News Release

Two languages in one child's brain - When is bilingual language learning best

Peer-Reviewed Publication

Dartmouth College

HANOVER, N.H. - A Dartmouth research team has determined that bilingual children exposed to two languages early in life are not language delayed, nor are they language confused, which fuels the scientific and political debate over when to introduce children to a second language.

Laura-Ann Petitto, Professor in Dartmouth's Department of Psychological and Brain Sciences and Department of Education, and Dartmouth graduate student Ioulia Kovelman, report their findings at the Society for Neuroscience's annual meeting, November 2-7, in Orlando, Fla.

"We found that if children are exposed to two languages from a very early age," says Petitto, "they will essentially grow as if there were two monolinguals housed in one brain, and this will occur without any of the dreaded 'language contamination' often attributed to early bilingual exposure."

This finding coincides with the November 5th election where continuing or abolishing bilingual education is a ballot question in Mass.

"Some experts say that a second language shouldn't be introduced until a child has a firm grasp of a primary language," says Petitto. "Often people think that later bilingual exposure is safer, but we found that early bilingual exposure is better."

The researchers studied 15 bilingual children exposed to two languages from varying ages. Each age group of young bilinguals was at a different stage in child brain development, including bilingual babies exposed to two languages from birth (group 1), babies exposed to one language from birth with intensive bilingual exposure beginning within ages 2-3 years (group 2), babies exposed to one language from birth with intensive bilingual exposure beginning within ages 4-6 years (group 3), and babies exposed to one language from birth with intensive bilingual exposure beginning within ages 7-9 years (group 4).

"By matching the time of bilingual language exposure to key maturational stages of brain development," says Petitto, "we anchor our findings in the biology of the way the brain grows."

Four cross-linguistic populations of children were studied, including Spanish and French, French and English, Russian and French, and Sign Language and French. The researchers then intentionally studied young children who were receiving their dual language exposure across the three contexts that are most typical of a child's exposure to a new language: some of the children were exposed to two languages in their homes; some received intensive exposure to a new language when they moved into a new language community; and some children spoke one language at home and were then exposed to another language in an instructional classroom setting only.

"We wanted to study how all of the children's basic knowledge of their two languages developed over time and, thus, in our attempt to be as comprehensive as possible, we examined children across multiple languages, ages and contexts," explains Petitto.

The findings also indicate that late exposure to a second language coupled with restricted input, which is common in instructional classroom settings, may never allow a child full mastery in that language. However, a child's two languages can and will flourish, even if exposure comes at a relatively late age if they have extensive exposure to both languages.

The Petitto team is now studying whether bilingual children read better when they are exposed earlier in childhood to their two languages rather than later.


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