Hypnosis Revisited

[Este artículo está disponible en español. La traducción al español apareció por primera vez en la revista Pensar.]

Is hypnosis for real? Do people actually go into a trance, or is it just a matter of imagination and role playing? Some people swear by it. One website proclaims that “Your mind power is limitless…The highly focused, yet deeply relaxed state of mind achieved via hypnosis yields many great benefits, digging to the root cause of many of our mental, physical, and psychological problems. Used for centuries, the popularity of hypnosis continues to grow, as modern science embraces its life-transforming potential.” It is said to do everything from restoring memories of past lives to making people stop smoking. Is all that true? I’m skeptical.


Perhaps the first to describe the hypnotic state was Avicenna, a Persian physician who wrote about “trance” in 1027. Hypnosis was introduced to the modern world by Franz Mesmer, a German doctor whose treatments became known as mesmerism. Working in Paris in the late 18th century, he claimed that an invisible force he called “animal magnetism” influenced health. At first he used magnets, but then decided magnets were not necessary. He found he could get the same results by merely passing his hands over a patient’s body. Later he treated groups of patients who sat around a “baquet” and were connected by iron rods and ropes; Mesmer made hand motions but did not touch the patients. The treatment provoked striking responses such as vomiting or convulsions.

King Louis XVI wondered about Mesmer’s methods. He appointed a Board of Inquiry to investigate. The Board, which included the scientific luminaries Antoine Lavoisier and Benjamin Franklin, concluded that Mesmer’s results were due to belief and imagination rather than to any invisible energy. Benjamin Franklin wrote the majority opinion, calling Mesmer a fraud. The term hypnotism is derived from the Greek word for “sleep,” but it has nothing to do with sleep. The word was popularized by James Braid, a Scottish surgeon who thought it was a mere contrivance to induce responses that were easily explained by ordinary psychological and physiological principles.

Through the years there were many advocates and practitioners of hypnosis as well as many skeptics. Much misinformation surrounded hypnosis. Some thought it could be used to force a person to commit a crime. It was linked to popular music and to satanic ritual abuse. Some saw it as a political threat, fearing the French could use it to subdue England. The opinions of religious people were mixed: some saw it as the work of the devil; others thought Jesus had practiced it; and Mary Baker Eddy claimed animal magnetism could lead to moral and to physical death.

Sigmund Freud was trained in hypnosis. He practiced it for years, using hypnotic regression to help patients recover repressed memories. But he eventually abandoned it in favor of psychoanalysis. He toyed with the idea of augmenting psychoanalysis with hypnosis, thinking it might hasten recovery but then deciding it might weaken the outcome.

Hypnosis has been depicted in books and movies, often inaccurately. The fictional hypnotist Svengali exploited a young girl with evil intent. In Edgar Allan Poe’s short story “The Facts in the Case of M. Valdemar” a man was hypnotized at the moment of death and continued to speak from beyond the grave.

Fun with hypnosis

In his autobiography, Mark Twain wrote about his experience with a stage hypnotist who performed in Hannibal, Missouri for two weeks. Twain was fifteen at the time and liked the idea of getting all that attention, so after failing to be hypnotized several nights in a row, he went along with the suggestions and pretended to be hypnotized. Soon Twain was the hypnotist’s only subject and was the star of the show. He relates how they fooled everyone in town except for a few skeptics. Many years later, he tried to set the record straight by confessing the deception to his mother. But she refused to believe him, insisting vehemently that he really had been hypnotized!

I heard about a local dermatologist who had a patient with a rash on his arm that wouldn’t heal because he kept scratching an unexplained itch. He hypnotized the patient and suggested that instead of scratching, the patient would drop whatever he was holding when the itching started. It worked beautifully. It seems the itching was triggered whenever his wife criticized him or nagged him, usually at the dinner table. He didn’t consciously remember the suggestion, but he followed it faithfully, dropping his fork, food, water glass, or whatever was in his hand at the time. Without knowing why, she became conditioned to stop nagging him. I guess she got tired of cleaning up the mess.

My personal experience

I was taught in medical school to think of hypnosis as the SASI state: not a trance but a state of Selective Attention/Selective Inattention produced by strong suggestion. Attention is focused and subjects ignore all other sensory inputs. Readers might accuse me of being unfair, saying I shouldn’t knock it until I tried it. But I have tried it. In medical school I participated in group sessions and found it very relaxing and enjoyable. We were given the useful post-hypnotic suggestion that we would never succumb to “highway hypnosis” and fall asleep at the wheel. I still remember the warning and I have never been in danger of falling asleep at the wheel (but probably not because of the post-hypnotic suggestion). I also had an individual experience during my residency training when another doctor hypnotized me and suggested I had a non-anatomical area of decreased sensation on my arm. An orthopedic doctor examined me and was appropriately puzzled until we revealed the trick. I even tried self-hypnosis but quickly lost interest. It produced a nice, relaxed feeling, but I didn’t think it was worth the time and effort involved.

