Retirement savings is probably behavioral economists' greatest success story. It is a prototypical behavioral-economics problem because saving for retirement is cognitively hard - figuring out how much to save - and requires self-control.

Everyone's lost a lot of money on their 401k plans. I've heard some people calling them 201k plans. So it's even more important to get people to be saving more for retirement. Behavioral economics has helped us learn a lot about how to do that.

Every American worker should be able to save for retirement via payroll deductions.

Maybe you'll take the cash out. So a credit card company or a bank that goes into the business of saying we're going to be the broker, we're going to sell you a mortgage that you're going to be able to pay off, we're going to help you reduce your credit card debt, we're going to help you save for retirement, we're going to put you into mutual funds that have low fees rather than high fees.