While last week it was Kanye's intellectual "Stronger," currently the masculine melody of "Love Story" has Taylor Swift's voice resonating through my head as I try to take derivatives. However, as a 19-year-old who has heard many addictive tunes in my short existence thus far, having a song stuck in my head is nothing new--in fact it's rather regular. So what causes this phenomenon? Researchers at Dartmouth have worked on this very problem, and I think I can recreate their results in a little at-home experiment.
We'll try a little experiment and see what we can learn. You need: a friend, a computer with high volume, and Sample 1, Sample 2, Sample 3, and Sample 4. (odds are you already have five of these materials right in front of you!). Have a friend take the computer and turn the screen away from you so that you cannot see it. Then, your friend should click on "Sample 1" (depending on your browser, you might want to open these in another tab/window). Your friend should let the song play for 20 or so seconds from the beginning (or s/he can skip to a random place within the song) and then abruptly pause the song without warning. Your job, as the test subject, is to pay attention to what your brain does in the few seconds immediately following your friend's pause. The samples are below.
I tried this on a couple of people in my dorm and the results were as follows.
DON'T READ PAST THIS POINT IF YOU HAVEN'T ALREADY PERFORMED THE EXPERIMENT!
Sample 1 is very recognizable from anywhere in the song, and most people's brains will automatically fill in the missing sounds in perfect rhythm after pause is stopped for a few beats. Then the song will taper off (but still may keep playing, depending on the person); this song is very easily retained by your memory.
Sample 2 can be recognizable at different places in the song and results can be similar to Sample 1. However there are also portions of the song that some may not be familiar with; this song shouldn't get stuck inside your head as easily due to this result.You may or may not know the notes after pause is pressed.
Sample 3 is not recognizable to most people who aren't album-buying (or album-ripping/downloading) fans of Taylor Swift. This song will probably not get stuck inside your head after listening, and you most likely aren't able to guess the notes after pause is pressed.
Sample 4 is similar to the results of Sample 1. And it is a classic case of being Rickroll'd (see: Urban Dictionary: Rickroll'd).
What the Dartmouth researchers showed using expensive MRI equipment is the same thing (hopefully) that we've just shown using a computer, some YouTube clips, and an unsuspecting buddy--the brain fills in musical gaps, and much more strongly when the song is a very familiar song.
(In the Dartmouth study, the researchers played songs like the ones above, but would replace some of the beats with silent gaps. In very familiar songs, the brain scans showed that the auditory cortex remained active even during the silent gaps, and individuals reported that they "heard" the whole song even though they recognized there were gaps. See: BBC NEWS' "How tunes get stuck in your head")
These findings directed the Dartmouth researchers to conclude that the auditory cortex can remain active even after music is stopped, thus potentially replaying parts of a song in the cortex's "memory." If you happened to buy the Levitin book rather than downloading the reading and you read the chapter that discussed this phenomenon, you would note that Levitin has a similar explanation.
Thus, I can now blame my auditory cortex for letting Taylor Swift ask me about once every 30 seconds, "Is this in my head/I don't know what to think."