Illustration: Olivier Heiligers
In the physical world, Tracy was about halfway through a telehealth therapy session. Her eyes were closed and her arms were crossed over her chest, her fingers rhythmically tapping alternating shoulders: left-right-left-right. But in her mind, she was in her old basement, hiding from her ex as he screamed obscenities at her from the floor above. She kept tapping. After about a minute, the voice of her new therapist broke in from her laptop, asking, “What are you noticing?”
Fear, mostly. In the basement, she’d felt frozen with terror, convinced that this time, her ex’s anger would turn violent. The memory had lately been torturing Tracy, who’s in her early 40s and lives in Kansas City, Missouri, where she is a licensed professional counselor. (Therapists need therapy, too.) The memory would pop into her brain at random, sending her into debilitating panic attacks on a weekly basis. Now, with her own therapist, she was recalling the moment on purpose. Three more times, for about a minute at a time, Tracy’s therapist directed her to hold the memory in mind while tapping her shoulders. “You know that thing where you use one hand to tap on the top of your head and the other to rub your stomach?” she asked me. “It feels like talking and doing that at the same time.” Two or three sessions later, it was the strangest thing: The basement memory — once so emotionally charged — felt a little bit duller. She started having fewer panic attacks, too.
EMDR, as Eye Movement Desensitization and Reprocessing is colloquially called, has been around for four decades but only somewhat recently become a mainstream treatment option. An analysis from the online health-care platform Zocdoc found that its users booked 79 percent more EMDR appointments in 2025 compared to the previous year. It has newfound cultural cache too: In the latest season of The Secret Lives of Mormon Wives, Mikayla Matthews sees an EMDR therapist to deal with the sexual abuse she experienced as a child. (The therapist holds up her pointer and middle fingers and waves them left to right as Matthews follows with her eyes. The movement seems to unlock something in Matthews, and she starts to cry as she describes deep feelings of guilt.) In 2024’s Babygirl, EMDR makes a brief cameo — alongside Botox and cryotherapy — as one of many self-care treatments undertaken by Nicole Kidman’s character, Romy, a tech CEO. And last summer, Miley Cyrus credited the therapy with changing her life. “It sounds so trippy, but this is medical,” Cyrus told the New York Times. “This is real.”
A number of major medical associations are in agreement with Cyrus, at least when it comes to post-traumatic stress disorder. In the 2010s, the World Health Organization recognized EMDR in its clinical guidelines for the treatment of PTSD, and the U.S. Veterans Affairs Department and the American Psychological Association also named the therapy as an effective trauma-treatment method. More than 30 randomized controlled trials have shown it to be an effective treatment, with about the same success rate as other therapeutic techniques, like cognitive behavioral therapy, in reducing PTSD symptoms. What’s surprising, though, is that many therapists don’t understand why it works — and among those who do understand the scientific theories that underscore it, there’s serious doubt as to whether the theories truly make sense.
EMDR’s origin story is somewhat unusual: On a sunny spring day in 1987, a psychology student named Francine Shapiro went outside for a walk, mulling a personal problem as she strolled around a lake. After a while, her worries quieted down. “The odd thing was that my nagging thought had disappeared. On its own,” she wrote in her 1995 book, EMDR: The Breakthrough Therapy for Overcoming Anxiety, Stress, and Trauma. “When I brought it back to mind, I found that its negative emotional charge was gone.” Fresh air and exercise tend to have that effect on people. But during her walk, Shapiro noticed she was moving her eyes back and forth as she thought through her problem. Could those eye movements explain her lighter mood?
It wasn’t the most intuitive conclusion. But Shapiro took it and ran with it, designing studies and refining the treatment until she and others eventually developed a neurobiological theory around the side-to-side eye movements, which eventually became known as “bilateral stimulation” — sensory experiences that alternate between the left and right sides of the body, thus engaging both sides of the brain. Bilateral stimulation can involve moving the eyes back and forth, but it can also incorporate auditory cues in alternating ears or physical touches such as shoulder tapping. One long-held theory proposes that bilateral stimulation may mimic REM sleep, which is thought to play a part in memory storage. “Most people have had the experience of getting into an argument with your best friend, and you went to sleep and you woke up the next day and it felt better,” said Wendy Byrd, board president for EMDRIA, a nonprofit that provides training and certification in EMDR for therapists. “The brain pruned and moved information around and stored it in a different place so that it’s not so active. That’s what EMDR does.”
Another explanation for how and why EMDR works — potentially, a better one, argue some researchers — is the working memory model, which is based in psychology, not neurobiology, said Ad de Jongh, emeritus professor of anxiety and behavior disorders at the University of Amsterdam. This theory is pleasingly intuitive: It’s hard to do two things at once, as anyone who’s ever tried to hold a thoughtful conversation with their partner while also answering work emails can attest. “In EMDR, we bring up a traumatic memory to our working memory — and then if we do another task at the same time, those tasks start to compete with each other,” says Suzy Matthijssen, a researcher and clinical psychologist in the Netherlands. Without your full focus on the memory, its intensity diminishes.
According to this theory, the sensory tasks associated with bilateral stimulation, or BLS as it’s commonly nicknamed, are effective not because they engage both sides of the brain, but because they tax the working memory, says Matthijssen. In other words, she told me: “BLS is b.s.” Matthijssen and de Jongh are currently developing a therapy called EMDR 2.0, which de-emphasizes the use of bilateral stimulation in favor of working-memory taxation. With EMDR 2.0, clients might be asked to spell a word backward while holding their disturbing memory in mind. Or Matthijssen might make them do math problems or walk around the room in a specific (and deliberately confusing) pattern. “EMDR is a fantastic therapy,” she told me. “The only thing I’m really trying to unravel is that magical belief in bilateral stimulation.”
