For music buffs, it will come as one of the understatements of the year: the music you listen to can, according to researchers at Cambridge University, cause people to make spot judgments about your character. Spot judgements? Pah. Entire friendships and vendettas can be forged merely on the strength of your playlist. Like Vampire Weekend? You're in. Fan of Enrique Iglesias? You're definitely out.
It's not a new phenomenon. Go back 30 years and a flick through one's record collection would have provided all the evidence needed for future compatibility. But in a world where studies seem to be carried out on everything, from whether if zombies actually existed, could they wipe out the human race, to the effect of country music on suicide rates, a study was also required to determine this long-known fact. What judgements exactly, the researchers asked, would be made on fans of certain types of music.
The results are predictable: classical music types are seen as upper class, intellectual, unattractive and boring, while fans of rap are viewed as being of a lower social class, athletic, energetic and hostile. People may want to give rock fans a wide berth if such stereotyping is to be believed, since nestling somewhere in between "rebellious" and "artistic" lies the rather more worrying description, "emotionally unstable".
More interesting than that, surely, is a closer study of people's playlists. A love of certain bands is, rather like one's choice of suburb or tea bags, reflective of social mores, political orientation and, of course, cool. Take, for example, Kiefer Sutherland. As the renegade terrorist trouncer Jack Bauer in 24, he is pretty cool. But let's take a look at what's on his iPod (bearing in mind that this information is up on the iTunes website for all to see, so he may have given it a few tweaks first). There's U2, David Bowie, Snow Patrol and Marvin Gaye. Surprisingly approachable, you might think. And anything but subversive. Not quite the tightly wound nutter he would have us believe.
And Carla Bruni, a part-time musician herself of course, appears, when not clad in chicest Dior, to have something of a 70s folk chick in her. Scroll through her iPod, and you'll find The Clash mixed in with Bob Dylan, Lou Reed and Marianne Faithful. Based on the strength of that, we might even be friends. More often that not, though, it seems to add up. The colourful British comedian Stephen Fry's playlist is a heady cocktail of Abba, Rufus Wainwright, EMF and Nina Simone. While Dev Patel, the nice-guy actor of Slumdog Millionaire fame, seems, well, pretty nice. He likes Estelle, Puff Daddy's I'll be Missing You, Fatboy Slim and Kanye West.
Scarlett Johansson, one of the more hip young actors in Hollywood, seems keen to show her cerebral side, listing Brian Wilson alongside Cat Stevens, Billie Holiday and Ella Fitzgerald. And then there are the pipsqueaks, like the ubiquitous Zac Efron and Vanessa Hudgens, of the High School Musical franchise, who are desperate to have their music taken seriously, but don't want to alienate their tween audience. Keeping them entertained on long plane journeys are Bad Day by Daniel Powter, Accidentally in Love by the Counting Crows and Elvis' Hound Dog.
The only trouble with this theory is that the sizeable storage capacity on iPods means you can afford a few more wild cards than if, say, you only had one shelf on which to keep all those clunky cassette tapes. Purists might see it as a way to expand their horizons. But others, like myself, may take the opportunity to indulge in a few guilty pleasures. Pussycat Dolls? Why not? Lady Gaga? May as well.
Anyone flicking through one of these lists will feel thoroughly confused as to their owner's orientation. And well they might. Most of us have a few howlers lurking in the shadows just in case the moment arises when only NSync will cut it.