Books in Review

Thorana Nelson (Editor)

Wampold, Bruce E. (2001). The great psychotherapy debate: Models, methods, and findings. Mahwah, NJ: Lawrence Erlbaum
Reviewed by Douglas H. Sprenkle, Ph.D.

Bruce Wampold's The Great Psychotherapy Debate is, in my judgment, one of the most important books in the history of psychotherapy research. Based on a comprehensive and exceptionally careful meta-analysis of almost all controlled psychotherapy research, he addresses a central question of great interest to both practitioners and researchers-- namely why is psychotherapy effective?

There is both wonderful and troubling news in this volume. The good news is that, as other meta-analyses have shown, there is compelling evidence that psychotherapy is remarkably effective. In fact, Wampold's findings probably render the no treatment control group unnecessary. The bad news, for passionate proponents of specific therapy models, is that there is very little evidence that sound psychotherapies are "differentially effective" (relative to each other).

Since many of us have spent a great deal of effort mastering our preferred models, and often have strong convictions about them, it may be disquieting to learn how little evidence there is that "specific" factors that are unique to particular therapeutic models explain why psychotherapy works. In fact, Wampold's careful analysis demonstrates that at most, 8 percent of the outcome variance in psychotherapy is due to the unique contributions of models (including such sacred cows as cognitive behavior therapy). About 70% of the variance is due to "general factors" that are shared by all successful psychotherapies, and about 22% of the variance is unexplained.

In short, Wampold's conclusions strongly support those scholars (like Barry Duncan and Scott Miller within family therapy) who argue that "common factors" are primarily responsible for therapeutic change. These refer to client, therapist, and client-therapist relationship characteristics, as well as generic interventions that are not the province of particular models.

While Wampold's book is about psychotherapy research in general, it is important to note that the major meta-analyst of the family therapy research literature, William Shadish, has reached the same conclusion: "Despite some superficial evidence apparently favoring some orientations over others, no orientation is yet demonstrably superior to any other" (Shadish, Ragsdale, Glaser, & Montgomery, 1995, p. 348).

Wampold would be the first to admit that many single psychotherapy studies show differences between models. But what meta-analysis enabled him to do was to control for the many factors that bias results like the allegiance of the investigator to the model, the use of reactive measures, and so forth. Once these confounds are controlled across many studies, most of the differences among model effectiveness wash out. William Shadish made a similar discovery in analyzing MFT research literature. "There is little evidence for differential efficacy among the various approaches to marriage and family interventions, particularly if mediating and moderating variables are controlled" (Shadish & Baldwin, 2002, p. 365).

A particularly interesting aspect of Wampold's analysis is the attention he gives to therapist effects, which he considers to be an "ignored but critical factor" in explaining therapeutic outcomes. The chapter on therapist effects alone is worth the price of the volume. It offers strong evidence that the efficacy of the therapist often contributes much more to outcome than the particular therapy he or she happens to be using. Taken as a whole, the volume supports a comment I once heard Jim Framo make that good therapists, of whatever stripe, are remarkably similar.

Finally, Wampold offers a number of controversial recommendations (e.g. "limit clinical trials") which are certain to be criticized by the proponents of what he calls the medical model of psychotherapy research, which he juxtaposes with his own "contextual model."

This volume may not be the last word. It is certainly possible that there are, in fact, meaningful differences among our models but that they are too "fine grained" to be teased out by existing research methods or the research questions we are asking (Sprenkle, 2002). However, it is hard to argue with Wampold's analysis of the data now available. This volume is a tour de force of clinical scholarship. He truly puts the onus on those advocates of model specificity to "show us the evidence."

Douglas H. Sprenkle, Ph.D.

Professor of Marriage and Family Therapy, Purdue University

References:

Shadish, W.R., Ragsdale, K., Glaser, R.R., & Montgomery, L.M. (1995). The efficacy and effectiveness of marital and family therapy: A perspective from meta-analysis. Journal of Marital and Family Therapy, 21, 345-360.

Shadish, W. R. & Baldwin, S. A. (2002). Meta-Analysis of MFT interventions. In D.H. Sprenkle (Ed.). Effectiveness research in marriage and family therapy (pp. 339-370). Alexandria, VA: American Association for Marriage and Family Therapy.

Sprenkle, D.H. (2002). Editor's introduction. In D.H. Sprenkle (Ed.). Effectiveness research in marriage and family therapy (pp. 9-25). Alexandria, VA: American Association for Marriage and Family Therapy.