It is true that parents tend to talk more to toddlers who talk back. This is because communication is a two-way process, and when a child responds to their parent’s speech, it encourages the parent to continue the conversation.
When a child is just learning to talk, they often have limited vocabulary and struggle to form coherent sentences. As a result, parents may have to initiate most of the conversation and do most of the talking. However, as a child’s language skills improve and they become more confident in their ability to communicate, they are likely to talk back more and engage in more meaningful conversations.
Hummus. Chewbacca. Tofu. These are just a few of the thousands of words decoded from over 2,000 hours of infants’ daily lives by scientists at Duke. They recently used these data to see if the amount of language children hear can explain why girls have larger vocabularies than boys early in life.
No, it does not.
This research shows that children actively shape their own language environments as they grow. People have long noted that there are sometimes differences between girls and boys for different language skills. For example, language delays and deficits are more common in boys than in girls, raising the question of why.
Shannon Dailey
Instead, Shannon Dailey, Ph.D., a Duke University postdoctoral scholar, and the study’s lead author, discovered that rather than talking more to their young daughters, caregivers appear to talk more to young children who are already talking, regardless of gender. This provides important information for language development.
“This research shows that children actively shape their own language environments as they grow,” Dailey said. Dailey’s new findings stem from her time as a graduate student in the lab of co-author and Duke psychology and neuroscience professor Elika Bergelson, Ph.D. The paper was published in the journal Child Development.
“People have long noted that there are sometimes differences between girls and boys for different language skills,” Bergelson said. “For example, language delays and deficits are more common in boys than in girls, raising the question of why.”
Dailey and Bergelson hypothesized that girls’ typical (and temporary) vocabulary advantage stemmed from their parents providing them with more “language input” than boys. To put that theory to the test, the researchers and a team of research assistants counted the utterances of 44 children (21 girls and 23 boys) over the course of a year, beginning when the children were only six months old. This age range is ideal because they can track what kids are hearing from six months, well before they start talking, to 18 months, when most kids start talking, according to Dailey.
Once a month, babies were given a bright vest that concealed a pocket-sized audio recorder capable of recording a full day (~16 hours) of conversation. On a separate day once a month, they wore a small camera-embedded cap on their head to record video, from which the team extracted audio for analysis.
Bergelson recorded a total of 8,976 hours of audio.
“I’ll be happy if it’s completely transcribed by the time I retire,” Bergelson said.
This is because trancribing a single hour of recorded audio with “fine grain of detail” can take up to eight hours, according to Bergelson. To save time, the team concentrated on the most chatty few hours of each recording, totaling 2,112 hours of sound to unpack.
Still, with 48 hours of audio from each of the 44 kids, a researcher working nonstop starting January 1 wouldn’t finish transcribing it until December 5 the following year (appropriately, that happens to be National Communicate With Your Kids Day). Unfortunately, Siri and its peers aren’t smart enough to automatically transcribe baby talk (or even everyday caretaker talk), so Bergelson relies on research assistants in her lab to annotate everything by ear.
The team’s efforts were rewarded with the release of their latest batch of findings from their massive “corpus,” or finely detailed set of spoken words. Dailey and Bergelson discovered, as others before them, that girls have larger vocabularies than boys and grow their vocabularies faster throughout childhood. Dailey and Bergelson estimated vocabulary size in this case by counting the number of unique nouns children uttered.
“Most of what kids under 18 months say is nouns,” Bergelson said. “So it’s a nice proxy for language development and vocabulary.”
The team then proceeded down the line, attempting to determine what might account for girls’ larger lexicon. Dailey and Bergelson discovered that girls aren’t more talkative than boys — girls and boys spoke the same amount, a finding that others have found persists into adulthood, Bergelson said. That made it less likely that more conversational practice might lead to a bigger vocabulary.
The girls’ larger vocabs were also not due to them speaking earlier. While girls typically warbled their first words around the time of their first birthday, boys lagged behind and began talking a month later, at 13 months of age.
Finally, the team was unable to account for the girls’ larger vocabulary based on what they heard before they uttered their first words. Rather, they found that parents talked more to their kids once they started talking, regardless of gender.
