Understanding ACT · 02 / 04
The History of ACT
From the question of why people can suffer from their own thoughts to a model of psychological flexibility.
Acceptance and Commitment Therapy wasn't created in a single day. It grew over several decades out of research on behaviour, language and human suffering – and is still being developed scientifically today.
ACT did not start out as a finished method.
Acceptance and Commitment Therapy has no single founding moment. It emerged from a longer line of behavioural research – shaped by behaviourism and behaviour analysis, that is, by the question of how behaviour is formed by its context and consequences.
Over the course of the 1980s, a further question came to the fore: what role does human language play in the fact that people can suffer from their own thoughts? Out of this question, a parallel research programme on language and cognition developed, which later became closely intertwined with clinical work.
It was never only about which thoughts or feelings occur, but about what function they have in a particular context – and how a person responds to them. This focus on context and function, rather than content alone, still shapes the thinking behind ACT today.
What is known as ACT today was therefore not a finished concept presented on a specific date, but the result of a process of development that stretched over decades – and continues into the present.
A development over decades
Not a complete chronicle, but key landmarks of a line of research that continues to this day.
1980s
Early clinical work takes shape around what is initially called “cognitive distancing” or “comprehensive distancing” – an early precursor of what later becomes ACT.
1986
One of the early randomised studies from what would become the ACT research programme is published – a starting point for the empirical testing of the approach.
Early 1990s
The name “Acceptance and Commitment Therapy” becomes established for the developing approach.
1994
An early academic publication already carries “Acceptance and Commitment Therapy” in its title.
Late 1990s / early 2000s
Relational Frame Theory (RFT) and ACT continue to develop as an interconnected programme of basic research and application – theory and clinical practice grow in parallel.
2000s
ACT is increasingly researched internationally and discussed in the context of the so-called “third wave” of behavioural therapy.
2010s
Psychological flexibility increasingly becomes the central organising model behind ACT.
2020s
ACT research now spans numerous countries and fields of application. An analysis by Hayes & King (2024) examines around 1,000 randomised controlled ACT trials from the period 1986–2022.
A central figure: Steven C. Hayes
Steven C. Hayes is a psychologist and professor emeritus at the University of Nevada, Reno. His research covers, among other things, human language and cognition, Relational Frame Theory, Acceptance and Commitment Therapy, psychological flexibility and contextual behavioural science.
ACT, however, is not the work of a single person, but the result of a research field to which many scientists have contributed over decades.
Research focus
- Human language and cognition
- Relational Frame Theory
- Acceptance and Commitment Therapy
- Psychological flexibility
- Contextual behavioural science
From behaviour to context
Within ACT, what matters is not only which thoughts or feelings a person has, but what function they have in a particular context – and how the person responds to them. The same thought can barely register in one situation and severely restrict behaviour in another.
This perspective forms a bridge to what is known as functional contextualism and to Relational Frame Theory – a theory of how language and relational thinking help shape human experience.
Why ACT is sometimes counted as part of the “third wave”
Overviews of behavioural therapy often distinguish between several phases of development. This division is a simplification, but a helpful one for placing the development in context.
First wave
The focus is on observable behaviour and the principles of learning theory.
Second wave
Cognition comes more into view: how thoughts and appraisals help determine behaviour.
So-called third wave
Approaches such as ACT additionally emphasise context, function, mindfulness, acceptance and a flexible repertoire of behaviour.
These waves don't replace one another, and none refutes the previous one. They describe different emphases within a shared scientific field. Being classed as “third wave” is therefore no evidence that ACT is superior to another approach such as classical cognitive behavioural therapy – both continue to be researched and applied side by side.
Today: psychological flexibility
Today the term ACT describes more than a particular collection of exercises or techniques. Increasingly, a model sits at its centre: psychological flexibility – the ability to be present in the current moment, to open up to difficult thoughts and feelings, and still act in the direction of your own values.
This model continues to be researched, refined and applied in different areas – from clinical work to everyday situations.
Today the term ACT refers above all to a model: psychological flexibility.
Sources & further reading
- Hayes, S. C., Strosahl, K. D. & Wilson, K. G. — Acceptance and Commitment Therapy: The Process and Practice of Mindful Change.
- Hayes, S. C. (2004) — Acceptance and Commitment Therapy, Relational Frame Theory, and the Third Wave of Behavioral and Cognitive Therapies.
- Hayes, S. C. & King, J. (2024) — Review of around 1,000 randomised controlled ACT trials from the period 1986–2022.
- Association for Contextual Behavioral Science (ACBS) — international professional society for ACT, RFT and contextual behavioural science.
Further reading
From theory back into real life.
History and theory are background – not a prerequisite for starting a conversation.
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Understanding ACT