Psychotherapy research at the start of the 21st century: the persistence of the art versus science controversy.

This article offers an overview of prominent general trends in the field of psychotherapy research. We consider 3 areas of the literature: metaanalytic reviews addressing the effectiveness of psychotherapy, the movement to identify empirically supported treatments (EST), and research on the "common factor" or "contextual" models of psychotherapy. We present narrative reviews of selected literature associated with each area. The reviews highlight several issues currently confronting the field. Metaanalytic reviews underscore 2 conclusions: psychotherapy is superior to the absence of treatment, and different approaches to psychotherapy yield equivalent effects. In counterpoint to these findings, the EST movement emphasizes the empirical demonstration that specific psychotherapies have efficacy for specific disorders. Misinterpretation of EST findings has led to considerable controversy. Although EST research can identify causal effects of therapy, it has less capacity to explain how these effects come about. We suggest an appropriate perspective on EST findings. Considerable evidence supports the importance of common factors as mechanisms of change; at present, however, this evidence is predominantly correlational. We conclude that a blending of EST studies and research on the common factors represents the greatest potential for advancing the field. Studies to identify specific ESTs are key to validating the efficacy of psychotherapy approaches and need to be undertaken with the psychodynamic and experiential therapies. Greater emphasis on common factors in research, training, and practice can advance understanding about change processes in efficacious therapies, facilitate the development of sensitive clinicians, and increase the effectiveness of mental health services.