A melody that’s simple, familiar and repeated over and over can make a song catchy. What makes a song catchy though raises more questions than we have the answers to, for now.
My friend’s son who is pursuing his bachelors’ degree in music points out that a (catchy) pop song moves easily from one chord to the next and then back to the “root” chord. The notes in the melody fall closely to one another on the musical scale.
A study at the University of London suggests that a chorus which combines a hook over three different pitches was found to be catchy. Just listening to the chorus of some of the catchy songs I grew up with – Madonna’s “Into the Groove,” Whitney Houston’s “I Wanna Dance with Somebody,” Belinda Carlisle’s “Heaven on Earth” – suggests it’s one of the things that makes a song so catchy.