Psychotherapy Bulletin

Psychotherapy Bulletin

Clinical Impact Statement: All participants did show improvement, but effect sizes were smaller than in prior studies of FAP. This article can help researchers understand key facets of treatment.

Given the unresolved nature of the Dodo Bird Verdict (de Felice et al., 2019), clarification of psychotherapy mechanisms remains important and may indicate which clients will respond to treatment (Goldfried et al., 2014), reduce theory-practice gaps (Dobson & Beshai, 2013), and provide insight into why some individuals in control groups show improvement above and beyond treatment groups (Carey & Stiles, 2016). How the investigation of psychotherapeutic mechanisms is carried out is important. Many mechanism studies utilize variables that may be better classified as outcomes (Carey et al., 2020). Consequently, it may be beneficial to start investigations of mechanisms of change in well-established functional mechanisms to prevent the proverbial tail from wagging the dog.’

One important example of a functional mechanism of change is found in operant conditioning (Skinner, 1937). Among the therapies that propose a mechanism anchored in operant conditioning is Functional Analytic Psychotherapy (FAP; Kohlenberg & Tsai, 1991). A recently proposed model for applying FAP, deemed the Awareness, Courage, and Love (ACL) Model (Maitland et al., 2017), proposes increasing client awareness of their own and others behaviors, engaging in adaptive disclosure, expression, and requests that have previously been punished (courage), and skillful acceptance and production of responses to courage (love) through naturalistic contingent responding to those behaviors in session. While FAP does not rule out a priori any treatment targets, the implementation of the treatment implicitly intervenes upon feelings of connection, making those feelings a logical target (Maitland & Gaynor, 2012).

A series of studies have implemented the FAP Rating Scale (FAPRS; Callaghan et al., 2008) to evaluate FAP’s proposed mechanism of action. The first study in this line of research (Callaghan et al., 2003) concluded that an increase in FAP consistent, effective responding was correlated with an increase in client effective in-session responding and increased social functioning outside of session. A second study found that decreases in problematic in-session behaviors and increases in desirable in-session behavior occurred throughout a single successful case of FAP (Busch et al., 2010). A third study suggested adherence to FAP rules was associated with reports of out-of-session target behaviors (Landes et al., 2013). Other research found FAP adherence predicted increases in Working Alliance Inventory (WAI) scores (Maitland & Gaynor, 2016), that WAI scores mediate the relationship between treatment and changes in social functioning, and that FAP adherence mediated outcomes on psychological distress (Maitland et al., 2016).

While the evidence reviewed above is compelling, it remains limited. No studies have investigated micro (FAPRS coding), mid-level (in-session relating), and macro processes (social functioning and psychological distress) in FAP simultaneously. As such, the research on FAP mechanisms of action remains disjointed and speculative. The purpose of the current study is to comprehensively evaluate FAP’s mechanism of action by incorporating all the previously utilized investigation techniques into one well-controlled study.



Three undergraduate students participated in the study. All three individuals self-reported difficulties with interpersonal relationships, psychological distress, and scored one standard deviation below the mean on measures of social functioning.


A concurrent multiple baseline across participants design was utilized. The baseline consisted of the participant and therapist taking a role in a two-person play. This controlled for effects resulting from interaction or emotional expressions and minimized the likelihood of incidental mechanism engagement. The treatment condition involved a principal based FAP intervention anchored in the ACL model. The focus of the FAP sessions was on evoking and providing natural social positive reinforcement to occurrences of behavior that facilitate the development of the in-session relationship.

The study consisted of 12 sessions. Each participant received between three and five baseline sessions and was scheduled to receive between seven and nine FAP sessions. The transition from the baseline to FAP condition was determined based on demonstrated stability on measures of social functioning. Two of the participants completed all sessions, and one dropped out after completing three baseline sessions and four sessions of FAP.

Assessments occurred every session. At the start of each session, participants completed the Fear of Intimacy Scale (FIS; Descutner & Thelen, 1991), the UCLA loneliness scale (UCLA; Russell, 1996), and the Psychiatric Diagnostic Screening Questionnaire (PDSQ; Zimmerman & Mattia, 2001). At the end of each session, participants completed process measures including the WAI (Hatcher & Gillaspy, 2006), the Therapeutic Presence Inventory (TPI; Geller et al., 2010), and a modified version of the Fear of Intimacy Scale that prompted the participant to answer questions about the therapist. The therapist completed a therapist version of the TPI at the end of every session to capture the therapist’s perspective of process variables. All sessions were coded using the FAPRS.

