Common Factors Theory
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Common factors theory, a theory guiding some research in
clinical psychology Clinical psychology is an integration of social science, theory, and clinical knowledge for the purpose of understanding, preventing, and relieving psychologically based distress or dysfunction and to promote subjective well-being and persona ...
and
counseling psychology Counseling psychology is a psychological specialty that encompasses research and applied work in several broad domains: counseling process and outcome; supervision and training; career development and counseling; and prevention and health. ...
, proposes that different approaches and
evidence-based practice Evidence-based practice (EBP) is the idea that occupational practices ought to be based on scientific evidence. While seemingly obviously desirable, the proposal has been controversial, with some arguing that results may not specialize to indiv ...
s in
psychotherapy Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of psychological methods, particularly when based on regular personal interaction, to help a person change behavior, increase happiness, and overcome pro ...
and counseling share ''common factors'' that account for much of the effectiveness of a psychological treatment. 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. However, according to one review, "it is widely recognized that the debate between common and unique factors in psychotherapy represents a
false dichotomy A false dilemma, also referred to as false dichotomy or false binary, is an informal fallacy based on a premise that erroneously limits what options are available. The source of the fallacy lies not in an invalid form of inference but in a false ...
, and these factors must be integrated to maximize effectiveness." In other words, "therapists must engage in specific forms of therapy for common factors to have a medium through which to operate." Common factors is one route by which psychotherapy researchers have attempted to integrate psychotherapies.


