[1] This is in contrast to the view that the effectiveness of psychotherapy and counseling is best explained by specific or unique factors (notably, particular methods or procedures) that are suited to treatment of particular problems.
[5] John Dollard and Neal E. Miller's 1950 book Personality and Psychotherapy emphasized that the psychological principles and social conditions of learning are the most important common factors.
[10] After Lester Luborsky and colleagues published a literature review of empirical studies of psychotherapy outcomes in 1975,[11] the idea that all psychotherapies are effective became known as the Dodo bird verdict, referring to a scene from Alice's Adventures in Wonderland quoted by Rosenzweig in his 1936 article; in that scene, after the characters race and everyone wins, the Dodo bird says, "everybody has won, and all must have prizes.
[13] A number of studies after 1975 presented more evidence in support of the general efficacy of psychotherapy,[14] but the question of how common and specific factors could enhance or thwart therapy effectiveness in particular cases continued to fuel theoretical and empirical research over the following decades.
[15] The landmark 1982 book Converging Themes in Psychotherapy gathered a number of chapters by different authors promoting common factors, including an introduction by Marvin R. Goldfried and Wendy Padawer, a reprint of Rosenzweig's 1936 article, and further chapters (some of them reprints) by John Dollard and Neal E. Miller, Franz Alexander, Jerome Frank, Arnold Lazarus, Hans Herrman Strupp, Sol Garfield, John Paul Brady, Judd Marmor, Paul L. Wachtel, Abraham Maslow, Arnold P. Goldstein, Anthony Ryle, and others.
[24] Lambert's research later inspired a book on common factors theory in the practice of therapy titled The Heart and Soul of Change.
[2] In 2001, Bruce Wampold published The Great Psychotherapy Debate, a book that criticized what he considered to be an overemphasis on ESTs for particular problems, and he called for continued research in common factors theory.
[29] The articles emphasized the compatibility between ESTs and common factors theory, highlighted the importance of multiple variables in psychotherapy effectiveness, called for more empirical research on common factors (especially client and therapist variables), and argued that individual therapists can do much to improve the quality of therapy by rigorously using feedback measures (during treatment) and outcome measures (after termination of treatment).
[29] The article by Stefan G. Hofmann and David H. Barlow, two prominent researchers in cognitive behavioral therapy, pointed out how their recent shift in emphasis from distinct procedures for different diagnoses to a transdiagnostic approach was increasingly similar to common factors theory.
[32] Terence Tracy and colleagues modified the common factors of Grencavage and Norcross, and used them to develop a questionnaire which they provided to 16 board certified psychologists and 5 experienced psychotherapy researchers; then they analyzed the responses and published the results in 2003.
In one example, at least three independent groups have converged on the conclusion that a wide variety of different psychotherapies can be integrated via their common ability to trigger the neurobiological mechanism of memory reconsolidation.