What is Functional Analytic Psychotherapy?


Functional analytic psychotherapy (FAP) is a psychotherapeutic approach based on clinical behaviour analysis (CBA) that focuses on the therapeutic relationship as a means to maximise client change. Specifically, FAP suggests that in-session contingent responding to client target behaviours leads to significant therapeutic improvements.

FAP was first conceptualised in the 1980s by psychologists Robert Kohlenberg and Mavis Tsai who, after noticing a clinically significant association between client outcomes and the quality of the therapeutic relationship, set out to develop a theoretical and psychodynamic model of behavioural psychotherapy based on these concepts. Behavioural principles (e.g. reinforcement, generalisation) form the basis of FAP (See The five rules below).

FAP is an idiographic (as opposed to nomothetic) approach to psychotherapy. This means that FAP therapists focus on the function of a client’s behaviour instead of the form. The aim is to change a broad class of behaviours that might look different on the surface but all serve the same function. It is idiographic in that the client and therapist work together to form a unique clinical formulation of the client’s therapeutic goals, rather than one therapeutic target for every client who enters therapy.

The Basics

FAP posits that client behaviours that occur in their out-of-session interpersonal relationships (i.e. in the “real world”) will, if clients are given a therapeutic relationship of sufficiently high quality, occur in the therapy session as well. Based on these in-session behaviours, FAP therapists, in collaboration with their client, develop a case formulation that includes classes of behaviours (based on their function not their form) that the client wishes to increase and decrease.

In-session occurrence of a client’s problematic behaviour is called clinically relevant behaviour 1 (CRB1). In-session occurrence of improvements is called clinically relevant behaviour 2 (CRB2). The goal of FAP therapy is to decrease the frequency of CRB1s and increase the frequency of CRB2s.

The FAP therapist evokes (i.e. sets the context for) CRB1s and in response gradually shapes CRB2s.

The five Rules

“The five rules” operationalise the FAP therapist’s behaviour with respect to this goal. It is important to note that the five rules are not rules in the traditional sense of the word, but instead a set of guidelines for the FAP therapist.

  • Rule 1 – Watch for CRBs:
    • Therapists focus their attention on the occurrence of CRBs that are in-session problems (CRB1s) and improvements (CRB2s).
  • Rule 2 – Evoke CRBs:
    • Therapists set a context which evoke the client’s CRBs.
  • Rule 3 – Reinforce CRB2s naturally:
    • Therapists reinforce the occurrence of CRB2s (in-session improvements), increasing the probability that these behaviours will occur more frequently.
  • Rule 4 – Observe therapist impact in relation to client CRBs:
    • Therapists assess the degree to which they actually reinforced behavioural improvements by noting the client’s behaviour subsequent behaviour after Rule 3.
    • This is similar to the behaviour analytic concept of performing a functional analysis.
  • Rule 5 – Provide functional interpretations and generalise:
    • Therapists work with the client to generalise in-session behavioural improvements to the client’s out-of-session relationships.
    • This can include, but is not limited to, providing homework assignments.

The ACL Model

Researchers at the Centre for the Science of Social Connection at the University of Washington are developing a model of social connection that they believe is relevant to FAP. This model – called the ACL model – delineates behaviours relevant to social connection based on decades of scientific research.

  • Awareness (A):
    • Behaviours include paying attention to your own and the other’s needs and values within an interpersonal relationship.
  • Courage (C):
    • Behaviours include experiencing emotion in the presence of another person, asking for what you need, and sharing deep, vulnerable experiences with another person in the service of improving the relationship.
  • Love (L):
    • Behaviours involve responding to another’s courage behaviours with attunement to what that person needs in the moment. These include providing safety and acceptance in response to a client’s vulnerability.

FAP has the potential to target awareness, courage, and love behaviours as they occur in session as described by the five rules above. More research is needed to confirm the utility of the ACL model.

Research Support

Radical behaviourism and the field of clinical behaviour analysis have strong scientific support. Additionally, researchers have conducted a number of case studies, component process analyses, a study with non-randomised design on FAP-enhanced cognitive therapy for depression, and a randomised controlled trial on FAP-enhanced acceptance and commitment therapy for smoking cessation.

Third Generation behaviour Therapy

FAP belongs to a group of therapies referred to as third-generation behaviour therapies (or third-wave behaviour therapies) that includes dialectical behaviour therapy (DBT), acceptance and commitment therapy (ACT), behavioural activation (BA), and integrative behavioural couples therapy (IBCT).


FAP has been criticised for “being ahead of the data”, i.e. having not enough empirical support to justify its widespread use. Challenges encountered by FAP researchers are widely discussed There is also criticism of using the ACL model as it detracts from the idiographic nature of FAP.