Hypnosis: Medical Tool or Illusion?

A  The image most people have of the mysterious art of hypnotism is of a stage trick. But hypnotists are much more likely nowadays to be scientists seeking ways to probe the subconscious mind, or find a new way to relieve pain. But is hypnosis a real phenomenon? If so, what is it useful for? Over the past few years, researchers have found that hypnotized individuals actively respond to suggestions even though they sometimes perceive the dramatic changes in thought and behavior they experience as happening "by themselves." During hypnosis, it is as though the brain temporarily suspends its attempts to authenticate incoming sensory information. Some people are more hypnotizable than others, although scientists still don't know why. To study any phenomenon properly, researchers must first have a way to measure it. In the case of hypnosis, that yardstick is the Stanford Hypnotic Susceptibility Scales. The Stanford scales, as they are often called, were devised in the late 1950s by Stanford University psychologists. One version of the Stanford scales consists of a series of 12 activities—such as holding one's arm outstretched or sniffing the contents of a bottle—that test the depth of the hypnotic state. In the first instance, individuals are told that they are holding a very heavy ball, and they are scored as "passing" that suggestion if their arm sags under the imagined weight. In the second case, subjects are told that they have no sense of smell, and then a vial of ammonia is waved under their nose. If they have no reaction, they are deemed very responsive to hypnosis; if they grimace and recoil, they are not.

B  Researchers with very different theoretical perspectives now agree on several fundamental principles of hypnosis. The first is that a person's ability to respond to hypnosis is remarkably stable during adulthood. In addition, a person's responsiveness to hypnosis also remains fairly consistent regardless of the characteristics of the hypnotist: the practitioner's gender, age and experience have little or no effect on a subject's ability to be hypnotized. Similarly, the success of hypnosis does not depend on whether a subject is highly motivated or especially willing. A very responsive subject will become hypnotized under a variety of experimental conditions and therapeutic settings, whereas a less susceptible person will not, despite his or her sincere efforts. (Negative attitudes and expectations can, however, interfere with hypnosis.)

C  Under hypnosis, subjects do not behave as passive automatons but instead are active problem solvers who incorporate their moral and cultural ideas into their behavior while remaining exquisitely responsive to the expectations expressed by the experimenter. Nevertheless, the subject does not experience hypnotically suggested behavior as something that is actively achieved. To the contrary, it is typically deemed as effortless—as something that just happens. People who have been hypnotized often say things like "My hand became heavy and moved down by itself" or "Suddenly I found myself feeling no pain." Many researchers now believe that these types of disconnections are at the heart of hypnosis. In response to suggestion, subjects make movements without conscious intent, fail to detect exceedingly painful stimulation or temporarily forget a familiar fact. Of course, these kinds of things also happen outside hypnosis—occasionally in day-to-day life and more dramatically in certain psychiatric and neurological disorders.

D  Scientists think that hypnosis may relieve pain by decreasing the activity of brain areas involved in the experience of suffering. Positron emission tomography (PET) scans of horizontal and vertical brain sections were taken while the hands of hypnotized volunteers were dunked into painfully hot water. The activity of the somatosensory cortex, which processes physical stimuli, did not differ whether a subject was given the hypnotic suggestion that the sensation would be painfully hot or that it would be minimally unpleasant. In contrast, a part of the brain known to be involved in the suffering aspect of pain, the anterior cingulate cortex, was much less active when subjects were told that the pain would be minimally unpleasant.

E  Perhaps nowhere has hypnosis engendered more controversy than over the issue of "recovered" memory. Cognitive science has established that people are fairly adept at discerning whether an event actually occurred or whether they only imagined it. But under some circumstances, we falter. We can come to believe (or can be led to believe) that something happened to us when, in fact, it did not. One of the key cues humans appear to use in making the distinction between reality and imagination is the experience of effort. Apparently, at the time of encoding a memory, a "tag" cues us as to the amount of effort we expended: if the event is tagged as having involved a good deal of mental effort on our part, we tend to interpret it as something we imagined. If it is tagged as having involved relatively little mental effort, we tend to interpret it as something that actually happened to us. Given that the calling card of hypnosis is precisely the feeling of effortlessness, we can see why hypnotized people can so easily mistake an imagined past event for something that happened long ago. Hence, something that is merely imagined can become ingrained as an episode in our life story.

F  So what are the medical benefits of hypnosis? A 1996 National Institutes of Health technology assessment panel judged hypnosis to be an effective intervention for alleviating pain from cancer and other chronic conditions. Voluminous clinical studies also indicate that hypnosis can reduce the acute pain experienced by patients undergoing burn-wound debridement, children enduring bone marrow aspirations and women in labor. The pain-relieving effect of hypnosis is often substantial, and in a few cases the degree of relief matches or exceeds that provided by morphine. Hypnosis can boost the effectiveness of psychotherapy for disorders such as obesity, insomnia, anxiety and hypertension.