Data Analysis

Data were analyzed using Robust Improvement Rate Difference (R-IRD), a metric of effect size, which was used to assess the effectiveness of the treatment. Visual analysis of data meeting reliable change (Jacobson et al., 1984) was conducted to assess the temporal order of change in captured variables. FAPRS coding was conducted by two independent coders familiar with FAP.


Participant R-IRD scores on the WAI were 1, 1, and 1, respectively, indicating higher scores at every data point in the FAP condition compared to the control condition and pre-treatment assessment. On the therapist focused FIS, R-IRD scores were .833, 1, and .5, suggesting improvements in FAP sessions, but of a more limited nature. TPI (.857, 1, and .35) and Therapist TPI scores (1, 1, .5) were similar. Scores improved for all participants on the UCLA (.667, .333, .691) with some iatrogenic effects indicated on FIS (.667, .667*, .4048) and PDSQ (.667, .667, .857*). The temporal order that each participant reached reliable change can be found in Table 1. The results of the temporal assessment of the reliable change index suggested an inconsistent pattern across measures. FAPRS coding indicated no FAP consistent therapy moves were conducted in the baseline condition. In the FAP sessions, more turns of speech were focused on the relationship than on either FAP rules 2 or 3, which correspond to FAP’s purported mechanism of action detailed in Table 2.

Table 1

Table 2


The findings from the current study are relatively inconsistent with previous findings on FAP (Kanter et al., 2017). Despite evidence that the treatment was implemented with fidelity, the effect size of the current study is smaller in magnitude than previous studies on FAP. While all participants made improvements on at least one process variable and one measure of social functioning, the temporal order of the findings is not consistent with hypothesized outcomes.

The current study is novel in terms of the independent variable and control condition. It is possible that a FAP intervention based on the ACL model deemphasizes the idiographic case conceptualization and intervention utilized in past research. While the ACL model is accessible and easily disseminated, it may come at the cost of treatment efficacy (Callaghan & Follette, 2020). FAPRS data suggested that instead of incorporating FAP’s proposed mechanism of action, the study therapist spent significant time focusing on the therapeutic relationship. It is also possible that the control condition had a meaningful impact on participant engagement in therapy. While WAI scores were high, scores regularly did not approach the levels found in similar studies (Maitland & Gaynor, 2016).

Another possible explanation for the unexpected findings may lie in study measurement techniques. While the relationship between the therapist and participant was emphasized, no measure of connection was collected. It is possible that fear of intimacy was insufficient for capturing the behaviors that were targeted. While in longer therapy, these behaviors would be shaped to a final target, given the brevity of treatment, it is possible that the final form of the behavior was not sufficiently shaped. Additionally, the PDSQ, used to measure distress, captures endorsement of DSM symptoms. Metrics of psychological distress focused on the social environment might indicate different outcomes. While those were thought to be captured by the FIS and UCLA, it is possible a broader construct such as social connection was impacted.

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Daniel W. M. Maitland, Ph.D. is an Assistant Professor at Morehead State University in the Department of Psychology. He is a licensed psychologist in Kentucky and Texas. Dr. Maitland earned his doctorate in Clinical Psychology from Western Michigan University with Dr. Scott T. Gaynor as his advisor. His dissertation work was a randomized controlled trial investigating Functional Analytic Psychotherapy (FAP) compared to a watchful waiting control group. Dr. Maitland completed his clinical internship at the University of Wisconsin Psychiatric Institute and Clinics and has previously held appointments as a research associate at the University of Washington and assistant professor at Texas A&M University – Corpus Christi. Dr. Maitland’s research focuses on psychotherapy processes and outcomes of therapies anchored in contextual behavioral science, especially FAP. Given that FAP prototypically targets a client’s interpersonal problems, Dr. Maitland’s research interests have recently expanded to include the role of disruptions to interpersonal functioning in domains of mental and physical health, and issues of social importance such as racism.

Cite This Article

Maitland, D. W. (2021). An exploration of mechanisms of change in Functional Analytic Psychotherapy. Psychotherapy Bulletin, 56(1), 14-19.


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