A new study on children who are raised bilingual examined the effects on children's development of growing up speaking two languages. The study found that different factors were responsible for the language- and non-language-related outcomes of bilingualism found in previous research.
The research was carried out at York University in Toronto and published in the journal Child Development.
Bilingual children show differences in how they develop language and cognitive skills through the early school years. Children who grow up speaking two languages have slower language acquisition in each language than children raised speaking just one language. However, they have better metalinguistic development that gives them a deeper understanding of the structure of language, a skill that's important for literacy. And they perform better on tests of nonverbal executive control, that is, tests that measure children's ability to focus attention where necessary without being distracted and shift attention when required.
Because bilingualism is often tied to other factors—including differences in culture, socioeconomic status, immigration history, and language—it's difficult to determine which aspect of the bilingual experience is responsible for outcomes, or indeed, whether it's bilingualism at all.
To determine what effects can be associated with being raised speaking two languages, researchers compared more than 100 6-year-old monolingual and bilingual children (English monolinguals, Chinese-English bilinguals, French-English bilinguals, and Spanish-English bilinguals) using three tasks that measured verbal development and one nonverbal task that measured executive control. All the children had similar levels of socioeconomic status.
The bilingual groups differed in the degree of similarity between languages, cultural background, immigration history, and language of schooling. Nevertheless, on an executive control task in which children needed to switch between two sorting rules to classify a set of pictures, all bilingual groups performed similarly and exceeded monolinguals. Differences in language, culture, and immigration all produced the same bilingual advantage compared to the monolinguals. In contrast, the best performance on the language tasks was achieved by bilingual children whose language of instruction was the same as the language of the test and whose two languages had more overlap.
"In sum, executive control outcomes for bilingual children are general, but performance on verbal tasks is specific to factors in the bilingual experience, like how close a child's two language are, and whether they are assessed in the same language they are taught in school," according to Ellen Bialystok, Distinguished Research Professor in the department of psychology at York University, who took part in the study.