Trombone and carolers. (Photo: Chris Darling/flickr)

When a song gets stuck in our head, the trigger could be anything. The scent of freshly baked holiday cookies. The sight of a Christmas tree glowing with lights. The ambient melody of the dreidel song blasting from the windows of a Mitzvah tank as it barrels passed you on the street, filling Brooklyn with echoes of Hanukkah music.

The first thing to know about earworms–the colloquial name for a song that gets stuck in your head–is that they’re not really songs at all.

“People don’t hear earworms,” says James Kellaris, a composer and marketing professor at the University of Cincinnati Lindner College of Business, who has studied earworms extensively. “They imagine them.”

Earworms are an elusive, even nebulous, phenomenon. Even with most people experiencing them regularly, and scientific literature steadily accumulating around them, little is known about how they work and why. One theory links them to memory, outside stimuli, and the idiosyncratic associations we draw from them. Another says earworms represent a minor breakdown in mental control processes by which people get trapped into fixating on what they’re trying to avoid (“There are stories of atheists haunted by hymn tunes,” Kellaris writes via email.) Another theory calls earworms a “cognitive itch.”

Singing carols at a tree-lighting cememony in Nantucket. (Photo: Massachusetts Office of Tourism/flickr)

Whatever their cause, earworms may find the holiday season, with all its music, kitschy imagery, and nostalgia-arousing traditions, especially fertile ground. In response, we can either hate them, try to banish them from our ears, or we can ponder their cognitive value. This year, when “The Twelve Days of Christmas” gets lodged in your brain, try tracing it back through time. Maddening and pernicious as earworms may be, if we attempt to locate their source, we might discover something about how our brain processes music, memories, and other information. 

“Sometimes it’s really obvious you know because you just heard it,” says Elizabeth Hellmuth  Margulis, author of On Repeat: How Music Plays the Mind, and director of the Music Cognition Lab at University of Arkansas. Margulis says that while most earworms spring from recent listening experiences, others are more tangential, arising from a soup of information: “Sometimes when you trace how an earworm got activated, it’s so sideways, like some little resonance.”

Tracking that resonance down involves some mental detective work. Margulis describes an example from her own life: One night at home, a ditty from Beauty & The Beast got stuck in her head. It had been at least two years since she had had taken her kids to see the musical, so why that song, she wondered? Where had it come from?

Holiday shopping, a prime time for exposure to catchy music. (Photo: Mark Hillary/flickr)

Margulis retraced her day in her mind, all the way back to the doctor’s office, where she had spotted a poster of a doctor whose face had looked familiar. She remembered she had said to herself in that moment, “That guy looks like Gaston,” the villain from Beauty & The Beast. 

“It’s like Gaston had activated this whole Disney Beauty & The Beast network, and it planted a little seed that came out later in the form of an earworm,” Margulis says. “So sometimes it’s not straightforward, but it’s traceable. You don’t have to literally hear the song. You could just hear the name of the song. You could see a Christmas tree, or smell pine needles, or burning candles, and then think of ‘O’Tannenbaum.’ You could see an object that’s tangentially related to the subject material and suddenly it’s activated all of these associations.”

Lassi Liikkanen, a cognitive scientist and teacher at the Helsinki Institute for Information Technology, who has done broad studies of Finnish music listeners, describes a similar, but slightly different, experience. His latest earworm is a recurring one, not unlike a dream, that happens every night, before he goes to bed. It’s prompted by the moment Liikkanen takes his smartphone in his hand and turns on the “PowerSave” mode. Like clockwork, as soon as Liikkanen sees the phrase “PowerSave” on his screen, “Power Slave,” a song by Iron Maiden, starts playing in his mind.

Research shows that earworms often occur when we’re doing something that doesn’t require much attention, like wrapping gifts. (Photo: Shimelle Laine/flickr)

Liikkanen says he understands his earworm, which doesn’t last long, in terms of “musical imagery,” a phrase experimental psychologists use to describe how various sensory experiences are represented in the brain.

“Just as you have a mental image of what your refrigerator looks like, you might have a mental image, or in this case, an auditory image, of the sound your refrigerator produces, or an olfactory image of how your refrigerator smells.” Earworms work in a similar way, Liikkanen says; they are auditory images that “pop up” involuntarily.

What makes an earworm “sticky” provokes another line of questioning. Research has found that songs with a lot of repetition–“Who Let the Dogs Out,” “Whoomp There It Is,” “The Lion Sleeps Tonight”–are more likely to give rise to earworms than, say, experimental jazz. That’s why Margulis, who is currently researching the connection between words and music, is partial to a theory that’s based on the tight coupling in our brains between hearing and motor control. That may explain why, for instance, when some listeners hear a piece of orchestral music, they may imagine pirates battling it out on ship.

“We know from separate works that the more you hear a piece, the more motorically involved you are. Even if you’re sitting still in your car, there’s a sense that you’re moving through a song. By singing ahead in your mind what’s going to happen, you have a sense of virtual participation,” Margulis explains. “The way a song’s encoded, it wants to pull you through, and you want to think it through until you reach the end of that phrase or a resting point. So once a little bit of the song gets going, you have to finish it out. That’s why people call it a cognitive itch.”

Research shows that earworms tend to strike when we’re tired, stressed, hyper-exposed to catchy music, or doing an activity that doesn’t demand too much mental attention, as when we’re swooshing down a ski slope, standing in line, or wrapping gifts. Earworms have also been linked to low-grade neuroticism, obsessive thinking, and other conditions that interfere with normal mental control. Holiday shopping may also pose a risk.

“Music is aesthetically engineered to capture bio-parameters,” Kellaris writes by email. “Music can sort audiences…control the pace of traffic…bend time perception…reinforce brand image…and lower sales resistance. The brain can do only so much at once. Attention to auditory stimuli is involuntary. (We have eyelids, but no ear lids). So if music is playing, the brain is processing it, thereby reducing cognitive resources available for other tasks.”

Carol singing on London’s Trafalgar Square. (Photo: Kathleen Conklin/flickr)

Kellaris adds: “Hyper exposure to catchy music and fatigue are conditions known to exacerbate earworm episodes, so holiday shoppers are particularly at risk, but more likely to blame the song than the retailer who harnessed its power to its advantage.”

Lacking earlids, our ability to block an earworm before it happens may be limited. But we are equipped to quash them after they strike. The best approach is to make a mental pivot, to distract your brain with another activity. Or grab a stick of gum, since chewing it may intercept the same auditory mechanism your brain uses to play the song in the first place, as one new study suggests. 

But there are other times when an earworm may be pleasurable, even useful, from a psychological standpoint.  “We know that people use music to regulate their moods,” Liikkanen says. “When a song pops into our heads, we might be unconsciously bringing about memories or songs that have some relation to our emotional state or life situation, which might help us cope or deal”–a trick that could come in handy during stressful family gatherings.