History

Saul Rosenzweig Saul Rosenzweig (1907–2004) was an American psychologist and therapist who studied subjects such as repression, psychotherapy, and aggression. Rosenzweig, who, with a co-author, has been credited with being the first to attempt to "elicit repres ...
started the conversation on common factors in an article published in 1936 that discussed some psychotherapies of his time.
John Dollard John Dollard (29 August 1900 – 8 October 1980) was an American psychologist and social scientist known for his studies on race relations in America and the frustration-aggression hypothesis he proposed with Neal E. Miller and others. Life and ...
and Neal E. Miller's 1950 book ''Personality and Psychotherapy'' emphasized that the psychological principles and social conditions of
learning Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machine learning, machines ...
are the most important common factors.; more recently, Warren Tryon has championed learning as a common factor, e.g. : "Therapists, and the therapeutic approaches that currently divide us, differ only with regard to what is to be learned and how it is to be acquired... This makes learning and memory basic to our science and profession and should motivate us to search for mechanisms that underlie all effective psychological interventions..." Sol Garfield (who would later go on to edit many editions of the ''Handbook of Psychotherapy and Behavior Change'' with Allen Bergin) included a 10-page discussion of common factors in his 1957 textbook ''Introductory Clinical Psychology''. In the same year,
Carl Rogers Carl Ransom Rogers (January 8, 1902 – February 4, 1987) was an American psychologist and among the founders of the humanistic approach (and client-centered approach) in psychology. Rogers is widely considered one of the founding fathers of ps ...
published a paper outlining what he considered to be common factors (which he called "necessary and sufficient conditions") of successful therapeutic personality change, emphasizing the
therapeutic relationship The therapeutic relationship refers to the relationship between a healthcare professional and a client or patient. It is the means by which a therapist and a client hope to engage with each other and effect beneficial change in the client. In psyc ...
factors which would become central to the theory of
person-centered therapy Person-centered therapy, also known as person-centered psychotherapy, person-centered counseling, client-centered therapy and Rogerian psychotherapy, is a form of psychotherapy developed by psychologist Carl Rogers beginning in the 1940s and ...
. He proposed the following conditions necessary for therapeutic change: psychological contact between the therapist and client, incongruence in the client, genuineness in the therapist, unconditional positive regard and empathic understanding from the therapist, and the client's perception of the therapist's unconditional positive regard and empathic understanding. In 1961,
Jerome Frank Jerome New Frank (September 10, 1889 – January 13, 1957) was an American legal philosopher and author who played a leading role in the legal realism movement. He was Chairman of the Securities and Exchange Commission, and a United States circu ...
published ''Persuasion and Healing'', a book entirely devoted to examining the common factors among psychotherapies and related healing approaches.; the legacy of Frank's work is discussed in Frank emphasized the importance of the expectation of help (a component of the
placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general ...
effect), the
therapeutic relationship The therapeutic relationship refers to the relationship between a healthcare professional and a client or patient. It is the means by which a therapist and a client hope to engage with each other and effect beneficial change in the client. In psyc ...
, a rationale or conceptual scheme that explains the given symptoms and prescribes a given
ritual A ritual is a sequence of activities involving gestures, words, actions, or objects, performed according to a set sequence. Rituals may be prescribed by the traditions of a community, including a religious community. Rituals are characterized, b ...
or procedure for resolving them, and the active participation of both patient and therapist in carrying out that ritual or procedure.See also : "A historical overview of Western psychotherapy reveals that the dominant psychotherapeutic approach of an era reflects contemporary cultural attitudes and values, and that the same techniques (e.g., abreaction) reappear under new names. Common to all psychotherapies are (a) an emotionally charged, confiding relationship; (b) a therapeutic rationale accepted by patient and therapist; (c) provision of new information by precept, example and self-discovery; (d) strengthening of the patient's expectation of help; (e) providing the patient with success experiences; and (f) facilitation of emotional arousal. Prevalent forms of disability and their treatment include drug therapy for constitutional vulnerabilities, emotional support for environmental crises, spiritual guidance for existential anxieties, and therapeutic maneuvers to correct faulty perceptual and behavioral habits learned early in life. Only the latter form requires therapists trained in specific psychotherapeutic methods." After
Lester Luborsky Lester B. Luborsky (1920–2009) was one of the founders of scientific research in psychotherapy. Luborsky was born and raised in Philadelphia. He graduated from Philadelphia Central High School and then earned his bachelor's degree at Penns ...
and colleagues published a literature review of empirical studies of psychotherapy outcomes in 1975, the idea that all psychotherapies are effective became known as the
Dodo bird verdict The Dodo bird verdict (or Dodo bird conjecture) is a controversial topic in psychotherapy, referring to the claim that all empirically validated psychotherapies, regardless of their specific components, produce equivalent outcomes. It is named after ...
, referring to a scene from ''
Alice's Adventures in Wonderland ''Alice's Adventures in Wonderland'' (commonly ''Alice in Wonderland'') is an 1865 English novel by Lewis Carroll. It details the story of a young girl named Alice (Alice's Adventures in Wonderland), Alice who falls through a rabbit hole into a ...
'' 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." Luborsky's research was an attempt (and not the first attempt, nor the last one) to disprove Hans Eysenck's 1952 study on the efficacy of psychotherapy; Eysenck found that psychotherapy generally did not seem to lead to improved patient outcomes. A number of studies after 1975 presented more evidence in support of the general efficacy of psychotherapy, 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. 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 John Dollard (29 August 1900 – 8 October 1980) was an American psychologist and social scientist known for his studies on race relations in America and the frustration-aggression hypothesis he proposed with Neal E. Miller and others. Life and ...
and Neal E. Miller,
Franz Alexander Franz Gabriel Alexander (22 January 1891 – 8 March 1964) was a Hungarian-American psychoanalyst and physician, who is considered one of the founders of psychosomatic medicine and psychoanalytic criminology. Life Franz Gabriel Alexander, in ...
,
Jerome Frank Jerome New Frank (September 10, 1889 – January 13, 1957) was an American legal philosopher and author who played a leading role in the legal realism movement. He was Chairman of the Securities and Exchange Commission, and a United States circu ...
,
Arnold Lazarus Arnold Allan Lazarus (27 January 1932 – 1 October 2013) was a South African-born clinical psychologist and researcher who specialized in cognitive therapy and is best known for developing multimodal therapy (MMT). A 1955 graduate of South Africa' ...
,
Hans Herrman Strupp Hans Hermann Strupp (August 25, 1921 – October 5, 2006) was born in Frankfurt, Germany and died in the U.S. He moved from Nazi Germany to the U.S. and he pursued a PhD in Psychology at George Washington University in Washington, D.C. where the Dep ...
, Sol Garfield, John Paul Brady, Judd Marmor, Paul L. Wachtel,
Abraham Maslow Abraham Harold Maslow (; April 1, 1908 – June 8, 1970) was an American psychologist who was best known for creating Maslow's hierarchy of needs, a theory of psychological health predicated on fulfilling innate human needs in priority, cul ...
, Arnold P. Goldstein,
