September 24, 2015

Babies Time Their Smiles to Make Their Moms Smile in Return

Babies are trying their moms smiles as much as possible,
while they smile as little as possible.

Toddler-like robot allows researchers to confirm their findings

(September 24, 2015)  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.

Researchers detail their findings in an innovative study that combines developmental psychology, computer science and robotics—an approach that has never been tried before, to the best of the researchers’ knowledge. The study is part of an effort funded by the National Science Foundation to use robots to better understand human development. It gives developmental psychologists a tool for studying non-verbal children and adults, such as those with autism, researchers said.

To verify their findings, researchers programmed a toddler-like robot to behave like the babies they studied and had the robot interact with undergraduate students. They obtained the same results: the robot got the undergraduates to smile as much as possible, while smiling as little as possible.

“If you’ve ever interacted with babies, you suspect that they’re up to something when they’re smiling. They’re not just smiling randomly,” said Javier Movellan, a research scientist in the Machine Perception Laboratory at the University of California, San Diego, and one of the study’s authors. “But proving this is difficult.”

Diego-san, a toddler-like robot, interacted with undergraduates during three-minute sessions.

To find out what babies are really up to, researchers turned to optimal control theory, a tool often used in robotics. The method allows researchers to design and program robots to perform a specific behavior based on specific goals. In this study, the researchers used the method to reverse engineer what the babies’ goals were based on their behavior.

Researchers used data from a previous study that observed the face to face interactions of 13 pairs of mothers and infants under the age of four months, including when and how often the mothers and babies smiled. After running the data through their reverse-control theory algorithms, researchers were actually surprised by the findings, said Paul Ruvolo, a professor at Olin College of Engineering and an alumnus of the Jacobs School of Engineering at UC San Diego. “We thought either the babies had no goal or it was about mutual smiling,” he said. Researchers are careful to point out that they can’t determine if the babies are conscious of what they’re doing. “We are not claiming that a particular cognitive mechanism, for instance conscious deliberation, is responsible for the observed behaviors. Our methods are agnostic to this question.” Ruvolo said.

journal reference (Open Access) >>