedback from the napkin to find the card. She knew that Mead had made no bones that it was a trick, and yet here she was, arguing for something far less likely. Swept up in the moment, her cognitive dissonance had taken her for a wonderful ride down a magical road.

When you make a decision between two things that seem equivalent, cognitive dissonance frequently comes into play. You elevate the value of your choice for the simple reason that it was your choice. Have you ever had a boss who made a dumb decision that became immutable policy long after she realized she had been in the wrong? Cognitive dissonance. Have you yourself ever made a dumb decision concerning your children, but then stuck to your guns so as to "provide consistency"? Cognitive dissonance. Have you ever looked down on people who live in a rival sports team's city for no other reason than that their zip code places them in the enemy camp? Cognitive dissonance.

Cognitive dissonance happens because our free will isn't truly free; it's highly constrained by our context and history. And history, we know, is written by the victors. This is as true of the potential thoughts and deeds that populate our minds as it is of cultures and nations: the winning choice orchestrates emotion, language, and memory to make itself the inevitable and infallibly correct one. In reality, all behavioral decisions are nothing more than a reflection of our genetic and environmental history.

Many people get upset when neuroscientists and philosophers state that free will is an illusion. Those who believe that the mind is wholly separate from the brain-a supposition called dualism-tend to believe that free will is a fundamental property of the mind. According to this view, free will is a separate, numinous quality of being that is not subject to physical laws or reducible to chemistry and circuitry.

But in the realm of neuroscience, there is not a shred of evidence for dualism. The mind is what the brain does. Consciousness and mind are products of your brain.

How could that be? You feel as if you are in full control of your mind. Sure, your brain carries out many tasks without your being conscious of them. You drive home on automatic pilot. You put cups into a dishwasher while carrying on an interesting conversation. But making important decisions? Isn't mental life dependent on the fact that you are free to choose among different possible courses of action? Your decision-making process seems to be driven by your own volition. This feeling fits your sense of justice and moral responsibility.

Let's look at several lines of evidence for the idea (dare we say fact) that free will is an illusion. In the 1970s, Benjamin Libet, a neurophysiologist at the University of California, San Francisco, carried out a series of studies that first challenged the notion that we make decisions consciously and freely. Libet asked people to stare at a clocklike timer with a ball moving around the periphery once every three seconds. They had to press a b.u.t.ton with their right index finger whenever they felt an urge to do so and afterward tell Libet where the ball was (what time it was) when they decided to make the move. Two testing devices-an EEG (electroencephalograph) and an EMG (electromyograph)-recorded their brain activity and the electrical activity of their muscles. Libet found that partic.i.p.ants had the conscious sense of willing the movement about 300 milliseconds after the onset of the muscle activity. Moreover, the EEG showed that neurons in the part of their motor cortex where movements are planned became active a full second before any movement could be measured. You might think that the delay was due to the conduction time between the brain and the muscles. But a full second? No way. There was definitely something interesting happening here.

The findings mean that your brain unconsciously makes the decision to move well before you become aware of it. In other words, your brain, not your conscious mind, makes the decision. This does not match your experience, but it is how your mind actually works. Before you get dis...o...b..bulated, know that there is a silver lining to these results: while decisions are unconsciously prepared ahead of time, you can still veto your actions. According to Libet and others, you may not have free will, but you do have "free won't."

Unwillingly Well Endowed.

The feeling of free will is pervasive to our psyche, but carefully designed laboratory conditions, such as in Libet's experiment, can reveal free will for what it is: a sophisticated cognitive illusion. And if we pay close attention, we can also find rare instances in our everyday life in which the illusion breaks down. Have you ever been flung uncontrollably down a trajectory of complex behavior that you couldn't control no matter how hard you tried? We're not talking about bodily functions like coughing, sneezing, or o.r.g.a.s.m. Those are certainly complex behaviors in which you feel dissociated from the actions of your body, but they are reflexes rather than choices. Drug addicts, alcoholics, and patients with a variety of neurological disorders lose the sense of free will, but what about healthy people?

