Babies raised in a bilingual home show enhanced cognitive control

People used to think that being raised bilingual could be harmful to a child's language development. A new study adds to a growing literature showing that the opposite is true. Agnes Kovacs and Jacques Mehler tested the ability of 7-month-old pre-lingual babies to suppress a previously learned response and found that those raised in a bilingual home were able to do this, whereas babies from a monolingual home were not.

Dozens of babies learned that when they heard certain nonsense words, a puppet would always appear on the same side of a screen. All the babies - whether from monolingual or bilingual homes - soon learned to anticipate the appearance of the puppet, and shifted their eyes promptly to the appropriate side of the screen.

During the second phase of the experiment, the location of the puppet moved to the other side of the screen. Crucially, the babies from bilingual homes managed to learn to anticipate the new location, but the babies with monolingual parents did not - they were stuck on the previously learned response. The bilingual babies, by contrast, appeared to have the cognitive control needed to inhibit the previous response.

This difference between the two groups of babies persisted even when the task was made easier by using different nonsense words for when the puppet changed location, and it also persisted when visual stimuli, rather than spoken words, were used to cue puppet appearance.

The researchers said their findings suggested there's an early mental benefit of being raised in a bilingual environment - one that's apparent even before a baby can utter any words of their own. "Just processing two languages and having to deal with the representations of each of them is sufficient for enhancing cognitive control," the researchers said.

The babies in this study were recruited via parents in Trieste in Italy. The babies from bilingual homes had been exposed to two languages since birth. Although the researchers matched the bilingual and monolingual babies in terms of the sociodemographic background of their parents, I suspect it is possible some of the effects seen here are traceable to genetic influences, rather than to the effects of a bilingual environment.
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Kovacs, A., & Mehler, J. (2009). Cognitive gains in 7-month-old bilingual infants. Proceedings of the National Academy of Sciences, 106 (16), 6556-6560 DOI: 10.1073/pnas.0811323106

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.