"Why have some movie directors made classic early films, but subsequently failed to match their initial successes, whereas other directors have begun much more modestly, but have made great movies late in their lives? This study demonstrates that the answer lies in the directors' motivations, and in the nature of their films. Conceptual directors, who use their films to express their ideas or emotions, mature early; thus such great conceptual innovators as D. W. Griffith, Sergei Eisenstein, and Orson Welles made their major contributions early in their careers, and declined thereafter. In contrast experimental directors, whose films present convincing characters in realistic circumstances, improve their techniques with experience, so that such great experimental innovators as John Ford, Alfred Hitchcock, and Akira Kurosawa made their greatest films late in their lives. Understanding these contrasting life cycles can be part of a more systematic understanding of the development of film, and can resolve previously elusive questions about the creative life cycles of individual filmmakers"--National Bureau of Economic Research web site.