By Jana Jaran Art by Hailey Kopp
What comes to mind when you hear the word “hypnotism”? Are you picturing a leather armchair and a stopwatch? Maybe you’re recalling a magic show where volunteers are miraculously convinced to quack like ducks in front of a crowd of people. Picture the infamous hypnotism scene in the 2018 Academy Award-winning film, Get Out. Chris, played by Daniel Kaluuya, sits comfortably in an armchair across from Mrs. Armitage as she slowly stirs her tea, brushing her spoon melodiously around the sides of the cup. Through close-up shots that jump from the teacup to Chris’s eyes to his arms sinking into the chair, we see Chris gradually lose all sense of control over his body. With only three simple words—“You can’t move”—Chris falls into complete catalepsy, unable to move his body at all [1].
In Get Out, hypnotism renders Chris conscious but entirely beholden to the will of his hypnotist. While licensed hypnotists are certainly capable of inducing catalepsy, a state of muscle rigidity and loss of sensation, hypnotism in film and television is usually dramatized to tell a more compelling story [2]. In reality, there is a great deal of personal agency involved in hypnotic behavior, and neurological indicators help to explain what is happening when people enter this elusive state [2,3].
Clinicians and psychologists currently define hypnosis as the process of inducing an individual into an altered state of consciousness known as a hypnotic trance [4]. While in the trance state, people display focused attention and an enhanced capacity to respond to suggestions given by a hypnotist [5]. Brain imaging researchers have distinguished between the hypnotic state and other states of consciousness such as normal wakefulness, sleep, deep relaxation, and meditation. In the unique trance state, physiological, cognitive, and affective (emotion-driven) processes can be modified based on patients’ therapeutic goals, and desired behaviors can be produced in response to simple hypnotic suggestions [4]. For example, a patient might receive hypnotherapy to ease their feelings of anxiety and stress prior to a surgical procedure. Others might see a hypnotherapist to change their habits around substance use.
Hypnosis has been used as a clinical treatment for disorders of both the body and mind since the late 1700s, but clinicians haven’t always understood the mechanisms behind its effects [6]. Early practitioners believed in the power of hypnosis to treat psychological and somatic conditions and even observed improved patient symptoms after hypnosis treatment, but they lacked the technology to understand what was happening in the body and mind while patients were in the trance state [6]. As a result, they formed theories involving mystical energy, sleep, and subconscious memories, but we now know that much of the trance is related to brain regions involved in attention and focused control. By looking at the history of hypnosis, we can understand how public misconceptions have been formed and see the clinical patterns and theories that drive contemporary hypnosis research.
One of the first prominent practices of hypnosis was in the mid-18th century by Austrian doctor Anton Mesmer [6]. Mesmer believed in a theory he called “animal magnetism,” which claimed that redistributing magnetic energy in patients could alleviate physical and psychological symptoms. In contrast to modern hypnosis, Mesmer’s technique often consisted of physically touching patients in “hypochondriac regions” on the chest and belly or coating them with “magnetic fluid,” which was thought to have energetic powers. Over time, his procedure grew more and more theatrical; the patient would sit in a shallow water tub, often tied to other patients with rope. Some patients experienced a convulsive crisis when induced into the state. Others fell into a sleep-like daze. But it wasn't long before people began to question the validity of Mesmer's technique, which came to be known as "mesmerism." In 1784, the King of France commissioned a panel to investigate Mesmer and determine the legitimacy of his animal magnetism theory. Although Mesmer’s patients frequently displayed improved symptoms, the panel concluded that the alignment of magnetic fluid was not the cause. Rather, their investigation pointed to the curative effects of suggestion and imagination, neither of which were considered legitimate enough to merit scientific inquiry at the time. While most of Mesmer’s practices had more to do with showmanship than science, his work highlighted unique therapeutic characteristics of hypnosis, including variation in patient susceptibility, rapport between the hypnotist and patient, and the power of suggestion and imagination in a sleep-like trance state [6].
Despite the growing skepticism of Mesmer’s techniques among European contemporaries in the early 19th century, some of his students continued to believe in the power of mesmerism and explored its therapeutic effects in clinical applications [6]. In the early 1800s, the naturalist J. P. F. Deleuze published works which characterized Mesmer’s magnetism as a therapy to be used in conjunction with conventional treatments for acute illness and bodily disorders. He recommended combining hypnotism with medication and breathing exercises to treat spasms, paralysis, migraine, and digestive problems. Further, British physicians John Elliotson and James Esdaile began to use mesmerism extensively as an anesthetic before surgical procedures [6]. In 1843, Elliot published a pamphlet detailing several reportedly successful and pain-free medical operations performed while the patient was in a mesmeric trance [7]. More and more practitioners began to note that they could only induce a relaxed or sleep-like state in their patients, rather than the occasional “crisis” convulsion that Mesmer had claimed to induce. The trance became so closely associated with a sleep-like state that a Scottish physician, James Braid, gave it a new title—“hypnotism”—from the Greek word “hypnos,” meaning to sleep [6]. With its new title, hypnotism began to build an identity distinctly separate from that of its mystic predecessor. Over time, consistent clinical patterns of sleep-like trance induction and its anesthetic capabilities helped to shift conceptions of hypnosis away from Mesmer’s now-disproven theory of magnetism and opened the door for new theories to explain its therapeutic effects [8].
