EMDR FORUM ARCHIVE, 2000
Re: differential mechanism
Cahill · 11/03/01 at 7:45 PM ET
Part 5 From our prior exchange: (you) "The R for Reprocessing, as you probably are aware, was added later, as Shapiro felt that desensitization inadequately accounted for the treatment effect in EMDR, though it was my impression that this was not limited to the actual intallation phase of the treatment. Incidentally, the term reprocessing is also used in CBT (e.g. Rothbaum)." First, often times the same term can be used in at least three different ways. At one level, a term can be used to refer to a specific set of operations, regardless of outcome and irrespective of the presumed mechanism. For example, an operational defining of the term "exposure" could be something like "being in the presence of a stimulus previously identified as fear-evoking." This definition says nothing about whether the person registers the stimulus or what will happen when the a person undergoes exposure. A second way a term can be used includes a description not only of the procedure, but the expected outcome. This is an empirical or functional definition. So, exposure in this sense might not only entail the person being in the presence of the stimulus, but also requires an expected response, such as an increase in fear as indexed by self-report, heart-rate, etc. that will then decline with continued exposure. If the expected response does not occur, we infer that exposure did not occur. For example, the person may be in the room with a dog, but is not aware of this fact (i.e., hasn't seen or heard the dog). From this empirical or functional perspective the person has not yet undergone exposure. Finally, we can use a term in a theoretical sense. Thus, when we say exposure, we may have mind not only the procedures and results, but a specific mechanism in mind. Thus one theoretical explanation of the empirical effects of exposure is that when the procedures of exposure result in an activation of fear followed by a dimuntion of fear that transfers over time or situations, then there has been a change in fear structure that is responsible for the change in behavior. It may be helpful to examine use of the terms "processing" and "reprocessing" in this way. It is true that Shapiro and Rothbaum and others (e.g., Foa) use these terms. I think there is much common ground with respect to theoretical and empirical (or functional) use of these terms. Functionally, the terms processing and reprocessing imply that some procedure has resulted in the reduction of distress and specific symptoms of PTSD (or whatever disorder you are observing). If resolution of distress and symptoms do not occur, we are likely to infer that processing or reprocess has also not occurred. Theoretically, I think most contemporary theories of PTSD would assert that processing or reprocess involves making changes in the underlying memory or fear structure, although they may differ about the details. Some theories may argue that the therapeutic elements change the existing memory. Other theories may argue that a new "safe" memory is acquired, which then competes with the old memory for expression. The focus of my earlier post, however, was at the procedural level: What is it that the therapist does in EMDR that results in the reduction of symptoms. At a very simple level of analysis, we can divvy up any intervention into elements that are common to other therapies and which contribute to outcome, elements that are common to other therapies but do not contribute to outcome, elements that are unique to the therapy and which contribute to outcome, and elements that are unique to the therapy and do not contribute to outcome. Many of us who are skeptical of EMDR doubt NOT that EMDR works (the evidence indicates that it does), but we doubt that it works through different mechanisms than other therapies. We note that EMDR has several features that are common to many other effective treatments (developing a "therapeutic alliance," providing them with an explanation for and normalizing of their symptoms, reassuring them that "in my clinical experience" or that "research indicates" these procdures have helped many people with similar problems, etc., a simple opportunity to talk about their problems and feelings to a non-judgemental other) AND that EMDR also incorporates the specific feature of repeated exposure to the trauma memory. From our perspective, proponents of the view that EMDR achieves its outcomes through different mechanisms than other therapies face two important tasks. The first task is to identify those elements of EMDR that are unique to the therapy. The second task is to conduct research to determine which of those unique elements contributes to outcome and which do not, keeping the wheat while discarding the chaff (incidentally, the same standards apply to other therapies). The reason we assert that the onus is on demonstrating the unique elements of EMDR contribute to treatment outcome is that the opposite position (that we skeptics have to prove the unique elements don't contribute to outcome) is logically impossible: you cannot prove the null hypothesis. The logic of scientific investigation is to assume that two things are the same, and then determine if there is adequate evidence to reject this null hypothesis and thereby indirectly advance the alternative position that things are not the same. The point in all of this discussion leads up to the role of dismantling studies in the search for the active ingredients in EMDR, and the failure thus far of such studies to provide any convincing evidence that features most uniquely identified with EMDR have any significant impact on therapeutic outcome.
(me) "In the case of EMDR, there are at least three features of the procedure that are (or at least one time were) so integral to the procedure that they were specified in the name: eye movements, desensitization (read exposure), and reprocessing (read installation trials)."
I think that I have been guilty of mixing up, or at the very least not being clear, about my use of terms. I may also have oversimplified things by equating "reprocessing" with installation trials. Thanks for pointing this out. Let me try to be more clear about my position.
The seminal paper on EMDR (Shapiro, 1989) put eye movements in the role of the single most important unique feature of EMDR (then simply EMD). Over time, there has been a shift in the emphasis on eye movements. It shifted from eye movements to laterally alternating stimuli, and now (as indicated in your post) dual attention. In addition, there has been greater emphasis on procedures I would describe, for lack of a better term, as "cognitive" interventions represented by the installation trials and the cognitive interweave. This was what I intended when I, perhaps oversimplistically, equated the "reprocessing" term with installation trials.
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