Hypnosis today

Today hypnosis is widely used for many purposes, from entertainment to forensics to medical treatment to self-improvement. Some think it is an altered state of consciousness; others call it a placebo, an interaction with a therapist, or an imaginative role enactment. Scales of “hypnotizability” have been devised, and some therapists have estimated that up to 25% of the population can’t be hypnotized. 

Retrieving lost memories. When I attended an airplane accident investigation course in the Air Force, we were taught that hypnosis could retrieve lost memories and should be used on witnesses to help them remember forgotten details like the numbers on license plates. That’s simply not true. It doesn’t retrieve actual memories but encourages subjects to fantasize and create false memories. Hypnotherapy to retrieve repressed memories of childhood sexual abuse is more likely to result in tragedy than truth: people who were falsely accused have gone to jail. Under hypnosis, people are more suggestible and more open to fantasy and imagination, and it is impossible to distinguish between a true event and a fantasy. Psychological studies have shown that memory is unreliable. It doesn’t record like a video camera but is malleable. Every time we recall something it can be subtly altered or confused with another memory. False memories are easy to create and can seem more real than true memories.

Age regression. In age regression, subjects are asked to return to an earlier time in their life. They confabulate, making up false memories that can’t be independently confirmed. They talk as they imagine a child of that age would talk, but not the way a child of that age really talks.

Past life regression. Past life regression has been thoroughly debunked. It is a method that uses hypnosis to recover memories of past lives, requiring a belief in reincarnation. In the case of Bridey Murphy, a housewife recalled living in 19th century as an Irish woman. Her story seemed very convincing but careful investigation completely discredited it.  Fact checking proved many of the details false, and the ones that were true were determined to be a result of cryptomnesia. She had remembered things she had heard or seen during childhood, but she had forgotten the source of the memories. Curiously, those who report past lives always claim to have been important people like Cleopatra or Napoleon, never common swineherds or kitchen maids. The details they relate can’t be corroborated and they can’t properly speak the language they would have used in the previous life.

The military. Hypnosis was investigated by the military. They found no evidence that it could be used for military applications.

Surgery. There are reports of patients undergoing surgery with hypnosis  instead of conventional anesthesia, but they are not properly documented and no conclusions can be drawn.

The scientific evidence

There is no objective way to tell whether a person is hypnotized. We have to rely on self-reports and on observations of their behavior. If they claim to have amnesia for what happened during hypnosis, we can’t rule out the possibility that the memory still exists somewhere in their brain. One intriguing study divided subjects into two groups. One group was hypnotized, and the other group was asked to just pretend they were hypnotized. Their behavior was identical. Moreover, all the effects attributed to hypnosis have been replicated without hypnosis.

The scientific evidence is far from convincing, and hypnosis is categorized by many medical organizations as a form of alternative medicine. Medical applications of hypnosis have been widely studied in clinical trials. There are reports of its success for smoking cessation, but a 2019 Cochrane systematic review  of published studies found no clear evidence that hypnosis was effective. For weight loss, when hypnosis was added to cognitive behavioral therapy, it increased success rates. It has been found useful for managing pain and for reducing anxiety about surgery.

In Robert Baker’s book They Call It Hypnosis he claims there is no such thing as hypnosis. He says it is a form of learned behavior and compliance with the suggestions of an authority figure.

So, is it real?

After reviewing the evidence, I’m not convinced that the “hypnotic trance” is a real thing. The procedures used to induce hypnosis are tricks that focus attention, reduce peripheral awareness, enhance the patient’s response to suggestion, and encourage fantasy. I will continue to think of hypnosis as the SASI state of selective attention/selective inattention. The ability to focus and to direct one’s thoughts are undoubtedly very useful in many contexts, but hypnosis is not the only way to achieve those goals. Cognitive behavioral therapy and meditation can accomplish some of the same things. I wouldn’t mind being hypnotized again to recreate the enjoyable relaxation I experienced; but I wouldn’t rely on it to retrieve a memory, to replace anesthesia for surgery, or to do all the other things hypnosis is claimed to do. And I don’t intend to ever go on stage and act like a chicken!

This article was originally published as a “Reality Is the Best Medicine” column in Skeptical Inquirer

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine Blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.

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