Selling Sounds: The Commercial Revolution in American Music says that "although there was no definition for what made a song catchy, all the songwriting guides agreed that simplicity and familiarity were vital".
These songs are referred to as earworms due to their parasitic characteristics; their entrance and exit from our mind cannot be controlled and despite our best efforts they may refuse to leave.
The article explains that it has a chorus which is "melodically easy on the ear, simple enough to stay in your head all day, and is topically appealing to Jepsen’s target pop demographic."
These incongruities are intended to capture the listener's attention and to preserve their level of interest throughout the song, regardless of the simple and otherwise repetitive lyrical content.
[9] A 2014 study by the University of Amsterdam and the Museum of Science and Industry in Manchester found "Wannabe" by the Spice Girls to be the catchiest pop song of the last 60 years in the UK.
What makes Wannabe work so well is that it isn’t a difficult song to sing, it has a conventional melody that repeats itself a lot, and it’s just relentless.
"[11] Additionally, the book FutureHit DNA by Jay Frank says "Wannabe felt like it should have been a 3+1⁄2- to 4-minute pop song, just like every other hit at that time.