"A marvelous book... thought provoking and highly entertaining." --Jerome Groopman, New York Times bestselling author of How Doctors Think "An important book. Full of valuable and entertaining insights that will make an impact on your business, professional, and personal life." -- Jack M Greenberg, Chairman, Western Union Company, Retired Chairman and CEO, McDonald's Corporation Why do our headaches persist after we take a one-cent aspirin but disappear when we take a fifty-cent aspirin? Why do we splurge on a lavish meal but cut coupons to save twenty-five cents on a can of soup? When it comes to making decisions in our lives, we think we're making smart, rational choices. But are we? In this newly revised and expanded edition of the groundbreaking New York Times bestseller, Dan Ariely refutes the common assumption that we behave in fundamentally rational ways. From drinking coffee to losing weight, from buying a car to choosing a romantic partner, we consistently overpay, underestimate, and procrastinate. Yet these misguided behaviors are neither random nor senseless. They're systematic and predictable--making us predictably irrational