The scientific approach to understanding the world includes the process of carefully separating out variables and effects. Experiments, in fact, are designed specifically to control for variables. This can be especially challenging in medicine, since the body is a complex and variable system and there are always numerous factors at play. We often characterize the many variables that can influence the outcome in a clinical study as “placebo effects” or “non-specific effect” – things other than a specific response to the treatment in question.

A common error to make when interpreting clinical studies is to confuse non-specific effects – those that result from the therapeutic interaction or the process of observation – with a specific effect from the treatment being studied. While this is broadly understood within the scientific medical community, it seems that within certain fields proponents are going out of their way to sell non-specific effects as if they were specific effects of the favored treatment.

This is perhaps most true for acupuncture. As has been discussed numerous times on SBM, the consensus of the best clinical studies on acupuncture show that there is no specific effect of sticking needles into acupuncture points. Choosing random points works just as well, as does poking the skin with toothpicks rather than penetrating the skin with a needle to elicit the alleged “de qi”.

The most parsimonious interpretation of the evidence is that the needles (i.e. acupuncture itself) are superfluous – any perceived benefit comes from the therapeutic interaction. This has been directly studied, and the evidence suggests that the way to maximize the subjective effects from the ritual of acupuncture is to enhance the interaction with the practitioner, and has nothing to do with the acupuncture itself. Acupuncture is a clear example of selling a specific procedure based entirely on non-specific effects from the therapeutic interaction – a good bedside manner and some hopeful encouragement.

This phenomenon is by no means limited to acupuncture. Perhaps another example is Eye Movement Desensitization and Reprocessing (EMDR), a practice that is increasingly popular among psychiatrists.

The concept of EMDR – how it is supposed to work – sounds pseudoscientific to this neurologist. According to the EMDR Institute:

During treatment various procedures and protocols are used to address the entire clinical picture. One of the procedural elements is “dual stimulation” using either bilateral eye movements, tones or taps. During the reprocessing phases the client attends momentarily to past memories, present triggers, or anticipated future experiences while simultaneously focusing on a set of external stimulus. During that time, clients generally experience the emergence of insight, changes in memories, or new associations.

The external stimulus – whether moving the eyes or tapping on the client or playing certain tones – is supposed to help the brain reprocess memories and information, and is alleged to be useful for a wide range of psychiatric symptoms. The proposed mechanism sounds highly dubious. While the brain certainly has plasticity, the ability to change its wiring through use, it is hard to imagine how such a simple procedure could have a significant effect on this plasticity. There are many who suspect that the eye movement component to EMDR therapy may be the equivalent to the needle component of acupuncture.

In psychotherapy there are many sources of non-specific effects that would need to be carefully controlled for before the effects of any specific component can be determined. The interaction with the therapist, the time taken to focus on ones problems and symptoms, and the introduction of a novel element into the therapeutic relationship are all recognized factors. In addition, EMDR (not surprisingly) has evolved into a multifaceted treatment approach, that includes many standard elements of therapy. This always reminds me of the commercials who proudly advertise that their products are “part of this nutritious breakfast.” Yes, but are they an important part – or is the breakfast nutritious without it?

A 2002 review of EMDR in general concluded:

Current component analyses of EMDR have failed to effectively evaluate the relative weighting of its procedures.

And a more recent 2006 review of EMDR compared to cognitive-behavioral therapy for post traumatic stress disorder (PTSD) concluded:

Our results suggest that in the treatment of PTSD, both therapy methods tend to be equally efficacious. We suggest that future research should not restrict its focus to the efficacy, effectiveness and efficiency of these therapy methods but should also attempt to establish which trauma patients are more likely to benefit from one method or the other. What remains unclear is the contribution of the eye movement component in EMDR to treatment outcome.

The last line is most significant – what contribution, if any, does the actual EMDR have? The research has not clearly established that the eye movements are having a specific neurological or psychological effect. Perhaps it’s just all the other components of the therapy that is having the perceived effect. And yet EMDR has been widely accepted as a treatment modality. This acceptance seems premature.

It also seems that this is another failure of the evidence-based medicine (EBM) approach – EMDR  is being hailed as an evidence-based practice. There are indeed studies that show that EMDR therapy works. But a science-based approach would consider more deeply the question of plausibility and mechanism, and from this question whether or not EMDR has indeed been established as having specific efficacy.


EMDR, like acupuncture, is likely nothing more than a ritual that elicits non-specific therapeutic effects.  While there are some who may consider this a justification for both modalities, there is significant risk to this approach. First, the non-specific effects are often used to justify alleged specific mechanisms of action which are likely not true. This sends scientific thought and research off on a wild-goose chase, looking for effects that do not exist. Science is a cumulative process built on consilience – scientific knowledge must all hang together. These false leads are a wrench in the mechanics of science.

Second, the false specificity of these treatments is a massive clinical distraction. Time and effort are wasted clinically in studying, perfecting, and using these methods, rather than focusing on the components of the interaction that actually work.

And in the end these magical elements do not add efficacy. For example, as the review above indicates, EMDR is no more effective than standard cognitive-behavioral therapy.

Rather than getting distracted by alluring rituals and elaborate pseudoscientific explanations for how they work, we should focus on maximizing the non-specific elements of the therapeutic interaction, and adding that to physiological or psychological interventions that have specific efficacy.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.