How do babies learn to talk? Across languages and cultures, parents simplify their speech significantly in response to babies’ babbling and early speech – an exchange that appears fundamental to early language development, new Cornell research finds.
The researchers’ analysis of more than 1,500 transcripts of parent-child interaction in 13 languages found this “simplification effect” not only in the industrialized West, but in a community of subsistence farmers known for a distinctly different parenting style.
In each case, caregivers simplified their “contingent” speech – their immediate responses to babies’ and toddlers’ vocalizations – but not other communication with the children, who were between 5 and 30 months old.
The findings show babies and toddlers actively shaping conditions that make language easier for them to learn, the researchers said, rather than picking it up passively, as some have theorized. And by reducing the complexity of their contingent speech – often unconsciously – adults complete a feedback loop that drives learning and may be key to how languages are transmitted from one generation to the next.
“Babbling has long been thought of as immature, incomplete acoustic noise from a system that doesn’t yet know how to produce well-formed adult speech,” said Michael Goldstein, professor in the Department of Psychology and the College of Arts and Sciences, and director of the Behavioral Analysis of Beginning Years (B.A.B.Y.) Laboratory. “It’s actually an instrument babies and toddlers use to get learnable information from their environment.”
Goldstein is the corresponding author of “Immature Vocalizations Elicit Simplified Adult Speech Across Multiple Languages,” published Feb. 6 in Current Biology with first author Steven Elmlinger, Ph.D. ’23, now a ³Ô¹ÏÍøÕ¾ Institutes of Health postdoctoral fellow at Princeton University; and co-author Jacob Levy ’22.
Goldstein and Elmlinger in previous research identified behavior they dubbed the simplification effect: parents using shorter sentences with fewer types of words, including more one-word utterances, when reacting (within three seconds) to babbling. They set out to see if that phenomenon was widespread despite differences in language structure and child-rearing practices.
Analyzing time-stamped transcripts spanning five language families, most collected by the Child Language Data Exchange System (CHILDES) database, they found the effect was indeed common and robust, whether caregivers spoke French or Spanish, Swedish or Estonian, Korean or Japanese, as well as several additional languages.
“Across many languages, babies and toddlers producing immature speech quickly elicit speech from caregivers that has a simplified structure relative to the rest of the caregivers’ speech,” Elmlinger said. “They create these ideal moments of learning from mature speech patterns.”
Importantly, the research team observed the simplification effect even among the Tseltal Mayan, subsistence farmers in southern Mexico known not to engage with children in the singsong, face-to-face manner prevalent among American caregivers. Some developmental psychologists saw that variance as evidence that infants don’t rely on their social environment to develop language, so they must either possess an innate understanding of it or learn in an indirect way.
“The traditional theory says that if adults in a culture don’t produce this infant-directed speech, their children must be passively learning language by overhearing other people,” Elmlinger said. “We’re really overturning that. These parents are providing direct feedback and learnable information in vocal turn-taking with their kids.”
Babies’ ability to coax simpler language models from adults highlights what the researchers say is an advantage, not drawback, of humans being a slowly developing (altricial) species. Instead of worrying about survival, infants’ have an extended period during which they can focus resources on learning, including a culture’s communication norms. That places a greater onus on caregivers to provide verbal feedback, which most instinctively do – though B.A.B.Y. Lab research has found many don’t realize they’ve simplified their contingent speech.
The findings may have implications for parent interventions. For example, scholars and policymakers have long known that lower-income children are exposed to many fewer words by elementary school than those in more affluent families. Instead of simply encouraging parents to talk to their children more, Goldstein and Elmlinger said, the emphasis should be on the timing and quality of parents’ speech. Infants and toddlers are capable of leading conversations, and parents should respond to their immature vocalizations quickly, since contingent responses are naturally simplified in ways that create learning opportunities.
“We want parents to know, not only are your kids listening to you when you react to their immature behavior, they’re learning in the moment and they’re learning fast,” Goldstein said. “To see it in languages where we thought caregivers weren’t giving their kids that kind of feedback is pretty remarkable.”
A ³Ô¹ÏÍøÕ¾ Science Foundation grant supported data collection for the research.
