although music's repetitiveness has been a perennial topic of theoretical and philosophical interest, we know surprisingly little about the psychological processes underlying it. As one step in the larger enterprise of examining the psychology of musical repetition, a preliminary question addresses repetition detection: Which repetitions are listeners able to identify as such, and how does this ability change across repeated exposures of the same work? In this study, participants with minimal formal training heard short excerpts and were instructed to press a button whenever they heard something from earlier in the piece repeat. Additional exposures facilitated repetition detection for long units, but impaired repetition detection for short ones, exposing an attentional shift toward larger temporal spans across multiple hearings.