Anthony Ryle Anthony Ryle (2 March 1927 – 29 September 2016), was an English medical doctor. He studied at Oxford and University College Hospital, qualified in medicine in 1949. He worked as a General Practitioner in North London, then directed the Univ ...
, and others. The chapter by Goldfried and Padawer distinguished between three levels of intervention in therapy: #''theories'' of change (therapists' theories about how change occurs); #''principles'' or strategies of change; #therapy ''techniques'' (interventions that therapists suppose will be effective). Goldfried and Padawer argued that while therapists may talk about their ''theories'' using very different
jargon Jargon is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular Context (language use), communicative context and may not be well understood outside that context. The conte ...
, there is more commonality among skilled therapists at the (intermediate) level of ''principles'' or strategies. Goldfried and Padawer's emphasis on principles or strategies of change was an important contribution to common factors theory because they clearly showed how principles or strategies can be considered common factors (they are shared by therapists who may espouse different theories of change) and specific factors (they are manifested in particular ways within different approaches) at the same time. Around the same time, James O. Prochaska and colleagues, who were developing the
transtheoretical model The transtheoretical model of behavior change is an integrative theory of therapy that assesses an individual's readiness to act on a new healthier behavior, and provides strategies, or processes of change to guide the individual. The model is ...
of change, proposed ten "processes of change" that categorized "multiple techniques, methods, and interventions traditionally associated with disparate theoretical orientations," and they stated that their processes of change corresponded to Goldfried and Padawer's level of common principles of change. In 1986, David Orlinsky and Kenneth Howard presented their ''generic model of psychotherapy'', which proposed that five process variables are active in any psychotherapy: the therapeutic contract, therapeutic interventions, the therapeutic bond between therapist and patient, the patient's and therapist's states of self-relatedness, and therapeutic realization. In 1990, Lisa Grencavage and John C. Norcross reviewed accounts of common factors in 50 publications, with 89 common factors in all, from which Grencavage and Norcross selected the 35 most common factors and grouped them into five areas: client characteristics, therapist qualities, change processes, treatment structure, and therapeutic relationship. In the same year,
Larry E. Beutler Larry E. Beutler ABPP is a clinical psychologist. Biography Beutler received his Ph.D. from the University of Nebraska and subsequently served on the faculties of Duke University Medical Center, Stephen F. Austin State University, Baylor Colleg ...
and colleagues published their ''systematic treatment selection model'', which attempted to integrate common and specific factors into a single model that therapists could use to guide treatment, considering variables of patient dimensions, environments, settings, therapist dimensions, and treatment types. Beutler and colleagues would later describe their approach as "identifying common and differential principles of change". In 1992, Michael J. Lambert summarized psychotherapy outcome research and grouped the factors of successful therapy into four areas, ordered by hypothesized percent of change in clients as a function of therapeutic factors: first, ''extratherapeutic change'' (40%), those factors that are qualities of the client or qualities of his or her environment and that aid in recovery regardless of his or her participation in therapy; second, ''common factors'' (30%) that are found in a variety of therapy approaches, such as empathy and the therapeutic relationship; third, ''expectancy'' (15%), the portion of improvement that results from the client's expectation of help or belief in the rationale or effectiveness of therapy; fourth, ''techniques'' (15%), those factors unique to specific therapies and tailored to treatment of specific problems. Lambert's research later inspired a book on common factors theory in the practice of therapy titled ''The Heart and Soul of Change''. In the mid-1990s, as managed care in
mental health Mental health encompasses emotional, psychological, and social well-being, influencing cognition, perception, and behavior. It likewise determines how an individual handles stress, interpersonal relationships, and decision-making. Mental health ...
services became more widespread in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, more researchers began to investigate the efficacy of psychotherapy in terms of ''empirically supported treatments'' (ESTs) for particular problems, emphasizing
randomized controlled trial A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical te ...
s as the
gold standard A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from the la ...
of empirical support for a treatment. In 1995, the
American Psychological Association The American Psychological Association (APA) is the largest scientific and professional organization of psychologists in the United States, with over 133,000 members, including scientists, educators, clinicians, consultants, and students. It ha ...
's Division 12 (
clinical psychology Clinical psychology is an integration of social science, theory, and clinical knowledge for the purpose of understanding, preventing, and relieving psychologically based distress or dysfunction and to promote subjective well-being and persona ...
) formed a task force that developed lists of empirically supported treatments for particular problems such as agoraphobia,
blood-injection-injury type phobia Blood-injection-injury (BII) type phobia is a type of specific phobia characterized by the display of excessive, irrational fear in response to the sight of blood, injury, or injection, or in anticipation of an injection, injury, or exposure to bl ...
,
generalized anxiety disorder Generalized anxiety disorder (GAD) is a mental and behavioral disorder, specifically an anxiety disorder characterized by excessive, uncontrollable and often irrational worry about events or activities. Worry often interferes with daily function ...
,
obsessive–compulsive disorder Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...
,
panic disorder Panic disorder is a mental and behavioral disorder, specifically an anxiety disorder characterized by reoccurring unexpected panic attacks. Panic attacks are sudden periods of intense fear that may include palpitations, sweating, shaking, short ...
, etc. 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. In the 2000s, more research began to be published on common factors in
couples therapy Couples therapy (also couples' counseling, marriage counseling, or marriage therapy) attempts to improve romantic relationships and resolve interpersonal conflicts. History Marriage counseling originated in Germany in the 1920s as part of the eu ...
and
family therapy Family therapy (also referred to as family counseling, family systems therapy, marriage and family therapy, couple and family therapy) is a branch of psychology and clinical social work that works with families and couples in intimate relationsh ...
. In 2014, a series of ten articles on common factors theory was published in the APA journal ''
Psychotherapy Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of psychological methods, particularly when based on regular personal interaction, to help a person change behavior, increase happiness, and overcome pro ...
''. 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). The article by
Stefan G. Hofmann Stefan G. Hofmann (born 1964) is a German-born clinical psychologist. He is the Alexander von Humboldt Professor and recipient of the LOEWE Spitzenprofessur for Translational Clinical Psychology at the Philipps University of Marburg in Germany ...
and
David H. Barlow David H. Barlow (born April 30, 1942) is an American psychologist and Emeritus, Professor Emeritus of Psychology and Psychiatry at Boston University. He is board certified by the American Board of Professional Psychology. Barlow is known for his ...
, two prominent researchers in
cognitive behavioral therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to reduce symptoms of various mental health conditions, primarily depression and anxiety disorders. CBT focuses on challenging and changing cognitive distortions (suc ...
, 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.


