Researchers used IBM's data crunching 'Watson' software to analyze the tones of thousands of songs across some the world's most popular artists from Elvis to Adele, and from Nirvana to Ariana Grand to determine their mood.
Coldplay are as worried and fearful as you might expect
The Rolling Stones are angrier than expected
Nirvana aren't quite as angry as the reputation would have them
Kanye is probably scared of Kim and has less confidence than you might expect
Yoko did make The Beatles sad