Neural responses to a repeated stimulus typically diminish, an effect known as repetition suppression. We here demonstrate what appear to be parallel effects of repetition on subjective duration, even when stimuli are presented too rapidly for explicit temporal judgments. When a brief visual stimulus (e.g., a letter, word, object, or face) was serially flashed in different locations, several stimuli appeared to be present simultaneously due to persistence of vision—we term this the Proliferation Effect. Critically, fewer stimuli were perceived to be simultaneously present when the same stimulus was flashed repeatedly than when a different stimulus was used for each flash, indicating that persistence of vision (and hence subjective duration) shrinks for predictable stimuli. These short-timescale experiments demonstrate that subjective durations are computed at a preconscious and implicit level of processing, thereby changing the temporal interpretation of visual scenes. Further, these findings suggest a new, instant diagnostic test for deficits in repetition suppression, such as those found in schizophrenia.