It is like when you take a plastic ruler and you start bending it. At first it will be flexible and it will bend and you can bend it back again. But if you bend it too much it will suddenly break. Once it is broken you can not just bend it back and get it back to the state it started with.
Aberrations have often been installed by going over a threshold. A traumatic incident has installed certain patterns by overwhelming the person. We work the incident until it flips over another threshold so it no longer controls the person's behavior automatically.
You can use knowledge of thresholds to put unwanted conditions out of business and to anchor positive resources that the person wants.
Thresholds are a powerful tool. Don't use it unless it is clear what is wanted. For example, there is a lot of mileage we can get out of addressing an unwanted feeling with re-experiencing. There might be faster ways of crossing the threshold and transforming the feeling, but it might not be desirable before we have found out what the whole thing is about.
It you have learned enough about a feeling and it is still there and it is clear that it would be valuable for the whole person not to have it, you could use a direct threshold technique. For example, an unwanted feeling can be blown out. You can deliberately increase the controlling quality of the feeling out of proportion towards infinity.
If the client wants to stop smoking, and there is a certain feeling that gets her to do it, we can blow out that feeling. You can increase the intensity, either by magnifying it, or by repeating it quickly. First you need to find the perceptual distinction that is the main trigger. For example, if there is a picture involved, it might be the size. If the closer a picture of a cigarette is, the more she feels like smoking it, then you can take that picture and quickly make it infinitely large. Maybe it has to be done repeatedly, maybe it just has to be increased infinitely. At a certain point, a threshold will be crossed where a bigger picture will no longer increase the feeling. It is like the person suddenly says "Hey, I've had enough, I admit that I am really cause over this." At that point the feeling will transform and the automatic circuit is broken. But remember, you need to be sure that it was really what would be beneficial for the client, because you wouldn't be able to put it back the same way.
Similar things can be done to put in a positive feeling and make it automatic. For example, if the client makes a positive visualization of the future, with good feelings attached to it. You can make the picture come towards her, getting bigger as it gets closer (if that is what makes the feeling better for her), and then, when it gets really close, a new picture, exactly the same, opens up the middle of it and it gets closer and bigger, and then a new picture opens up, gets closer and bigger. And so forth, repeatedly, very quickly. After a few times of doing that it would usually set up a circuit of automatically moving towards that scenario.
Many processes are built on thresholds without it being immediately apparent. A recursive process is essentially a threshold process. You repeat the same action or question again and again until you break down some unwanted pattern or until the client breaks through to a new understanding.