If they're the type of people who have to sort through the connections to all the other things they know, that can really take a lot of time. Actually, I don't think that you ever finish connecting the dots, but there are a lot of simple connections to make right when you get introduced to something new.

Also, confusion is a sign of learning. If there's no confusion at all, they think they already know it. Whether they're correct about that is another matter entirely.