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In the late 1980s, an American psychologist named Francine Shapiro noticed that if she thought about disturbing memories while walking through the woods, the thoughts would dissipate without her actively trying to do anything about them. Eventually, she realized that when she recalled the traumatic memories as she walked, her eyes were moving from side to side.

And that when that happened, it felt like the memory would bother her less the next time it came to mind. She started looking into the idea, and soon, eye movement desensitization reprocessing, or EMDR therapy, was born. But as promising as some research makes it sound, EMDR is actually pretty controversial, and there's a whole lot of back and forth about whether the eye movements that set EMDR apart really do anything.

The therapy is mostly used to treat post-traumatic stress disorder, or PTSD, which can happen when someone hasn't been able to process and recover from a trauma they've experienced. Even years later, the trauma can affect their life in all kinds of ways — they might have flashbacks, sleep and concentration problems, persistent feelings of anger and shame, or any of a whole bunch of other symptoms. As the name suggests, treating PTSD with EMDR therapy centers around those side-to-side eye movements.

Its proponents think that by moving their eyes back and forth, patients can reprocess traumatic memories that have basically gotten “stuck” because the usual ways the brain deals with trauma didn't work. In each session, you're told to focus on a specific traumatic memory: the details, the emotions it brings up, and your reaction to it. While you're doing that, the therapist holds up a finger in front of you and moves it quickly from side to side for about 15 seconds while you follow the movement with your eyes.

You'd almost expect them to start saying “youuu are gettting sleeepierrr...”, except that this isn't hypnosis and you're not on a Hollywood set in the 1940s. The hope is that as you recall different details related to the memories, they become less and less disturbing. Then, once you're more desensitized, you can start associating positive lines of thinking with the previously traumatic memory.

Maybe something like “that wasn't my fault.” Or, “I am a good person.” The concept is so simple that it doesn't even seem like it should work. And yet, meta-analyses of the research on EMDR have consistently shown that it does improve PTSD symptoms — at least compared to no treatment at all. The thing is, there's no real consensus about how it works.

Almost all effective therapies for PTSD involve reprocessing traumatic memories in some way, since those stuck memories seem to be the main cause of the disorder. With EMDR, researchers think the eye movements allow the brain to do that reprocessing, but there's some debate about the exact mechanism behind it. One possibility is that performing an extra task — moving your eyes back and forth — overloads your working memory, which handles everything you're consciously doing at any given time.

Your working memory can only deal with a few different things at once, and the idea is that if you start filling it up with tasks, there's less room for the negative stuff that would normally be triggered by traumatic memories. Other researchers think that the eye movements mimic what's known as an orienting response — what your brain automatically does when you're exposed to a new environment or stimulus, in order to process and understand it for the first time. Or, EMDR could improve communication between the hemispheres of your brain, or the effect could have to do with REM sleep, or … you get it.

There are a lot of options, but not a lot of answers. Some researchers argue that this isn't a big deal — we use lots of things in medicine that we don't entirely understand the mechanisms of. Antidepressants, for example, or general anesthesia.

Others are a lot more skeptical. Yes, meta-analyses have shown that EMDR is an effective treatment for PTSD. But they've also consistently shown that it isn't more effective at treating PTSD than similar therapies that don't involve moving your eyes around.

Like trauma-focused cognitive behavioral therapy, where you're gradually re-exposed to the trauma and learn to make sense of what happened and how it affects your thoughts and behaviors. A meta-analysis published in 2006 looked at seven studies comparing these two therapies, and found no evidence that one was more effective for PTSD than the other. That might seem like a point in favor of EMDR, but if you're trying to sell the idea that eye movements add a new, super effective layer to therapy, this isn't good news.

If the eye movements used in EMDR were actually triggering something in the brain to help process traumatic memories, you'd expect it to work better than a therapy that's similar in almost every way except the eye movements. So, a lot of psychologists believe that even though EMDR is as effective as some other treatments for PTSD, it doesn't actually offer anything revolutionary. Their perspective is basically that what's effective isn't new, and what is new isn't effective.

But! Regardless of whether the eye movements offer something new, EMDR is still a highly recommended treatment for PTSD. Yes, there are a lot of questions about it, but we're not just going to throw an effective treatment out the window.

If nothing else, the way therapists conduct EMDR — like the fact that it doesn't involve too much discussion of the trauma — might work better for some patients. But with future research, hopefully we'll learn more about how to help people process trauma … and whether simple eye movements can hack your brain's memory circuits. Thanks for watching this episode of SciShow Psych!

If you're interested in learning about the history of another strange therapy, you can check out our video about the dangerous past of electroconvulsive therapy and what it's used for today. [ ♪ OUTRO ].