I think that is a good way to think about the eye-contact phenomenon👍. No, I am referring to the same definition of “block” as you. What I mean is that if I’m in deep thought and someone suddenly talks to me, even if I know what I want to say to respond to them, it’s like my brain hasn’t kicked into gear yet, so I have the throat tension, etc. that you are referring to. It’s cognitive inflexibility that leads to a block in this instance. Basically being under-acclimated/disassociated from the current social situation causes a lag in the physical part of speaking, and thus blocking.