By the late 19th century, two major practitioners, Pierre Janet and Sigmund Freud, had started using hypnosis as a therapeutic tool to explore aspects of patients’ subconscious minds [6]. In contrast to the recently popularized use of hypnosis by physicians to treat somatic conditions, Janet expanded the clinical use of hypnosis to treat patients afflicted with dissociative conditions and other psychological disorders. Through psychological analysis and induction of the hypnotic trance state, he believed that patients could access painful experiences otherwise inaccessible to their conscious mind. Sigmund Freud, a student and contemporary of Janet, similarly integrated the reframing of memories and processing of traumatic experiences during the trance state into his psychotherapeutic practice. While Janet was the first to theorize that subconscious ideas might be involved in the trance state, Freud popularized the practice alongside his other theories regarding the importance of the dream state and the distinction between states of consciousness. In comparison to Mesmer’s patients, who received their treatment in communal water tubs, Freud’s patients typically received hypnosis sessions individually, on a couch in his personal therapy office [6]. By adding hypnosis to their professional therapeutic repertoires, Janet and Freud redeemed the hypnotic process as a legitimate tool for psychological intervention. At the same time, their work added to the discourse regarding the state of consciousness induced by the hypnotic trance, which remains relevant today. Was it possible that the trance induced a subconscious state of awareness? And how could hypnosis treat mental conditions as well as somatic?
Today, hypnosis looks strikingly different from Mesmer’s ritualistic practices of the 18th century, but it remains at least somewhat similar to Freud’s hypnotic psychoanalysis. It is typically performed in clinical settings by a licensed hypnotherapist, but it can also be performed through digital recordings without the aid of a clinician [2]. Once properly trained, patients can even begin to induce themselves into the trance state on their own [9]. The first step is called induction, and it involves establishing rapport between the hypnotist and patient, typically followed by instructions for the patient to perform a series of progressive relaxation exercises, focus their attention, and close their eyes [8]. Once in the hypnotic trance state, the hypnotist may suggest that the patient perform certain movements, engage in particular imaginative experiences, or change perceptions, memories, and beliefs [8]. For example, the hypnotist might propose that a patient revisit a traumatic memory, then provide suggestions to ease the trauma out of this sensory experience [9]. If the memory is physically painful, the hypnotist might suggest neutral replacements like feelings of warmth or cold. They may offer methods of conceptualizing the self as separate from the traumatic experience or simply train the patient to find this state of comfortable dissociation when these memories resurface in daily life [9]. Hypnosis, when administered this way, is shown to be an effective treatment for acute distress, anxiety, depression, complex post-traumatic stress disorder (PTSD), and chronic pain [10-12].
Yet, there are still many aspects of hypnosis’s practice that remain clouded by popular skepticism, influenced by ill-informed media depictions and its historical reputation. It remains difficult to rid hypnosis of its reputation as a practice of mystical clairvoyance rather than a medically-sound therapy [6]. Fortunately, since the start of the 21st century, developments in hypnosis research and brain imaging have aided in clarifying the role of the brain in hypnotic behavior, understanding conscious versus subconscious responses, and characterizing individual differences in experiences of the trance state. These studies have helped carve a space for hypnosis within psychological and neuroscientific literature, alongside other clinically proven behavioral therapies like progressive muscle relaxation and cognitive behavioral therapy [2].
So what can brain imaging and modern behavioral research tell us about our state of consciousness during a hypnotic trance? Is it possible that we are just responding to suggestions in the same way we would when fully conscious? In the early 2000s, a series of studies sought to examine both the behavioral and neural indicators of bodily control during a hypnotic trance. In 2003, a group of researchers from University College London examined the differences in brain activity associated with arm movements to better understand how individuals experience motor suggestions in a hypnotic trance [13]. Subjects were hypnotized and placed in a Positron Emission Tomography (PET) scanner, which measures glucose consumption in the brain as a proxy for neuronal activity. While in the scanner, they experienced one of three distinct types of arm movement: active movement (voluntary), passive movement (through an automated pulley system), and deluded passive movement (hypnotic suggestion that the arm would move on its own). The active movement and deluded passive movement (hypnosis) conditions were both correlated with activity in brain regions associated with voluntary movement. However, the deluded passive movement (hypnosis) condition also showed activity in regions associated with passivity and external agency, or lack of personal control over thoughts, speech, and action. These regions of increased activity were the secondary somatosensory cortex of the parietal lobe in the right hemisphere of the brain and the left inferior parietal cortex. Both of these regions receive inputs from the cerebellum, the brain region primarily responsible for voluntary movement. Researchers thus concluded that the hypnotized state may interfere with the cerebellar-parietal network in the brain, preventing motor intentions from being recognized as having originated from the self. They likened the brain activity of this involuntary control to that of patients living with schizophrenia who describe their own thoughts, speech, and actions as having been controlled or replaced by someone other than themselves [13]. This may help to explain why the subjective experience of hypnotism is often described as feeling both authentic and involuntary, as though outside of conscious control [4].
