Specific and nonspecific treatment factors in the experimental analysis of behavioral treatment efficacy.

Interest in the empirical demonstration of the clinical efficacy of psychosocial treatments has been rekindled by societal concerns over accountability and cost-effectiveness in the delivery of mental health services. Behavior therapy has had a long history of experimental research on treatment efficacy and enjoys a visible presence in contemporary mental health practice. The demonstration of behavioral treatment efficacy, however, requires experimental evidence that shows the efficacy of prescriptive structured procedures beyond nonspecific factors in delivery of such procedures. The authors provide an analysis of the nature of nonspecific treatment factors and nonspecific effects and suggest experimental procedures testing the incremental validity of specific treatments. They examine two widely promoted, prescriptive structured treatments to analyze the specificity of their clinical efficacy: eye movement desensitization and reprocessing for anxiety disorders and cognitive-behavioral treatment of generalized anxiety disorder. They conclude that the treatments show different levels of efficacy and different degrees of specificity.