It seems hypnosis has been nearly everywhere over the past few centuries: onstage with entertainers swinging fat, gold watches; on couches with reclining psychoanalysis patients; in movies, books, and even children's cartoons. But the one gig hypnosis couldn't get was the scientific laboratory.
The long-controversial practice of inducing a trancelike state through suggestion is getting a modern makeover by scientists armed with the latest neuroimaging tools and techniques. These researchers are beginning to offer evidence that, neurologically at least, hypnosis is entirely real.
"It makes sense that we are using modern tools of neuroscience research to understand what is a fascinating phenomenon," said David Spiegel, a psychiatrist at Stanford University. "It's good for hypnosis, and it's good for neuroscience."
The first report of hypnosis in practice dates back to the 18th century and an Austrian physician named Franz Mesmer, whose alleged otherworldly techniques for putting patients in trancelike states spawned the word "mesmerism."
Almost from the beginning, the technique was controversial.
Skeptics have charged that the so-called phenomenon is nothing more than social role-playing, its use in medicine simply another form of the placebo effect. Its employment in psychotherapy has been challenged, particularly in light of claims that it can be used to implant false memories. And the idea, espoused by some hypnotists, that hypnosis involves an altered state of consciousness known as "trance," has only made it seem more questionable.
Though experts quibble over the exact definition of hypnosis, they agree that it involves intense concentration, increased relaxation, and heightened suggestibility. In 2000, Spiegel and others conducted experiments involving perceptual and sensory experiences that demonstrated some of the effects hypnosis has on the brain.
In Spiegel's study, subjects—some hypnotized, others fully alert—viewed pictures in both color and grayscale. When hypnotized subjects were told they would see photos in color, the brain regions involved in the visual processing of color were activated, even if the subjects were actually viewing the grayscale photos. And when hypnotized subjects were told they would see photos in grayscale, the activation of the color processing regions decreased, regardless of which photos actually appeared.
Many studies have also shown that hypnotic suggestion can prompt changes in the brain's pain processing centers. Such research has illustrated that when people are hypnotized before painful procedures, the areas of their brains that process pain are less active.
"When they use hypnosis to alter perception, the subjective experience is altered in measurable changes in just the right part of the brain," Spiegel said. "When people say they are feeling less pain, they really are feeling less pain."
"It's providing objective evidence that hypnosis is real," he continued.
But scientists still lack what would be the ultimate validation of this sort of research: a distinct neurological signature of hypnosis. So far, it has been difficult to disentangle the effects of hypnotic suggestion from those of suggestion alone. Researchers must also differentiate between the brain structures that play a role in hypnosis and those that are merely involved in the perceptual tasks subjects are asked to perform in these studies.
However, scientists are beginning to make some intriguing observations, particularly in the prefrontal cortex, the brain region responsible for the brain's so-called executive functions: integrating the work of other brain structures, governing decision making, and, perhaps most relevantly, regulating attention. Researchers have long noted that hypnosis can be characterized as an extreme, narrowly focused form of attention.
Some researchers have found that areas in the prefrontal cortex—particularly the anterior cingulate cortex, which seems to be involved in attention, error detection, and resolving conflicts—change their activation patterns during hypnosis.
Scientists are hoping that, as more studies help pin down the brain structures involved in hypnosis, the phenomenon will become a more popular—and acceptable—focus of research, especially since the work could help illuminate other neurological phenomena.
"There's two basic ways that neuroimaging is used in hypnosis research," said Michael Nash, a psychologist at the University of Texas and the former editor of the International Journal of Clinical and Experimental Hypnosis. "One is to use neuroimaging to try to understand hypnosis. But the other way is to use hypnosis to produce in-the-laboratory experiences that can be studied through neuroimaging."
For instance, hypnosis, which can prompt perceptual experiences similar to hallucination, may be a technique researchers can use to induce, and then study, hallucinations. Hypnosis might also be a tool for studying cognitive development—children are much more hypnotizable than adults—and for providing researchers with more information about attentional networks.
"As we do more and more research in laboratories, we can, in a sense, 'domesticate' hypnosis," Nash said. "The neuroscience link adds a component to the credibility of hypnosis."
So, too, might another modern science: genetics.
People vary widely in their ability to be hypnotized, but studies of identical and fraternal twins indicate that susceptibility to hypnosis may have a genetic component. Amir Raz, a psychiatrist at Columbia University, and his colleagues are now trying to pin down the specific genes that might be responsible for those variations. Researchers hope that finding a gene that modulates hypnosis—and the neurochemical pathway it affects—might finally silence skeptics.
"Part of the reason it hasn't been explored before is because of the checkered reputation of hypnosis," said Raz, who has published numerous neuroimaging studies of hypnosis. "Once you see people getting published in good and reputable journals with hypnosis studies, it's going to prompt a whole wave of interest."