Great question, perfect question actually, that is essentially the most mind numbing aspect to stuttering. I can speak perfectly with so much confidence alone, but given the right circumstances, I second guess every sound I make (causing a stutter). It’s a learned habit. It can be unlearned. I think exposure therapy is the only way to do it. I don’t see how reading out loud alone (a popular stuttering remedy) would decrease our fear of stuttering, because we already feel no speech tension alone. Reading out loud in front of people, or talking to big groups of people without stuttering, now that would yield some real progress with unlearning our speech hesitancy.