Common Factors: What Are They and What Do They Mean for Humanistic Psychology?

Abstract

Although common factors have been widely discussed in the clinical literature, the two questions addressed in this article remain relevant: (a) What are the common factors? (b) What do they mean for humanistic psychology? The first question is important because there is no “definitive list” of common factors, and lists presented in the literature often differ dramatically. In response to this question, the article suggests that an evidence-based list of nine common factors by Wampold provides a useful and credible list. The second question is also important, particularly to humanistic psychologists. Among other answers, the article shows that research findings on common factors provide scientific support for humanistic psychology’s emphasis on the importance of the human and relational factors in psychotherapy.

Keywords

common factors humanistic psychology implications of common factors

During the past 20 years, common factors have received a great deal of attention in the clinical literature (e.g., Bohart & Tallman, 2010; Duncan, 2014; Duncan, Miller, Wampold, & Hubble, 2010; Elkins, 2015; Wampold, 2001, 2010, 2015). Yet the two questions posed in the title of this article remain relevant. This article will address those questions.

The Contemporary Common Factors Movement

The contemporary common factors movement began with Bruce Wampold, a professor and researcher at the University of Wisconsin–Madison. In 2001, Wampold published The Great Psychotherapy Debate. Wampold pointed out that on one side of the debate are proponents of the medical model who believe that theories and techniques are the agents of change in psychotherapy, and on the other side are those who believe that “contextual factors” (i.e., common factors) are the agents of change. In an attempt to settle the debate, Wampold and his associates (Ahn & Wampold, 1997; Messer & Wampold, 2000; Waehler, Kalodner, Wampold, & Lichtenberg, 2000; Wampold et al., 1997) conducted analyses and meta-analyses of hundreds of published studies to identify the factors in psychotherapy that were responsible for its effectiveness. The findings showed that theories and techniques have little to do with effectiveness while common factors are potent agents of change. As Wampold (2001) put it, “Clearly, the preponderance of the benefits of psychotherapy are due to factors incidental to the particular theoretical approach administered and dwarf the effects of theoretically derived techniques” (p. 209). Subsequent analyses of published studies on treatments for posttraumatic stress disorder, children’s disorders, and alcohol disorders (Benish, Imel, & Wampold, 2007; Imel, Wampold, Miller, & Fleming, 2008; Miller, Wampold, & Varhely, 2008) confirmed the earlier findings. These studies by Wampold and his associates started the contemporary common factors movement. It is worth noting that Wampold and his associates had no official ties to the humanistic movement and they did not conduct the research to bolster humanistic psychology (HP). Instead, they conducted the research to determine how psychotherapy works, to identify the factors in psychotherapy that are responsible for its effectiveness. However, what they discovered turned out to be meaningful for HP, as this article will show.

As the common factors movement grew, humanistic psychologists also made scholarly contributions. For example, Arthur Bohart (Bohart & Tallman, 1996, 1999, 2010), a humanistic psychologist and professor emeritus at California State University, along with his associate Tallman, focused on the client as a common factor, citing research suggesting that, in fact, the client is the most important determinant of therapy outcome. Bohart believes that the client’s active and creative processing is the center of psychological healing and that, in a sense, the client is the real therapist. Bohart’s work is an important contribution to the contemporary common factors movement.

I have also made contributions to the common factors literature (e.g., see Elkins, 2007, 2009, 2012, 2015). In my work, I have summarized research to show that theories and techniques have little to do with effectiveness in psychotherapy while common factors, particularly human and relational factors, are potent determinants of effectiveness. In The Human Elements of Psychotherapy (Elkins, 2015), I summarized findings from clinical psychology, attachment theory, neurological research, and evolutionary theory to show that humans are evolved to give and receive emotional healing through social means, and I suggested that psychotherapy, properly understood, is a subset of this evolved ability. I argued that common factors, particularly the human and relational factors, are the most potent determinants of effectiveness in psychotherapy because they draw on our evolutionarily derived ability to heal one another emotionally through social means. In other words, psychotherapy is simply a more formal and intense expression of this more general and evolved ability. Along with Bohart’s contributions, I hope my work has been a useful contribution from the humanistic tradition to the common factors movement.

