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Acceptance and Commitment Therapy (ACT)

Published onJul 17, 2019
Acceptance and Commitment Therapy (ACT)

Brief Historic Overview

Over the last several years a third wave of behavior therapy has emerged from within both the cognitive and behavioral traditions. Grounded in an empirical, principle-focused approach, this third wave is particularly sensitive to the context and functions of psychological phenomena, not just their form, and thus tends to emphasize contextual and experiential change strategies in addition to more direct and didactic ones. As a group, these new methods have ventured into areas such as acceptance, mindfulness, cognitive defusion, dialectics, values, spirituality, and relationship.

One of the primary examples of this third wave is Acceptance and Commitment Therapy (known as “ACT” – pronounced as one word, not initials).

The ACT approach to psychopathology and its treatment is based on a 15-year program of basic research on the behavioral processes underlying language and cognition.

Between the end of the 1970s and the beginning of the 1980s, Steven Hayes, Robert Zettle and collaborators developed the Comprehensive Distancing model, based on cognitive therapy and their radical behaviorist background (Radical Behaviourism — everything an organism does is behaviour, including processes such as thinking, feeling and remembering). The Comprehensive Distancing model focused on interventions to reduce verbal ruling of behaviour. Unsatisfied with the Skinnerian concepts of rules, verbal behaviour and rule governed behaviour, Hayes developed a new theory dedicated to the explanation of language and cognition, founded on the basic processes of behavior — Relational Frame Theory (RFT). This theory was developed into a comprehensive basic experimental research program used to guide the development of ACT itself.

Premises of RFT

  1. Verbal behaviour (language) is operant behaviour.

  2. Language demands the derivation of relations between stimuli that originate relational frames.

According to RFT, the core of human language and cognition is the learned and contextually influenced ability to arbitrarily relate events, and to change the functions of specific events based on their relations to others. When we think, reason, speak with meaning, or listen with understanding, we do so by deriving relations among events. When a human interacts verbally with his or her own behavior, the psychological meaning of both the verbal symbol and the behavior itself can change (i.e., transformation of stimulus functions). RFT argues that it is this bidirectional property that makes human self-awareness useful.

“But wordless conditioning is crude and wholesale; cannot bring home the finer distinctions, cannot inculcate the more complex courses of behaviour. For that there must be words, but words without reason. (…)

Till at last the child’s mind is these suggestions, and the sum of these suggestions is the child’s mind. And not the child’s mind only. The adult ́s mind too – all his life long. The mind that judges and desires and decides – made up of these suggestions. But all these suggestions are our suggestions!”

— Aldous Huxley, in Brave New World


Acceptance and Commitment Therapy (ACT) is a mindfulness, acceptance, and values-based psychotherapy, grounded in the cognitive behavioral tradition. As a form of behavior therapy, ACT postulates that behavior is regulated by its consequences, which influence the probability of (re)occurrence of a certain behaviour.

Its goals are to develop effective actions in valued directions, and to create an rich, full and meaningful life, while accepting the pain that inevitably goes with it. Thus, the ACT acronym emerges:

  • A – Accept your thoughts and feelings, and be present

  • C – Choose a valued direction

  • T – Take action

ACT is based on a variety of pragmatism known as functional contextualism (FC) — “ongoing act in context." ACT conceptualizes psychological events as a set of ongoing actions of a whole organism interacting with historically and situationally defined contexts. From the viewpoint of FC, no thought or feeling is inherently problematic, dysfunctional, or pathological. The functions and meanings of behavior are to be found within the interaction. Removal of a client's problematic behaviors from the contexts that participate in that event (e.g., merely analyzing manifested behavioral symptoms themselves) is thought to miss the nature of the problem and avenues for its solution.

Objectives of Functional Conceptualism

  1. Predict and influence events with precision, depth and in an abrangent manner.

  2. Emphasize workability as a criterion of truth.

  3. Make thoughts and emotions to not be conceptualized as inherently right or wrong, but as useful or useless to achieve a valued life.

As such, the goal in ACT is not changing the frequency, intensity, or duration of certain private events; instead, the focus is on trying to change the context in which these events happen.

ACT Model of Psychopathology — Psychological Inflexibility

ACT Model in Psychopathology. In Hayes, S.C. et al. Behaviour Research and Therapy 44 (2006).

