It´s deeper. You are not only anticipating words that you know you will stutter but also people and events. Your brain is constantly predicting the next most probable situation and prepares for shutdown. I think we do this because we are trying so hard not to stutter. So if we know in advance (anticipation) that we are going to stutter, we can try to create some kind of technique to avoid blocking. The problem is it does not work that way. It only make´s it stronger. The anticipation itself serves as cue for your nervous system to active the neural pathways that create stuttering. The solution is to stop trying not to stutter. Give yourself permission to feel. Change your relationship with blocking. Make a new one. A kind and loving one. If you genuinely accept it, the stimuli that actives the stuttering pathway will be gone.