Decision theory studies how people make a decision under the circumstance of uncertainty. We use an idea of probability and expectation.
One of the famous stories related to this problem is "Monty Hall Problem":
"There are three boxes and there's a ball in one of the three boxes and nothing in each of the left two boxes."
(Question) "If you choose the box 1 and open another box (box 2) and see nothing in the box 2, should you stick with the initial choice(box 1) or swap your choice(box 3)? "
What's your answer? Swap or not?