From ACT perspective, a main problem that clients have is the narrowness and inflexibility of his or her behavior repertoires. Thus, psychopathology emerges from the way language and cognition interact with direct contingencies to produce an inability to persist or change behavior in the service of long-term valued ends.

Figure 1 shows the six processes of Psychological Inflexibility, namely:

  1. Cognitive Fusion — entanglement in our thoughts so that they dominate our awareness and have a huge influence over our behavior (excessive or improper regulation of behavior by verbal processes, such as rules and derived relational networks); literalization of cognitive content.

  2. Experiential Avoidance — the attempt to alter the form, frequency, or situational sensitivity of private experienced even when doing so causes behavioral harm.

  3. Dominance of the Conceptualized Past and Feared Future — processes of worry and rumination, which entail lessened contact with the present moment and direct experience, and the dominance of behaviour and cognition through historically programmed reactions.

  4. Attachment to the Conceptualized Self — construction of a sense of self based on verbal processes/narratives ,present since childhood.

  5. Lack of Values Clarity/Contact — lack of direction; decisions are made to service experiential avoidance, placing the individual’s behaviour under aversive control.

  6. Inaction, Impulsivity, or Avoidant Persistence (Unworkable Action) — incapacity to act effectively in valued directions, as a consequence of experiential avoidance, loss of contact with the present moment and attachment to the conceptualized self.

ACT Model of Psychological Flexibility — Hexaflex

Each of the components of Psychological Inflexibilkity are targeted in an ACT intervention, in order to promote the positive psychological competencies that allow for Psychological Flexibility — the ability to be in contact with the present moment and to develop effective actions in valued directions. They are represented in Figure 2, and explained below.

  1. Defusion (Watch Your Thinking) — learning to “step back” and separate or detach from our thoughts, images, and memories; different way to relate to inner experience, reducing the literal quality of experience.

  2. Acceptance (Open Up) — making room for painful feelings, sensations, urges, and emotions.

  3. Contact with the Present Moment (Be Here Now)— being psychologically present: consciously connecting with and engaging in whatever is happening in this moment.

  4. Self as Context (Pure Awareness) — the observing self, the aspect of us that is aware of whatever we’re thinking, feeling, sensing, or doing in any moment (in contrast with the thinking self — the part that is always generating thoughts, beliefs, memories, judgments, fantasies, plans).

  5. Values (Know What Matters) — desired qualities of ongoing action — they describe how we want to behave on an ongoing basis.

  6. Commited Action (Do What It Takes) — taking effective action, guided by our values.

[In Hayes, S.C. et al. Behaviour Research and Therapy 44 (2006).]

There are two general domains of Psychological Flexibility — Mindfulness and Acceptance and Commitment and Behaviour Change. “Contact with the Present Moment” and “Self As Context” belong to both domains, since all psychological activity involves consciousness of the present moment.

Given these processes, an operational definition of Psychological Flexibility would be an affirmative answer to the question:

“Given the distinction between yourself and the things you are struggling with and trying to change, are you available to experience them, fully and without defense, by what they are, and not by what they say they are, and do what’s necessary to go in the direction of chosen values, in this moment and in this context?”

Types of Intervention

ACT includes both more traditional CB interventions, such as exposure, skills training and behavioral activation, as well as experiential strategies — one of the things that makes ACT different from many other therapies is that during therapy sessions, a lot of time will be spent practicing skills such as learning new ways to handle difficult thoughts and feelings more effectively, rather than just discussing them.

Given the possibility of paradoxical effects of deliberate attempts to control private experiences, ACT uses a less confrontational manner and less directive forms of verbal interaction, such as metaphor, paradoxes, and experiential exercises, to loosen the entanglement of thoughts and the self.

There are several more specific domains of ACT intervention, such as creative hopelessness, the control agenda and acceptance as the alternative, transcendency of the sense of self, delusion of language and cognition, value definition, willingness and commitment, and the ACT therapeutic relationship. Each has its own specific methodology, exercises, homework, and metaphors.

Fig. 3. From suffering to vitality.[In Harris, R. (2009)]

The main tasks for a first session are to build rapport, obtain informed consent, and make a basic assessment. When assessing the current problems, the therapist looks for fusion, avoidance, and unworkable action. And when assessing desired outcomes of therapy, they look for values and values-congruent goals. Worksheets can be used within the session, or prescribed as homework.

