1898 studies of philosophy and psychology in Prague, Berlin and Würzburg; 1904 Ph.D. in psychology under Oswald Külpe with a dissertation entitled Experimentelle Untersuchungen zur Tatbestandsdiagnostik; 1910 assistant at the Psychological Institute of Frankfurt am Main, experimental research in apparent movement (the phi phenomenon); founded the Gestalt school with his professorial dissertation Experimentelle Studien über das Sehen von Bewegungen in 1912; 1912-16 teaching philosophy and psychology in Frankfurt; 1916 move to Berlin, associate professor in 1922; 1921 publishing the new journal Psychologische Forschung with Kurt Koffka, Wolfgang Köhler, Kurt Goldstein and Hans Walther Gruhle; 1929 return to the University of Frankfurt as full professor of philosophy and psychology; 1933 emigration to the USA, teaching at the New School for Social Research.