Financial incentives abound in health care. They are found in the ways physicians are paid and in the ways health insurance coverage, co-payments, and deductibles are structured for patients. The effects of these incentives are often understood through conventional economic principles, with the assumption that individuals are self-interest maximizers who respond directly to changes in incentives. In contrast, behavioral economics imports insights from psychology and recognizes that individuals often do not respond to incentives as rationally as they might. In some cases, individuals lack information, but in others, they just seem to act contrary to their own known interests, for example, when they overeat, fail to take medication, or neglect to wear seat belts.