How babies learn words: Scientists support what parents have known

ST. LOUIS – Brevity, as the Bard said, may well be the soul of wit. But, according to research at Washington University in St. Louis, brevity may help infants learn their first words.

Michael Brent found that before the age of 15 months the words infants learn are mainly those that their mothers utter in isolation. Hearing “kitty,” “red,” or “come” in isolation may make learning those words much easier for young infants than hearing them buried in a longer sentence.

Contradicts theory.

Brent’s findings challenge recent language acquisition theory, which suggests that infants rely heavily on segmenting longer utterances into their individual words.

The segmentation-based perspective emerged in recent years as a number of studies in other laboratories began to show that infants can segment longer sentences.

But in the analysis of eight mothers’ conversations with their infant children, Brent found that 9 percent of all utterances the mothers spoke to their children were isolated words. The words were not only nouns and verbs, but some adjectives and adverbs, too.

Brent said this confirmed that infants have ample opportunity to learn from isolated words, despite suggestions in the scientific literature that they might not.

“We’re saying, ‘Wait a minute, they can segment, but is this ability actually called upon for early word learning?’ We think that speech segmentation is important later on, when kids are learning words really fast, but it may not be relied upon at the beginning, when they’re learning slowly,” Brent said.

Short and sweet.

The current study shows that the first words children tend to learn are words their mothers speak in isolation, suggesting that such isolated words may form a foundation for early vocabulary learning.

The notion that mothers’ isolated words help young infants learn is part of Brent’s larger theory about how our instinctive style of speech to children helps them learn language.

“Short utterances lay bare the structure of language,” he said. “For example, in a long sentence like ‘I know the famous scientist you’re discussing,’ it may be difficult for a child to figure out what the phrase ‘you’re discussing’ relates to. Does it modify ‘scientist,’ or is it what the speaker knows? In a short utterance like ‘I know Elmo,’ it’s obvious that ‘Elmo’ is the direct object of ‘know’.”