We are very good at seeing faces in things. There are even blog sites devoted to it. However, it's a lot more complicated than that. A new-born baby with no visual knowledge of life, will fixate on a face for much longer than other shapes, indicating it must be innate. Babies will even attend to a round card with felt-pen dots for eyes, and an 'O' mouth. We can measure the point at which the 'face' becomes 'not-face-appearing-enough' to hold a baby's attention. There are some interesting studies that attempt to measure the 'interest' a baby has in looking at a face. It seems we are extremely good at seeing tiny differences in faces when we are born, but it is thought that our baby brains become less discerning over the first year, due to limited exposure to variety of facial types. Here's more.