Hit songs rely on increasing “harmonic surprise” to hook listeners, study finds

Enlarge / A study of “harmonic surprise”—points where the music deviates from listener expectations—in popular music over several decades found that Childish Gambino’s “This is America” had the most contrastive harmonic surprise. (credit: YouTube/Donald Glover)

Hip-hop artist Childish Gambino (aka actor Donald Glover) made a splash in 2018 with the release of his Grammy-winning hit single, “This is America.” With its stark, sudden shifts between choral melodies in major chords and menacing percussive elements drawn from the trap subgenre, the song constantly defies the listener’s expectations throughout.

That’s why “This is America” also tops the list of pop songs rich in so-called “harmonic surprise,” or points when the music deviates from listener expectations. This is according to a recent study published in the journal Frontiers in Human Neuroscience that analyzes Billboard hits from 1958 to 2019. And it’s no coincidence that the tune is among the most recent: the study also found that harmonic surprise in popular music has been increasing over the decades—a phenomenon the authors have dubbed “inflationary surprise.”

“Music is culture. Culture evolves over time, so the content of music needs to evolve as time goes by, just to have the same success as previously released music,” said co-author Scott Miles, a neuroscientist specializing in how music preference forms in the brain. “This study gets to the heart of what is a dynamic effect within popular culture, in a very concrete and measurable way. These findings [also] help further our understanding of how music is processed in the brain.”