ACT is part of the behavior therapy / behavior analysis / and cognitive behavior therapy tradition writ large so it would be silly to compare ACT to CBT as a whole which ACT is part of and which ACT has been influencing. “Traditional CBT-interventions” presumably means interventions organized around the idea that thoughts cause emotions and behavior. Even that subsection encompasses a broad range of things – theoretically and procedurally, so only generalizations are possible given such a question. What is different is the philosophy, basic science, applied theory, targeted processes of change, and many of the techniques of change. That is a pretty long list and it would take volumes to fully explain them. In outline form:
1. Philosophy
ACT is rooted in the pragmatic philosophy of functional contextualism, a specific variety of contextualism that has as its goal the prediction and influence of events, with precision, scope and depth. Contextualism views psychological events as ongoing actions of the whole organism interacting in and with historically and situationally defined contexts. These actions are whole events that can only be broken up for pragmatic purposes, not ontologically. Because goals specify how to apply the pragmatic truth criterion of contextualism, functional contextualism differs from other varieties of contextualism that have other goals, such as hermeneutics, narrative psychology, dramaturgy, social constructionism, feminist psychology, Marxist psychology, and the like which are forms of ”descriptive contextualism” because their goal seems to be to appreciate the participants in the whole event. There are contextualistic varieties of CBT (the constructivists, for example) but they look more like descriptive contextualists than functional contextualists.
The mainstream of CBT is elementalistic and integrative (it is looking for an overall model of parts, relations and forces). The word for this kind of philosophy can create problems because it has negative connotations: mechanistic. Remember though that philosophy is not a metter of good and bad, or right and wrong. Philosophy is a matter of owning ones assumptions and assumptions are nothing to thump one’s chest over. Mechanism is a very powerful set of assumptions and it has done well in many areas of science. But it is different than the assumptions underlying ACT. If you think people think sort of like computers calculate, you will probably not like ACT. It will feel strange.
Take things like the importance of values in ACT or the importance of cognitive defusion. The former is needed in order to specify the criteria for the application of workability, which is what a pragmatist takes to be ”true.” The later is what language looks like if you hold to that pragmatic assumption. If a person states an irrational thought, a traditional CBT person may want to know how it biases the facts – exactly what is demanded by the ontological assumption of mechanism – while an ACT person wants to know what saying that is in the service of and what functional role it plays due to history and context -- exactly what is demanded by the pragmatic assumptions of contextualism.
2. Basic Theory
Nearly a decade and a half passed between the earliest randomized trials on ACT and those in the modern era. In that interval, the basic theory of human language and cognition underlying ACT, Relational Frame Theory was developed into a comprehensive basic experimental research program. RFT is not a basic theory of ACT. It is a basic theory of cognition. But if RFT is workable and if ACT makes sense, you have to be able to do a basic analysis of ACT using RFT – just as you would have to be able to do an analysis of any cognitive procedure using RFT. That is the aspiration – and if you know behavior analysis you will recognize that it is an entirely traditional aspiration for people who do work on behavioral principles – the difference is that now we now think we have an angle on human cognition that is empirically and conceptually workable. We are not fully there yet, of course, but we are now seeing the RFT studies of defusion, acceptance, values, and so on and the early data are tremendously exciting.
According to RFT, the core of human language and cognition is the learned ability to arbitrarily relate events, mutually and in combination, and to change the functions of events based on these relations. For example, very young children will know that a nickel is larger than a dime by physical size, but not until later will the child understand that a nickel is smaller than a dime by social attribution. RFT researchers have shown that such relations as knowing that one event is “larger” than another arbitrarily can be trained as an operant and will alter the impact of other behavioral processes. We even have some new data seemingly showing that the symmetry of names and objects are trained as an operant in infants. There are neurobiological data showing that the brain lights up when performing RFT tasks much as it does when doing natural language tasks modeled by the theory.
