Before long, hypnotism started finding its way into the world of modern medicine. The use of hypnotism in the medical field was made popular by surgeons and physicians like Elliotson and James Esdaille and researchers like James Braid who helped to reveal the biological and physical benefits of hypnotism. According to his writings, Braid began to hear reports concerning various Oriental meditative practices soon after the release of his first publication on hypnotism, Neurypnology (1843). He first discussed some of these oriental practices in a series of articles entitled Magic, Mesmerism, Hypnotism, etc., Historically & Physiologically Considered. He drew analogies between his own practice of hypnotism and various forms of Hindu yoga meditation and other ancient spiritual practices, especially those involving voluntary burial and apparent human hibernation. Braid's interest in these practices stems from his studies of the Dabistān-i Mazāhib, the "School of Religions", an ancient Persian text describing a wide variety of Oriental religious rituals, beliefs, and practices.
In hypnosis, patients typically see practitioners by themselves for a course of hourly or half-hourly treatments. Some general practitioners and other medical specialists use hypnosis as part of their regular clinical work and follow a longer initial consultation with standard 10- to 15-minute appointments. Patients can be given a post-hypnotic suggestion that enables them to induce self-hypnosis after the treatment course is completed. Some practitioners undertake group hypnosis, treating up to a dozen patients at a time—for example, teaching self-hypnosis to prenatal groups as preparation for labor.
Not every person is hypnotizable to the same degree; some aren’t hypnotizable at all. “Hypnotizability … is modestly correlated with absorption, a personality construct reflecting a disposition to enter states of narrowed or expanded attention and a blurring of boundaries between oneself and the object of perception,” writes John F. Kihlstrom, a psychologist at the University of California, Berkeley, in a 2013 paper in Cortex. “Absorption, in turn, is related to ‘openness to experience,’ one of the ‘Big Five” dimensions of personality.”
Finally, the neural underpinnings of PHA will be even clearer when we incorporate its most important aspect in imaging studies—the dissociation between implicit and explicit memory. In PHA (and in functional amnesia) the person is unable to explicitly recall certain information, yet we see evidence of this material on implicit measures. For instance, a participant given PHA may fail to recall the word “doctor,” learned earlier, but will have no trouble completing the word fragment “d _ _ t _ r”. Mendelsohn et al. did not assess implicit memory. Rather, they tested recognition, which in a sense confounds explicit and implicit memory. We’d like to compare brain scans of a PHA group trying to explicitly recall the movie (they should show reduced activation, as above) with brain scans of the same group completing an implicit memory measure of the movie (they should show normal activation). This would be tricky to do—implicit measures of complex material such as movies and autobiographical memories are hard to find or construct. But it would contribute to a more complete neural picture of the processes involved in these fascinating forms of forgetting.
The patient must be made to understand that he is to keep the eyes steadily fixed on the object, and the mind riveted on the idea of that one object. It will be observed, that owing to the consensual adjustment of the eyes, the pupils will be at first contracted: They will shortly begin to dilate, and, after they have done so to a considerable extent, and have assumed a wavy motion, if the fore and middle fingers of the right hand, extended and a little separated, are carried from the object toward the eyes, most probably the eyelids will close involuntarily, with a vibratory motion. If this is not the case, or the patient allows the eyeballs to move, desire him to begin anew, giving him to understand that he is to allow the eyelids to close when the fingers are again carried towards the eyes, but that the eyeballs must be kept fixed, in the same position, and the mind riveted to the one idea of the object held above the eyes. In general, it will be found, that the eyelids close with a vibratory motion, or become spasmodically closed.
