A new study from the University of Sussex shows that we start stereotyping babies based on gender as young as three months old. We assume that babies with higher-pitched cries are female, and that the higher-pitched the cry relative to gender, the more discomfort the baby is in. The study recorded real babies in a situation almost guaranteed to make them wailbath time. The recordings were were made at home, over a period of four months. After some processing, the sounds were played back to participants in randomized, double-blind tests. The listeners were found to assess the babies sex based on the pitch of their cries, and to attribute stress levels dependent on pitch. Men assumed male babies were more stressed than females when both were crying at the same pitcha result the author believes indicates gender stereotyping is more ingrained in men.