Music Stickiness

In studies by psychologists, they often track no jut musical stickiness. But phrases pieces of poetry or news casts or movie lines. Parl mcartney has said in interviews that he intentionally didn't want to learn to write down music. And so he only writes the ones that get stuck. You're usually carrying one or another. I've had elbows myside captain's in my head for about a week. How long's the loop? How long before i repeated? What the actual little piece of music, the one in your head i've got?