The tricky part here is not to shame them too much; otherwise, they might stop answering questions at all.

Yes, very tricky balance. With people in as fragile a situation as students, even explicitly calling them out at all might be too much. That's why I meant that the unreward should come from within the student.

Maybe it's just a matter of not rewarding it. I don't know.

It's much easier with adults. At least with adults they will sometimes tell you what they are thinking.