In an interview on Behavioural Economics

Your next choice, Robert Cialdini’s book Influence, is all about persuasion techniques. I loved how he even managed to apply his principles to the Watergate scandal. A group of people were persuaded to go ahead with what was really a very stupid and pointless plan to break into Democratic National Committee headquarters, just because of the way it was presented to them.

The Cialdini book is very important because it covers a range of ways in which we end up doing things, and how we don’t understand why we’re doing them. It also shows you how much other people have control, at the end of the day, over our actions. Both of these elements are crucial. The book is becoming even more important these days. Firstly, because electronic communication now gives us the ability to tailor messages. We have more ways of reaching people. Secondly, because we need to persuade people to start behaving differently – for example by saving energy. There’s a very nice company called Opower, which prints out information about your energy bill. They are trying to use the Cialdini principles to get you to behave slightly better.

Does this approach work? I thought in New York, where they started printing calorie counts on menus in restaurants to get people to eat more healthily, people ended up ignoring that information and continuing to order high calorie foods as much as ever.

This is very important. The New York intervention was based on the idea that all people need is more information. People don’t know how many calories this food has, we only need to tell them and everything will be fine. This was the theory. The Cialdini approach is not about information. It’s not saying that people don’t know that there are a lot of calories in this food, and if you only told them they wouldn’t eat it. We have learned that there are very few things where just by giving people more information, you can get them to behave better. What the Cialdini approach says is that people need to be pushed into behaving better. In particular they need to have social proof. They need to be told something like, “Smart, intelligent people choose this.”

Which is what the Opower energy plan does?

Yes. People are already getting their energy bill. They know what it is. What Opower does on top of that is give people a little note that says, “This is how much energy you are using compared with your neighbours.” They also give you a smiley face, or a sad face, to reflect your performance. It turns out that this makes a huge difference.

The Cialdini book dates from the 1980s.

These are old techniques, but they’re finding new ways to apply them. In the past, it was difficult to print an individually tailored energy bill for every person. Now we can do it. There was an experiment recently by one of Cialdini’s former students, Noah Goldstein. He went to look at hotels, which are always begging us to recycle our towels. He tried to figure out what message would be the most persuasive. They decided that if you applied the Cialdini principles, you would need to have a message that appeals to people, and tells them that other people like them are behaving in this way. What they came up with was the message, “76% of the people who have stayed in your room have been recycling their towels.” And it turns out that that was the most successful intervention.

And if you just say that recycling towels helps the environment?

It’s much less successful. It’s not zero. But if you compare something that has an environmental appeal with something that has a social appeal, the social appeal wins hands down.