"Look at the, uh, zebras, honey," a mom might say to her 2-year-old during a visit to the zoo. While the stumble or hesitation may seem like the most unimportant part of the conversation, it can play a major role in the toddler's language development.
So says a new study from the University of Rochester published in the journal Developmental Science. Researchers found that young children used those "ums" and "uhs," technically known as speech disfluencies, to acquire new words.
"Around the age of 2, kids start being able to use speech disfluencies to anticipate what the speaker is likely to talk about," said Celeste Kidd, the lead author of the study.
Kidd, a fourth-year doctoral candidate specializing in language development and attention in infants and children, said people mostly use such sentence fillers when the word being sought is not used often or has not yet come up in the conversation.
"Perhaps the most important aspect is that the study shows it's not just the words toddlers are attending to, but it's these nonlinguistic cues as sources of information," said Kidd.
The study included 16 children between 18 and 30 months old. As the researchers did their work, the children sat on their parents' laps in front of a screen with an eye-tracking machine. On the screen, two images appeared: One was a picture of a familiar item, such as a car or book, and the other was a made-up image with a made-up name, like "biffle" or "spad."
A voice recording then talked about the objects in simple sentences. When the voice stumbled and said, "Look at the, uh ..." the children turned their eyes to the made-up image 70 percent of the time.
Significant differences were found only in children 2 years old or older.
"The most important finding [here] is that children at about age 2 are highly sensitive to features in the environment that help them learn language," said Dr. Heidi Feldman, a professor of developmental and behavioral pediatrics at Stanford University School of Medicine.
Between the ages of 2 and 3, children can usually put together basic sentences of two to four words. Infants learn to recognize the language of their environment depending on how often sounds occur together, Feldman said. And toddlers learn words and concepts according to the number of words they hear, learning grammar from the kinds of requests their parents make.
"Word learning is typically thought of as a map, where there is an object in the world and that gives a map to some spoken set of sounds," said Kidd. But the study, she said, suggests that very young children seem to understand words in a broader, more general way too.
Don't Change to All 'Ums' and 'Uhs'
The researchers, however, do not encourage parents to intentionally pause or hesitate when speaking to their children.
"The point is to talk frequently to children, and the natural processes you use within the language will support the child's learning," Feldman said.
"This study shows that what is said and how it is said is important in language learning," said Sandra G. Combs, assistant professor in the department of communication sciences disorders at the University of Cincinnati. "Quantity and quality both matter."
Feldman said the study suggests that toddlers are good language learners -- they detect subtle cues about when to fix their attention on difficult words. She encourages parents to use a rich and varied vocabulary with children.
"We know that children who are good language learners become good readers," said Feldman. "We know that children who are poor readers rarely catch up with others after the third grade."
"Talk with your children," said Feldman. "Describe the world around you. Expose them to new words every day. Read books together. Keep those simple commands to a minimum. These experiences improve your child's learning and mature your child's brain."