We saw a great example of someone "losing it" in 2005 while visiting Susana's hometown of A Coruna, Spain. A politician in the mayor's office, Carlos Gonzalez-Garces, was on television giving a boring press conference on a new program regarding the city's fire safety readiness.

"This last year twelve specialization courses were offered, with a very strong focus in the courses given to new firefighters," he said. Some minor details about firefighter courses followed before he began discussing the fire department's equipment status.

"They are well endowed," Gonzalez-Garces told the reporters. He gave a small smile and corrected himself: "They are well endowed in regards to material resources." But then he realized he'd made the situation worse and gave an even bigger smile, which he then tried to suppress. The poor guy tried to hide his face by looking down and to the side of the bank of microphones. "As a matter of fact, this year a concrete investment was made." He was openly laughing now, punctuated by giggles. "I did it by accident," he said, and began rocking side to side, as if to stave off peeing his pants. By this time, his staff was laughing with him. "It was not premeditated," he a.s.sured the press. Gonzalez-Garces regained control briefly but then lost it as the reporters' guffaws could be heard in the background. "Okay, let's see," he said before another failed attempt to suppress laughter. He was now wiping the tears from his eyes. "Never...this never happened to me before." He wiped his eyes again and tried to plow ahead. "All right, so the thing is...a specific truck was bought..." but he couldn't keep himself from another fit of laughter "...for the old part of the city." He was giggling again. "Ay-ay-ay." He sniffled against his running nose and once again failed to suppress the laughter. Like a marionette on a string, Gonzalez-Garces threw himself against the back of his chair, convulsing with mirth. "This seems so childish...it is a laugh attack." He snorted, wiping both eyes. "Ay-ay-ay. Okay. Forgive me." He cleared his voice, brought his chair closer to the table, sniffled, cleared his voice again, and suppressed his giggles. "Okay, here you have the number of vehicles," he started, but he was still completely out of control. He threw himself back in his seat again, laughing uproariously. "And no further explanation is needed," he explained by way of surrender. "If you have any questions about the firemen's endowment," he added between guffaws, "the gentleman who is in charge can answer you."38 The politician's uncontrolled laughter was not a reflex, which by definition is a process that takes place in the shortest possible route through a given neural pathway. When the doctor hits your knee with a hammer and your leg jerks, that is a reflex. No brain required. Laughter, on the other hand, involves a highly complex series of emotional, cognitive, and motor actions that you think you can control. You always have the option of not laughing when you don't want to, right? You have control over your body and behavior, correct? Wrong. This example of the poor guy laughing so hard he almost wet himself on TV shows that while we feel we are in control, we are actually just along for the ride.

A colleague of ours, John-Dylan Haynes of the Max Planck Inst.i.tute in Berlin, Germany, recently reprised Libet's work using functional brain imaging. He wanted to see what happens in people's brains when they make conscious choices. If you had taken part in the study, you would be lying in a scanner when Haynes tells you that you can decide if you want to press a b.u.t.ton with your right hand or left hand. You are free to make this decision whenever you want, but you have to remember the time when you feel you have made up your mind. The researchers used a sophisticated computer program trained to recognize typical brain activity patterns preceding each of the two choices.

Haynes was astonished to find that brain signals-tiny patterns of activity in your frontal lobes-predict your decision (that is, whether you will press the b.u.t.ton with your left or right hand) up to seven seconds before you make a conscious choice. This means that parts of your brain can sometimes know what choices you are going to make several seconds before you become consciously aware of them. Because these brain areas are clearly active with information indicating the choice you are about to make, well ahead of the time that you consciously feel you've made a decision, it seems likely that these brain areas serve to bias your upcoming decision. You may be convinced that your decision was a free, open choice, but it's just not true.

If your actions are determined by the prior neural activity happening in your unconscious brain seconds before you consciously make a decision, do you have a choice about anything? Are you responsible for what you do? In his book The Illusion of Conscious Free Will, the Harvard psychologist Daniel Wegner digs into such questions by comparing the illusion of free will to the perception of magic. You perceive magic, he says, when an apparent causal sequence (the magician saws his a.s.sistant in half) obscures a real causal sequence (the box is rigged so the saw blade never touches her). You do not perceive the real thing even though the apparent sequence violates common sense and you know it's impossible.