In 2004, the same researchers conducted a similar experiment and found that subjects tended to rate finger movement produced by hypnotic suggestion as significantly less voluntary than the real voluntary movement, despite the fact that both movements were generated entirely by the participant [14]. It seemed that movements performed in the hypnotic state were perceived at a unique level somewhere between active and passive, and researchers interpreted this as evidence that the hypnotic trance involves a change in conscious experience without any corresponding change in physical actions. Using both imaging tools and behavioral analysis, both London studies helped to better characterize the subjective experience of the trance state [13,14]. The studies highlight brain regions important in active and passive awareness—most notably in the parietal cortex—and demonstrate that behaviors produced independently can often be misattributed to an external agent when in the hypnotic trance.
Understanding the distinct state of voluntary awareness and control associated with hypnosis has been a major breakthrough in realizing its potential as a clinical treatment. But across modern neuroimaging and perceptual studies of hypnotized subjects, there has remained one area of inconsistency—some people are much more easily hypnotizable than others [2]. Practitioners since Mesmer have noted differences in individuals’ abilities to enter the trance state and achieve varying levels of hypnotic depth [6]. In the 1900s, the issue of hypnotizability limited subject inclusion in hypnosis research and thus limited the generalizability of research results. Even Freud claimed that the inconsistency of his patients’ response to hypnosis treatment was one reason why he abandoned the practice altogether [6,15]. In the 1930s, researchers began to actively seek out trait-level indicators of hypnotic susceptibility and develop predictive scales to determine whether an individual might be categorized as high, medium, or low in hypnotic susceptibility [16]. It was not until the 1960s that the Stanford Hypnotic Susceptibility Scales and the later adapted Harvard Group Scale of Hypnotic Susceptibility firmly quantified hypnotic susceptibility by standardizing assessments of subject behavior while in the trance state [8]. During the assessments, participants are given a series of suggestions involving arm movement, catalepsy, imaginative occurrences, and amnesia [17]. Their behavioral responses, such as whether or not they raise their arm when given the suggestion to, are scaled as binary indicators adding up to a cumulative susceptibility score [17]. Besides these scales which require hypnotic induction to score susceptibility, the only other reliable behavioral correlate with hypnotic susceptibility is trait absorption, or the tendency to become absorbed in various imaginative sensory and cognitive experiences [8]. For example, a physician might seek to understand a patient’s level of trait absorption by asking them about their typical experience in a movie theater: once the movie has ended, does the patient typically leave instantly or take a few minutes to remove themselves from the compelling experience of the show? Those who indicate the latter would likely score high on the Tellegen Absorption Scale, a standard questionnaire devised to measure trait absorption [18,19]. In developing these scales, researchers created a system that directly quantifies individual differences which might make one patient more or less likely to benefit from hypnosis treatment.
Aside from assessments based on behavioral responses, neuroimaging studies from the past two decades have presented a new mode of predicting hypnotic susceptibility. They have even begun to assess the efficacy of treatment modalities across hypnotizability [19]. Electrical activity patterns in the brain in response to hypnotic induction demonstrate distinct differences between individuals scoring high, medium, and low on hypnotic susceptibility scales [2]. Structural and functional magnetic resonance imaging (MRI) studies are also often used to study brain anatomy and indirectly examine neuronal activity through the movement of blood to activated neurons in the brain. One such MRI study suggested that individuals with high hypnotic susceptibility exhibit greater volume in the rostrum of the corpus callosum, a brain region that allows for the sharing of information regarding sensation, inhibition, and attentional processing between the two hemispheres [20]. Researchers theorized that this could indicate that those who are highly hypnotizable may have more effective frontal attentional systems which are important for inhibiting unwanted stimuli from conscious awareness [20]. In other words, if you have a larger corpus callosum, you may be more adept at focusing your attention—a behavior we know to be important in the hypnotic trance.
