What is it about?

The question about whether bilingualism affects children's intelligence has been debated for about 100 years, but the answer has changed dramatically. In early studies, the conclusion was that bilingualism confused children and reduced their intelligence; in later studies, bilingualism was considered to enhance intelligence. We argue that these conflicting conclusions are based on different types of research. Positive outcomes began to appear after research switched from using standardized intelligence tests to cognitive tasks for which there are beneficial effects of bilingualism. However, the results showing categorically negative or categorically positive effects on intelligence tests have never been replicated. The present study reports the results of over 6,000 participants performing standardized intelligence tests and finds no effect of bilingualism.

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Why is it important?

Bilingualism is a common experience that on some estimates includes more than half of the world's population. Therefore it is important to understand whether managing two languages impacts children's intelligence. By distinguishing between intelligence tests and cognitive tasks, we showed that whatever controversy continues to be played out over cognitive task results, there is no evidence that bilingualism systematically impacts children's intelligence. There are direct applied implications. Based on the false belief that bilingualism decreases intelligence, parents have removed languages from children's experiences, including home heritage languages, clinicians have misdiagnosed bilingual children as having language or learning disabilities, educators have confused language proficiency with intelligence, and children have been deprived of the opportunity to connect with their culture, heritage, and extended family.


The question about the potential impact of bilingualism on development has become highly charged with strong opinions and counter-opinions being proposed. By showing that some of that discussion is based on a confusion between two different research traditions, it is possible to evaluate the evidence objectively. In so doing, we find that there is no difference in intelligence scores for monolinguals and bilinguals.

Ellen Bialystok
York University

Read the Original

This page is a summary of: The swerve: How childhood bilingualism changed from liability to benefit., Developmental Psychology, April 2022, American Psychological Association (APA),
DOI: 10.1037/dev0001376.
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