During this time, he published two philosophical papers that showed the direction of his thinking at the time, but which he later dismissed as adolescent thought. His interest in psychoanalysis, at the time a burgeoning strain of psychology, can also be dated to this period. Piaget moved from Switzerland to Paris, France after his graduation and he taught at the Grange-Aux-Belles Street School for Boys. The school was run by Alfred Binet, the developer of the Binet-Simon test (later revised by Lewis Terman to become the Stanford–Binet Intelligence Scales). Piaget assisted in the marking of Binet's intelligence tests. It was while he was helping to mark some of these tests that Piaget noticed that young children consistently gave wrong answers to certain questions. Piaget did not focus so much on the fact of the children's answers being wrong, but that young children consistently made types of mistakes that older children and adults did not. This led him to the theory that young children's cognitive processes are inherently different from those of adults. Ultimately, he was to propose a global theory of cognitive developmental stages in which individuals exhibit certain common patterns of cognition in each period of development. In 1921, Piaget returned to Switzerland as director of the Rousseau Institute in Geneva. At this time, the institute was directed by Édouard Claparède. Piaget was familiar with many of Claparède's ideas including that of the psychological concept 'groping' which was closely associated with "trials and errors" observed in human mental patterns. In 1923, he married Valentine Châtenay (7 January 1899 – 3 July 1983) the couple had three children, whom Piaget studied from infancy. From 1925 to 1929, Piaget worked as a professor of psychology, sociology, and the philosophy of science at the University of Neuchatel. In 1929, Jean Piaget accepted the post of Director of the International Bureau of Education and remained the head of this international organization until 1968. Every year, he drafted his "Director's Speeches" for the IBE Council and for the International Conference on Public Education in which he explicitly addressed his educational credo. Having taught at the University of Geneva and at the University of Paris, in 1964, Piaget was invited to serve as chief consultant at two conferences at Cornell University (11–13 March) and University of California, Berkeley (16–18 March). The conferences addressed the relationship of cognitive studies and curriculum development and strived to conceive implications of recent investigations of children's cognitive development for curricula.