Can EMDR's effects be attributed to placebo or non-specific effects?
No. A number of studies have found EMDR superior in outcome to placebo treatments, and to treatments not specifically validated for PTSD. EMDR has outperformed active listening (Scheck et al., 1998), standard outpatient care consisting of individual cognitive, psychodynamic, or behavioural therapy in a Kaiser Permanente Hospital (Marcus et al., 1997), relaxation training with biofeedback (Carlson et al., 1998). EMDR has been found to be relatively equivalent to CBT therapies in seven randomized clinical trials that compared the two approaches. Because the treatment effects are large and clinically meaningful, it can be concluded that EMDR is not a placebo treatment. For example, in a meta-analysis of PTSD treatments, Van Etten and Taylor (1998), calculated the mean effect sizes on self-report measures for placebo and control conditions as 0. 43, for EMDR as 1.24, and for CBT as 1.27 (p. 135). Several studies (e.g., Thordarson et al., 2001) have measured the credibility of the treatments being provided, as a way to determine if EMDR elicited more confidence from clients, thereby producing larger effects; no study found EMDR more or less credible. Because EMDR is not more credible than these other therapies, it appears that the effects cannot be attributed to suggestion or a heightened placebo effect.