Who's Turn is it?

So, as in my previous post I mentioned that I have been thinking about awkward silence during conversations. I was wondering what exactly causes these awkward pauses during our conversations. My theory is that it is one of two things:

1. There is an error in communication of the transition relevance place. This means that there is a misunderstanding of who's turn it is to talk. Perhaps the speaker did not get the point across and the hearer is waiting for more information to be relayed, thus, making the entire conversation irrelevant and uncomfortable.

2. There is a element of inappropiateness within the context of the speaker's utterance. Our converstaions (her in the U.S.) have been shaped by what we call social norms. In other words, society trains us to socially operate within a certian appropriateness and when this boundary is breached, we are unable to normally function while outside the area that contains these social norms.