Babies who learned two languages mastered language-specific rules faster than monolingual babies, a new study found.

Researchers at the National University of Singapore conducted a study involving about 70 babies that explored their knowledge of the rules of Mandarin.

Published in Frontiers in Psychology, the study investigated infants’ mastery of the Mandarin tone system in monolingual Mandarin infants and English-Mandarin bilingual infants at 12 months.

Mandarin is a tonal language, in which different tones on phonetically identical words connote different meanings. English, however, is a non-tonal language in which tone can convey varying emotions or emphasis.

The researchers found that the bilingual babies were able to interpret tone accurately at 12 months when learning new words in Mandarin. At the same time, these bilingual babies ignored tone changes when learning new words in English.

Monolingual Mandarin infants were unable to use tone when learning words in Mandarin at 12 months and only demonstrated sensitivity to Mandarin tones at 18 months. This suggests that at the tender age of 12 months, bilingual babies are able to internalize and apply different language rules across English and Mandarin, even when the linguistic rules conflict each other.

Associate Professor Leher Singh says that the results dispel commonly held beliefs about bilingual children being slower when learning words. “The bilingual babies showed different strategies for processing English and Mandarin. When they’re learning a new word in Mandarin, they listened out for tone. When they’re learning a new word in English, they correctly ignored tone changes,” she says. As such, learning two different languages could be beneficial to mastering each language individually, she adds.

The researchers also found that bilingual babies develop dual language skills when they were just a year old. “This is a novel finding and the first study we know of that shows accelerated word learning in bilingual babies, strongly suggesting that babies are not thwarted by learning two very different languages,” says Singh.

The research team’s upcoming projects include understanding how babies track words and process sentences in speech and how proficiently they detect errors in each language, as well as exploring whether bilingualism plays a role in influencing babies’ social and moral judgments in their perception of people.