To summarize, using money to motivate people can be a double-edged sword. For tasks that require cognitive ability, low to moderate performance-based incentives can help. But when the incentive level is very high, it can command too much attention and thereby distract the person’s mind with thoughts about the reward. This can create stress and ultimately reduce the level of performance.

The problem with opportunity cost is that opportunity cost is divided among many, many things.

If I gave you now, $10 as a gift, how happy would you be? Would you be happy, is the marginal $10, the best use of $10 you can use? Of course not. If I have you a CD, you know exactly what you are getting and you will have a value for it. So, money has lots of problems with it.

Money is very difficult to think about. So, we think about money as the opportunity cost of money. So, we at some point went to a Toyota dealership and we asked people, what will you not be able to do in the future if you bought this Toyota? Now, you would expect people to have an answer. But people were kind of shocked by the question. They never thought about it before. So, the most we got was people said, "Well, if I can't buy this Toyota, if I buy this Toyota, I can't buy a Honda." What is this thing? What is this value of price? Very hard to think about it.

Linking financial element to energy consumption I think has a huge role if you think about a display instrument that could teach us about what we are using, how much it costs us, how much it is saving, and therefore change our decisions.

We're actually trying to develop an iPhone app, now that the Droid is out, we'll do it for that as well, if we ever learn how to program on this thing. But the idea is that to make money concrete. So, you can do this app, and it's not out there, but you can do the app. And you say, "I like vacation in the Bahamas, shoes, lattes, and books." And now, when you are tempted to buy something, that thing translates in terms of the things you are interested in.

One percent of people will always be honest and never steal," the locksmith said. "Another one percent will always be dishonest and always try to pick your lock and steal your television. And the rest will be honest as long as the conditions are right - but if they are tempted enough, they'll be dishonest too. Locks won't protect you from the thieves, who can get in your house if they really want to. They will only protect you from the mostly honest people who might be tempted to try your door if it had no lock".