Our six year old son has difficulty paying attention, so we often quiz him afterward about things he was supposed to be paying attention to. He has started hemming and hawing for a long time (like a minute or more), when he doesn't know the answer. We didn't notice at first because subconsciously it makes us want to give hints or even supply the answer. We think it is a sort of defense mechanism, and the frequency with which he uses it suggests he also uses it at school, which makes us worry he is not learning as much as he should be.
So how long is it normal to hem and haw at his age? How can we differentiate between when he is honestly thinking or just stalling? What are some good strategies to address it?