This is it can seem close to impossible and then suddenly there it is that elusive

seemingly joyous grin while 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 Plus 1.

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 mother smiled at them.

Three, they wanted to experience simultaneous smiling and four, no smiling at all.

By studying when smiles happens and what the subsequent effect

was the investigators were able to figure out that for mothers the goal

70% of the time was to be smiling simultaneously. While for babies, 80% of the time they just wanted their mother smiling at them.

So mothers want the interaction, while babies just want to be smiled at.

So your baby may not be able to feed itself, talk, or even turn over yet.

But when it comes to smiles, baby seems to know exactly what they're up to.

Thanks for the minute.

For Scientific Americans 60 Second Science,

I'm Erica Barris.