ABSTRACT
In 1936, Rosenzweig suggested that common factors were responsible for the apparent efficacy of existing psychotherapies. The logical inference was that psychological treatments that contained the common factors would produce beneficial outcomes, and consequently all psychotherapies would be roughly equivalent in terms of their benefits. The uniform efficacy of psychotherapies was emphasized in the subtitle of Rosenzweig's article by reference to the Dodo bird's conclusion at the end of a race in Alice in Wonderland: "At last the Dodo said, 'Everybody has won, and all must have prizes'" (Rosenzweig, 1936, p. 412). Since that time, uniform efficacy, which has been referred to as the Dodo bird effect, has been considered empirical support for those who believe that common factors are the efficacious aspect of psychotherapy. On the other hand, advocates of particular therapeutic approaches believe that some treatments (viz., those that they advocate) are more efficacious than others.
