The reinforcement theory is used to encourage desired behaviors in people, for example when John passes the test, that is a desired behavior and outcome, so he gives himself a reward so he will continue to pass tests to get the reward.
Hunger is when you consume the necessary calories and need to eat more food in order for you body to continue working properly, as Marcus just ran a marathon he consumed a lot of calories that he needs to re-stock soon, so he is hungry and eats a lot of pasta.
