New parents are bombarded by well-meaning advice about how their parenting techniques could affect their child’s developing brain. A lot of this advice is exaggerated, like the potential benefits of showing your tots “Baby Einstein” videos. However, there’s a scientific consensus that infancy and early childhood is the best time to become bilingual, and that early exposure to two languages can have lasting, generally positive effects on cognition.
But why is it that? Scientists are just beginning to understand how bilingualism affects brain development in infants, and a new study from the University of Washington’s Institute for Learning & Brain Sciences adds another piece to the puzzle.
Basically, switching back and forth between two languages is like mental gymnastics for your child, building the cognitive equivalent of both strength and flexibility. Study co-author Patricia Kuhl told Science Daily,
“The bilingual brain is fascinating because it reflects humans’ abilities for flexible thinking — bilingual babies learn that objects and events in the world have two names, and flexibly switch between these labels, giving the brain lots of good exercise.”
Between eight and nine months of age, monolingual babies lose their ability to distinguish sounds not used in their native language. This is the reason that people who grew up in Asian countries and learned to speak English later in life will often substitute “r” sounds for “l” sounds- the “l” sound isn’t used, so they literally have to reprogram their brains to hear a difference between the two.
When your brain distinguishes between two contrasting sounds, something called the “mismatch response” occurs. The study fitted infants with EEG caps to measure their brain responses to contrasting sounds from different languages. At about six months, monolingual babies from English-speaking households were able to distinguish contrasting sounds taken from both English and Spanish, but by ten to twelve months, their brains only reacted to contrasting sounds found in the English language.
There was a definite contrast with the bilingual babies. At six to nine months, the bilingual babies’ brains showed no response to the contrasting sounds in either language. However, at ten to twelve months, the age when monolingual babies were losing the ability to detect contrasting sounds in Spanish, the bilingual babies were able to pick them out in both languages. Plus, the stronger the “mismatch response” was for both languages at ten to twelve months, the more words from each language the child was able to learn at 15 months.
It seems that raising children bilingually literally changes the way their brains work to allow them to successfully use both languages later on in life.