I don't know, you know? Discourse markers and knowledge claims

Anyone doing work on discourse markers in English might want to look at Greta Van Susteren's recent interview with Bristol Palin. I find the use of the discourse markers 'you know', 'I don't know', and 'I guess' interesting, especially compared with the actual knowledge claims in the exchange. Here is a sample; the transcript is from FOXNews.com, emphasis added.

VAN SUSTEREN: You know, it always is sort of a difficult thing, you know, when it's a question of youth, and no one ever really knows what to say to a young person in your situation.

BRISTOL: Yes. I don't know. I just -- I hope that people learn from my story and just, like, I don't know, prevent teen pregnancy, I guess.

VAN SUSTEREN: What happened at school?

BRISTOL: I was -- it was during summer and school had just gotten out, so I just knew that I had to finish up high school and focus on getting an education.

VAN SUSTEREN: You know -- you know, we all learned about it in August or so, after -- and the media, I guess, dogged you a little bit.

BRISTOL: Yes.

VAN SUSTEREN: What was your reaction to that?

BRISTOL: I mostly just didn't pay attention to it because my family's strong and it doesn't matter what the -- like, what tabloids say or anything like that.

VAN SUSTEREN: Did you read any of the tabloids?

BRISTOL: I've seen some of them, and I think people out there are just evil because they don't know what was going on at all.