Models[edit]

There are many models of common factors in successful psychotherapy process and outcome.^[31] Already in 1990, Grencavage and Norcross identified 89 common factors in a literature review, which showed the diversity of models of common factors.^[21] To be useful for purposes of psychotherapy practice and training, most models reduce the number of common factors to a handful, typically around five. Frank listed six common factors in 1971 and explained their interaction.^[10] Goldfried and Padawer listed five common strategies or principles in 1982: corrective experiences and new behaviors, feedback from the therapist to the client promoting new understanding in the client, expectation that psychotherapy will be helpful, establishment of the desired therapeutic relationship, and ongoing reality testing by the client.^[17] Grencavage and Norcross grouped common factors into five areas in 1990.^[21] Lambert formulated four groups of therapeutic factors in 1992.^[24] Joel Weinberger and Cristina Rasco listed five common factors in 2007 and reviewed the empirical support for each factor: the therapeutic relationship, expectations of treatment effectiveness, confronting or facing the problem (exposure), mastery or control experiences, and patients' attributions of successful outcome to internal or external causes.^[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.^[33] Their multidimensional scaling analysis represented the results on a two-dimensional graph, with one dimension representing hot processing versus cool processing (roughly, closeness and emotional experience versus technical information and persuasion) and the other dimension representing therapeutic activity. Their cluster analysis represented the results as three clusters: the first related to bond (roughly, therapeutic alliance), the second related to information (roughly, the meanings communicated between therapist and client), and the third related to role (roughly, a logical structure so that clients can make sense of the therapy process).^[33]


In addition to these models that incorporate multiple common factors, a number of theorists have proposed and investigated single common factors, common principles, and common mechanisms of change, such as learning. 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.^[34] For further examples, see § Further reading, below.