In the 1940s, American movies changed. Flashbacks began to be used in outrageous, unpredictable ways. Soundtracks flaunted voice-over commentary, and characters might pivot from a scene to address the viewer. Incidents were replayed from different characters' viewpoints, and sometimes those versions proved to be false. Films now plunged viewers into characters' memories, dreams, and hallucinations. Some films didn't have protagonists, while others...