When James Braid first described hypnotism, he did not use the term "suggestion" but referred instead to the act of focusing the conscious mind of the subject upon a single dominant idea. Braid's main therapeutic strategy involved stimulating or reducing physiological functioning in different regions of the body. In his later works, however, Braid placed increasing emphasis upon the use of a variety of different verbal and non-verbal forms of suggestion, including the use of "waking suggestion" and self-hypnosis. Subsequently, Hippolyte Bernheim shifted the emphasis from the physical state of hypnosis on to the psychological process of verbal suggestion:
In the 1980s and 1990s, a moral panic took place in the US fearing Satanic ritual abuse. As part of this, certain books such as The Devil's Disciples stated that some bands, particularly in the musical genre of heavy metal, brainwashed American teenagers with subliminal messages to lure them into the worship of the devil, sexual immorality, murder, and especially suicide. The use of satanic iconography and rhetoric in this genre provokes the parents and society, and also advocate masculine power for an audience, especially on teenagers who were ambivalent of their identity. The counteraction on heavy metal in terms of satanic brainwashing is an evidence that linked to the automatic response theories of musical hypnotism.
In 2007, a meta-analysis from the Cochrane Collaboration found that the therapeutic effect of hypnotherapy was "superior to that of a waiting list control or usual medical management, for abdominal pain and composite primary IBS symptoms, in the short term in patients who fail standard medical therapy", with no harmful side-effects. However the authors noted that the quality of data available was inadequate to draw any firm conclusions.
But the reason why this ever works, for anyone, is still not clear. Some researchers argue that hypnosis may help us tap into “the autonomic nervous system to influence physical systems that aren’t usually under voluntary control,” Marchant writes in her book. She points to Karen Olness, a retired pediatrician and former member of the NIH Council for Complementary and Alternative Medicine, who has worked with children who could, through hypnosis, increase the temperature of their fingertips “way beyond what would be achieved merely from relaxation.”
In the brain, this state looks stranger still. A landmark study in the prestigious journal Science in the late 1990s, led by Pierre Rainville of the University of Montreal, described a study in which hypnotized people briefly placed their left hand in either painfully hot water, heated to 116 degrees Fahrenheit, or room-temperature water. Some of them had been told that they would be experiencing pain, but that they wouldn’t be very bothered by it — if, on a scale of one to ten, the hurt would normally register at an eight, they’d feel it as if it were a four. As all the participants placed their hands in the 116-degree water, their brains were scanned. The results were clear: Those who had been told that the pain would be less intense showed less activity in their brains — specifically, in the anterior cingulate cortex, which is associated with pain processing.
Abnormal results can occur in instances where amateurs, who know the fundamentals of hypnosis, entice friends to become their experimental subjects. Their lack of full understanding can lead to immediate consequences, which can linger for some time after the event. If, for example, the amateur plants the suggestion that the subject is being bitten by mosquitoes, the subject would naturally scratch where the bites were perceived. When awakened from the trance, if the amateur forgets to remove the suggestion, the subject will continue the behavior. Left unchecked, the behavior could land the subject in a physician's office in an attempt to stop the itching and scratching cycle. If the physician is astute enough to question the genesis of the behavior and hypnosis is used to remove the suggestion, the subject may experience long-term negative emotional distress and anger upon understanding exactly what happened. The lack of full understanding, complete training, and supervised experience on the part of the amateur places the subject at risk.
Controversy surrounds the use of hypnotherapy to retrieve memories, especially those from early childhood or (supposed) past-lives. The American Medical Association and the American Psychological Association caution against recovered-memory therapy in cases of alleged childhood trauma, stating that "it is impossible, without corroborative evidence, to distinguish a true memory from a false one." Past life regression, meanwhile, is often viewed with skepticism.
After hypnosis, participants’ memories were tested twice while the fMRI scanner recorded their brain activity. For Test 1, they were asked 40 questions about the content of the movie (for example, the actress knocked on her neighbor’s door on the way home) and 20 questions about the context in which they saw the movie (for instance, during the movie, the door to the study room was closed). These questions required a “yes” or “no” response. For Test 2, participants were asked the same 60 recognition questions, but first they heard the cue to cancel PHA. So Test 1 measured memory performance and brain activity while the PHA suggestion was in effect and Test 2 measured memory performance and brain activity after it was cancelled.