‘Bilingual’ Babies Show Cognitive Gains


by Maria Schamis Turner

June 18, 2009

A recent study shows that being exposed to two languages directly from birth enhances executive function in infants before they begin to talk.

Neuroscientist and lead author Ágnes Melinda Kovács, from the Hungarian Academy of Sciences, and her colleague Jacques Mehler, from the International School for Advanced Studies in Trieste, Italy, performed three eye-tracking experiments with 7-month-old infants to compare the performance of those who had been exposed to two languages since birth with those who had been exposed to only one language. The groups were matched for age, sex and socioeconomic status.

In the first experiment, all infants were tested on a “switch” task, requiring the use of executive function. First, they were presented with a sound followed by a visual reward (a puppet) that would always appear on the same side of a blank screen. In just three or four trials, both sets of infants learned to predict, based on the sound they heard, which side of the screen the puppet would appear on. Learning was measured by using an eye tracker to record where the infants directed their gaze.

Next, researchers switched the side of the screen the puppet appeared on, requiring the infants to redirect their attention and disregard what they had just learned, tasks that involve increased cognitive control. In the post-switch trials, the infants exposed to two languages learned much faster to predict where the puppet would appear than did those from monolingual households.

The researchers repeated the experiment in similar groups of infants, first by adding another auditory cue to indicate the switched side, then by using visual cues instead of auditory ones. In both of these follow-up experiments, the infants exposed to multiple languages again reacted faster.

Previous studies have shown that bilingual adults and children have improved cognitive control, which has been ascribed to their need to inhibit one language in order to speak the other. “It was thought that the verbal response was critical for the enhancement of executive functions,” says Mehler.

The results of this experiment suggest that processing two languages leads to enhanced cognitive control even before the onset of speech. The study was published online April 13 in the Proceedings of the National Academy of Sciences.

“I think the results are very exciting and very interesting,” says Linda Polka, a researcher with the School of Communication Studies and Disorders at McGill University, who was not involved in the study. One question that arises, she says: “Do you really have to have two different languages in your environment for this effect? What if you have two very different dialects of the same language?” Polka says the research also raises questions about what this “edge in executive function” gives bilinguals. “Does it give you a leg up on learning a third language, or in other cognitive tasks?” she says.

Mehler is careful to point out that the results do not mean that infants exposed to more than one language are smarter than infants who are not. The message, rather, is that bilingualism isn’t bad for you.

“I think that you can see our study as yet another demonstration that babies can adjust to a bimodal distribution of rhythms or languages,” says Mehler. “If there is an opportunity to raise your baby with two languages in this way, it will not harm him. If anything, it will give the baby a head start in one cognitive function.”