Psychiatrist David Spiegel has Zoraida Smith roll back her eyes to test her hypnotizability. “Hypnosis is poised between two sacred cows,” he says, “that the body is a machine and that we are individuals.”

Kirsch often uses hypnosis in his practice, and he doesn’t deny that it can be effective. “With hypnosis you do put people in altered states,” he says. “But you don’t need a trance to do it.” He likes to illustrate the point with an ancient talisman of the hypnotic trade: the pocket watch hanging on a chain. Put your elbow on a table, he says, holding the chain between your thumb and forefinger, and let the weight swing freely. Now, keeping your hand as steady as possible, imagine that the pendulum is moving back and forth parallel to your chest. “Just focus on it moving in that direction. Side to side,” he says. “Ignore everything else and imagine it going side to side at its own rhythm.” Once it’s swaying that way, and it inevitably will, imagine it swinging another way—clockwise, say, or toward you—just to prove to yourself that it’s not a coincidence. Once again, the weight will obey your mind. This little trick works on even the most skeptical and unhypnotizable of people. You don’t have to enter a trance for your subconscious and your body—in this case, the tiny muscles in your fingers—to respond to a suggestion. “I could have hypnotized you and done the same thing, but it wouldn’t have been a result of the hypnosis,” Kirsch says. “It would have been a result of your focusing on moving it in a particular direction.”

Spiegel disagrees. One of his best-known studies found that when subjects were hypnotized and given suggestions, their brain-wave patterns changed. He admits that suggestion alone is a powerful tool but believes that hypnosis magnifies its effects. In another of Spiegel’s studies, people under hypnosis were told their forearms were numb, then given light electrical shocks to the wrists. They didn’t flinch or respond in any way, and their brain waves resembled those of people who experienced a much weaker shock.


To Kirsch, this still wasn’t enough to prove the power of trance, but Stephen Kosslyn  was willing to be convinced. Kosslyn is an exceedingly polite man, with a gray, philosophical beard and perpetually raised eyebrows. The hypnosis literature is rife with examples of subjects aping what they believe is hypnotic behavior, he says. Such “demand effects” are exactly what make placebos so effective. As for the brain-wave study, other events in the lab—such as interaction with the investigators—could have caused the shift in the subjects’ state of mind. “Is it just playacting?” Kosslyn wondered, when he first saw Spiegel’s data. “Or is there something really going on in the brain?”

To find out, Spiegel and Kosslyn decided to collaborate on a study, focusing on a part of the brain that is well understood: the fusiform circuit. Located on the occipital lobe, the circuit has been found to process the perception of color. Neuroscientists zeroed in on it by placing subjects in a positron-emission tomography (PET) scanner to measure blood flow in the brain, then having them look at cards with color rectangles. Spiegel and Kosslyn wanted to see if subjects could set off the same circuit by visualizing color while under hypnosis.

The first step was to find the right study subjects. Only a small fraction of the population—known as highs in hypnotic circles—can enter a deep trance, just as only a few people cannot be hypnotized at all. The rest of us fall on a spectrum in between. (See “Can You Be Hypnotized?” page 60.) Spiegel and Kosslyn selected eight people from a pool of around 120 subjects, then Kosslyn’s team ran the experiment at Massachusetts General Hospital in Boston. As in the previous studies, subjects were put inside a PET scanner, shown a slide with color rectangles, and their brain activity was mapped. Then they were shown a black-and-white slide and told to imagine its having a color. Both tasks were repeated while under hypnosis.

The results, published in the American Journal of Psychiatry in 2000, were striking. When the subjects truly saw the color rectangles, the fusiform circuit lit up on both sides of their brain; when they had to imagine the color, the circuit only lit up in the right hemisphere. Under hypnosis, though, both sides of the brain became active—just as in regular sight. Under hypnosis, imagination seemed to take on the quality of a hallucination.

After the experiment, Kosslyn’s raised eyebrows, for once, came down. “I’m absolutely convinced now that hypnosis can boost what mental imagery does,” he says. “It sort of gives it a shot of vitamin A or something.” But Kirsch remains skeptical. The color experiments demonstrate that people “are really experiencing the effects of hypnotic suggestion,” Kirsch says, but not necessarily that they enter a trance. The subjects were told to see the card in color when they were hypnotized but only to imagine it in color when they weren’t, Kirsch points out. “Being told to pretend that you’re having the experience is a very different thing than the suggestion to have the experience.”

“Technically, he’s right,” Kosslyn says. Because the eight subjects were all highly hypnotizable—or at least highly suggestible—Kosslyn and Spiegel were afraid that if the subjects were told to see the color, just as they had been when hypnotized, they would slip into a trance. Kosslyn doubts that changing the wording would have made a difference. “The hypnotized people would tell you that they could literally see. ‘Lows’ couldn’t even do the task. They simply couldn’t do it.”