Division 30 defines hypnosis as “a state of consciousness involving focused attention and reduced peripheral awareness characterized by an enhanced capacity for response to suggestion” (Elkins, G. R., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 63, No. 1, 2015). Yet the definition of hypnosis has been the subject of debate for the better part of a century. While some experts believe hypnotic induction results in an altered state of consciousness, others argue it’s not so much a distinct state as a shift in attention. What experts on both sides of the debate agree on, however, is that hypnosis allows for a special kind of focused attention that opens people up to suggestion.
In hypnotherapy, a clinician starts with a hypnotic induction, spoken prompts that encourage the client to shift their focus and deepen relaxation. Then, the clinician provides therapeutic suggestions to guide the client toward the wanted change. “Our brains soak up information from the environment and combine it with our prior beliefs and experiences and memories to form a conscious experience of the moment,” said Afik Faerman, PhD, a postdoctoral fellow in clinical neuropsychology at Stanford University and president-elect of Division 30. “Hypnosis is one context during which our brain edits that conscious experience. As the facilitator of a hypnosis session, I can provide guidance about how to edit those experiences, but it’s up to that person to act on my suggestions.”
Those suggestions are what set hypnosis apart from meditation and mindfulness-based interventions. Both mindfulness and hypnosis are built on the backbone of focused attention; however, mindfulness aims for nonjudgmental awareness and acceptance. “Hypnotherapy has some important advantages,” said Guy Montgomery, PhD, a professor of psychology and director of the Center for Behavioral Oncology at the Icahn School of Medicine at Mount Sinai in New York City, who uses and studies clinical hypnosis for reducing pain in cancer patients. “Whereas meditation helps you accept a problem, hypnosis allows people to make changes to do something about the problem,” he said.
Research has shown evidence that posthypnotic suggestion can elicit striking changes in perception and behavior. Two classic—and colorful—studies illustrate the power of hypnotic suggestion. In one, Amir Raz, PhD, a cognitive neuroscientist at McGill University in Montreal, and colleagues showed that hypnosis could disrupt the Stroop effect, the popular laboratory task that instructs participants to name the font color of written words. People respond much slower and make more mistakes when these words are color names and the word and the font color are different and thus interfere with each other (for example, the word “blue” written in red font). But when highly hypnotizable participants were instructed under hypnosis to pay attention only to the font color and not the text, the Stroop interference effect disappeared (Archives of General Psychiatry, Vol. 59, No. 12, 2002). The study has been replicated many times by multiple labs. One recent example showed that while hypnosis itself did not eliminate the Stroop effect, posthypnotic suggestion did—a finding confirmed by electroencephalogram (EEG) (Zahedi, A., et al., Neuropsychologia, Vol. 96, No. 1, 2017). Such findings offer a vivid example of the ways that hypnosis can exert a top-down influence on cognition, even for automatic processes like reading.
In another experiment, David Spiegel, MD, a professor of psychiatry and behavioral sciences at Stanford University, and colleagues gave participants a suggestion to view color when looking at grayscale images. Brain scans showed that the color-processing regions of their brains lit up even though the photos in front of them contained nothing but shades of gray (The American Journal of Psychiatry, Vol. 157, No. 8, 2000).
Both studies tested people considered “highly hypnotizable,” those who become hypnotized quickly and easily and respond strongly to hypnotic suggestions. Spiegel’s research suggests that people who are higher in hypnotizability have more functional connectivity—essentially, more communication—between the central executive network, which manages executive functions such as decision-making and working memory, and the salience network, which is tasked with prioritizing important incoming information (Hoeft, F., et al., Archives of General Psychiatry, Vol. 69, No. 10, 2012). “We believe that the executive network of individuals who are high in hypnotizability has a greater ability to moderate where their attention goes during hypnosis,” said Faerman, a postdoctoral scholar in Spiegel’s lab.
Hypnotizability is a trait that follows a normal distribution: 10% to 20% percent of people aren’t very hypnotizable, and about the same proportion are highly responsive; everyone else falls somewhere in between. Several measures exist to assess a person’s potential to respond to hypnosis, such as the brief Hypnotic Induction Profile (Spiegel, H., & Spiegel, D., Trance and Treatment: Clinical Uses of Hypnosis, American Psychiatric Association Publishing, 2004) or the Elkins Hypnotizability Scale (Kekecs, Z., et al., International Journal of Clinical and Experimental Hypnosis, Vol. 69, No. 1, 2021).
While responsiveness varies, however, most people can benefit from hypnosis to some degree, said Gary Elkins, PhD, ABPP, a professor of psychology and neuroscience at Baylor University. “People in the higher range may respond more quickly, but almost anyone can be a candidate for clinical hypnosis,” he said. “If people are in the lower range, they may just need more sessions or more practice to achieve the same results.”
Elkins’s research has indicated that clinical hypnosis may have benefits even in people who are not especially high in hypnotizability. In recent work, he’s tested a hypnotherapy intervention for treating hot flashes in menopausal women and breast cancer survivors. In one trial, menopausal women received five weekly sessions of clinical hypnosis or a structured-attention control intervention. Those in the hypnosis group reported hot flashes were reduced by more than 74%, whereas the control group reported a 17% reduction in hot flashes. Objective physiological monitoring of hot flashes supported their reports, showing a 57% reduction in hot flashes for women who had hypnosis compared with a 10% reduction for control participants (Menopause, Vol. 20, No. 3, 2013).
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