What is EMDR? How Does EMDR Actually Work?

As a psychotherapist specialising in trauma, I am often asked a deceptively simple question: how does EMDR actually work?

Many people know that EMDR involves following a therapist’s fingers, watching movement on a screen or using alternating taps or sounds. But bilateral stimulation is only one part of a structured psychological therapy.

EMDR, or Eye Movement Desensitisation and Reprocessing, is an established treatment for post-traumatic stress disorder (PTSD). Research shows that it can reduce PTSD symptoms, although scientists are still investigating exactly which psychological and neurological mechanisms produce those effects.

This article explains what happens during EMDR therapy, how traumatic memories may remain distressing, why working memory has become an important explanation for eye movements and what the research can and cannot currently tell us.

What Is EMDR Therapy?

EMDR is a structured psychological therapy developed by psychologist Francine Shapiro in the late 1980s.

It was initially developed for traumatic memories and is now particularly well established as a treatment for PTSD.

In the UK, NICE recommends EMDR for adults with PTSD or clinically important PTSD symptoms in specified circumstances.

NICE states that EMDR should:

be based on a validated manual
be delivered by trained practitioners with ongoing supervision
be delivered in a phased manner
include psychoeducation and strategies for managing distress
identify and treat specific traumatic memories
use repeated bilateral stimulation during memory processing

So EMDR is considerably more than eye movements alone.

How Does EMDR Work?

During the memory-processing phases of EMDR, the client brings aspects of a distressing memory to mind while simultaneously engaging in bilateral stimulation.

This most commonly involves guided side-to-side eye movements, although alternating taps or sounds can also be used where appropriate.

The client may attend to:

an image connected with the memory
negative beliefs associated with it
emotions
physical sensations
new thoughts, images or memories that arise during processing

Over the course of treatment, the aim is for the memory to become less distressing and for more adaptive meanings or beliefs to become available.

What remains less certain is exactly why this procedure produces therapeutic change.

The Working Memory Theory of EMDR

One of the better-supported explanations involves working memory.

Working memory is the limited-capacity system we use to hold and manipulate information temporarily.

Psychologist Alan Baddeley’s influential model describes several components of working memory, including systems involved in processing visual and verbal information alongside attentional control.

The important point for EMDR is that working memory has a limited capacity.

If you vividly recall a distressing image while simultaneously performing another demanding task, such as making rapid eye movements, the two tasks compete for those limited resources.

This is sometimes called dual tasking.

Why Might That Matter?

Imagine trying to hold a very detailed image in your mind while simultaneously concentrating on something else.

The image may become harder to maintain with the same vividness and intensity.

Experimental research has found that eye movements and other sufficiently demanding secondary tasks can reduce the vividness and emotionality of recalled memories.

A systematic review of proposed EMDR mechanisms found reasonable empirical support for the working-memory hypothesis, although it also concluded that research into exactly how EMDR works remains at a relatively early stage.

Read the systematic review of EMDR mechanisms on PubMed.

A Simple Working Memory Example

One way to visualise this is to imagine your working memory as a computer with limited processing capacity.

Recalling a vivid traumatic memory uses some of that capacity.

Tracking rapid eye movements at the same time uses additional capacity.

With both tasks competing for resources, the memory may temporarily become less vivid or emotionally intense.

That metaphor should not be taken literally. EMDR is not deleting a memory or corrupting a file in the brain.

The person still remembers what happened. The therapeutic goal is for remembering it to become less distressing and less likely to feel as though the danger is happening again in the present.

What Happens to Traumatic Memories?

Traumatic memories can differ from ordinary autobiographical memories in important ways.

For someone with PTSD, reminders of a traumatic event may trigger vivid recollections, emotional distress, physical reactions or a sense that the danger is happening again.

Triggers might include:

sounds
smells
places
particular words
physical sensations
situations that resemble some aspect of the original event

This does not mean that traumatic memories are literally stored as disconnected pieces in different areas of the brain or remain physically “frozen in time”.

Memory science is considerably more complicated than that.

It is more accurate to say that trauma can affect the way memories are experienced, retrieved and connected with present-day threat responses.

If you would like to explore trauma and memory in more detail, read Big T vs Little t Trauma.

The Adaptive Information Processing Model

EMDR is also based on Francine Shapiro’s Adaptive Information Processing (AIP) model.

Within this theoretical model, some disturbing experiences may remain insufficiently processed, allowing associated emotions, beliefs and sensations to continue being triggered in the present.

EMDR aims to facilitate further processing so the experience can become integrated with other information.

For example, someone who experienced an assault may hold a belief such as:

“I’m powerless.”

Through successful treatment, the person may still remember the assault clearly but experience less distress and recognise something more appropriate to their present circumstances, such as:

“I survived it and I am safe now.”

The AIP model is an important part of EMDR theory, but it should not be confused with a proven neurological account of exactly what happens in the brain.

Does EMDR Work by Stimulating Both Sides of the Brain?

This is one of the most common explanations of EMDR online.

It is also too simplistic.

Because EMDR uses alternating left-right stimulation, it is sometimes claimed that the treatment works by “activating both hemispheres of the brain”.

Current evidence does not justify presenting that explanation as established fact.

The brain’s hemispheres constantly communicate during ordinary activity. EMDR cannot be reduced to simply switching both sides of the brain on at once.