Models

There are many models of common factors in successful psychotherapy process and outcome. Already in 1990, Grencavage and Norcross identified 89 common factors in a
literature review A literature review is an overview of the previously published works on a topic. The term can refer to a full scholarly paper or a section of a scholarly work such as a book, or an article. Either way, a literature review is supposed to provid ...
, which showed the diversity of models of common factors. 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. 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. Grencavage and Norcross grouped common factors into five areas in 1990. Lambert formulated four groups of therapeutic factors in 1992. 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. Terence Tracy and colleagues modified the common factors of Grencavage and Norcross, and used them to develop a
questionnaire A questionnaire is a research Research is "creativity, creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, ...
which they provided to 16
board certified Board certification is the process by which a physician or other professional demonstrates a mastery of advanced knowledge and skills through written, practical, or simulator-based testing. Certification bodies There are more than 25 boards that ...
psychologists and 5 experienced psychotherapy researchers; then they analyzed the responses and published the results in 2003. Their
multidimensional scaling Multidimensional scaling (MDS) is a means of visualizing the level of similarity of individual cases of a dataset. MDS is used to translate "information about the pairwise 'distances' among a set of n objects or individuals" into a configurati ...
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 Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense) to each other than to those in other groups (clusters). It is a main task of ...
represented the results as three clusters: the first related to bond (roughly,
therapeutic alliance A therapeutic alliance, or working alliance, is a partnership between a patient and his or her therapist that allows them to achieve goals through agreed-upon tasks. The concept of therapeutic alliance dates back to Sigmund Freud. Over the cour ...
), 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). 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 Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machine learning, machines ...
. 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 Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition. A memory trace is a change in the nervous system caused by memorizing something. Consolidation is distinguished into two specific processe ...
. For further examples, see , below.


