We constantly make predictions about what’s coming next, from what time we can leave work, to how much money we expect to find when we check our balance at the ATM. When what happens is better than what we expect, it is literally an error in our forecast of the future: Maybe we get to leave work early, or we find a hundred dollars more in checking than we expected. That happy error is what launches dopamine into action. It’s not the extra time or the extra money themselves. It’s the thrill of the unexpected good news.
