At first blush, layers of a personality peel back slowly. Upon meeting someone new, a rudimentary judgment blooms based on apparent age, posture, gender, style of dress and even language spoken: Liberal. Likely shops at Whole Foods. Listens to NPR. Intelligent and neat. Clearly owns a cat. Maybe two. Is that a sperm whale tattoo? We are definitely going to be friends. While our brain is adapted to make snappy assumptions, research points to a much faster (and more accurate) way of unlocking key personality elements: listening to their playlist.