Is There a Reward System in the Brain?

Eating vegetables is more rewarding than eating rocks. The reward system evolved for certain things, but it can be tricked by signals. If i see or taste a doughnut, it's pleasurable and rewarding. But after i've eaten three doughnuts, then the sight or taste of the doughnut has a very different effect. Back to a the cn of the fact that you can't actually get a discussed response. Yes, if you get overfull. It's not the stimulus itself, necessarily that's rewarding or not; it's the match between the stimulusis a motivational state of the organism. And that's known as inpsychology, appraisal theory.