Dan Ariely, best-selling author of Predictably Irrational and The Upside of Irrationality, has spent a lot of time thinking about — and studying — how people shop. In particular, he examines the trends in human behavior that become particularly apparent when we’re spending money. Here’s a video clip of Ariely giving a fascinating description of a study he did on fakes — fake designer accessories, bags, clothes, and more. Specifically, he sought to discover what buying and wearing fakes will do to our thought processes — and whether or not, even though no one else may know it’s a fake, the fact that we know will affect our behavior. His conclusions are nothing short of amazing, and alarming (we really do love our fake D&G glasses).