For all of the work that record-company folks and artists do to try to figure out what people like to listen to -- and with the exception of Yoko Ono, nearly every musician who's ever recorded wants to be listened to, no matter what they say -- there is no way yet of determining what makes songs stick in people's heads.
Over at Today I Found Out, a writer explores some of the reasons that songs become earworms, and I imagine those same music folks have pored over these ideas to see what kind of combination of catchiness, repetition, hook and whatever else you can think of actually makes a song something that you can't get out of your head.
The problem for them is that no two heads are alike (except maybe for Vice President Joe Biden and Peanut), so the triggers that will make a song stick in my head are not necessarily the triggers that will make one stick in your head. Even if the triggers are the same, the qualities that trip those triggers might not be. I may be an unreconstructed punk who will start bobbing my head and drumming out a rhythm on the armrest at "I Was Wrong" or "Bad Luck." You may be a later music lover who has the same reaction to a Tony Bennett/Lady Gaga duet (in which case may the Lord and all of his angels help you before it's too late). The point is that a record company that wants to find a formula for a hit can't make a song that will cause both of us to click on iTunes and demand it take our money.
It's hard to see that as a bad thing. The music industry already has enough pieces of the magic formula puzzle to make a distinct majority of the songs on my radio sound the same and to make a star out of Robin Thicke (for which the Lord and all his angels have said, "You're going to pay for that one"). If they were to completely solve it so that some neuroscience magic could make a foolproof earworm, then every song would sound like it.
Until, of course, people got tired of that sound and someone dared to offer something a little different. Which would then sell like mad because it was something brand new, and the cycle would begin again. And if you think you can solve that, then I've got a bridge for sale. Call me, maybe.