Babbling babies need timely responses to learn language, social norms

Deploying a remote-controlled car that would approach and produce speech sounds in response to babbling, researchers found that within 10 minutes, babies formed strong expectations that the car would respond to their vocalizations. When it stopped doing so, the babies erupted in bursts of babbling and play directed at the car -- a stronger reaction than when they were communicating with people.

The study shows that in early development, foundational learning about where to direct one's attention hinges on "contingency" -- caregivers' responses close in time to the baby's behavior, the researchers say. At least in the first year, they suggest, babies are highly "plastic," or flexible, in what they will learn from contingently, even including machines that lack human features.

The finding counters assumptions by some developmental psychologists that babies, like other slowly developing animals, rely on built-in, genetically based knowledge, such as face recognition, to learn, said psychology professor Michael Goldstein.

"We're showing the opposite," said Goldstein, director of the Behavioral Analysis of Beginning Years (B.A.B.Y.) Laboratory. "What's built into the baby is to pay attention to timing, and the world takes care of the rest. Babies are learning machines, and it's on the adults to be responsive in the right ways to drive that learning."

Goldstein is the corresponding author of "Contingency Enables the Formation of Social Expectations About an Artificial Agent," published in the journal Infancy.

More than 60 babies, ages 7 and 8 months, were placed (with caregivers present) in a large playroom with either a remote-controlled car or a person they didn't know. For some infants, the car or person responded when they babbled -- contingently -- at the same rate their caregiver would. The car would roll forward and emit a vowel sound from an attached speaker, while the unfamiliar person would make a similar sound, touch the baby's shoulder and smile. For other groups, the car or person responded on a random schedule not triggered by the baby's vocalizations, known as a yoked control.

After 10 minutes of social interaction, the car or person stopped responding for two minutes. That prompted the babies in each group to became more vocal -- but none more than the ones playing with the car that was responsive to them.

"When that contingent car stopped responding, the babies grabbed the car, moved the car, they babbled like crazy at it," said Goldstein.

The researchers suspect the plasticity the babies exhibited, which starts at around five months, is an advantage while they are learning how to learn -- but may fade as they gain language proficiency.

The findings may offer insight into foundational learning mechanisms, something Goldstein's lab is beginning to study in babies at risk for autism, who might prefer more predictable response rates than typically developing babies.

The research was supported by the National Science Foundation and the National Institute of Child Health and Human Development.