There is a long-held belief that bilingual children have an advantage over children who speak just one language when it comes to cognition. But new evidence reveals it may be a myth.
In a series of recent papers, researchers, including Western’s J Bruce Morton and Cassandra Lowe, show that the notion of a bilingual advantage in children is propped up by weak evidence and bias in the reporting of scientific findings.
In a recent publication that appeared in the high-impact journal Psychological Science, the Western neuroscientists reviewed 25 years of evidence and found that after correcting for publication bias the effect of bilingual language status on children’s executive function dropped to zero.
“Despite a quarter-century of confirmation bias, we discovered that there is ultimately no difference in cognitive ability when comparing children who are bilingual versus those who are monolingual,” said Morton, principal investigator at Western’s Brain and Mind Institute. “Yes, there are advantages to being bilingual when it comes to career opportunities and traveling the world, but there is zero evidence it makes children any smarter, in the traditional sense.”
Why then have so many studies found evidence of the bilingual advantage?
To address this question, Morton teamed up with researchers at Yonsei University in Seoul, Korea, and Brandeis University in Waltham, Mass., to critically re-examine foundational evidence, including a 1999 paper published in the journal Child Development titled, “Cognitive complexity and attentional control in the bilingual mind.” This paper, which has been cited more than 1,100 times since its publication, claimed that bilingual children are advantaged relative to monolinguals based on evidence that Chinese-English bilingual preschoolers outperform English monolingual preschoolers on measures of attention.
“The problem with this evidence,” said Morton, “is that it is well-known that preschool children from East Asia outperform preschool children from North America on tests of attention. And if you look at the 1999 study, it is obvious that language status and country of origin are perfectly confounded.”
The researchers first showed flaws in the design of the 1999 study by proving East Asian bilingual children outperform English monolinguals on measures of attention. However, they then compared East Asian bilingual children with East Asian monolingual children and found that East Asian monolingual children performed just as well as the East Asian bilingual children, with both groups “advantaged” compared to English monolinguals.
Morton believes the findings of the 1999 study say more about the strength of Asian childcare systems than the importance of bilingual language experience.
“Regrettably, what we consider foundational evidence in support of the bilingual advantage in children is critically flawed,” said Morton. “Looking at the broader picture, it is clear that bilingual language status has zero effect on children’s attention.”