Why do our headaches persist after taking a one-cent aspirin but disappear when we take a 50-cent aspirin? Why do we splurge on a lavish meal but cut coupons to save twenty-five cents on a can of soup? We think we’re making smart, rational choices. But are we? MIT Behavioral Economist Dan Ariely discusses the medical effectiveness of placebos, and outlines how expectations of a given situation will affect our experiences of that situation.