Nick Milton recently wrote a blog post recently explaining why transferring knowledge through discussion is 10 times more effective than written documents.
The maths as Nick himself confesses is a little finger in the air but it reminded me of a post in my blook Sharing Knowledge through Face-to-Face Conversation where I explain in a somewhat different way why conversation is so effective at transferring knowledge.
In a face-to-face conversation, you can offer information about the issue; you can probe deeper into the situation; you can gain a sense of what the other already knows and so determine at what level to construct your answer; you can ask about the meaning of a term you are not familiar with; you can seek the reasoning behind a conclusion if it's not evident and you can correct false assumptions.
The speaker and listener repeatedly swap places many times in a short period; the listener frequently interrupting the speaker and the roles changing. Both parties actively try to make sense of what the other is attempting to convey.
My post was based on some earlier work by Nancy Dixon Conversations That Share Tacit Knowledge