FLickr via alex-camposSo you hear a song on the radio or at a party and four days later you find you are still humming it in the elevator on the way to the office.

You’ve been infected by an “earworm,” a persistent song or sound that repeats in your brain until you consider kicking the person who introduced it to you. 

They can be annoying, distracting, and can be infuriatingly difficult to get rid of.

Why do our own brains do this to us?

Ira Hyman might have a few answers. He is a psychologist at Western Washington University who studies memory, and is an authority on repetitive memories and “intrusive thoughts” like earworms.

Hyman and his team performed several experiments to study what they called “intrusive thoughts.” In their paper on the phenomenon, published in the journal Applied Cognitive Psychology in December 2012, this is what they found will make you more likely to be victimized by an earworm:

1. You actually like the song.

They found that “contrary to the belief that only obnoxious songs get stuck, we found that songs people know and like frequently became intrusive.”

So, the idea that only awful or irritating songs stick to the brain is kind of a myth.

“Although annoying songs may become intrusive, this appears to be relatively rare,” the paper says. In fact, two thirds of the participants surveyed in their first experiment liked the song glued to their heads.

“The myth is that this is obnoxious, and people talk about having ‘It’s a Small World’ from Disneyland stuck in their head, or some awful jingle from a TV commercial,” Hyman told Business Insider. “But typically, the reason these things get started is because you have been exposed to the music recently. And for most of us, we listen to things we like.”

Hate to say it, but you might like that “annoying” Justin Bieber tune more than you think. 

2. Something reminds you of the song. 

This one might seem obvious, but it’s true.

If you hear a word or a phrase, or go to a place that reminds you of a song, its likely to pop back into your head. A Queen fan might hear the phrase “another one bites the dust” and think of the song by the same name.

Because you enjoy the song, it gets stuck on repeat.

3. The song reflects your own individual tastes and psychology.

Also, oddly, the “intrusive song” is more likely to be unique to you. Only one quarter of the people surveyed in Hyman’s experiments had the same song as someone else. 

Another scientist named Valerie Salimpoor recently published a study in the journal Science on April 12, which found that playing completely new songs stimulated the part of the brain responsible for pattern recognition. 

Her experiments led her to conclude that “you can’t find two people in the world who have the exact same preferences in music. This is the reason why … each brain has been shaped by the music you have heard in the past.”

4. You’ve heard it dozens of times.

Though we all have our our tastes in music, popular songs seem to have a better chance of sticking in people’s heads. Probably because you have heard it several times. 

What sucks is when people dislike the music they hear on repeat — for example if they work in a department store or coffee shop. Even the songs they dislike — when heard over and over — stand a good chance of getting stuck in their brain.

5. You are doing something too easy.

Boredom and lack of interest tend to allow intrusive thoughts to rush in. Doing dishes or walking on a treadmill are pretty easy on the brain, and leave a lot of open space for whatever thoughts happen to be waiting in the wings. 

Research published in the journal Consciousness and Cognition in March 2009 suggests that people doing boring tasks are more likely to let their mind wander, and wandering minds are more open to earworms. 

Hyman’s research found the same thing: People were more likely to recall and repeat a song while doing things that required “low cognitive load,” such as walking, exercising, or daily routines.

6. You are doing something too difficult.

On the flip side, brain-taxing tasks can make your mind wander too.

A gruelling economics midterm study session is liable to induce mind wandering. 60-five per cent of the participants in one of Hyman’s experiments reported experiencing intrusive songs when doing schoolwork (all participants were college students). 

In another experiment, Hyman’s team gave participants Sudoku puzzles — some were given easy ones and others were given tougher ones. The subjects with the easier puzzles were mostly able to complete them without letting in their intrusive song.

Those with the tougher puzzles not only had a harder time solving them, but also found they were distracted by their song more often.

7. Someone is messing with you.

“One thing you don’t get to write about is just how darned easy it is to do this,” Hyman said. “You can get someone to have a thought that will stick with them for the rest of the day by humming a piece of music into their ear, if it’s something they know.”

“You can ruin someone’s day by getting them to remember a song they don’t like,” he continued. “My students and I play games like this all the time now, where we will walk past one another in the hall and say a line from a song. It is astonishingly easy to disrupt someone’s consciousness.”

But WHY?

These intrusive thoughts may have some kind of evolutionary purpose, Hyman said. Our brains are built to see patterns in the world and to make associations among our memories and new things we encounter. 

“I think these thoughts serve a lot of functions, and that is the reason we have evolved some sort of mechanism that works this way,” Hyman said. “Say you are engaged in conversation with some friends and somebody says something and it reminds you of something that has happened to you. You might be at work reading something which reminds you of something else.” 

The mind seems to have a capacity for an “ongoing retrieval of possibly relevant things,” Hyman said, and this may be related to qualities like creativity, or even survival.

Getting that song out of your head.

A song stuck in your head is not all that different from any other repetitive thought popping up in your head — like worries over work, painful memories, or recollections of embarrassing gaffes.

“Involuntary thoughts, intrusive thoughts, mind wandering, attempts at thought suppression, having a song in your head, are probably different instantiations of the same underlying problem of consciousness — the failure to stay focused, the failure to keep control,” Hyman said. 

The best thing to do is let them come and go on their own, and return to whatever task you happen to have at hand. It helps to pick a task that you enjoy, and that is neither too boring, nor too difficult.

“How actively engaged you are at any given moment also predicts whether a song is going to come back into your head,” Hyman said. “My students liken this to a Goldilocks effect. … if [your engagement level is] just right, if it’s in that sweet area where it has you completely cognitively engaged, where there is not that much space left over in consciousness, it will keep these other sorts of thoughts out.”

He added that you are better off choosing something you like, and that tends to vary from person to person. If you are going to read something, it has to be interesting to you. If you are going to do Sudoku, you have to like Sudoku.

FlickrPreventing the earworm to begin with.

If earworms are a big problem for you, devoting a few minutes a day to doing some kind of mindfulness exercise can make a huge difference, Hyman said.

He pointed to work by psychologists such Michael Mrazek, Jonathan Schooler, and Jonathan Smallwood, who have been working on experiments showing that just a few minutes of mindfulness training can improve focus and prevent mind wandering — including when that wandering is an intrusive song.

“What they have found is when people with even a little bit of mindfulness training engage in other tasks, they can stay more focused, and it seems to expand their working memory capacity. It also means they go mind wandering less often,” he said.

It’s also important to recognise that these thoughts can be natural, and even have benefits. So people shouldn’t feel any need to expel all wandering thoughts from their minds. 

“To a certain extent you want to allow a little mind wandering; you want to see if there are things out there that are related to what’s in your head,” Hyman said. “Smallwood and others have suggested that people whose minds wander more are sometimes more creative. You don’t want to be always focused on one thing at a time, but at the same time you don’t always want to be distracted by your thoughts. It’s a fine balance.”