Those particular symptoms, while obvious from the outside perspective, are pretty much undetectable from the inside perspective, because they're the result of two people who are paying more attention to how they are coming off than they are to the other person. Embarrassment, nervousness, fear, uncertainty. These dispel themselves with a little bit of awareness; if, for example, the other party embarrasses themselves, and you're aware of it, it's very easy to rectify by sharing an embarrassing story of your own - and most people will do this automatically. If you embarrass yourself - well, again, you're worrying too much about how you come off, and not paying enough attention to how the other person is responding.