What Are the Common Factors?

This question is more difficult than it might appear. There is no “definitive list” of common factors. In fact, lists of common factors in the clinical literature often differ dramatically. For example, Jerome Frank (1961, 1973; Frank & Frank, 1991), a pioneer in common factors research, identified four common factors. According to Frank, the four features common to all psychotherapies are (a) an emotionally charged, confiding relationship with a helping person; (b) a healing setting; (c) a rationale, conceptual scheme, or myth that provides a plausible explanation for the client’s symptoms and prescribes a ritual or procedure for resolving them; and (d) a ritual or procedure that requires the active participation of both patient and therapist and is believed by both to be the means of restoring the patient’s health (see Frank & Frank, 199l). In contrast, Grencavage and Norcross (1990), in a review of 50 psychology publications, identified 89 common factors. More recently, Tschacher, Junghan, and Pfammatter (2014), in a review of the psychotherapy research literature, identified 22 common factors. Other examples could be given, but these are sufficient to show how widely lists of common factors can differ. So which list is correct? Are there four common factors, 89 common factors, 22 common factors, or some other number? The clinical literature is confusing, to say the least, when it comes to naming and numbering common factors.

A Credible List of Common Factors

Wampold (2015), as part of his contextual model of psychotherapy, presented a list of nine common factors whose contributions to effectiveness in psychotherapy are supported by evidence. Instead of relying on clinical theory, literature reviews, or personal speculation to identify these factors, Wampold relied on “meta-analyses of primary studies” (p. 5). The nine factors on Wampold’s list are (a) goal consensus/collaboration, (b) empathy, (c) alliance, (d) positive regard/affirmation, (e) therapists (naturalistic settings), (f) congruence/genuineness, (g) therapists (RCTs), (h) cultural adaptation of evidence-based treatments (EBTs), and (i) expectations. Wampold’s (2015) article provides an explanation of each factor and the percentage of outcome variance for which it accounts (also see Laska, Gurman, & Wampold, 2014).

It is important to note that most, if not all, of the factors on Wampold’s list are human and relational in nature. Of course, this should not be surprising because, in a sense, the entire common factors movement is about the human and relational core of effective psychotherapy (Duncan, 2010, 2014; Duncan, et al., 2010; Elkins, 2015; Wampold, 2007, 2015). This point is highly relevant to the second question posed in the title of this article, which is addressed next.

What Do Common Factors Mean for Humanistic Psychology?

As noted previously, the originators of the contemporary common factors movement have no official ties to HP. Yet, as this section will show, the research findings on common factors are highly relevant and meaningful to HP.

What They Do Not Mean

Before discussing what common factors mean for HP, it seems important to discuss what they do not mean. Because research on common factors shows the importance of human and relational factors in psychotherapy, it would be easy for humanistic psychologists to conclude that this means that humanistic therapy is “right” and other therapies are “wrong.” However, that would be a mistake. The research on common factors does not support any particular therapy over any other therapy. Instead, it affirms that common factors found in all therapies are responsible for client change. This means that all bona fide therapies, including therapies from the behavioral, psychodynamic, and humanistic traditions, can be effective. To put it another way, the common factors perspective transcends the “battle of the brands” because it affirms that common factors, not specific “brands” of therapy, are the primary agents of change in psychotherapy. Thus, for humanistic psychologists to claim that research on common factors supports humanistic therapy over other therapies represents a serious misunderstanding of common factors and the evidence that supports them. In a similar vein, when Wampold (2007) used the term “humanistic” in his article Psychotherapy: The Humanistic (and Effective) Treatment, he was not endorsing humanistic psychotherapy. Instead, he was describing the nature or character of all effective therapy. Thus, humanistic psychologists should not use the title of Wampold’s article to support humanistic therapy over other therapies. To do so is to misunderstand and misrepresent Wampold’s meaning.