But many researchers I spoke to told me that with BLS or not, EMDR is not well understood. In the late 1990s, Richard McNally, a professor of psychology at Harvard, compared the therapy to mesmerism, a 19th-century therapeutic craze in which the practitioner would place magnets around the patient’s body in order to encourage the movement of an invisible healing fluid. Likewise, University of Washington psychologist Gerald M. Rosen has been writing critically about EMDR since the 1990s (one paper written with McNally and others argued that EMDR’s “theoretical explanation approaches the limits of neurobabble”) and still refuses to let the issue drop, publishing his latest critique in 2024. He has another in the works. “I appreciated what was developing and saw through the claims from the start,” Rosen told me of his decades-long crusade. McNally, though, changed his mind after hearing about the working-memory taxation theory. He quoted the economist John Maynard Keynes: “‘When the facts change, I change my mind.’”
Delivering effective therapy is hard, and for some, what might be making it harder is a gap between scientific understanding and clinical practice. Many therapists told me that the EMDR training they received emphasized the neuroscientific component of the therapy, something many of them were not trained to fully grasp. “You see it all the time,” de Jongh, the Dutch psychologist, told me. “You go to conferences, and a presenter shows you pictures of the brain — everyone is looking at it going, Oh my gosh!” Measurable changes in the brain seem more objective and convincing than patients’ own reports of their experiences, he explained. In 2024, de Jongh published a paper outlining the “state of the science” of EMDR. In his opinion, the strongest scientific support for EMDR is psychological, not neurobiological.
At first, Angela Nauss, a licensed marriage and family therapist in Colorado, was drawn to the neuroscience associated with the therapy. In 2017, she was a brand-new therapist still working under supervision at a Southern California drug and alcohol rehab facility. She often felt ill prepared to address the enormity of her clients’ mental-health needs, and her supervisor was usually too busy to answer her questions. (She once asked how to best handle bipolar disorder. “Google it,” came the reply.) EMDR’s detailed protocol, along with the invocation of neuroscience, was instantly appealing. “I was like, Finally, I know what I’m supposed to do in session,” she told me. “All I wanted was to feel like therapy actually does something, because I was working in the trenches.”
Nauss came to appreciate EMDR so much that she decided she wanted to present about its transformative power at a psychotherapy conference. But as the conference deadline approached, she found that some of her clients — those who had initially improved with the therapy — had regressed. Eventually, she paid $4,000 for a second round of EMDR training. Meanwhile, she kept researching EMDR for her proposed presentation. The more she looked into it, the more her sense of certainty around the treatment diminished. Eventually, her research evolved into a critical article published in The Therapist in 2022. In the article, she asserts that the neuroscientific evidence explaining EMDR’s efficacy is weak — and that most therapists don’t realistically grasp the science, anyway. “If you ask three different EMDR counselors to explain how EMDR works, they will likely give you three different answers,” she wrote, “possibly because EMDR research is dense and difficult to understand without sufficient training in neuroscience.”
While researching her article, Nauss discovered that many of her colleagues had altered the EMDR protocol to suit their own preferences, sometimes incorporating the therapy with other modalities. Freestyling isn’t something Byrd, the EMDRIA board president, encourages, nor would most EMDR researchers. “I don’t know what would happen,” Byrd told me, “but you couldn’t say that you were doing EMDR, because that’s not what EMDR is.” But several EMDR-trained therapists told me they have customized the treatment anyway.
Tracy, the Kansas City therapist whose traumatic memories of her ex-boyfriend lost most of their power after five EMDR sessions, is one of them. (She still has panic attacks sometimes, but she’s able to calm herself down before they spiral out of control.) She delivers her own version of EMDR to her patients: “I kind of slice EMDR up into pieces,” she told me. She doesn’t always follow the steps in order, for example. But using EMDR “buzzers” (handheld paddles that vibrate to produce a tactile version of bilateral stimulation) really does seem to help steady her clients, especially those who tend to feel their emotions physically. “It appears to be just a little bit of set dressing,” she said, “and if some prefer that, great.”
She has a theory as to why EMDR worked so well on her, and it has little to do with neuroscience. Tracy doesn’t like to sit still when she’s upset. On a bad day, she told me, she’d rather get out her sewing machine and start an elaborate new crafting project than lie on the couch and watch TV. She thinks the shoulder tapping may have appeased a similar impulse. “I don’t think a lot of fancy shit’s going on in my brain,” she said. “I think it just gave me something to do.” That’s how she explains EMDR to her clients, too. “As long as the therapist is bought in and the clients are bought in, does it matter if you say, ‘I need you to wear purple shoes with jingle bells on them?’” Tracy went on. “If that ends up having some positive effect, and no one was harmed — does it matter?”
McNally pointed out that scientists don’t agree on why SSRIs work, either. “But they can help people,” he said. And so can EMDR, he added. At the same time, there’s no question that knowing why a therapeutic technique works is preferable. “If we know why it works, we can also make our therapies better, because then we know where and when to tweak,” Matthijssen explained.
But does a client need to know that? Does a therapist? Is it the treatment method that makes the difference, or is the catalyst more ineffable, like the relationship between the therapist and the client and their mutual belief in the treatment, that predicts whether therapy will be effective? In 2019, one psychologist argued that this debate is beside the point: Both are critical. Decades’ worth of research stresses the importance of the “therapeutic alliance,” or the idea that the therapist and client must have a good relationship and agree on both the goals of their work together and the methods they’ll use to meet them. “You have to find somebody whose approach to life matches the same sort of ethos that you have,” Tracy said. “That’s part of the therapeutic magic.”
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