Ten children’s day-nurseries all introduced a small fine for parents who were more than 10 minutes late collecting their children at the end of the day. The parental response? Rather than arriving more promptly, twice as many parents started arriving late. Introducing a monetary fine effectively wiped out any feelings of guilt, and was interpreted

Research shows that more extrinsic rewards do not add up to greater inner drive. In fact, they have the opposite effect—a decline in intrinsic motivation. Nor do extrinsic rewards motivate children, or any of us, in the long term. The most they provide is a short-term lift.