"Why do those holiday tunes get stuck in your head so much?" I was invited to pose this question to Dr. Robert Zatorre, Co-Director of the BRAMS: Brain Music and Sound lab at the Montreal Neurological Institute at McGill University. Dr. Zatorre is a leading expert in neuroscience research on the biological basis of music; if anyone is able to explain why Jingle Bell Rock is haunting me, it's him.
Commonly known as earworms, some songs repeat in our mind. They are "typically annoying," said Dr. Zatorre. We often can't control it, the sounds won't go away, and they loop, repeating a refrain or short segment of music. I asked if earworms are related to symptoms of obsessive-compulsive disorder and he said they are "maybe a mild form of obsessive thoughts" since they are intrusive, but everyone experiences them.
The auditory cortex is extremely efficient, he explained. In neuroimaging studies (like this one) he discovered that the same regions of the brain are active when you experience external sound as in imagining music. He theorizes that with intrusive imagined music, the auditory cortex is hyper-excited and "goes off on its own."
I asked why it's so easy to remember a song even we haven't heard it for a long time: it's the way it's encoded, and the context. "We know from psychology experiments that the more information, the more it sticks around," he said.
In pre-literate cultures, bards shared knowledge through songs, which may have been an evolutionary advantage (despite Stephen Pinker's claim that music is "auditory cheesecake" - in a 2007 Science article Zatorre was quoted as saying, "Pinker has served as a useful foil" for music biology researchers). He explained that trying to remember a list of 12 words on their own is difficult, but if he put them into a weird story then set it to music they're far easier to recall. It links one piece of information to another. As well, lyrics are easier to remember than regular speech because they are more poetic and rhythmic. He said that "may be the reason songs get stuck in your head: they are hard to forget, and also hard to suppress."
But if you don't want to think about Rudolph's shiny nose, "dashing through the snow" or you can't get Kylie Minogue's voice out of your head, Dr. Zatorre offers some advice. Substitute another song, but don't just listen to it, "active engage in other musical activity. It's much better to sing or play an instrument, since it's using more of that circuitry." Even with mashups and multitasking, you can't have more than one earworm in your mind simultaneously.
Still, beware Frosty the Snowman - he'll be back again one day.