Wegner argues that the "self" is magical in this same sense: "When we look at ourselves, we perceive a simple and often astonis.h.i.+ng apparent causal sequence-I thought of it and it happened-when the real causal sequence underlying our behavior is complex, multi-threaded, and unknown to us as it happens."

Wegner wonders how people develop this magic sense, what the philosopher Daniel Dennett calls "some concentrated internal lump of specialness." Why do we experience our actions as freely willed, arising mysteriously from the self? And why, too, do we resist attempts to explain those actions in terms of real causal sequences, events that are going on behind the curtain of our minds?

We feel as if we have free will because we have in dependent thoughts and desires that are then acted upon accurately by our bodies. Our brains are correlation machines, as the magicians prove to us over and over with the presentation of impossible causal events. Because we have the ability to connect cause and effect, there is no evolutionary pressure to develop the sensory pathways necessary to track every bit of the information flowing through our brains. Remember that our neural resources are limited and that we cannot attend to everything in our visual field. Well, that attentional limit would be even more woefully deficient if we also had to attend to every single little process in our brains. Do you really want to know every minute detail of the information that the neurons in your prefrontal cortex are sending to your primary motor cortex in order to reach for a gla.s.s of water? Suffice it that when we are thirsty, our arm successfully picks up a gla.s.s of water and brings it to our mouth. We conclude that our free will directs the action because we didn't tell anybody else about our internal wishes.

Wegner designed an experiment to see if he could prime people to experience thoughts consistent with an event they did not cause and if they could be convinced that they caused it.

Roll back the clock and a.s.sume you are a partic.i.p.ant. You are asked to help with a study on psychosomatic influences on health. Your task is to play the role of a witch doctor who lays a voodoo curse on another partic.i.p.ant, a victim, by sticking pins into a doll. In reality, this person is a confederate in the study (she works for Wegner). Not long after you jab the pins into her ersatz doll body, she feigns a headache. Would you believe you caused her headache? Many of the study partic.i.p.ants did. Moreover, if the "victim" acted in an obnoxious manner, the level of magical witch doctor thinking increased. But no harm had really been done at all.

This readiness to make correlations ill.u.s.trates the general processes by which people succ.u.mb to the belief in the paranormal, especially clairvoyance, precognition, and psychokinesis, says Wegner. Our bodies respond effortlessly to our wishes, and we witness the result as a correlation between our wishes and our body's reaction. It's not too far afield, then, for us to wish for the improbable and, when it happens, to believe that we caused it with our hopes and prayers.

Because we are so used to getting what we wish for in life (like one foot stepping in front of the other), we can't stop ourselves from wis.h.i.+ng for the physically forbidden. An exception may be the ancient Greeks, who believed that each of their motivations and feelings was granted to them by a G.o.d. Chuck Palahniuk, the American novelist, explains, "Apollo was telling them to be brave. Athena was telling them to fall in love. Now people hear a commercial for sour cream potato chips and rush out to buy, but now they call this free will. At least the ancient Greeks were being honest."

You can prove to yourself easily enough that the universe does not accede to your every whim. Wish to perform a Chopin etude on the piano when you've never taken a lesson, and it won't happen. But Wegner explains why we nevertheless overextend our propensity for wishful thinking: "If our wishes seem to prompt a range of activity within our personal sphere of influence, why not hope for more? Many forms of supernatural belief, including belief in prayer, may develop as a natural next step from the magic we perceive in ourselves. If mere wis.h.i.+ng can pop the lid off a bottle of beer, why not wish for the moon?"

Two psychological effects further influence the illusion of free will. In the priority effect, your sense of agency seems causal when the thought of an action occurs just prior to the action. For example, you can be led to experience the arm movements of another person as if the movements were your own. In our professional opinions as neurobiologists, we can tell you that this effect is downright freaky. Imagine you are draped in a robe, arms at your sides. A helper stands behind you and puts his arms through the sleeves. He wears gloves. You hear instructions for how to move your arms through a headset. As the helper makes the movements, you feel as if you have control over his arms. It is an illusion of agency. Has anyone ever called you on the telephone at the same time you were thinking about him or her? It's a coincidence, but you feel agency. But then every feeling of free will that you have is an illusion of agency.

