Why do babies smile?: Study Why Babies Smile

Published: September 27, 2015

Why do babies smile?: Study Why Babies Smile, Smiling is not necessarily an emotional behavior for babies. According to a new study out of UC San Diego, smiling is first and foremost a social and relational act destined to make the mother smile in return.

Babies often smile with a goal in mind: to make the person they are with smile in return. To prove this hypothesis, a team of computer scientists, roboticists and developmental psychologists from the University of California – San Diego programmed a toddler-like robot to behave like the babies they studied and had the robot interact with undergraduate students.

Their conclusions, published in the Sept. 23 issue of PLoS ONE, reveal that the robot got the undergraduates to smile as much as possible while smiling as little as possible.

A mix of developmental psychology and robotics, this innovative study used the robot as a tool for scientific research. Scientific teams already use it to better understand nonverbal communication between children and adults, particularly in cases involving autism.

“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.”

This is why the team turned to optimal control theory, a tool often used in robotics. This method allowed the researchers to design and program a robot to perform a specific behavior based on specific goals. For the purpose of this study, the researchers used the method to reverse engineer what the babies’ goals were based on their behavior.

The team 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.

The researchers were surprised that the control theory data analysis found that 11 out of the 13 babies in the study showed clear signs of intentional smiling.


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