SYSTEMATIC-DESENSITIZATION AND NONSPECIFIC TREATMENT EFFECTS - METHODOLOGICAL EVALUATION

The extent to which the therapeutic effects of systematic desensitization may be attributed to a specific therapy ingredient beyond nonspecific treatment effects is evaluated. The vast majority of studies have not determined empirically whether desensitization and nonspecific treatment control conditions are equal in credibility and expectancy for improvement generated in the clients. Recent research suggests that control conditions commonly employed in desensitization research are less credible than desensitization and generate less expectancy for improvement on the part of the patients, and that desensitization is not superior to control groups that unambiguously rule out as a rival hypothesis differential expectancies across treatment and control conditions. A review of the research that has controlled for expectancies for improvement does not support the proposition that desensitization has a specific therapeutic ingredient. This review does not impugn the efficacy of desensitization. On purely methodological grounds, it appears that nonspecific treatment effects, at least at present, cannot be ruled out in accounting for the effects of desensitization. Strategies to control for differential credibility and expectancies for therapeutic change generated by treatment and comparison groups are presented.