An ACT therapist will embody the entire ACT model in session: to be mindful, nonjudgmental, respectful, compassionate, centered, open, receptive, engaged, warm, and genuine, and regard the client as an equal: a fellow human being who, just like us, gets caught up in his mind and ends up struggling with life.

Main Uses

ACT has been scientifically studied and shown to be effective with a wide range of conditions including anxiety, depression, obsessive-compulsive disorder, social phobia, generalized anxiety disorder, schizophrenia, borderline personality disorder, workplace stress, chronic pain, drug use, psychological adjustment to cancer, epilepsy, weight control, smoking cessation, and self-management of diabetes.


Within ACT, depression is conceptualized as a consequence of the individual’s attempts to avoid or escape from negative private experiences, with an inability to live a meaningful life. The ACT model for treating depression is based on the resolution of rigid patterns of Fusion, Evalutation of Experience, Avoidance of Experience and Reason-giving for behaviour/Rumination (often referred to by the acronym FEAR), and promotion of committed action congruent with the individual’s values.

Anxiety Disorders

ACT postulates that the attempts to regulate anxiety, rather than any levels of anxiety themselves, are the main maintenance processes in anxiety disorders. People with these disorders end up living life to the service of aversive control, doing anything to avoid their fear and unwanted thoughts. In this light, ACT aims to enhance the patient’s repertoire of answers to the experience of anxiety, promoting acceptance and mindfulness strategies, while also using more traditional CBT techniques such as exposure, in a way that allows them to maintain valued action even in the presence of discomfort.


The efficacy of ACT has been established for some time — there are randomized controlled trials dating back to 1986 showing it to be equivalent or superior to traditional CBT for treatment of depression.

Steven Hayes writes that ACT is committed to a high standard of empirical evaluation, which includes not just controlled assessment and evaluations of outcomes but also the specification and evaluation moderations and of the putative processes of change, as well as an understanding of the links between these processes of change and basic functional behavioral principles, including those drawn from RFT.

Links to peer reviewed assessments of the ACT evidence base can be found on

Comment from an expert

“Acceptance and commitment therapy (ACT) is oddly counterintuitive. The mind fights it. Even experienced ACT therapists and successful ACT clients can connect with something in the work, move forward, and then weeks later suddenly find that the vitality is gone from that connection because they have subtly reformulated it mentally into something more “normal” but also much less useful.

ACT is not about training the normal mode of the mind. It is about getting out of your mind and into your life. Minds don’t like that agenda.”

— Steven Hayes, in “ACT Made Simple”.

Comment from a trainee

ACT (Acceptance and Commitment Therapy) is a third generation cognitive-behavioral therapy whose acronym summarizes its essence: Accept your thoughts and feelings and be mindful, Choose a direction and Take action.

From my perspective, ACT is a reviving of behaviorism, enriched by a strong motivational component and a new way of dealing with the inner experience based on mindfulness and acceptance: we have inner experiences (thoughts, emotions and bodily sensations resulting from our genetics, early experiences and a mind designed to survival) that we cannot control/choose and our attempt to change them can paradoxically increase our suffering and prevent us from living the life we truly want.

ACT is highly experiential, allowing therapists to break the barriers of language, skipping helpless debates that patients “understand but still feel badly” and providing the chance to get in touch (during and between sessions) with how trying to control their inner experience can be unproductive and exhausting and how letting go of that control can be a liberating experience, allowing people to control their action instead and live a meaningful life.

— Cátia Martins, psychiatry trainee from Porto (Portugal) and member of the Portuguese Association of Behaviour Therapy (APTC).

Books, manual, videos, application, published online courses or international association

Passengers On A Bus - an Acceptance & Commitment Therapy (ACT) Metaphor


For Professionals

  • Hayes, S. C., & Smith, S. (2005). Get out of your mind and into your life: The new Acceptance and Commitment Therapy. Oakland, CA: New Harbinger.

  • Harris, R. (2009). ACT Made Simple: An Easy-To-Read Primer on Acceptance and Commitment Therapy. Oakland, CA: New Harbinger.

