The idea that you will make the right decision every time is very unlikely.

Interesting thing that is happening in American society is that people are starting to talk about money. I don't know how you feel about this, but for a long time, nobody was talking about money. It was a secret. And it's kind of very interesting because we do lots of stuff to portray to people about how much money we have, the clothes we wear and the cars we have and the house - they all kind of depict to other people, signal how much money we make, but we don't talk about it specifically.

The retail industry has its own headache: it loses $16 billion a year to customers who buy clothes, wear them with the tags tucked in, and return these secondhand clothes for a full refund.

The bad news is that ignoring the performance of people is almost as bad as shredding their effort in front of their eyes. Ignoring gets you a whole way out there. The good news is that by simply looking at something that somebody has done, scanning it and saying "Uh huh," that seems to be quite sufficient to dramatically improve people's motivations.

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

Money is all about opportunity cost. Every time you spend on something, that's something you can't spend on something else.

Do you know how much money you would save if you changed your light bulb to compact florescent light bubs? How much would you save if you decreased your temperature of your house in the winter by one degree, or increase it by one degree? We just don't know these numbers, but I think displays could make it a memorable change in terms of attention, and also help us translate it in terms of concrete ways on what you can get.