Stammering is different than stuttering. Stutterers have trouble with the letters, while stammerers trip over entire parts of a sentence. We stammerers generally think of ourselves as very bright. My own private theory is that stammerers have so many ideas swirling around their brains at once that they can't get them all out, though I haven't found any scientific evidence to back that up.

I Shouldn't Even Be Doing This!: And Other Things That Strike Me as Funny (ed. Hachette Books, 2006) - ISBN: 9781401385996