  • Luoma, J. B., Hayes, S. C., & Walser, R. D. (2007). Learning ACT: An Acceptance & Commitment Therapy Skills-Training Manual for Therapists. Oakland, CA: New Harbinger & Reno, NV: Context Press.

  • Hayes, S. C., Strosahl, K. D., & Wilson, K. G. (1999). Acceptance and commitment therapy: An experiential approach to behavior change. New York: Guilford Press.

Self Help

  • Harris, R. (2009) ACT with Love. Oakland, CA: New Harbinger.

  • Harris, R. (2007) The Happiness Trap. Wollombi, NSW, Australia: Exisle Publishing.


  • Hayes, S. C. (2004). Behavior Therapy, 35, 639-665.

  • Hayes, S. C. (2004). Acceptance and Commitment Therapy and the new behavior therapies: Mindfulness, acceptance and relationship. In S. C. Hayes, V. M. Follette, & M. Linehan (Eds.), Mindfulness and acceptance: Expanding the cognitive behavioral tradition (pp. 1-29). New York: Guilford.

  • Hayes, S. C., Luoma, J., Bond, F., Masuda, A., & Lillis, J. (2006). Acceptance and Commitment Therapy: Model, processes, and outcomes. Behaviour Research and Therapy, 44(1), 1-25.

Scales and Questionnaires

  • AAQ (Acceptance and Action Questionnaire, Bond et al., 2001), and adaptations for different types of disorders;

  • ATQ-B (Automatic Thoughts Questionnaire - Believability, Zettle & Hayes, 1986);

  • BAFT (Believability of Anxious Feelings and Thoughts Questionnaire, Herzberg et al., 2012);

  • CAQ (Committed Action Questionnaire, McCracken et al., 2013);

  • CAMS-R (Cognitive and Affective Mindfulness Scale - Revised, Feldman et al., 2007);

  • CFQ (Cognitive Fusion Questionnaire, Gillanders et al., 2014);

  • DDS (Drexel Defusion Scale, Forman et al., 2012);

  • ELS (Engaged Living Scale, Trompetter et al., 2013);

  • FFMQ (Five Facets Mindfulness Questionnaire, Baer et al., 2006);

  • FMI (Freiburg Mindfulness Inventory, Walach et al., 2006);

  • KIMS (Kentucky Inventory of Mindfulness Skills, Baer et al., 2004);

  • MAAS (Mindfulness Attention Awareness Scale, Brown & Ryan, 2003);

  • PHLMS (Philadelphia Mindfulness Scale - Revised, Cardaciotto et al., 2008);

  • SACS (Self-as-Context Scale, Gird & Zettle, 2013);

  • VLQ (Valued Living Questionnaire, Wilson et al., 2010);

  • VQ (Valuing Questionnaire, Smout et al., 2014);

  • WBSI (White Bear Suppression Inventory, Wagner & Zanakos, 1994).

Online Resources

International Societies


  1. Blackledge, J. T., & Drake, C. E. (2013). Acceptance and commitment therapy: Empirical and theoretical considerations. Advances in relational frame theory and contextual behavioral science: Research and application, 219-252.

  2. Harris, R. (2009). ACT Made Simple: An Easy-To-Read Primer on Acceptance and Commitment Therapy. Oakland, CA: New Harbinger.

  3. Hayes, S. C., Masuda, A., & De Mey, H. (in press). Acceptance and Commitment Therapy and the third wave of behavior therapy. Gedragstherapie (Dutch Journal of Behavior Therapy).

  4. Hayes, S. C. (2004). Acceptance and commitment therapy, relational frame theory, and the third wave of behavior therapy. Behavior Therapy, 35, 639–665.

  5. Hayes, S. C., Luoma, J.B., Bond, F.W., Masuda, A., & Lillis, J. (2006). Acceptance and commitment therapy: Model, processes and outcomes. Behaviour research and therapy, 44(1), 1-25.

  6. Lucena-Santos, P., Pinto-Gouveia, J., Oliveira, M.S. (2015). Terapias Comportamentais de Terceira Geração — Guia Para Profissionais. Synopsis Editora.

  7. Wilson, K. G., & Hayes, S. C. (1996). Resurgence of derived stimulus relations. Journal of the Experimental Analysis of Behavior, 66, 267-281.

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