Mommies, take note: when your babies smile, it’s not just to react to you but to make you smile in return. They do so with great comic timing, performing the act while smiling as little as possible.

These are the findings of a University of California San Diego study published on the Sept. 23 issue of PLOS One, where a team of computer scientists, roboticists, and development psychologists found that babies smile with a purpose.

“They’re not just smiling randomly. But proving this is difficult,” said Javier Movellan, a cognitive scientist from the Machine Perception Laboratory at U.C. San Diego.

Researchers programmed a robot named Diego-San to behave like a baby and simulate how babies smile. Interacting with student volunteers during individual 30-minute sessions, the robot elicited lots of smiles – with little effort.

“When we ‘transplanted’ the strategies that infants use in smile games, into the robot, these strategies had the predicted effect,” Movellan said, who himself used to watch his three-month-old baby Marina smile and wonder if she was trying to communicate with him.

The robot’s behavior was patterned after those of babies from a previous study, which observed the face-to-face interactions of 13 pairs of mothers and babies under four months of age. From the control theory data analysis they discovered that 11 of 13 babies showed clear signs of intentional smiling.

“They are active game players with their own agenda, rather than passive responders to what mom does,” Movellan added.

Study co-author Dan Messinger from the University of Miami highlighted the uniqueness of the study.

“[P]revious approached to studying infant-parent interaction essentially describe patterns. But we couldn’t say what the mother or infant is trying to obtain in the interaction. Here we find that infants have their own goals… even before four months of age,” he said.

The findings are believed to help create robots in the future that will mimic social interactions between babies and their parents – technology that could help scientists better analyze the social development of kids, including atypical ones such as in the case of autism.

Movellan will demonstrate related work at the Contextual Robotics Forum at the Jacobs School of Engineering at UC San Diego on Oct. 30.

Photo: David Salafia | Flickr