If you’re wondering why a particular song is catchy, it may be because you've heard it before on the radio, in a store, on a soundtrack. Elizabeth Hellmuth Margullis, director of the Music Cognition Lab at the University of Arkansas, says that repetition creates an opening for the listener to become imagined participants in the song. In this TED video she's quoted as saying, “Repetition gives rise to a kind of orientation to sound that we think of as distinctively musical where we’re listening along with the sound, engaging imaginatively with the note about to happen.” Repetition also allows the listener to notice new things.