In the exclusivity effect, you perceive that your thoughts cause events for which there are no other plausible explanations. But there may be reasons for making choices that you are not aware of. Wegner gives a nice example. Say you are at a restaurant and the person next to you orders the shrimp special. You were about to order that but, wait, it might look like you were copying that person. So you change your order so as not to look influenced by the other. You think you are choosing of your free will but it isn't so. The fact that you can be influenced about something as trivial as an order of shrimp shows that your free will is a wet tissue. Indeed, no idea is an island.

Wegner says that we have only our conscious thought and our conscious perception to explain our actions post hoc. We may believe that they are connected to free will, but when we do so we take a mental leap over the demonstrable power of the unconscious that guides our actions and conclude that the conscious mind is the sole player. Your conscious thoughts merely provide a rationale for what you just did, which was motivated in a very unfree, deliberate way by your unconscious brain.

Can you break the spell? Some worry that if we prove free will is an illusion that arises from the flesh, the human spirit will be dead. But such a s.h.i.+ft in popular thinking is not likely to happen. The ubiquity of perceived conscious agency in our everyday life is sufficient to quell our inner skepticism telling us that our behaviors are caused by brain mechanisms and not by our free will. The illusion of the magic self cannot be easily suppressed. Moreover, many philosophers and scientists argue that conscious will may be an illusion, but responsible, moral action is quite real.

Can a Machine Read your Thoughts?

Can a machine read your thoughts? Can scientists read the contents of your mind via functional magnetic resonance imaging?

The answer depends on what you mean by "thoughts." Functional magnetic resonance imaging, or fMRI, has come a long way since its discovery in the early 1990s. In a nutsh.e.l.l, the technique measures brain activity by tracking increased blood flow, the idea being that more active brain regions will use more energy and will "light up" in the scanner. In the early days of fMRI research, scientists located regions that specialize in things like our basic sensory processes, speaking, reading, or feeling strong emotions. More recently, they found areas specialized to recognize faces or places.

But can the machines reveal what you are thinking? At the MRC Cognition and Brain Sciences Unit in Cambridge, England, scientists are using a new computational technique called multivariate a.n.a.lysis to predict your thoughts based on observed patterns of activity. If you were in their scanner, they might ask you to imagine playing tennis and then to imagine walking around the rooms in your home. Based on the patterns observed, they could tell you which activity you were thinking about.

Thus far such studies are highly constrained. Only a handful of mental states have been correlated with brain patterns, which are noisy, indirect measures of neural activity. For example, you could imagine playing soccer and moving around your office, and the machine might not be able to tell the difference. Thus researchers cannot do genuine mind reading-they cannot tell you that you are thinking of a hippopotamus, silently reciting the Gettysburg address, or wondering what you will have for dinner tonight. Mind reading remains science fiction.

Why Magic Wands Work.

Illusory Correlations, Superst.i.tion, Hypnosis, and Flimflam.

In the winter of 1983, Susana sat at a table in her mother's dining room with her friend Beatriz and her sister, Carolina. The three adolescent girls leaned over a Ouija board that Susana had made the week before. A Ouija board, in case you've never used one, is a device that allows players to ask questions of the spirit world and find answers from a marker, called a planchette, that moves, apparently of its own accord, across a board marked with letters of the alphabet, numbers, and the words "yes," "no," "maybe," and "good-bye." Susana was giddy with antic.i.p.ation. Unlike her sister and mother, she was the cold-blooded skeptic in her family. This would be fun.

The girls placed their fingertips gently on the planchette, which-instead of the usual heart-shaped device perched on three legs-was a huge silver coin embossed with the face of Spain's deceased dictator, Franco. A radio was blaring as Susana's mother shook her head in disapproval and walked away. To bug her little sister, Susana asked, "What is the name of the boy that Carolina is in love with?" Carolina scoffed and rolled her eyes.

