as a comprehensive approach (see Samelson, 1981), (in no small part because of the intervention of World War I), by the 1920s Watson's revolution was well underway. The central tenet of early behaviorism was that psychology should be a science of behavior, not of the mind, and rejected internal mental states such as beliefs, desires, or goals. Watson himself, however, was forced out of Johns Hopkins by scandal in 1920. Although he continued to publish during the 1920s, he eventually moved on to a career in advertising (see Coon, 1994). Among the behaviorists who continued on, there were a number of disagreements about the best way to proceed. Neo-behaviorists such as Edward C. Tolman, Edwin Guthrie, Clark L. Hull, and B. F. Skinner debated issues such as (1) whether to reformulate the traditional psychological vocabulary in behavioral terms or discard it in favor of a wholly new scheme, (2) whether learning takes place all at once or gradually, (3) whether biological drives should be included in the new science in order to provide a "motivation" for behavior, and (4) to what degree any theoretical framework is required over and above the measured effects of reinforcement and punishment on learning. By the late 1950s, Skinner's formulation had become dominant, and it remains a part of the modern discipline under the rubric of Behavior Analysis. Its application (Applied Behavior Analysis) has become one of the most useful fields of psychology. Behaviorism was the ascendant experimental model for research in psychology for much of the 20th century, largely due to the creation and successful application (not least of which in advertising) of conditioning theories as scientific models of human behaviour. Second generation francophone Genevan School In 1918, Jean Piaget (1896–1980) turned away from his early training in natural history and began post-doctoral work in psychoanalysis in Zurich. In 1919, he moved to Paris to work at the Binet-Simon Lab. However, Binet had died in 1911 and Simon lived and worked in Rouen. His supervision therefore came (indirectly) from Pierre Janet, Binet's old rival and a professor at the Collège de France. The job in Paris was relatively simple: to use the statistical techniques he had learned as a natural historian, studying molluscs, to standardize Cyril Burt's intelligence test for use with French children. Yet without direct supervision, he soon found a remedy to this boring work: exploring why children made the mistakes they