If we believe that something is true, we will focus on the number of times it is verified, less see the times when it is not verified, then it will confirm the belief, and as a result it will reinforce it. It ends up no longer see the counterexamples.
From the outside we can wonder how the person does not see or understand certain things but when someone experiences that, they do not see the bias.
Habits are very reassuring for many people and that's fine, it just becomes a problem when habits turn into obstacles to the deployment of abilities or cause suffering. That's not due to weakness or flaws, it is just mechanisms that were put in place for good reasons at one point and we don't remember.
When you don't remember certains things, it does not mean that they have disappeared, it means that you don't have access to them. The information still exists and is stored in a memory. It is not because we don't have access to it that the information is no longer active.
It can maintain an emotion, a belief or biases, causing you to interpret reality in a certain way that can lead to repetitive behaviors or strong reactions.
It think it is really important to know that at the beginning the mechanism, the belief, the behavior that was put in place was for good reasons. Criticisms and judgements are brakes.
It does not necessarily take long time to transform a behavior.
I remember a participant in a training who told me she had regained access to her creativity after an exercise. It was not even a training in creativity, it was a training whose title was "Influencing without authority". It was a two day course and of course there were different exercises, exchanges and the practice of tools.
Nevertheless, it only took two days.
I have so many other examples where people discovered important things in a short time that allowed them to make significant changes.
Contrary to some beliefs, it is not always long and hard to effect change, it needs a new attitude, an adjustment to better manage the so called problematic situation. It is not by doing more of the same that we will reach new results, it is by modifying how we act.