In a typical 401k plan, when you first become eligible you get a big pile of forms and you're told, fill out these forms if you want to join. Tell us how much amount you've saved and how you want to invest the money. In, under automatic enrollment you get that same pile of forms but the top page says, if you don't fill out these forms, we're going to enroll you anyway and we're going to enroll you at this saving rate and in these investments.

It would be much more consumer friendly for them to beep you when you swipe your card that says, uh-oh you're over your limit, are you sure you want to use that?

Most people start claiming benefits within a year of when they become eligible, although benefits increase substantially if they wait.

It turns out, that men, when they're taking care of their business, they're not fully attending to the task at hand, but, I'm sure there's an evolutionary explanation for this, if you give them a target, they will aim.

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.

Rip Van Winkle would be the ideal stock market investor: Rip could invest in the market before his nap and when he woke up 20 years later, he'd be happy. He would have been asleep through all the ups and downs in between. But few investors resemble Mr. Van Winkle. The more often an investor counts his money - or looks at the value of his mutual funds in the newspaper - the lower his risk tolerance.

I think one lesson we have to learn is that there's a lot more risk than we're giving credit to, a lot more what economist calls systematic risk.