While marketers and psychologists have long known that you can fool all of the people some of the time and some of the people all of the time, it has taken economic theory a little while to catch up with the idea. Most economic models are populated by decision-makers who have more in common with the cool-headed logician Mr Spock than the impulsive and self-destructive Homer Simpson.

There are good reasons for that. The main argument of my last book was that Spockish behaviour is far more common than most of us appreciate. But unSpockish behaviour certainly exists. Popular discussions of economic psychology tend to start and end with that observation. Yet there is much more to be said, and many economists are now exploring the real-world implications of different brands of unSpockishness.