If you manage a stressed dog, you likely think about thresholds quite a bit.
You think about whether your dog is "over threshold" in a given situation, and you may be continually planning how to keep him "under threshold" as much as possible.
Even if you don't have a dog with a tendency toward fear, reactivity, or stress, you want your dog to be in an optimal emotional state for learning, and that may lead you to thinking about what might push your dog "over threshold" and cause you to have to switch gears.
But just what is this "threshold?"