This is really fascinating and I've heard this kind of idea before. A learned outcome which then it begs the question, how did it start? How did the chain reaction begin that caused me to do it? And how do children of stutterers begin it, those in families where when child stutters and the other doesn't. If they are both in the same environment, what are the odds that one self learned it while the other didn't? Your last paragraph on your first reply (1st of the 3) is very powerful. If the concept were true, would knowing this allow us to no longer tense our muscles in that area, in such a way as to hinder our own speech? Once we know where the light switch is, can't we no longer turn it on? This idea is really hard to scrutinize but I could try to keep it in mind next time I get the chance and feel the muscle tension that, if I am creating subconsciously, I will try to see if I can un-tension consciously. Similar to slowing a heartbeat. Will I need to rely on ideas, reminders, or will knowing about this light switch, so to speak, be enough.