How Feelings Help You Think

If you’re in a grocery store, and you're hungry, everyone knows you're going to buy more stuff. You go into the store, you have certain data. If you go when you're in a non-hungry state, you have all that data in front of you, and all those choices to make, and you make a series of choices. If you go when you're in a hungry state, same data, same information, and you make totally different decisions. That's a good illustration of what emotions do. The emotions are a framework for your logical processing. It affects how you evaluate data, how skeptical you are of certain ideas versus how accepting you are of those same ideas. Your brain doesn't process in a vacuum. 

Leonard Mlodinow, quoted in GQ