Why do songs get stuck in your head?

A song gets stuck in your head because catchy music is practically built to loop. Melodies tend to repeat their rhythm, which can lead to endless repetition unless a climax breaks the cycle, and your mind can keep replaying that fragment with no sound around you at all. The worst offenders usually have a fast tempo, an easy melody and an unusual interval or repetition that makes them stand out. You're in good company: about 98 percent of people get these earworms.

The word is borrowed from the German Ohrwurm, "ear worm", but the experience is much older. In 1876 Mark Twain published "A Literary Nightmare", in which a jingle he reads in the morning paper takes over his mind so completely that he forgets what he had for breakfast. The only cure he finds is to pass the jingle on to a friend. The real jingle was dreamed up by a small group of people after two of them noticed a fare sign on a tram.

Luckily, there are gentler cures than Twain's. Giving your working memory a moderately hard task, like an anagram, a puzzle or a good book, stops earworms and makes them less likely to come back. Chewing gum helps too, because it jams the silent inner "singing" your brain uses to rehearse the tune. And since an earworm is usually just a fragment, listening to the whole song from start to finish can finally close the loop.