Why do babies smile when they interact with their parents? Could their smiles have a purpose? In the Sept. 23 issue of PLOS ONE, a team of computer scientists, roboticists and developmental psychologists confirm what most parents already suspect: when babies smile, they do so with a purpose--to make the person they interact with smile in return.
In addition, babies reach that goal by using sophisticated timing, much like comedians who time their jokes to maximize audience response. But there is a twist: babies seem to be doing this while smiling as little as possible.