To recover from abuse or another traumatic experience, some people turn to a therapy called eye-movement desensitisation and reprocessing, or EMDR.

But this may present problems if these people pursue justice in the courts. In New South Wales, for instance, evidence obtained using EMDR can’t be used in a case unless it has been approved by the director (or deputy) of public prosecutions.

Prosecutors are concerned that after EMDR, trauma memories can’t be relied on as valid testimony. This has resulted in court cases not proceeding.

But what does the evidence say?

What is EMDR?

EMDR is one of the common exposure-based treatments for post-traumatic stress disorder (PTSD).

This group of therapies – which encompass prolonged exposure, cognitive processing therapy, EMDR and other variants – all ask a patient to recall their trauma. The therapists integrates this information and aims to correct unhelpful thought patterns that may be prolonging their distress.

Each of these treatments is recommended in most international guidelines for treating PTSD.

EMDR is different from the other exposure-based therapies because the therapist also asks the patient to move their eyes in a rapid side-to-side movement. This will typically involve following the therapist’s fingers move back and forth.

Proponents of EMDR initially proposed eye movements triggered neural processes that help people better adjust to or process trauma memories. However, the actual role of eye movements has been subject to much debate.

Although the mechanism isn’t yet fully understood, the weight of evidence suggests eye movements may reduce distress while recounting trauma memories because it depletes our working memory capacity. This results in less focus on the negative emotions associated with the memory.

Where did concerns about EMDR affecting memories come from?

EMDR has been criticised for potentially distorting people’s memories of traumatic events dates since the 1990s when the treatment increased in popularity.

This was also a period when when a controversial movement of “recovered memory therapies” emerged. These were used to guide people to reconstruct memories that were purportedly “hidden” or “repressed”.

This involved therapists directing patients to focus attention on internal states, suspend reality and allow themselves to be guided by the therapist to recover so-called “repressed memories”, often of satanic or ritual abuse.

In the wake of this movement, many studies showed this sort of guided intervention could lead to false, or even implanted, memories.

At the same time, researchers were concerned about hypnotic techniques. During hypnosis, people could reconstruct false memories. They were particularly susceptible to misleading information and had stronger confidence in these memories.

For this reason, authorities around the world cautioned against using hypnosis in cases that may involve the person subsequently needing to give testimony in legal proceedings.

Some likened EMDR to hypnosis, others were sceptical of its claims

Some agencies and experts considered EMDR a hypnosis-like intervention because it focused the person’s attention on their internal state, promoted increased absorption in memories and actively guided memories.

Many also likened the finger waving in front of the patient’s face as inducing a hypnotic state.

Because EMDR guided patients to process memories in a way that made them less distressing, some concluded EMDR-elicited memories were comparably susceptible to distortion as hypnotically-induced memories.

This perception of EMDR at the time may also have been influenced by much initial scepticism of the therapy.

In the early period of its popularity, EMDR proponents made excessive claims of its success, such as being able to completely resolve trauma memories in a single session, despite the lack of evidence.

What does the evidence actually say?

It’s difficult to test the claim that EMDR increases the likelihood of false memories because you can’t readily study this in clinical settings.

Instead, researchers have used experimental designs in people without PTSD to determine if eye movements themselves are likely to lead to false memories. The results are mixed.

Multiple studies have shown eye movements can lead to false memories. One study showed healthy research participants a video of a car accident. Half the sample then used eye movements. Then all participants were read an eye-witness narrative that involved false information about the video.

This study found those who used eye movements were more susceptible to the misinformation. It seems this effect may occur because eye movements reduce the vividness and intensity of emotions in memories, thereby making them more susceptible to false memories.

However, other laboratory-based studies have not replicated this effect. One study using the same design found using eye movements didn’t make memory more likely, reduce correct memory details, or affect the vividness or emotional intensity of the memory.

What does this all mean?

EMDR is one of a suite of exposure-based treatments for PTSD that involve recounting trauma memories and integrating new information about the trauma. These appear to be key in helping people resolve their traumatic stress. Although EMDR is not better than other exposure-based treatment, it is as effective as the others.

Although some evidence points to eye movements making a person more susceptible to false memories, other studies do not find this. Importantly, these studies are not actually testing EMDR.

There is no direct evidence that EMDR leads to false memories, just as there is no evidence that prolonged exposure or other exposure-based treatments do. Singling EMDR out as being particularly susceptible to memory distortion doesn’t appear to be supported by the scientific evidence.

The position of legal authorities to not accept testimony following EMDR is therefore not justified and may deny trauma survivors the right to legal proceedings.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14. The National Sexual Assault, Family and Domestic Violence Counselling Line – 1800 RESPECT (1800 737 732) – is also available 24/7 for any Australian who has experienced family violence or sexual assault.

Richard Bryant, Professor & Director of Traumatic Stress Clinic, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.