A universal sign of motherhood is the lullaby. The world over, mothers sing to their babies, whether Twinkle Twinkle Little Star, their favorite song from the radio, or even random notes. This universality makes the simple lullaby a great window into the human mind. In a new study, cognitive neuroscientists found that lullabies soothe both moms and babies simultaneously, while playsongs increase babies' attention and displays of positive emotion toward their mothers.