We know that the pace of learning is fastest during the first years of life. It is at this time that brain neuroplasticity is highest, predisposing the brain to collecting and storing the basic elements of language (particularly sounds). A Canadian research team wanted to know if first language acquisition could have an impact on the processing of another language system. How is the “presence” of this first language manifested even when it's no longer practiced?

For their study, published in Nature Communications, researchers from McGill University in Montreal looked at a cohort of 43 French-speaking children and adolescents from ages 10 to 17, some of whom had been exposed to Chinese at an early age. In compliance with Chinese adoption policy, and for the sake of comparison, all participants were girls. The subjects were divided into three groups. The first group consisted of 21 children adopted in China before the age of 3 by French monolingual families (these children thus had no further contact with the Chinese language); the second group consisted of 12 Chinese-French bilingual children (they had learned Chinese from birth and French from the age of 3); the third consisted of 10 French monolingual children that had never been exposed to Chinese.

The researchers had the children in the three groups listen to 36 French bi-syllabic pseudo-words: nonsense words that sounded like French words, such as “vapagne” and “chansette.” Pseudo-words are useful for studying the way in which the brain processes the sounds of a language that is fluently spoken based on the languages that were heard from a young age (without any lexical interference). The participants were invited to identify a target within a sequence of pseudo- words. In order to see which parts of the brain were activated during this phonological memory task, the researchers used a functional MRI.

Though each group performed equally well on the task, the groups showed different patterns of neural activity. Indeed, in all of the participants in groups 1 and 2, other regions of the brain (involved in memory and attention) were activated, but no such activity was seen in group 3 participants. The fact that the MRIs of the adopted Chinese participants closely matched the patterns of bilingual children provides evidence supporting the view that neural representations acquired during the first months of life are not lost, but continue to be maintained in the brain.

These results indicate that a first language experience, however brief, can influence the phonological processing of language learned later on. According to Lara Pierce, learning one language from a very young age could thus change the way we learn another language. The author notes, however, that there is currently no way to determine if learning a new language will be easier or more difficult for children exposed since birth to a different first language.