Try to get a baby to smile? It can seem close to impossible and then suddenly there it is: that elusive, seemingly joyous grin. Well it turns out those smiles aren't spontaneous they're strategic. Researchers have found that when babies smile, it's for a reason. They want whoever they're interacting with typically a parent to smile back. And they time it just so, a smile here and a smile there. The researchers call it sophisticated timing. The study is in the journal PLOS ONE. The researchers enlisted real mothers and infants and quantified their interactions, which fell into four categories. One: babies wanted to maximize the amount of time smiling at their mothers. Two: they wanted to maximize the time the mothers smiled at them. Three: they wanted to experience simultaneous smiling, and four: no smiling at all. By studying when smiles happened and what the subsequent effect was, the investigators were able to.