Acceptance and Commitment Therapy invites people to open up to unpleasant feelings, and learn not to overreact to them, and not avoid situations where they are invoked. Its therapeutic effect is a positive spiral where feeling better leads to a better understanding of the truth. In ACT, ‘truth’ is measured through the concept of ‘workability’, or what works to take another step toward what matters (e.g. values, meaning).

Technique
ACT is developed within a pragmatic philosophy called functional contextualism. ACT is based on relational frame theory (RFT), a comprehensive theory of language and cognition that is an offshoot of behavior analysis. Both ACT and RFT are based on B. F. Skinner’s philosophy of Radical Behaviorism.
ACT differs from some other kinds of cognitive behavioral therapy (CBT) in that rather than trying to teach people to better control their thoughts, feelings, sensations, memories and other private events, ACT teaches them to “just notice,” accept, and embrace their private events, especially previously unwanted ones. ACT helps the individual get in contact with a transcendent sense of self known as self-as-context—the you who is always there observing and experiencing and yet distinct from one’s thoughts, feelings, sensations, and memories. ACT aims to help the individual clarify their personal values and to take action on them, bringing more vitality and meaning to their life in the process, increasing their psychological flexibility.
While Western psychology has typically operated under the “healthy normality” assumption which states that by their nature, humans are psychologically healthy, ACT assumes, rather, that psychological processes of a normal human mind are often destructive. The core conception of ACT is that psychological suffering is usually caused by experiential avoidance, cognitive entanglement, and resulting psychological rigidity that leads to a failure to take needed behavioral steps in accord with core values. As a simple way to summarize the model, ACT views the core of many problems to be due to the concepts represented in the acronym, FEAR:

• Fusion with your thoughts
• Evaluation of experience
• Avoidance of your experience
• Reason-giving for your behavior

And the healthy alternative is to ACT:

• Accept your reactions and be present
• Choose a valued direction
• Take action

Core Principles
ACT commonly employs six core principles to help clients develop psychological flexibility:

• Cognitive defusion: Learning methods to reduce the tendency to reify thoughts, images, emotions, and memories.
• Acceptance: Allowing unwanted private experiences (thoughts, feelings and urges) to come and go without struggling with them.
• Contact with the present moment: Awareness of the here and now, experienced with openness, interest, and receptiveness. (e.g., mindfulness)
• The observing self: Accessing a transcendent sense of self, a continuity of consciousness which is unchanging.
• Values: Discovering what is most important to oneself.
• Committed action: Setting goals according to values and carrying them out responsibly, in the service of a meaningful life.