Buying a second-hand car at a good price feels good. But choosing a delicious-looking doughnut in the supermarket leaves us riddled with doubt. After all, we resolved to eat a healthier diet this year—so wouldn’t it be better to buy an apple? We’ve all experienced this feeling at one time or another: some decisions intuitively feel right, while others leave us feeling doubtful and may even cause us to revise our initial choice. But where does this feeling come from?