Babies experience the world even when they are still safe in their mother's womb. In fact, starting from the third trimester, the sounds of the outside world reach the fetus, and its developing brain begins to develop preferences, habits, and train for the tasks it will have to learn to perform once it comes into the world. One above all: talk. In fact, the brains of newborns born to bilingual mothers appear to be able to recognize a greater number of phonetic variations related to spoken language, while children born to monolingual mothers are more precisely tuned to those of the mother tongue. The discovery comes from a study by the University of Barcelona, published in the journal Frontiers in Human Neuroscience.
The research was carried out in Catalonia, a region of Spain where 12% of the population regularly uses at least two languages: Spanish (Castilian) and Catalan. It involved 131 new mothers and their newborns, in their first three days of life. Using external electrodes placed on their heads, the researchers monitored their brain activity while they heard a series of sounds ranging from the vowel “o” to “a” pronounced with different intonations, focusing in particular on a type of brain response called “frequency following response” (Ffr), which allows us to measure how precisely the sound heard is encoded by the electrical potential it evokes in the neurons. The more specific the Ffr, the more accurately the brain is able to recognize the sound in question.
41% of mothers who participated in the study were monolingual, while the remainder said they regularly spoke two languages during their pregnancy (Spanish and Catalan, or one of these and a second foreign language, such as English or Arabic). “Languages are very different when it comes to speaking tempo, for example rhythm or stress, but also intonation and phonetic information,” explains Carles Escera, professor of cognitive neuroscience at the University of Barcelona who coordinated research. “This means that we expect the fetuses of a bilingual mother to develop immersed in a more complex acoustic environment than those of monolingual mothers.”
In fact, the tests carried out revealed that bilingual newborns seem to recognize a greater range of tones of the two vowels used in the experiments, however at the expense of the precision of this recognition, which was greater in newborns born to monolingual mothers. According to the authors, the study therefore demonstrates that the brain begins to train to recognize the mother tongue already in the brain, maximizing its efficiency when there is only one language, and instead reducing it when it has to start tuning into a greater number of languages.
A discovery that underlines once again how active and exposed to the external environment the brains of fetuses are during the last weeks of gestation. But that – the authors of the study put their hands forward – does not provide any concrete indication for parents who wish to raise their children bilingually. “Based on our results, it is impossible to provide any recommendations to multilingual parents,” explains Jordi Costa Faidella, one of the authors of the study. “The sensitive period for language acquisition lasts well beyond birth, and so the postnatal experience may well eclipse the initial changes that occur in the womb. Future investigations into how a bilingual environment modulates sound recognition during the first year of life could shed more light on the topic.”