Research instead examines a range of possible processes including:

working-memory competition
changes in memory vividness and emotionality
attention
physiological arousal
memory reconsolidation
other neurobiological processes

No single mechanism yet provides a complete explanation.

Does EMDR Mimic REM Sleep?

Another frequently repeated theory compares EMDR eye movements with the rapid eye movements that occur during REM sleep.

The comparison is interesting and has prompted research into relationships between eye movements, sleep, memory and emotional processing.

However, EMDR has not been shown simply to recreate REM sleep while somebody is awake.

Nor is there good reason to state that EMDR works because it reproduces slow-wave sleep.

These should therefore be treated as hypotheses rather than established explanations.

Are Eye Movements Actually Important?

Researchers have investigated whether eye movements contribute something beyond simply recalling the traumatic memory.

A meta-analysis examining the contribution of eye movements found a significant additional effect in EMDR treatment studies and larger effects on memory vividness in laboratory experiments. :contentReference[oaicite:4]{index=4}

That does not mean eye movements explain every aspect of EMDR.

EMDR is a complete therapeutic protocol involving assessment, preparation, memory processing, cognitive and emotional work, bilateral stimulation and repeated review.

The relative contribution of individual components continues to be studied.

What Are the Eight Phases of EMDR?

EMDR treatment is conventionally organised into eight phases.

1. History Taking and Treatment Planning

The therapist develops an understanding of the difficulties bringing you to therapy, relevant experiences, current symptoms and whether EMDR appears appropriate.

2. Preparation

You learn about EMDR and develop strategies for managing distress before beginning more demanding memory-processing work.

3. Assessment

A particular memory may be identified along with associated images, beliefs, emotions and physical sensations.

4. Desensitisation

The memory is processed while bilateral stimulation is used. The therapist periodically pauses and asks what you notice.

5. Installation

Attention is given to a more adaptive belief or perspective associated with the memory.

6. Body Scan

You notice whether significant physical tension or disturbance remains when thinking about the memory.

7. Closure

The session is brought to an appropriate ending, including strategies for managing anything that arises afterwards.

8. Re-evaluation

At a later session, therapist and client review the previously targeted memory and assess what has changed.

You can see this process in more detail in What Does an EMDR Session Look Like?

Does EMDR Make You Forget What Happened?

No.

The goal of EMDR is not to erase traumatic memories.

A successful outcome is more commonly that the person can remember what happened without experiencing the same level of distress, threat or emotional activation.

The memory remains part of their autobiographical history.

What may change is the way it feels in the present.

Does EMDR Require Talking About Every Detail?

No.

Unlike some people’s expectations of trauma therapy, EMDR does not normally require a detailed verbal retelling of every aspect of the traumatic experience.

The therapist still needs enough information to understand the difficulty, work safely and formulate treatment appropriately.

But much of the detailed memory processing can take place internally.

This can be particularly important for people who find detailed disclosure difficult.

What Is EMDR 2.0?

The historic version of this article also discussed EMDR 2.0.

EMDR 2.0 is a development within the EMDR field that places particular emphasis on increasing working-memory load during memory processing.

Tasks may be made more demanding by combining memory recall with additional cognitive activities.

This may include variations in eye movements or tasks such as counting, spelling or other activities requiring attention.

The theoretical rationale draws heavily on working-memory research: if a secondary task places greater demand on working memory, it may have a stronger effect on the vividness or emotionality of an image.

However, describing EMDR 2.0 as automatically faster or more effective than standard EMDR would go beyond what can currently be concluded for every patient.

If you want to explore this approach separately, read Philip’s guide to EMDR 2.0.

Does EMDR Work?

The strongest clinical evidence concerns PTSD.

NICE recommends EMDR for adults with PTSD or clinically important PTSD symptoms in specified circumstances and advises that treatment should use a validated manual and be delivered by appropriately trained practitioners. :contentReference[oaicite:5]{index=5}

That evidence tells us that EMDR can be effective.

It does not mean that:

EMDR is proven to be the best therapy for every type of trauma or psychological difficulty
every person will respond to it
scientists have completely established its mechanism
bilateral stimulation simply “activates both brain hemispheres”
EMDR literally recreates REM sleep

This distinction between evidence that a treatment works and certainty about exactly how it works is important.

How Does EMDR Actually Work? The Short Answer

EMDR appears to help people process traumatic memories so that those memories become less distressing and less likely to trigger the same sense of present danger.

Working-memory competition offers one plausible and reasonably well-supported explanation for the effects of eye movements and other dual-attention tasks.

Other psychological, physiological and neurobiological processes may also contribute.

Research into EMDR’s mechanisms continues, so claims that it simply rewires the brain, balances the hemispheres or recreates sleep are more certain than the science currently allows. :contentReference[oaicite:6]{index=6}

Exploring EMDR Therapy

If you are experiencing PTSD, traumatic memories, flashbacks or other difficulties associated with traumatic experiences, assessment can help determine whether EMDR is appropriate for you.

You can learn more about EMDR therapy with Philip Bruce, including how he works and what treatment involves.

You can also explore the evidence for EMDR therapy if you would like a more research-focused overview.

If you would like to discuss whether EMDR may be suitable for your circumstances, you can contact Philip for an initial consultation.