To verify this hypothesis, Croizet and Autin conducted three studies among sixth graders in their city, Poitiers. In one experiment, they gave 111 sixth graders an impossible set of anagrams to solve. Then Autin told one group of kids that "learning is difficult and failure is common," but hard work will help, "like riding a bicycle." Autin asked a second group of kids how they attacked the problems after the test. When both groups, plus a control group, then took an exam that measured working memory -- a capacity often used to predict IQ -- the students Autin had counseled performed "significantly better" than both groups, especially on the tougher questions.