What They Do Mean

Confirmation of HP’s Human and Relational Emphasis

The central finding of common factors research is that common factors, particularly human and relational factors, are the most potent agents of change in psychotherapy, dwarfing the effects of theories and techniques (Duncan, 2010, 2014; Duncan, et al., 2010; Elkins, 2015; Wampold, 2001, 2007, 2010, 2015). From its beginning, HP has emphasized the importance of the human and relational elements of psychotherapy. In fact, the name, humanistic psychology, reflects that emphasis. For years, HP has been criticized, and even caricatured, for its human and relational emphasis. Most mainstream clinical psychologists refused to believe that the “softer” elements of psychotherapy such as empathy, genuineness, and acceptance could be the agents of change. They viewed such elements as “nonspecific ingredients” that were only important because they made the client more compliant with the “treatment,” meaning the techniques administered by the therapist. Now, the scientific tables have turned. The research on common factors shows the human and relational elements are potent agents of change. In fact, they are the “powerhouse” of effective therapy and without those elements, therapy could not work (Elkins, 2015). This is a major vindication of HP’s emphasis on the importance of the human and relational elements of psychotherapy.

Confirmation of Carl Rogers’s Views on Psychotherapy

As a subset of the preceding point, the research on common factors confirms Carl Rogers’s views of psychotherapy. In 1957, Rogers (1957) published “The Necessary and Sufficient Conditions of Therapeutic Personality Change.” In the article, Rogers named three conditions directly related to the therapeutic process itself: unconditional positive regard, empathic understanding of the client’s internal frame of reference, and therapist congruence (i.e., genuineness). Based on his research, Rogers had come to believe that these human and relational elements, not theories and techniques, were the agents of change in psychotherapy. The research on common factors confirms Rogers’s views: the human and relational elements are potent agents of change while specific theories and techniques have little to do with effectiveness. (For a detailed discussion of Carl Rogers and contemporary common factors research, see Elkins, 2009).

Confirmation of HP’s Emphasis on the Client–Therapist Relationship

This is another subset of the section on HP’s human and relational emphasis. HP has always emphasized the importance of the client–therapist relationship. Almost 40 years ago, Yalom (1980) wrote that “the single most important lesson the psychotherapist must learn” is that “it is the relationship that heals” (p. 401). This is a central tenet of humanistic therapy. Whatever else humanistic psychologists do in therapy, almost all of them believe that, ultimately, “it is the relationship that heals.” The research on common factors confirms the importance of the client–therapist alliance. Barry Duncan (2010), a leader in the contemporary common factors movement, summarized the evidence:

The amount of variance attributed to the alliance ranges from 5% to 7% of overall variance or 38% to 54% of the variance accounted for by treatment. Putting this into perspective, the amount of change attributable to the alliance is about five to seven times that of specific model or technique. (p. 23)

