Why You Can Understand What Your Baby Is Trying to Say

Adults might be hardwired to understand the nonsense baby-talk of toddlers, scientists have found.

This ability of grown-ups to parse the early attempts of children to talk may also help the children learn how to speak properly faster, a new study in the journal Nature Human Behaviour reveals.

As babies begin to learn language, they start by using single syllables such as "da" or "ba," which can be interpreted to mean a variety of things depending on the context of their lives. The adults in that child's life who have a lot of experience listening to that child are very effective at understanding what these early words actually mean, the paper says.

The authors of the paper created computational models using thousands of hours of audio of children ages 1 to 3 and their caregivers interacting, taken from Brown University data from the early 2000s. The models that used only the sounds of the children at the time were much less successful at predicting how the adult would interpret the child compared to models that made predictions based on preceding conversations between the adult and child.

Essentially, the models were more successful at predicting how the adult would respond if the previous context of their conversations were taken into account.

"We use what an adult human who is experienced in listening to this child thinks the child said as the 'ground truth' for what the child said, and then ask what information a model has to rely on in order to arrive at the same interpretation of the child's speech," Elika Bergelson, an associate professor of psychology at Harvard, and co-author of the paper, told Newsweek.

"We find that models need information about the recent conversation, knowledge of the kinds of things kids like to talk about, and knowledge of how children tend to mispronounce words. With all of these things, our best model interprets 90 percent of words that we look at children saying the same way that the human listener does," she said.

"For comparison, a model that only knows about how children are likely to mispronounce words interprets only 42 percent of words in the same way—so it looks like human adults are bringing a much richer set of helpful assumptions to the table to be able to understand what children say."

This suggests that adults are hard-wired to be skilled at making these context-dependent interpretations and that it may help the babies learn language. The adults can interpret a child's true meaning despite mispronunciations or misinterpretations—for example, that "weed" might mean "read" or that "da" might mean "dog" if a dog had previously been mentioned in the same conversation.

"Our skills at understanding speech are being honed constantly in our daily lives," Roger Levy, a professor of brain and cognitive sciences at MIT and co-author of the paper, told Newsweek. "When you're on a noisy sidewalk talking with a friend on the phone, the audio quality may not be very good, but the context of the conversation helps you figure out what your friend is saying.

"If your new coworker has a strong foreign accent, it becomes easier to understand them as you get used to their accent. The same factors help us listen through the "noise" to understand what young children say, especially as we gain experience interacting with them," he said.

This ability of adults to understand what a child is saying despite their mistakes and respond in kind is helpful for the child to learn how to speak properly, the researchers suggest, but this topic requires more research.

"We don't know that it does yet—this specific study is limited to figuring out how adults understand children's speech," Stephan Meylan, an MIT computational cognitive scientist and paper lead author, told Newsweek. "That said, we are interested in looking at this in future work.

These adult listening abilities might help children communicate very early and highlight that speech is a good way to share information with others," said Meylan. "That said, there is a lot of diversity in how adults and children interact across the world, both within and across different social and cultural contexts. This means that there are very likely many pathways to understanding language."

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