Daniel Kahneman, who is considered one of the world's foremost cognitive psychologists and won the Nobel Prize in Economics in 2002, has a fascinating story about juggling. As a young man, he was fascinated by the Conway Twaddler – a toy that can be juggling five balls simultaneously. He soon learned that it is much easier to juggle three balls than five balls. And yet, as he observed people juggle more balls, he realized that they continue to try to juggle more balls even when it is clear that they cannot. Why?