"If you've ever watched Who Wants to Be a Millionaire?, you've watched people engaged in something called metacognition. Contestants not only need to answer questions. They need to assess how confident they are in the cognitive processes in their own brain that produced the answer. 'You might have the opportunity to ask the audience or phone a friend,' says Steve Fleming, a neuroscientist at University College London. But, he adds, 'You need to know how sure you are about your own answer before you opt to use those lifelines.' That sort of self-monitoring is something we do all the time."