A company invites their employees to sign up for a plan where every time they get a raise, some part of that raise goes to increasing their contribution rate to the 401k plan. In the first company we convinced to adopt this plan, saving rates tripled.

There are cases when I can make myself better off by restricting my future choices and commit myself to a specific course of action.

he card companies will often, as a courtesy, honor that credit card, but hit you with a penalty. And you keep swiping your card for $3 at Starbucks for your latté, and you're getting hit with a $25 penalty because it's over your credit limit.

I think we also have learned the lesson that we have to have better incentive structures.

When should we nudge and when should we shove, I think, it's a political judgment. Obviously in some situations we need shoves, we need laws. Fraud is against the law, murder is against the law, drunk-driving is against the law. We don't need just nudges.

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.

My mantra is if you want to help people accomplish some goal, make it easy.