The reason why you just can't get some songs out of your head!

A new study has named Lady Gaga's 'Bad Romance' the catchiest song of all-time.
The 2009 hit is followed by Kylie Minogue's 2001 earworm 'Can't Get You Out of My Head' and Journey's 'Don't Stop Believing', from 1981.
Researchers from the American Psychological Association looked into what makes a song catchy, and identified a few key features.
"Musically sticky songs seem to have quite a fast tempo, along with a common melodic shape and unusual intervals or repetitions," says lead author Kelly Jakubowski of Durham University.
By "common", she means tunes that follow patterns commonly found in Western pop, such as the first phrase going up in pitch, and the second coming back down, like 'Twinkle Twinkle Little Star'.
The top nine earworms:
'Bad Romance' by Lady Gaga
'Can't Get You Out Of My Head' by Kylie Minogue
'Don't Stop Believing' by Journey
'Somebody That I Used To Know' by Gotye
'Moves like Jagger' by Maroon 5
'California Gurls' by Katy Perry
'Bohemian Rhapsody' by Queen
'Alejandro' by Lady Gaga
'Poker Face' by Lady Gaga
The researchers settled on the list of hits after polling 3000 people on what songs frequently got stuck in their heads, and comparing the most popular to songs that had similar chart success, but weren't named as earworms.