For all of us, it's very hard to think about money, and because of that, we need help. In the same way that for all of us, it is hard to eat well, and we need some help. The poor have a particular challenge, which is that their life is actually much more complex - and they're much more complex cognitively.

If you think of people as making decisions actively, every time we think about the cup of coffee, we say, "How much will I enjoy the cup of coffee, what else could I not do in the future because I buy this cup of coffee?

We need to believe that we're good people, and we'll do just about anything to maintain that perception.

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.

While we somehow understand revenge on an intuitive level between individuals, I do suspect that companies, assuming that people are rational, completely miss and underestimate the motivation people have for revenge.

Brands communicate in two directions: they help us tell other people something about ourselves, but they also help us form ideas about who we are.

If you want to spend more money in restaurants, use credit cards more than cash. If you want to spend less, use cash more than credit cards. But in general, we can think about how to use the pain of paying and how much of it do we want. And I think we have like a range. Credit cards have very little pain of paying, debit cards have a little bit more because you feel like today, at least it is coming out of your checking account, and cash has much more.