Thirty years ago, ginger pop legend Rick Astley promised that he would neither give you up or let you down, nor run around and desert you. On Thursday, the 51-year old acknowledged his hit song’s anniversary on Twitter, and a day later the damn tune is still stuck in our heads. Why’s that? Because once a song is an earworm, it will always be an earworm.

Earworms are the catchy songs that bop endlessly in your brain, usually to the point where you’ll either do anything to get them out or you just say “Fuck it” and put “Despacito” on again. Scientists studying the phenomenon say that earworms typically share three characteristics: a fast tempo, a common melodic shape, and an unusual interval structure.

Featuring Astley’s smooth baritone voice over digital synthesizer bass lines and a continuous drum beat, the melody of “Never Gonna Give You Up” follows a predictable rise-and-fall pattern that scientists call a “common melodic shape”. In the 2017 paper “Dissecting an Earworm” a team of psychology researchers explained that our brains are especially reactive to melodies that soar high and then low within a small interval. It’s thought that our brains latch onto this pattern because it’s the sort of easy, predictable melody that we’re used to. In other words, the brain likes what it already knows.

The “unusual interval structure” is the Goldilocks element of a perfect earworm. A sticky earworm has to be predictable enough to create patterns the brain enjoys — but unique enough that the brain doesn’t think it’s boring. While the chorus of “Never Gonna Give You Up” is fast and repetitive, the song’s verses feature unexpectedly drawn-out notes over a quick synthesized beat.

“There’s not one single formula for what becomes an earworm or not an earworm, but there are many, many different configurations of these features that can make an earworm,” Daniel Mullensiefen, Ph.D., a music psychologist at Goldsmiths, University of London, told Inverse in June. “You couldn’t, say, write a song where the contours are going up and the intervals are large. It doesn’t work that way.”

Another element that transforms a song into a certified earworm is repetition. The stickiness of “Never Gonna Give You Up” has transcended time because the unending repetition of its catch chorus satisfies the brain’s need for familiarity. Furthermore, a 2011 paper published in PLOS One pointed out, the songs that people emotionally connect are also the songs that they hear the most. It makes sense that we are partially unable to break free of Astley’s aural grip because of the trend of “rickrolling,” — the enduring bait-and-switch prank in which unwitting internet users are unexpectedly blasted with “Never Gonna Give You Up.”

“Never gonna make you cry, never gonna say goodbye,” Astley croons. He’s talking about his great love, but he could be just as easily be talking about his own song.

Photos via Giphy/YouTube