Max Wertheimer (mäks vĕrt´hīmər), 1880–1943, German psychologist, b. Prague. He studied at the universities of Prague, Berlin, and Würzburg (Ph.D., 1904). His original researches, while he was a professor at Frankfurt and Berlin, placed him in the forefront of contemporary psychology. Wertheimer came to the United States in 1933, shortly before the Nazis seized power in Germany. He immediately joined the graduate faculty of the New School for Social Research (1933–43). Wertheimer's discovery (1910–12) of the phi phenomenon (concerning the illusion of motion) gave rise to the influential school of Gestalt psychology. His early experiments, in collaboration with Wolfgang Köhler and Kurt Koffka, introduced a new approach (macroscopic as opposed to microscopic) to the study of psychological problems. In the latter part of his life he directed much of his attention to the problem of learning; this research resulted in a book, posthumously published, called Productive Thinking (1945, repr. 1978).