Defusion is a process of stepping back and separating or detaching from our thoughts.

Most of the time human beings are deeply caught or tangled up in their thoughts. Thoughts come in a way that feels inevitable and we get carried away by them. Sometimes there are lots of different thoughts coming and going and our mind races around in all the different directions of these thoughts. Other times there is one particular thought or set of related thoughts that stay and stay and our mind seems to get trapped in that one set of thoughts for hours or days or weeks. 

When we are totally caught up in our thoughts it sometimes seems like we are our thoughts, and that is all there is to us. This phenomenon is called ‘fusion’, and ‘defusion’ means undoing the fusion. Hayes and Smith (2005) say that “defusion leads to peace of mind, not because the mental war necessarily stops but because you are not living inside the war zone anymore (p70).

In defusion we step back from the thoughts, just let them come and go, and watch them from a distance. To capture this, Harris (2009) uses the catch phrase “Watch Your Thinking” as a memory aid to understand what defusion is about. He identifies 3 main features that describe what defusion involves:

  1. Looking at thoughts rather than from thoughts
  2. Noticing thoughts rather than being caught up in thoughts
  3. Letting thoughts come and go rather than holding on to them

There are many different metaphors that are used to help describe this process of watching our thoughts and the relationship with thoughts that we are trying to achieve. Thoughts can be likened to leaves floating in a stream, clouds floating in the sky, or cars in the street driving past our house. We can talk about holding onto thoughts lightly compared to clutching onto them tightly.

The aims of teaching defusion are to:

  1. See the true nature of thoughts: that they are nothing more or less than words and pictures; and
  2. Respond to thoughts in terms of workability (how helpful they are) rather than literality (how true they are).

ACT therapists would facilitate defusion in every session that they spend with a client, and defusion would be the main focus of some sessions in order to spend time dedicated to learning the basic skills. Subsequently it is necessary to return to defusion many many times in order to practice, refine the skills and turn the process a healthy habit.

There are 3 main techniques to the method or steps of the defusion process. These techniques can be used frequently in conversation with clients without formally introducing the concept of defusion or mindfulness.

We ask clients to notice their thoughts (e.g. ‘So what is your mind telling you now?”, “What thoughts are in your head at the moment?”, “What does your thinking self have to say about that?”, “Notice what your mind is doing”).

We ask clients to look at the workability of their thoughts (e.g. “So is that a helpful thought? If you hold tightly to it does it help you deal with the situation effectively?”, “If you go with that thought and let it tell you what to do, is that going to get you a good result?”, “So when your thinking mind tells you that you can’t possibly do this or that, do those thoughts help you move towards the goals you have set for yourself?”).

We ask clients to notice when they are fused with or defused from their thoughts (e.g. “So right now, how caught up are you in that thought?’’, “How much of the time is that thought dominating your view of the situation?”, “Have you been able to let go of that judgement and see the situation from another perspective?”.


These notes are based on Harris (2009), Chapters 1, 2 & 7; as well as Hayes and Smith (2005), Chapter 6.