Dorwin Cartwright, in his 1979 paper “Contemporary Social Psychology in Historical Perspective,” claimed that the person who had the greatest impact on the development of American social psychology was Adolf Hitler. Certainly World War II functioned as a great catalyst for intellectual cooperation between psychologists, sociologists, anthropologists, and psychiatrists, who worked within various wartime government agencies, such as the Army Information and Education Division, the OSS Assessment Staff, the Food Habits Committee of the National Research Council, and the Bureau of Program Surveys of the Department of Agriculture. These groups conducted studies on the attitudes, morale, and adjustment of combat troops (Stouffer, Lumsdane, et al., 1949; Stouffer, Suchman, et al., 1948b), French civilian reaction to the D-Day landings (Riley, 1947), the relationship between enemy morale and saturation bombing (U.S. Strategic Bombing Survey, 1946; Janis, 1951), and civilian morale and propaganda (Berelson, 1954; Watson, 1942). In a variety of quasi-experimental and field studies, Kurt Lewin (1947a) and Dorwin Cartwright (1949) explored “group dynamics” via programs designed to persuade housewives to change their food habits and to promote the sale of U.S. war bonds, initiating what came to be known as the Lewinian tradition of “action research.”

Another major impact on American social psychology of the actions of Adolf Hitler was the migration of academic refugees from Western Europe, which provided a massive infusion of talent into American science, culture, and psychology, including social psychology.