If you have ever heard someone describe EMDR therapy, you might have had a very reasonable question:

How is moving my eyes back and forth supposed to help with trauma?

It can sound strange at first.

During Eye Movement Desensitization and Reprocessing (EMDR) therapy, a therapist may ask you to bring a distressing memory to mind while simultaneously following their fingers with your eyes. Other forms of bilateral stimulation, such as alternating taps or sounds, may also be used.

But the eye movements are not hypnosis. They are not erasing memories. And there is no evidence that they somehow "unlock" a hidden part of your brain.

There is, however, a growing body of research examining what happens when we recall an emotional memory while performing another task at the same time.

One of the leading explanations involves something called working memory.

First, What Is Working Memory?

Working memory is essentially your brain's temporary mental workspace.

You use it when you hold a phone number in your mind long enough to type it, follow a conversation, solve a problem, or remember what you walked into a room to do.

Importantly, working memory has a limited capacity.

This becomes particularly interesting when we think about trauma.

When you deliberately recall a distressing experience, your brain uses working-memory resources to hold aspects of that memory in awareness. This can include images, thoughts, emotions, sounds, and physical sensations.

Now imagine asking your brain to do something else at the same time.

For example, tracking a rapidly moving object with your eyes.

Both tasks require cognitive resources.

Researchers have proposed that this creates competition within working memory.

The Working Memory Theory of EMDR

One of the most researched explanations for the eye movement component of EMDR is known as the working memory account.

The basic idea is surprisingly straightforward.

When you recall an upsetting memory while simultaneously performing eye movements, your brain has to divide its limited working-memory resources between remembering and tracking the moving stimulus.

The memory therefore becomes more difficult to hold with the same level of vividness and emotional intensity.

Experimental research has repeatedly tested this idea.

Van den Hout and colleagues, for example, demonstrated that eye movements place demands on working memory and that performing eye movements while recalling emotional material can decrease the vividness and emotionality of that material.

Other experiments have similarly found that recalling emotional memories while making eye movements can reduce their subsequent vividness and emotional intensity.

This is important because it suggests that the eye movements in EMDR may be doing something much more specific than simply distracting someone from an upsetting memory.

The brain is being asked to remember while simultaneously completing another cognitively demanding task.

Why Would Making a Memory Less Vivid Matter?

This brings us to another fascinating area of memory research.

Our memories are not stored like video recordings.

Remembering something is an active process.

When a memory is retrieved, it can temporarily become more flexible before being stored again. Researchers studying memory modification and reconsolidation have investigated how experiences occurring during retrieval can influence how a memory is subsequently experienced.

In laboratory studies of EMDR, researchers have found that recalling an emotional memory while making eye movements can produce changes that persist beyond the eye movement task itself.

For example, Leer and colleagues found evidence that eye movements performed during memory retrieval produced changes in the vividness and emotionality of memories that were detectable 24 hours later.

This does not mean that EMDR deletes or rewrites what happened.

You still know what happened.

Instead, the way the memory is experienced may change.

A memory that once felt immediate, vivid, overwhelming, or as though it were happening again may begin to feel more like something that happened in the past.

That distinction can be incredibly important in trauma therapy.

Are the Eye Movements Actually Necessary?

This question has generated considerable debate in EMDR research.

One influential meta-analysis by Lee and Cuijpers examined studies specifically looking at the contribution of eye movements to EMDR.

Across experimental studies, eye movements were associated with reductions in the vividness and emotionality of distressing memories. Their analysis provided evidence that the eye movement component contributes effects beyond simply recalling the memory.

That does not mean eye movements are magical.

In fact, the working-memory explanation predicts almost the opposite.

If working-memory competition is important, then other sufficiently demanding tasks performed during memory retrieval may also influence emotional memories.

Research has supported aspects of this prediction.

This may also help explain why different forms of bilateral stimulation are sometimes used in EMDR, although different tasks do not necessarily place identical demands on working memory. One experimental study, for example, found that eye movements taxed working memory more strongly than alternating auditory beeps.

So the important ingredient may not simply be "left, right, left, right."

It may partly involve what happens when the brain attempts to retrieve an emotional memory while attention and working-memory resources are simultaneously engaged elsewhere.

Is EMDR Basically Distraction?

Not quite.

If the goal were simply to distract you from the memory, you would expect treatment to involve avoiding it.

EMDR does the opposite.

During the processing phases of EMDR, the memory is deliberately activated while another task occurs at the same time.

That distinction matters.

The person is not being taught that the memory is too dangerous to approach. They are approaching it under carefully controlled therapeutic conditions while the way the memory is experienced begins to change.

What Is Happening in the Brain During EMDR?

This is where it is important to separate what we know from what we are still investigating.

Researchers have proposed several mechanisms that might contribute to EMDR, including:

working-memory competition
changes occurring when memories are retrieved and subsequently stored again
orienting and attentional responses
reductions in physiological arousal
extinction and inhibitory learning processes
changes in emotional memory networks

Neuroimaging and psychophysiological studies have also investigated changes associated with EMDR treatment.

