There’s an interesting section in Dan Siegel’s book, The Mindful Therapist: A Clinician’s Guide to Mindsight and Neural Integration, where he recounts a traumatic incident of his own — a horse riding accident in Mexico that happened while he was working for the World Health Organization. Then, years later, while watching the movie Seabiscuit Siegel
suddenly felt this sharp pain in my face and arm and my muscles tighten as I bent over to the side… now watching the movie I felt overwhelmed and out of control. And even though I quickly realized that the accident in Seabiscuit was just like the one I’d had, these feelings felt in the here and now. It did not feel like I was remembering anything from the past. That is the emergence of “implicit-only” memory.
Dr. Siegel suggests that implicit memory is more of a right-brain function. Implicit memory being the more visceral components of memory, which is present throughout the lifespan (unlike explicit memory which only starts encoding roughly around age 3), which does not require conscious attention for encoding, is automatic, etc. Explicit memory (as the theory goes) being the more language centered kind of memory, stored in the hippocampus, is retrieved with awareness, is factual and autobiographical, can be retrieved with intention, and so forth.
Siegel notes that until encoded with left-brain activity, implicit memory has its own distinct, visceral quality. In addition, he notes that through mindfulness practices (such as yoga, meditation, what have you) we can learn to discern the difference between these two states of awareness. He even cites a study on this:
Farb, N. A. S., Segal, Z. V., Mayberg, H., Bean, J. McKeon, D., Fatima, Z., et al. (2007). Attending to the present: Mindfulness reveals distinct neural modes of self-reference. Journal of Social, Cognitive, and Affective Neuroscience, 2, 248-258.
So what does this have to do with EMDR? Well, maybe nothing. The truth is we don’t know why Eye Movement Desensitization and Reprocessing therapy (EMDR) works. Is it possible that the waving of the clinician’s hand in front of the patient and the patient’s tracking of that movement, what’s known as a “bilateral stimulus,” somehow helps the brain to combine left- and right-brain activity to create an integrated memory? Could be.
Does the attention on the waving hand, somehow reduce the intensity of the recalled memory — the “desensitization” piece? Could be. Might it be a combination of these two factors? Possibly. Is it neither of these explanations? Possibly. More research will undoubtedly be done. In the meantime, Dr. Siegel has offered a very interesting and at least plausible hypothesis, that the processing during EMDR integrates free-floating implicit, right-brain memories, with left-brain tags about meaning, narrative, and fact — a procedure that fundamentally alters the quality of that memory.