Re: differential mechanism

Susan:

I take the point of your two posts on this topic to be that the procedural changes introduced in the Acierno et al. study constitute more than what I characterized as "a small difference in language."

Let me first say that my source for the criticism against Acierno et al. was Shapiro's 1996 reply to Lohr et al. (1995) that appeared in Journal of Behavior Therapy and Experimental Psychiatry ("Errors of Context and Review of Eye Movement Desensitization and Reprocessing Research"). Here is what Shapiro had to day about Acierno et al.: "the researchers were untrained and misinterpreted the description of the original EMDR articles (Shapiro, 1989a, 1989b) by having the client relax completely after each set of eye movements, which is entirely contrary to the standard procedure. In addition, Acierno et al. (1994) failed to use any of the protocols established for the treatment of phobias (see Shapiro, 1995, Fensterheim, 1996)." Perhaps the tone of her comments imply that there were all kinds of procedural problems in the Acierno et al. study (perhaps such as those you identified in your post), the only one that she specifies is that the he had the client relax between sets of eye movements. (Parenthetically, does anyone besides me think it a bit odd to criticize a study published in 1994 for not following protocols from rescources with 1995 and 1996 publication dates?)

Now, on to the more substantive point that I was trying to make in my earlier post, which was that EMDR is portrayed as being variously robust or particularly sensitive to procedural variations depending on the study being considered. When dismantling studies which have failed to find effects for eye movements or other bilateral stimuli are considered, the explanation offered is that EMDR contains many active elements and removing just one will not have much effect. However, when studies that fail to find an effect of EMDR at all are considered, some proponents of EMDR sift through the study report to find any deviation from the protocol in order to "explain" the lack of findings. There are two things to consider when evaluating whether or not I'm picking nits on this issue:

1. Over the course of the history of EMDR, eye movements and other bilateral stimuli have held a unique status in the EMDR protocol, elevated far above anything else. If removing eye movements or other bilateral stimuli don't produce significant reductions in treatment outcome, on what basis would you expect other procedural variables that don't have such elevated status would completely eliminate any therapeutic effect of the procedure? Let me just say that I grant you the logical point that, in principle, any deviation from the "standard protocol" could be responsible for differences in outcome. My focus here is a theoretical one: Why would the candidate difference(s) be responsible for such a dramatic loss of efficacy when more theoretically important variables have little or no effect? Such behavior appears to me to be grasping for straws, and says more about our lack of understanding about why EMDR works than anything.

2. Let's consider the Acierno et al. protocol violation of having the subject relax between sets of eye movements in context of theoretical statements about EMDR and other data about EMDR. In a 1991 paper in the Behavior Therapist (From EMD to EMDR - A New Treatment Model for Anxiety and Related Traumata), Shapiro presented a number of possible mechanisms through which the eye movements may work: (1) disruption of complex habitual physiological responses elicited by the memory; (2) distraction; (3) induction of a trance state similar to that experienced just before falling asleep; (4) interference with the trace memory caused by neuronal bursts that accompany the eye movements; (5) "neurophysiological aspects of eye movement effects such as REM-induced muscular inhibition" (p. 134). In the 1st edition of her book, Shapiro (1995, p. 30) boils it down to three possibilities: (1) activation and facilitation of information processing due to the client's dual focus of attention (present stimuli and past trauma); (2) differential effect of neuronal bursts, "which may serve as the equivalent of a low-voltage current and directly affect synaptic potential; (3) deconditioning caused by a relaxation response.

How would having subjects relax between sets of eye movements interfere with any of these proposed mechanisms? If anything, telling people to relax should further help to break up complex habitual physiological responses to the trauma memory and enhance induction of an altered state of consciousness. It should also enhance "deconditioning." I don't see how it would interfere with distraction or how it would disrupt the neuronal bursts associated with the previous eye movements interfering with the trace memory. And I really don't see how telling people to relax would interfere with eye movements recruiting "REM-induced muscular inhibition."

Not only do these attempts to "explain" failures of EMDR not square well with the proposed mechanisms behind them, they don't square with statements about the empirical data. Specifically, Shapiro as early as 1995 (p. 331) and as recently as 2000 (Leeds & Shapiro, EMDR and Resource Installation: Principles and Procedures for Enhancing Current Functioning and Resolving Traumatic Experiences) have cited as evidence for EMDR the D. Wilson et al. (1996) results characterized as "an automatically elicited and seemingly compelled relaxation response, which arose during the eye-movement sets" (Leeds & Shapiro, 2000, p. 531; cf. Shapiro, 1995, p. 331). Shapiro (1999) not only uses this line, she seems to endorse a further speculation offered by D. Wilson et al.: "D. Wilson, Silver, Covi, and Foster (1996) identified, by means of biofeedback equipment, what they referred to as a "compelled relaxation response" during the eye movement condition (supporting a conditioning model via the parasympathetic system). No such response was observed in the exposure condition, or with a motor activity control (which the authors pointed out may have been too complex and therefore 'interfered with the relaxation responses,' p. 227)."

Now, here is my problem: If a compelled relaxation response during the eye movements is good, then how can relaxation after a set of eye movements be bad? There is no consistency between the theoretical speculations as to why EMDR works and the procedural variations proffered as reasons why some investigators failed to find treatment effects. At the same time, no efforts have been made (at least none that have found their way into the peer reviewed literature as of yet) to investigate these apparently important (but theoretically neglected) procedural elements of EMDR. For example, no study has compared standard EMDR with a condition in which subjects relax between sets to see if doing so changes the efficacy of EMDR. In the absence of either a compelling and consistent theoretical rationale or compelling empirical evidence, these explanations for instances EMDR failures seem to me as post-hoc and desperate.

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