In 2009, Lady Gaga sang about being caught in a bad romance, and people the world over were, almost instantly, able to sing along.
Even now, seven years later, the odds are pretty good that her love woes are already playing on loop in your mind, based solely on the fact that you just read something about it.

"Rah-rah ah-ah-ah." Just in case you weren't there yet.
"Bad Romance" and many songs like it are well-known to musical experts as "earworms," due to their ability to stick inside your brain, on repeat, long after you've heard them. But a new study, published Thursday in the journal Psychology of Aesthetics, Creativity and the Arts, now has some insight into why this happens.

"We were interested because it's such a common phenomenon. ... People say certain songs are more catchy than others, but there wasn't a lot of scientific evidence on (this) topic," said Kelly Jakubowski, a music psychologist at Durham University in the UK who herself gets earworms all the time

It's estimated that 90% of us experience an earworm at least once a week, with some having them even more frequently than others. Jakubowski's team identified three main reasons why they occur, and it comes down to pace, the shape of the melody and a few unique intervals that make a song stand out.
"These three factors stood out above the rest ... (the songs) need to be not too simple and not too complex," Jakubowski said. "None of these have been revealed in previous research."
Making simple yet complex music

As for pace, the earworms highlighted in the study were faster and more upbeat in tempo and generally had a rhythm that people could move to. "We have a propensity to move to earworms," Jakubowski said, citing songs that people may use to pace themselves during a run.

Next on the list was musical shape or contour, with earworms generally being simple in structure, but with a rhythmic pattern. Sounds may rise in pitch, go back down low and then rise again as a pattern, such as "Twinkle, Twinkle, Little Star." Many nursery rhymes fit this pattern to help children remember them -- so their creators knew what they were doing.

"The quite simple melodic contour might help the brain to recall these things," said Jakubowski.
Last was the need for some unusual intervals within the song, just enough to add some catchy surprises while maintaining a simple, uniform pattern overall. "Although the overall melody has a simple shape, you'll find some unique intervals," Jakubowski said. "So it's simple but different."

The findings are much anticipated by neuroscientists and musicians alike.

"This is a timely and well-conducted study that adds to our knowledge of what kinds of music become earworms," said neuroscientist and musician Daniel Levitin, professor of psychology and behavioral neuroscience at McGill University in Canada, who was not involved in the research. "The reason that we get earworms in the first place is probably because music is an evolutionary adaptation, helping us to preserve factual and emotional information in an easily memorizable medium."

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