Then the Ouija board started to work. The planchette moved, as if on its own, to the letter J. After a brief moment, it began its journey to the letter A. Susana thought back to earlier that day when she had told Mother Silvia, one of the nuns at school, that she had made her own Ouija board at home. The nun urged Susana not to use it. "You can't be sure who you're talking to," the nun said. For many Christians, the Ouija board is a gateway to satanic control or demonic possession. For them, channeling or consulting the spirits of the dead is a serious sin.

Now the planchette moved toward the letter V. Suddenly a lightbulb exploded in the chandelier above the table. The girls shrieked and pulled their hands back from the sinister device, shaking with an odd mixture of terror and delight. What had just happened? Was the exploding lightbulb a coincidence? Or a warning from the spirit world? Was the explosion and imminent spelling of "Javier" a genuine correlation or an illusory one?

Susana recalls that she and the other girls were all a bit freaked out but pleased to have gotten such a strong "manifestation" before stopping the game for the day. Susana's mother was fairly superst.i.tious, the type of person who believes that you shouldn't tempt fortune. She wouldn't say the word "snake" or "viper" because that would bring bad luck. Susana's mother and sister believed that a supernatural hand had moved the planchette-and smashed the lightbulb.

As cognitive neuroscientists who study foibles of the human mind, we see superst.i.tious beliefs as examples of illusory correlation, the phenomenon of seeing a relations.h.i.+p between events when there is no factual evidence of such a relations.h.i.+p. Exploited by magicians and psychics alike, illusory correlations are the basis of stage acts, magical thinking, and all manner of flimflam. They also can cause enormous mischief in this world.

As scientists, we can explain how Ouija boards work. Spirits don't move the planchette; you and the other players do, via what is called the ideomotor effect. Your voluntary muscles can make tiny movements outside of your conscious awareness. When the movements of all the players reach a consensus (again, unconsciously), the planchette drifts toward a letter, then another, and so on. The ideomotor effect explains other supernatural phenomena including dowsing, automatic writing, and facilitated communication. The movements are self-generated, yet the illusion of an outside force is compelling.

You can try the ideomotor effect on yourself. Suspend a handheld pendulum over a sheet of paper on which you have written the words "yes," "no," "maybe." Ask any and all sorts of questions and the pendulum will give you answers.

And if you want to expose the illusion of the Ouija board, ask the players to put on blindfolds as they move the planchette. Their spelled-out messages will be gibberish.

Teller, the mute partner of the famous Penn & Teller duo and master of illusory correlation, walks on stage at the Magic of Consciousness symposium.39 He is small-but taller than you'd guess from seeing him next to the imposing six feet six of Penn Jillette on television or in their stage show at the Rio Hotel and Casino in Las Vegas-and agile, with an impish personality. Dressed in black trousers, black loafers, and a black s.h.i.+rt with dragons stenciled on the back, he looks like an elf king from the Lord of the Rings. Teller almost always wears a bemused expression, as if concealing a private joke, and clearly relishes the opportunity of explaining magic to the a.s.sembled scientists.

"One of the things magicians do," says Teller, "is take advantage of our natural inclination to study something we see done over and over again and think that we're learning something. Because in real life, if you see something done again and again, you study it, and gradually you pick up a pattern. If you do that with a magician, it's sometimes a big mistake."

Teller paces the stage. "Suppose I produce a coin." He holds his right hand high over his head and out of thin air produces a s.h.i.+ny silver coin. Then Teller drops the coin into a bra.s.s bucket held in his left hand. You hear a loud clink. He thrusts his right hand in a different direction and s.n.a.t.c.hes another coin from the air. Clink. Then another. Clink. And another. He bites it and says "This one is real" before dropping it into the bucket. Clink. "Maybe another one out there." Clink. With this last coin, Teller spreads his hand and fingers wide so that you can see he is not hiding anything.

Then Teller walks up to the audience and, combing his fingers through a man's white hair, pulls out yet another coin and tosses it into the bucket. Clink. He removes a guy's eyegla.s.ses and tips the lenses over the bucket's lid. Clink clink. He rapidly picks up another person's bag, rummages through it, and pulls out more coins. Clink clink clink. Finally he holds his hand up to his face and coughs, and out falls yet another coin that goes into the bucket with the rest. Clink!