Richard Thaler and Cass Sunstein's book Nudge was one of the most influential books of the year, finding its way into the speeches of Barack Obama and David Cameron and generating a huge amount of discussion. Its basic premise is that small changes in the way that choices are presented to citizens or consumers can have big effects on behaviour (for a fuller explanation, here's a video of Thaler). One of the quirkiest examples of "nudging" can be found in the men's urinals at Amsterdam airport, where an astutely positioned painted fly has been found to reduce "spillages" by 80%:
