EMDR and its Disputed Mechanism

I’ve been on the fence about writing about EMDR. It is a popular therapy modality that has helped a lot of people. But, it also has some aspects to it that deserve more attention, especially as it grows in popularity and more and more people encounter it.

What EMDR Claims To Do

EMDR, eye movement desensitization and reprocessing, is a psychotherapy treatment for trauma, most often associated with the treatment of Post Traumatic Stress Disorder. It is generally considered a mainline treatment, endorsed by the World Health Organization and the American Psychological Association.

The way it works, in general, is that you think about a distressing memory while following the therapist's finger back and forth (or a light bar, or a set of tapping or pulsing paddles). After a series of these sets, the memory stops having as negative of an impact on you as it did before the sessions. The amount of, and intensity, of negative memories and feelings are lessened. A proposed explanation is that this process helps the brain's natural information-processing system get "unstuck," finishing work it couldn't complete at the time of the original event.

Moving your eyes back and forth while thinking about something bad happening to you doesn't seem, on its face, like it should do much of anything. So, how does it work?

The Competing Explanations

According to meta-analyses EMDR does work (Chen et al., 2014; Simpson et al., 2025), but nobody agrees on why EMDR works, assuming it works in ways beyond what any trauma therapy provides. In other words, does EMDR work because therapy works, or does EMDR add something specific that makes it more effective?

One viewpoint with the most current support is the working memory hypothesis. Holding a disturbing memory in mind while simultaneously tracking a moving target is a dual task, and dual tasks compete for our limited attentional resources. The theory holds that this competition degrades the vividness and emotional intensity of the memory being recalled, and that repeated degradation is what produces lasting change. Recent peer-reviewed reviews lean toward this account (de Jongh, de Roos, & El-Leithy, 2024), though the effect is more consistently found in laboratory analogue studies than in actual clinical trials with PTSD patients.

There are two other hypotheses, but these seem to be losing popularity and favor. The first is the orienting response hypothesis which proposes that the eye movements trigger an investigatory reflex, the same reflex that makes you turn toward a sudden noise, and that this reflex has a calming, parasympathetic effect that inhibits the distress response (Armstrong & Vaughan, 1996). The other is the REM-sleep parallel, which suggests bilateral eye movements mimic what happens during dream sleep, when the brain is thought to consolidate and reprocess emotional memories.

Then there's the critical explanation; none of the benefit of EMDR is really about eye movements at all. Strip away the bilateral stimulation and you have pretty standard structured exposure. This is the process of holding a traumatic memory in mind repeatedly, in a safe context, until it loses its charge, and some cognitive restructuring. That's how most trauma-focused therapy works, EMDR included. The eye movements, in this account, aren't doing the work the theory claims. They may function more like a structured ritual that helps the exposure component happen in a tolerable, contained way, rather than an active ingredient in their own right. It’s window dressing for the actual therapy.

The History

EMDR was founded/created/discovered/invented by Francine Shapiro. The story goes, that back in 1987, Shapiro noticed during a walk in a park that her own eyes moved rapidly back and forth while a distressing thought lost its emotional charge, and built the observation into a treatment protocol (Shapiro, 1989). This story is often repeated in books and trainings. But it may not be accurate.

Psychologist Gerald Rosen, one of EMDR’s biggest critics, has spent several years documenting problems with it. Ordinary saccades, the kind of eye movement Shapiro described noticing in herself, aren't something research suggests a person can actually perceive happening to their own eyes; when Rosen directly tested this by asking people to try, none could (Rosen, 2023). Two years before the "discovery," Shapiro was already publishing on Neuro-Linguistic Programming and its theories about eye movement patterns, and was running paid NLP workshops through her own training institute, first documented by researcher Bruce Grimley in 2014 (Rosen, 2023). A newly surfaced 1985 photograph, predating the famous walk by two years, shows Shapiro in front of an NLP eye-accessing chart (Rosen, 2026).

So, maybe Shapiro was influenced by her work in NLP, maybe not. Separate from where the idea came from, the quick and seemingly all-encompassing adoption of EMDR into clinical use is the more substantive issue. EMDR moved from a personal observation to a trademarked, manualized protocol with a formal certification hierarchy, required training hours, approved consultants, continuing education requirements, faster than any research could keep pace with, and well before any evidence base had settled. It had a fad or cult-like appeal, which is part of why EMDR draws more scrutiny than treatments with less colorful founding stories.

What the Evidence Suggests

First things first; there is no neutral evidence. Nearly every strong empirical claim about EMDR, in either direction, comes from a source with a stake in the outcome. The researchers who find it works best are often funded by or affiliated with EMDR professional associations. The researchers most skeptical of its mechanism have built academic careers on that skepticism. Neither fact alone makes a given finding wrong, but it does mean that looking at the source as a proxy for "how much should I trust this" doesn't work cleanly here. We have to look at the methodology of the research itself.

Does EMDR reduce PTSD symptoms? Yes, this is reasonably well established. Multiple meta-analyses of randomized controlled trials show moderate to large effect sizes for PTSD symptom reduction (Chen et al., 2014). More recent reviews find EMDR performs comparably to trauma-focused CBT and better than waitlist or usual care (Simpson et al., 2025, a study funded by EMDR Association UK). Where EMDR ranks relative to other trauma treatments is itself an ongoing professional dispute: the American Psychological Association's 2025 guideline lists cognitive processing therapy, prolonged exposure, and trauma-focused CBT as first-line treatments and EMDR as second-line, a downgrade EMDR researchers have formally disputed as inconsistent with five other national and international guidelines that rank it first-line (Lee et al., 2026, published in EMDRIA's own journal).

Do the eye movements themselves contribute anything beyond what exposure-based treatment already provides? This is considerably less settled. Dismantling studies, trials that strip out the bilateral stimulation component while keeping everything else constant, have produced conflicting results. A 2001 meta-analysis found no incremental benefit from the eye movement component and concluded the technique was no more effective than other exposure therapies without it (Davidson & Parker, 2001), building on earlier trials like Pitman et al. (1996) and Renfrey & Spates (1994) that found fixed-eye conditions performed comparably to active eye movement conditions. A later meta-analysis reached the opposite conclusion, finding a significant additive effect and arguing the earlier null result reflected underpowered studies rather than a true absence of effect (Lee & Cuijpers, 2013). Subsequent systematic reviews have treated this as an open methodological dispute rather than a settled question (Cuijpers et al., 2020).

So, the treatment works, by the same standard used to validate most trauma therapies, though how it compares to other trauma treatments is itself contested among professional bodies with their own interests in that outcome. Whether the specific technique that gives EMDR its name and its marketing hook is doing anything the rest of trauma-focused therapy doesn't already do remains genuinely unresolved, not because the research is bad, but because the studies keep coming back with different answers.

What This Means For a Prospective Client

None of the above is a reason to avoid EMDR. The controversy is about why EMDR works, not really about whether it does. If you're choosing between EMDR and another trauma-focused approach like CPT or prolonged exposure, go with whatever feels tolerable and is accessible to you.