Understanding how infants acquire new words across cultures

EVANSTON, Ill. --- Infants show strong universals as they acquire their native language, but a recent study with infants acquiring Korean also reveals that there are striking language differences.

Sandra Waxman, Louis W. Menk Professor of Psychology at Northwestern University, is senior author of a new study providing the first ever evidence comparing how infants (monolingual, from Korea) acquiring Korean learn new nouns and verbs.

Researchers have long suggested that in noun friendly languages including English, infants' attention is focused primarily on objects, typically marked by nouns. In verb friendly languages including Korean, Japanese and Hindi, verbs are said to enjoy a more privileged status because infants' attention is focused more directly on the actions and relations typically marked by verbs.

Almost all of the research on infants acquiring these verb-friendly languages has looked at the nouns and verbs that they produce in their daily lives, said Sudha Arunachalam, lead author of the study and assistant professor of speech and hearing sciences at Boston University.

By using an experimental method instead, our approach lets us watch infants acquire new words, so we can get real insight into the mental processes that are at work during learning.

Waxman said their new work shows strong universals in language acquisition, but also shows some real cross-linguistic differences.

Like infants acquiring other languages, Korean infants very successfully learn nouns to name objects such as ball, bottle and boy, Waxman said. However, when it comes to learning verbs -- names for activities and relations -- like running, hugging, twirling, we see differences across languages.

Previous research had shown that in English, 24-month-old infants were better able to learn novel verbs for novel actions (e.g., petting) if the surrounding noun phrases were explicitly mentioned (e.g., The girl is petting the dog) than if they were dropped from the sentence (e.g., Look. Petting!). In contrast, the new research shows that in Korean (a language in which noun phrases are typically dropped in conversation) 24-month-olds were better able to learn novel verbs for novel actions if the surrounding noun phrases (e.g., the girl, the dog) were dropped; in fact, unlike English-acquiring infants, those acquiring Korean struggled if the nouns were explicitly mentioned.

We know that even before infants begin to say many verbs, they begin to understand them, Waxman said. What this new research tells us is that the information that infants need to 'get' that understanding varies, depending upon the native language they are learning. This piece of the language acquisition process is not universal; instead, it is 'language-specific.'

Even in the early stages of language learning, infants are shaped by the structure of their native language, so much so that the way they learn verbs is influenced by the way they've been hearing verbs in the ambient language, even before they could understand them. This means that like early speech and music perception, the structure of what infants passively hear influences how they actively learn, Waxman said.