Why does EMDR use eye movements?

EMDR uses eye movements because its founder, Francine Shapiro, noticed by accident in 1987 that they eased a distressing thought’s emotional charge. The best-supported explanation today isn’t the popular “brain hemisphere syncing” story. It’s working memory: holding a memory in mind while tracking a moving target competes for limited mental resources, leaving the memory feeling less vivid and intense.

Where did the idea come from?

In the spring of 1987, psychologist Francine Shapiro was walking through a park when she noticed something odd. A disturbing thought she’d been turning over lost its emotional weight while her eyes moved rapidly back and forth. She tested the effect further and published the first study on the technique in the Journal of Traumatic Stress in 1989.

That’s the honest origin story. Eye movements weren’t chosen because researchers already understood a mechanism. They were chosen because that’s what Shapiro happened to notice first. Everything since, including the theories below, has been an attempt to explain what she stumbled onto, and to test whether eye movements are doing real work or just came along for the ride.

What’s the leading scientific explanation?

The strongest current account is called the working memory theory. Working memory is the mental scratchpad that holds a small amount of information active at once, and its space is limited. Recalling a memory uses some of that space. Tracking a moving target with your eyes uses more.

A 2012 review in the Journal of Experimental Psychopathology by van den Hout and Engelhard found that this dual demand is what makes a memory feel less vivid and less emotionally charged, both during the exercise and afterward. Two tasks compete for one limited resource, and the memory loses out.

Do the eye movements have to go side to side?

No, and this is the part most explanations skip. A popular claim says horizontal eye movements are special because they force the brain’s two hemispheres to communicate with each other. The evidence doesn’t back that up.

A 2008 study in Behaviour Research and Therapy by Gunter and Bodner found that vertical eye movements reduced memory vividness and emotional intensity about as well as horizontal ones did. What mattered was the mental effort of tracking the movement, not its direction.

That finding has a practical payoff. If the benefit comes from taxing working memory rather than crossing the body’s midline, other rhythms should work too, and they do. Alternating tones and left-right taps follow the same logic. Our glossary entry on bilateral stimulation covers all three formats, and does tapping work as well as eye movements? compares them directly.

Is there real proof the eye movements themselves add anything?

Here the research is more honest than most summaries let on. An older, often-cited 2001 meta-analysis in the Journal of Consulting and Clinical Psychology by Davidson and Parker found no added benefit from eye movements when EMDR was compared with the identical procedure minus the eye movements.

A larger, later analysis pushed back on that. A 2013 meta-analysis in the Journal of Behavior Therapy and Experimental Psychiatry by Lee and Cuijpers pooled 15 clinical comparisons and 11 laboratory studies. It found eye movements added a moderate, measurable reduction in distress in the clinical studies (Cohen’s d = 0.53) on top of the same procedure without them.

A 2018 systematic review in Frontiers in Psychology surveyed the competing theories, including working memory, an older “orienting response” idea (the brain’s automatic alertness reflex to something new), and a proposed link to REM sleep, the dreaming stage when the brain does much of its own emotional processing. It named working memory the leading explanation, while noting that most of that evidence still comes from lab studies rather than therapy rooms. Our deeper look at the science behind EMDR walks through all of these theories side by side.

None of this dents EMDR’s overall evidence base for PTSD, which rests on results from the whole eight-phase therapy, not the eye movements considered in isolation. Does EMDR work? breaks down that wider evidence separately.

What does this mean if you practice bilateral stimulation yourself?

You don’t need a therapist’s moving fingers or a clinical light bar to use the mechanism this research describes. In session, a therapist typically moves their fingers back and forth for a “set” while the client’s eyes follow, pausing between sets to check in. Self-guided practice mirrors that same rhythm, minus the clinical protocol built around it.

EmEase, a self-guided EMDR app, offers both formats this research points to: visual bilateral stimulation with a moving on-screen target, and audio bilateral stimulation with alternating tones, at app.emease.com. Pick whichever is easier for your attention to track and stay with.

Either way, treat this as a wellness practice for everyday stress and looping thoughts, not a stand-in for trauma-focused therapy. If you’re weighing whether to try it solo at all, can you do EMDR on yourself? walks through exactly where that line sits.