However, there is currently no single established neurological mechanism that completely explains how EMDR works.

That is not unusual in psychotherapy.

We know that many psychological treatments are effective before we fully understand every biological and cognitive process responsible for their effects.

A broad review of proposed EMDR mechanisms by Landin-Romero and colleagues concluded that several psychological, psychophysiological, and neurobiological models have empirical support, with particularly meaningful evidence supporting working-memory explanations.

The science continues to evolve.

So, Does EMDR Actually Work?

This is a separate question from why EMDR works.

A treatment can have evidence supporting its effectiveness even while scientists continue debating its precise mechanism of action.

EMDR has been studied extensively as a treatment for post-traumatic stress disorder (PTSD).

Systematic reviews and randomized controlled trials have found that trauma-focused psychological treatments, including EMDR, can significantly reduce PTSD symptoms.

A Cochrane review of psychological therapies for chronic PTSD in adults found evidence that both trauma-focused cognitive behavioural therapy and EMDR performed better than waitlist or usual care conditions for reducing clinician rated PTSD symptoms.

It is important to be more cautious when discussing EMDR for conditions outside PTSD. EMDR is increasingly researched and clinically used for other difficulties, but the strength of the evidence varies considerably depending on the condition.

What Does This Mean If You're Considering EMDR?

You do not have to understand neuroscience to benefit from therapy.

But you are absolutely allowed to ask your therapist why you are doing something.

In fact, I think you should.

EMDR can look unusual from the outside. A good EMDR therapist should be able to explain what they are asking you to do, answer questions about the process, and acknowledge where the research is still developing.

The simplest scientific explanation we currently have is this:

Your brain has a limited amount of working-memory capacity. When you deliberately recall an emotional memory while simultaneously performing a demanding task such as eye movements, those tasks compete for resources. Research suggests that this can reduce the vividness and emotional intensity of the memory and may contribute to the changes we see during EMDR.

But EMDR is more than eye movements.

It is an eight-phase psychotherapy that includes history taking, preparation, assessment, memory processing, installation, body awareness, closure, and reevaluation. The bilateral stimulation happens within that larger therapeutic process.

And although we have increasingly sophisticated theories about what happens during that process, responsible science requires us to acknowledge something important:

We are still learning exactly how EMDR works.

That does not make the treatment unscientific.

It means researchers are continuing to investigate one of the more interesting questions in trauma psychology: how can activating a painful memory under particular conditions change the way that memory feels when we encounter it again?

For many people undergoing EMDR, the memory does not disappear.

It simply stops feeling quite so present.

Curious About Whether EMDR Could Be Right for You?

If you are considering EMDR but still have questions, that is completely okay. You do not need to feel 100% certain about the process before reaching out.

At Me Again Collective, we offer trauma-informed EMDR therapy for adults in Toronto and across Ontario. We take time to explain the process, answer your questions, and make sure you feel adequately prepared before beginning trauma processing.

EMDR is not about pushing you into painful memories before you are ready. Therapy can include preparation, stabilization, resourcing, and building a greater sense of safety before deciding together whether memory processing is the right next step.

Interested in exploring EMDR therapy? Book a free consultation with Me Again Collective to learn more and see whether EMDR might be a good fit.

References

Landin-Romero, R., Moreno-Alcazar, A., Pagani, M., & Amann, B. L. (2018). How does eye movement desensitization and reprocessing therapy work? A systematic review on suggested mechanisms of action. Frontiers in Psychology, 9, 1395.

Lee, C. W., & Cuijpers, P. (2013). A meta-analysis of the contribution of eye movements in processing emotional memories. Journal of Behavior Therapy and Experimental Psychiatry, 44(2), 231–239.

Leer, A., Engelhard, I. M., & van den Hout, M. A. (2014). How eye movements in EMDR work: Changes in memory vividness and emotionality. Journal of Behavior Therapy and Experimental Psychiatry, 45(3), 396–401.

Maxfield, L., Melnyk, W. T., & Hayman, C. A. G. (2008). A working memory explanation for the effects of eye movements in EMDR. Journal of EMDR Practice and Research, 2(4), 247–261.

Van den Hout, M. A., Engelhard, I. M., Rijkeboer, M. M., Koekebakker, J., Hornsveld, H., Leer, A., Toffolo, M. B. J., & Akse, N. (2011). EMDR: Eye movements superior to beeps in taxing working memory and reducing vividness of recollections. Behaviour Research and Therapy, 49(2), 92–98.

Van den Hout, M. A., & Engelhard, I. M. (2012). How does EMDR work? Journal of Experimental Psychopathology, 3(5), 724–738.

Van Veen, S. C., Engelhard, I. M., & van den Hout, M. A. (2016). The effects of eye movements on emotional memories: Using an objective measure of cognitive load. European Journal of Psychotraumatology, 7, 30122.