Another brain region shown to be important in determining hypnotizability is the anterior cingulate cortex (ACC). A series of neuroimaging studies indicated that highly hypnotizable individuals have larger ACCs compared to individuals with low susceptibility [21,22]. The ACC plays a crucial role in reducing the presence of intrusive or unrelated thoughts and memories, something that researchers call conflict monitoring. Reducing conflict monitoring results in behaviors such as dissociation and analgesia, or the reduction of pain sensations, both of which we know are common in hypnotic practice. In 2020, an MRI study was conducted using MEGA-PRESS technology, which measures the presence of neurotransmitters, brain chemicals involved in neural activation, in the ACCs of individuals across categories of hypnotic susceptibility [23]. Results showed a negative relationship between glutamate, the primary excitatory neurotransmitter, and imaginative involvement scales. On the other hand, they showed a positive relationship between GABA, the primary inhibitory neurotransmitter, and hypnotic responsiveness. Excitatory neurotransmitters are important for generating electrical signals in neurons, while inhibitory neurotransmitters typically prevent these signals. People who scored higher in trait absorption seemed to have fewer excitatory neurotransmitters and more inhibitory ones, meaning that highly hypnotizable people experienced reduced neural firing in the ACC during hypnosis compared to those with low hypnotizability. These distinct neurochemical differences suggest that there may be underlying differences in the conflict monitoring abilities across groups, making the trance state feel easy and comfortable for some people but fleeting for others [23]. Understanding the neuroanatomical correlates of hypnotic variation is incredibly important for advancing hypnosis research and its clinical applications. By identifying what brain indicators allow for increased depth of the trance state, clinicians may in the future be able to alter susceptibility or improve the efficacy of hypnosis-based treatments.
Today, clinical psychologists recommend hypnosis as a safe and effective complementary technique to reduce emotional stress related to medical and dental procedures and to ease symptoms of functional disorders like irritable bowel syndrome [4]. As we have seen, hypnosis possesses a unique ability to place patients into an altered state of consciousness without rendering them unconscious entirely. This can be important in procedures like waking craniotomies, which might consist of the removal of a brain tumor close to a speech area. For
such procedures, patients must remain awake for neurological testing, but it can be incredibly anxiety-inducing to endure this procedure in a normal state of consciousness. Hypnosis provides an opportunity for patients to dissociate into an inner place of tranquility to ease the operation. In other complex medical procedures like heart and gallbladder operations, hypnosis has been shown to significantly reduce anxiety and stress and reduce the need to consume pain-relievers and sedatives [4]. For functional disorders like irritable bowel syndrome and fibromyalgia, hypnosis has proven effective in reducing pain and controlling symptoms [4,11]. The reduction of widespread muscle pain following hypnotic suggestion was even shown to be correlated with a change in activity in the ACC, cerebellum, and inferior parietal cortex [23]. This is consistent with our understanding of the ACC’s role in hypnotic dissociation and reduced pain sensations and the role of the cerebellar-parietal network in voluntary movement and external agency [23].
Along with somatic disorders, practitioners use hypnosis as an effective psychotherapeutic treatment for depression, anxiety, and PTSD [2]. Unlike pharmacological treatments and other forms of behavioral therapy, hypnosis allows hypnotherapists to measure reliably how responsive their patients might be to the treatment before actually employing it [2]. Studies have shown that patients who score high on hypnotic susceptibility scales like the Stanford Scale also tend to score low on certain facets of the Five Facet Mindfulness Scale, a measure of the trait-like tendency for individuals to be aware of their inner feelings [24]. Perhaps, then, prescribing hypnosis treatment to highly hypnotizable individuals in combination with mindfulness suggestions could double the desired behavioral outcomes of the patient. In an ongoing study conducted by Dr. Kevin Ochsner and Dr. Philip Muskin at Columbia University, responsiveness to mindful acceptance is being measured for subjects in a hypnotic trance state as compared to a controlled resting state [19]. Ideally, continued practice and research will build upon our existing understanding of the mechanisms behind hypnosis and how we can use its unique and often perplexing characteristics to better treat mental disorders and somatic pain.
When we consider the origins of hypnosis, performed by a cloaked Anton Mesmer in a dark mirrored room, it makes sense why the thought of its practice as a legitimate medical therapy sounds bizarre. But advanced neuroimaging tools have shed light on the processes underlying hypnosis, including unconscious awareness, self-control, conflict monitoring, and focused attention. In the same way that these psychological concepts have neurological correlates, so too does the hypnotic trance state. Thus, current and future neuroscientific research can help clinicians understand how best to use hypnosis as a unique therapeutic tool that recognizes individual variation and capitalizes on natural patterns of responding. Despite its controversies—the misattributions of crystal balls and theatrical depictions of all-powerful hypnotists—modern technological tools have grounded hypnosis in solid neuroanatomical processes and distinct psychological characteristics. With researchers continuing to explore what it means to exist in the trance state, we can only expect to build our understanding of its unique neuroscientific underpinnings and specific applications in clinical settings.
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