Science, Please, Explain Why Catchy Songs Loop in Our Heads Forever

Is there more to an earworm than a snappy hook? We spoke to various clever people in music to understand.
Baby Shark video screenshot
Image via YouTube

I’ll start with the science. Distilled down to its purest form, ‘music’ is a succession of vibrating airwaves picked up by our ears, and interpreted by our brains. Memory is essential here as we’re only capable of hearing one tiny instance of sound at a time; our brains string these together and present them to us as continuous ‘sound’.

We can’t help trying to arrange the sounds our ears pick up into something cohesive, even when what they form isn’t close to being ‘music’ – if you make a two-second loop of pretty much any sound, your brain frantically searches for a pattern and a rhythm within it, and it usually finds one. So what happens when you listen to something that’s been precisely constructed to imprint itself on your memory for all of eternity?


This brings us neatly on to “Baby Shark,” the heinous children’s song documenting three generations of a shark family. Its precise origin is largely unknown – though it’s thought to have spawned out of singalongs at American summer camps – but Pinkfong, a Korean YouTube channel for kids, popularised it as an intense mash of gurgling synthesised bass overlaid with an indelible melody that cuts right to the very core of your soul. All the while, as the lyrics progress through the generations of shark from Baby to Daddy to Grandma and so on, the jaws of the accompanying ‘shark mouth dance’ grow wider, and wider, and wider until you’re utterly consumed. And then you play it again.

Last week “Baby Shark” swam to number 32 in the US Billboard Hot 100 chart. At the time of writing, it had been streamed 20.8 million times over the course of the previous week. But why exactly is it such a catchy song? Every so often, a particularly sticky hit makes stoner chat or pub chat or your inner monologue turn over the idea of what makes a song so hard to get out of your head. Normally, you chew it over for a bit, then move on. So I decided I needed to settle this, speaking to some experts about hooks, the patterns in songs that make them so loop-able and whether there’s a sharp science to making music this way.

Thomas Hodgson – Teaching Fellow in Ethnomusicology, Department of Music, King’s College London

I’ve just listened to it for the first time on YouTube – that’s 1:45m of my life I’ll never get back. I don’t think there’s really much to say about the song. Why is it catchy? Part of the answer is to do with familiarity. It follows a basic I-IV-V-I chord progression in C Major (So C, F, C, G), which you could say is a very common pattern in pop music (think: The Beatles’ “Twist and Shout” [actually written by Bert Berns and Phil Medley in 1961], The Troggs’ “Wild Thing’, The Ting Tings’ “That’s Not My Name,” “Mustang Sally”… etc etc.) In terms of the lyrics and melody, there’s not much going on here, is there? I wonder whether nonsense lyrics – the “doo doo doo doo” – appeals to certain audiences precisely because it’s nonsense.

You don’t need a full grasp of the language to follow the song, which may give it a broader appeal. I mean, this is a children’s song, right? Is one of the reasons it’s had so many streams simply because it’s played in the background, or incessantly repeated by toddlers on iPads (in which case, poor parents)? I think we need to be careful not to overstate importance of the stream count.


Interesting music is usually interesting because it deviates in some way from what we expect, or speaks to a part of us. And this is historically because music, like art and literature, is a human response to the world. Over time I’m sure AI will be able to imitate these responses, but that’s not the same as experiencing them. On a basic level I think we respond to music because we recognise it was written by someone as their experience of the world, something we can empathise with. Can we empathise with an algorithm?

I’m now going to listen to some other music in a probably vain attempt to get that song out of my head!

Elizabeth Hellmuth Margulis – Distinguished Professor and Director at Music Cognition Lab, University of Arkansas

There’s some evidence that we perceive songs as catchier when we move along with them. Those adorable little shark gestures in "Baby Shark" may actually be helping the tune burrow into your brain. Catchy songs also tend to feature an optimal mix between a conventional attribute that make them easy to remember, and surprising twists that make them distinctive.

"Baby Shark" is pretty easy to sing, which might make it harder to resist singing along in your head while you’re listening. Once you’ve done that, it’s that much easier for it to start auto-singing in your head without the external trigger. Some studies have exposed people to catchy music in the lab, and then counted the number of earworms they experience later during a mundane task. They tend to experience more earworms if they had moved to the music while listening.


Science doesn’t have a precise formula for a catchy song, because catchiness also depends on factors outside the notes themselves – for example, how recently and how often a person has heard a song, and their overall listening habits. Catchy songs tend to feature an optimal mix of surprise and predictability, but what seems predictable to any one listener can vary depending on the kinds of music they’ve listened to before.

Dr James Kellaris – composer, musician, and Professor of Marketing at the University of Cincinnati

Catchy songs in general tend to have three characteristics in common: simplicity, repetition, and incongruity. “Baby Shark” is a perfect storm of all three. Creating an earworm is more art than science, but those creating a catchy hook can apply known design principles of simplicity, repetition, and incongruity. Simplicity facilitates learning – perhaps ‘over-learning’. Repetition reinforces learning and may convey an implicit suggestion to the brain to continue the repetition mentally, even after the external source of the music is turned off. Incongruity is what causes a ‘cognitive itch’. Like a mental mosquito bite, when information is incongruous (or violates listeners' expectations) it motivates cognitive effort to resolve the incongruity. This cognitive effort involves thinking about the offending song.

Spoiler alert: the incongruity in “Baby Shark” is that whereas concluding musical phrases generally end on the tonic (the harmony composed of do-mi-sol; the C chord in the key of C) to signal finality, “Baby Shark’”’s final phrase comes to rest on the dominant (the harmony composed of sol-ti-re; the G chord in the key of C), which signals continuation. The specifics I’ve nailed down when deciding on catchiness are: simplicity, repetition, incongruity, and a secret ingredient that I can reveal to Noisey readers who send me $5 in an unmarked envelope. But really, which did you master first as a young child: the letters of the alphabet or the melody of the alphabet song? (Clue: birds, whales, and rodents all ‘sing’).

Mental repetition of melodies can become involuntary, similar to intrusive thoughts. Ironic process theory explains that to suppress a thought, one must remember the thought to be suppressed. Voilà – the ‘white bear’ effect. (If you tell someone not to think about a white bear, the harder they try the more they think about a white bear). But the best strategy for ridding oneself of an earworm may depend on the reason the song got stuck. For example, if a song is stuck due to overexposure, limiting exposure should help. If a song is stuck because one cannot recall the lyrics, a completion strategy may help. Look up the lyrics, sing through the song once in its entirety.

I think you have milked the limited wisdom I have to offer! Fun stuff…

So what can we take from this? There’s plenty of overlap in what these three say, perhaps especially with regards to repetition, simplicity, and something slightly unexpected or “incongruous” as Dr Kellaris puts it. But there’s also a consensus here that it’s not quite as formulaic as that, which is positively reassuring. “Baby Shark” hits these three criteria almost too on the nose which is probably why I can’t stop listening to it, but also probably why it fills me with utter horror every time I do. It’s just too slick and too perfect. It comes as somewhat of a relief then to hear professor Margulis say that science doesn’t have a definitive answer to what truly makes a song ‘catchy’. Sure there are common traits in catchy songs, but there will always be an indefinable beauty in the music we love that keeps us listening, and that’s a beautiful thing.

You can find Patrick on Twitter.

This article was amended on Wednesday 23 January to reflect that Pinkfong is a Korean company, though it publishes material in Japanese, Korean, Spanish, English and Mandarin.