In addition to ordering off foreign menus without having to see pictures, bilinguals have steely minds, more studies are showing. For starters, bilingualism can improve decision making, boost creativity, and stave off Alzheimer's.

Despite evidence for a bilingual advantage, there has been debate over whether it stems directly from speaking two tongues, or if it's the circumstances that allow someone to learn a second language that provide the leg up. For example, the bilinguals in most studies come from middle to upper class families in the US or Western Europe. Their mental skills could simply reflect their privileged childhood, including exposure to multiple cultures, broader experiences and better schooling.

Support for bilingual advantages among low-income individuals has been mixed. Some suggest that it may even be harmful because it confuses children with more words and slows their uptake of the primary language and integration into the culture they live in.

Over at Learning the Language, I read about a forthcoming study in Psychological Science that set out to settle the matter, testing whether bilingualism was boon or barrier for low-income kindergarteners. It turns out the bilingual advantage extends to poor children. Low-income bilingual children have enhanced focus compared to their low-income monolingual peers. This focus could help them overcome distractions that might otherwise impair performance in school.

Led by Pascale Engel de Abreu at the University of Luxembourg, the study tested a group of 40 second-generation Portuguese immigrant kindergarteners living in Luxembourg and a group of native Portuguese kindergarteners living in northern Portugal. Portuguese immigrants living in Luxembourg tend to have low education, provide manual labor, and make low wages. They mostly emigrate from northern Portugal, a poor region of the country.

Engel de Abreu first looked at the kindergarteners working memory. They tested it with the Dot-Matrix task, where dots appear one at a time in various locations in a 4x4 grid. The participant tries to remember the sequence where the dots appeared and then press buttons to indicate the pattern, like a bigger version of the 80s game Simon.

The bilinguals did not significantly differ from monolinguals on working memory. Whereas bilinguals completed an average of 19.1 dots, monolinguals did only slightly better at 20.3. So far, Engel de Abreu saw no evidence for a bilingual edge.

They next looked at measures of inhibitory control and selective attention using the Flanker task. In it, the kindergarteners see five yellow fish in a row across the middle of a computer screen. They are to press a button to indicate the direction the middle fish is facing, either left or right. There are two conditions, an easy and a more challenging one. Sometimes the surrounding fish face the same direction as the middle fish, but other times they face the opposite direction, providing a distraction. Inhibitory control is measured as the difference in response time between the easy condition and the distracting one.

Here, Engel de Abreu found a difference between the groups. Both bilinguals and monolinguals correctly identified the direction the middle fish was facing on 97-percent of trials, regardless of whether the surrounding fish were distracting. However, the bilinguals responded much faster than monolinguals in both the easy and distracting condition.

Bilinguals edge on the Flanker task suggests they are less swayed by irrelevant distractions and better able to focus on their assignment.

According to the authors, as the bilingual kindergarteners had better scores on measures of control, but not working memory, this study suggests that speaking two languages does not boost cognitive function all around. Instead, it provides specific advantages in a few areas—those trained by communicating and thinking in one language while holding the second in check. This skill helps train their cognitive control so that they can stay on task in the presence of distractions.

Importantly, adverse early experiences such as economic hardship can stunt cognitive development. The bilinguals in this study outperformed monolingual peers in measures of focus, despite growing up in impoverished conditions that might normally lead to poor performance. As the authors say:

The present study suggests that bilingualism might also provide protection against the adverse cognitive effects that are associated with poverty. From this perspective, regular use of more than one language is a mentally stimulating activity that provides the opportunity to strengthen executive control mechanisms that build a defense to counteract the negative impact of poverty on cognition.

Although this study looked at Portuguese children living in Luxembourg, here in the US a number of children speak a language other than English in the home, particularly among low-income families. The benefical effects of bilingualism on cognition shown in this study suggest that we should encourage these children to continue speaking both languages. Bilingualism may provide cognitive resources to excel in school and give them more opportunities later in life.

Education Week blog "Learning the Language," by Lesli Maxwell, provided this link to an unedited version of the manuscript to be published in Psychological Science

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