HP Has No Monopoly on Effective Psychotherapy

As suggested previously, the research on common factors suggests that HP has no monopoly on effective therapy. For some humanistic psychologists, this may be a bit disconcerting. Yet the evidence from common factors research makes it clear that common factors, not specific “brands” of therapy, are the primary agents of change. This means that therapies from the behavioral and psychodynamic traditions can be, and often are, effective. Perhaps the most persuasive evidence for the equivalence of therapies is the research conducted by Stiles and associates (Stiles, Barkham, Mellor-Clark & Connell, 2008; Stiles, Barkham, Twigg, Mellor-Clark, & Cooper, 2006). In the largest study of psychotherapy effectiveness ever conducted in a “real-world” clinical setting, Stiles and associates randomly assigned 5,000 clients needing therapy to receive either cognitive–behavioral, person-centered, or psychodynamic treatment. The results showed no differences in outcome between treatments. All three therapies were effective, and equally so. This study, along with many others, shows that all bona fide therapies can be effective. Thus, those of us in the humanistic movement should adopt a more accepting attitude toward other therapeutic traditions. The fact that all therapies, including psychodynamic, behavioral, and humanistic, depend on common factors for their effectiveness provides a foundation for a collaborative relationship among the various traditions. However, as a caveat to this section, it is important to raise some questions about “equivalency” of therapies. Because this is not the primary focus of this article, I will simply point to a major issue that needs further exploration before we accept equivalency of therapies as an established scientific fact. That issue has to do with the criteria for effectiveness used in the numerous studies that appear to support equivalency. To my knowledge, no one has done a thorough examination of this issue even though it is at the heart of deciding whether the evidence for equivalency is credible and should be accepted. “Paper and pencil tests,” while efficient in psychotherapy effectiveness research, tend to focus on “symptoms” and may not examine more profound dimensions of change in clients. Qualitative research methods, which can be designed to access deeper dimensions of change, might show that equivalency is a phenomenon that occurs only at the level of symptoms. Indeed, it would seem reasonable to think that humanistic therapies, which “major” in the common factors, particularly human and relational factors, might be more effective than therapies that “major” in techniques at more profound levels of client change. In other words, the “effectiveness” of psychotherapy is determined by the outcome variables that clinical researchers decide to measure and the types of measurement instruments used. For example, if researchers focus on symptoms and use “paper and pencil” tests to measure changes in those symptoms, then the results may suggest that therapies are equivalent in effectiveness. However, if researchers were to focus on deeper dimensions of client change and use qualitative research methods to assess those deeper dimensions, it is quite possible that the results would show greater effectiveness of therapies that emphasize client growth and transformation instead of changes in symptoms. This is an important issue that goes to the heart of psychotherapy theory. Humanistic theory, going all the way back to Carl Rogers, focuses on client transformation instead of on symptom alleviation. Thus, humanistic theory emphasizes the importance of creating a therapeutic milieu characterized by human and relational factors which provide clients with an opportunity to experience personal changes at deeper levels than mere symptom reduction. For example, clients may experience changes in their personal values, in their attitude toward life, in their existential and spiritual depth, and in the richness of their relationships to self, others, and the world. Such changes, although personally meaningful and even life-changing, are difficult to define in operational terms and difficult to measure using traditional research methods. However, qualitative research approaches can access these deeper, transformative levels of change. For example, researchers could begin by defining and describing transformative phenomena experienced by clients. Then these phenomena, once defined and described, could be used as criteria to evaluate psychotherapy effectiveness. Specifically, clients might be asked to indicate if and to what degree they experienced such transformation as part of their therapy. This would not eliminate the use of quantitative methods focused on symptoms but would broaden the definition and measurement of “effectiveness” to include qualitative methods designed to uncover more profound levels of client change. The bottom line is that more research is needed to determine whether “equivalency” is merely a “symptom level” phenomenon or one that extends to more profound levels of client change. Until such research is conducted, we should be cautious about claiming equivalency for all bona fide therapies.

Conclusion

In this article, I have attempted to answer the two questions posed in the title. In response to the first question, I have suggested that a list of evidence-based common factors by Wampold may be the most useful and credible list available at this time. In response to the second question, I have suggested that the research on common factors (a) confirms HP’s emphasis on the importance of the human and relational factors in psychotherapy, (b) confirms Carl Rogers’s views on psychotherapy, and (c) shows that humanistic therapy has no monopoly on effectiveness. However, as a caveat to this final point, I suggested that more research should be focused on equivalency of therapies before it is accepted as established scientific fact. I hope the article contributes to a better understanding of common factors and their meaning for HP.

Footnotes

Declaration of Conflicting Interests

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

David N. Elkins

Author Biography

David N. Elkins, PhD, is a licensed clinical psychologist and a Professor Emeritus of Psychology in the Graduate School of Education and Psychology at Pepperdine University. He is a fellow of the American Psychological Association (APA) and has served twice as president of Division 32, Society for Humanistic Psychology of APA. Now retired, he lives in Arizona with Sara, his wife.

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