Virtually every component of ACT is connected conceptually to RFT, and several of these connections have been studied empirically. Among other applied implications of RFT, its primary implications in the area of psychopathology and psychotherapy can be summarized as follows 1. normal cognitive processes necessary for verbal problem solving and reasoning underlie psychopathology, thus these processes cannot be eliminated; 2. the content and impact of cognitive networks are controlled by distinct contextual features; 3. cognitive networks are historical and thus are elaborated over time. Much as extinction inhibits but does not eliminate learned responding, the logical idea that cognitive networks can be logically restricted or even eliminated is generally not psychologically sound; and, 4. direct change attempts focused on key nodes in cognitive networks, tend to elaborate the network in that area and increase its functional importance. ACT is based on these ideas. Most of traditional CBT is not.
3. Applied Theory
From an ACT / RFT point of view, while psychological problems can emerge from the general absence of relational abilities (e.g., in the case of mental retardation), the primary source of psychopathology in most adults and language able children is the way that language and cognition interacts with direct contingencies to produce an inability to persist or change in the service of long term valued ends. This kind of psychological inflexibility is argued in ACT and RFT to emerge from weak or unhelpful contextual control over language processes themselves. The now vast literature on experiential avoidance is but one example of how this manifests itself. Other processes are cognitive fusion; the domination of temporal and evaluative relations over contact with the now; the effect of all of this on weak self-knowledge; attachment to a conceptualized self; unclear values or values based in looking good in the eyes of others or avoiding pain rather than self-congruent choices; and impulsivity or avoidant persistence.
The contextual theory behind ACT situates all of these processes in context – it does not leave them “in the head.” These contexts can be directly changed and that is exactly what ACT tries to do. The functional contexts that tend to have such deleterious effects include excessive or poorly regulated contexts of literality, reason-giving, and emotional control, among others. In essence, the contexts that support verbal / cognitive functions are too widespread and are over applied. Acceptance and mindfulness are a prophylactic for that excess.
4. Clinical Methods
ACT targets each of these core problems with the general goal of increasing psychological flexibility – the ability to contact the present moment more fully as a conscious human being, and to change or persist in behavior when doing so serves valued ends. The six targeted processes are acceptance, defusion, being present, a transcendent sense of self, values, and committed action.
These core ACT processes are both overlapping and interrelated. Taken as a whole, each seems to support the other and all target psychological flexibility. They can be chunked into two groupings. Mindfulness and acceptance processes involve acceptance, defusion, contact with the present moment, and self as context. Indeed, these four processes provide a workable behavioral definition of mindfulness. Commitment and behavior change processes involve contact with the present moment, self as context, values, and committed action. Contact with the present moment and self as context occur in both groupings because all psychological activity of conscious human beings involves being in the now as known.
You can draw lots of parallels to new developments in CBT, and even some in traditional CBT, but it is pretty obvious that these packages are not the same thing. I have trained several thousand therapists in ACT workshops of one day or more. I have literally never had a single CBT person do extensive training and come out saying “this is the same as traditional CBT.”
If you want to pick one of the most salient differences, pick defusion (also known as deliteralization). In ACT, a troublesome thought might be watched dispassionately, repeated out loud until only its sound remains, or treated as an external observation by giving it a shape, size, color, speed, or form. A person could thank their mind for such an interesting thought, say it very slowly, or label the process of thinking (“I am having the thought that I am no good”). They might note how the back and forth of a mental argument is like a volley ball game and then literally play that out while watching from the sidelines. There are perhaps 100 defusion techniques that have been written about somewhere in the ACT literature. Not a one of them involves evaluating or disputing these thoughts.
ACT is an approach to psychological intervention defined in terms of it philosophy, basic principles, and targeted theoretical processes. You can easily create and test protocols to test ACT with various disorders but it is not a specific technology anymore than, say, using candy contingently is “reinforcement.” In theoretical and process terms we can define ACT as a psychological intervention based on modern behavioral psychology, including Relational Frame Theory, which applies mindfulness and acceptance processes, and commitment and behavior change processes, to the creation of psychological flexibility.