Empirical research

While many models of common factors have been proposed, they have not all received the same amount of
empirical research Empirical research is research using empirical evidence. It is also a way of gaining knowledge by means of direct and indirect observation or experience. Empiricism values some research more than other kinds. Empirical evidence (the record of one ...
. There is general consensus on the importance of a good
therapeutic relationship The therapeutic relationship refers to the relationship between a healthcare professional and a client or patient. It is the means by which a therapist and a client hope to engage with each other and effect beneficial change in the client. In psyc ...
in all forms of psychotherapy and counseling. A review of common factors research in 2008 suggested that 30% to 70% of the
variance In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its population mean or sample mean. Variance is a measure of dispersion, meaning it is a measure of how far a set of numbe ...
in therapy outcome was due to common factors. A summary of research in 2014 suggested that 11.5% of variance in therapy outcome was due to the common factor of goal consensus/collaboration, 9% was due to
empathy Empathy is the capacity to understand or feel what another person is experiencing from within their frame of reference, that is, the capacity to place oneself in another's position. Definitions of empathy encompass a broad range of social, co ...
, 7.5% was due to
therapeutic alliance A therapeutic alliance, or working alliance, is a partnership between a patient and his or her therapist that allows them to achieve goals through agreed-upon tasks. The concept of therapeutic alliance dates back to Sigmund Freud. Over the cour ...
, 6.3% was due to positive regard/affirmation, 5.7% was due to congruence/genuineness, and 5% was due to therapist factors. In contrast, treatment method accounted for roughly 1% of outcome variance. (Table 1) Alan E. Kazdin has argued that psychotherapy researchers must not only find statistical evidence that certain factors contribute to successful outcomes; they must also be able to formulate evidence-based explanations for how and why those factors contribute to successful outcomes, that is, the
mechanism Mechanism may refer to: * Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that ...
s through which successful psychotherapy leads to change. Common factors theory has been dominated by research on psychotherapy process and outcome variables, and there is a need for further work explaining the mechanisms of psychotherapy common factors in terms of emerging theoretical and empirical research in the
neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...
s and
social science Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of soc ...
s, just as earlier works (such as Dollard and Miller's ''Personality and Psychotherapy'' or Frank's ''Persuasion and Healing'') explained psychotherapy common factors in terms of the sciences of their time. One frontier for future research on common factors is automated computational analysis of clinical
big data Though used sometimes loosely partly because of a lack of formal definition, the interpretation that seems to best describe Big data is the one associated with large body of information that we could not comprehend when used only in smaller am ...
.


Criticisms

There are several criticisms of common factors theory, for example: * that common factors theory dismisses the need for specific therapeutic techniques or procedures, * that common factors are nothing more than a good
therapeutic relationship The therapeutic relationship refers to the relationship between a healthcare professional and a client or patient. It is the means by which a therapist and a client hope to engage with each other and effect beneficial change in the client. In psyc ...
, and * that common factors theory is not scientific. Some common factors theorists have argued against these criticisms. They state that: * the criticisms are based on a limited knowledge of the common factors literature, * a thorough review of the literature shows that a coherent treatment procedure is a crucial medium for the common factors to operate, * most models of common factors define interactions between multiple variables (including but not limited to therapeutic relationship variables), and * some models of common factors provide evidence-based explanations for the
mechanism Mechanism may refer to: * Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that ...
s of the proposed common factors.


Notes


References

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Further reading


Sources emphasizing learning as a common factor

* * * * * * * * * * * * *


Sources emphasizing other common factors

* * * * * * * * * * * *


Sources emphasizing specific or unique factors

* * * * * * * * * * * * * * {{Psychotherapy Integrative psychotherapy