Bilingual children score higher on some cognitive tests than children who speak only English, a new Toronto study found.

It's known that children who grow up speaking two languages tend to be slower in picking up each language than children raised speaking just one, but the study suggests the benefits of bilingualism outweigh any drawbacks.

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Grade 1 students watch a replay on a video camera to practise their oral French skills. Bilingual children develop a deeper understanding of the structure of language, researchers have found. (Joanna Sanders Bobiash/Canadian Press)

Bilingual children develop a deeper understanding of the structure of language, an important skill for literacy, researchers from York University said in Wednesday's online issue of the journal Child Development.

"People always ask if the languages themselves matter and now we can definitively say no," study co-author, Prof. Ellen Bialystok, of York's psychology department said in a release.

The researchers compared 104 six-year-olds (English monolinguals, Chinese-English bilinguals, French-English bilinguals, Spanish-English bilinguals) to measure their cognitive development.

The experiments investigated the effects of language similarity, cultural background and educational experience on verbal and non-verbal abilities.

The children did a battery of tests that measured verbal development and one non-verbal task that measured executive control, in this case, the ability to focus attention where necessary without being distracted and shift attention when required.

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The benefits of bilingualism are evident from early childhood to the senior years, Prof. Ellen Bialystok says. (York University)

The three bilingual groups exceeded their monolingual peers in task switching.

"The results endorse the conclusion that bilingualism itself is responsible for the increased levels of executive control previously reported," the study's authors wrote.

To acquire language, bilingualism where the languages are similar in origin may have slight advantages, the researchers found. For example, Spanish-English bilinguals outperformed Chinese-English bilinguals and monolinguals on a test of awareness of the sound structure of spoken English.

Bilingualism tied to other factors

The findings suggested that performance on verbal tasks depends on how close a child's two languages are and whether they are assessed in the same language they are taught in school, Bialystok said.

Because bilingualism is often tied to other factors such as culture, socioeconomic status, immigration history and language, the researchers partly took those into account by enrolling participants who all attended public schools and came from similar socio-economic backgrounds.

All of the children lived in an English-speaking community in the Toronto area. The French-English bilingual children attended schools where they were instructed in French. The others attended schools where classes were in English.

Last year, Bialystok's team showed bilingualism may delay the onset of Alzheimer's disease.

The study was funded by the U.S. National Institutes of Health.