The quirks and perks of bilingualism

At least half of the people on Earth can speak more than one language. So what happens when we juggle two languages in one brain? 

Some multilinguals report that they communicate and respond differently according to characteristics of the language being used.   Thomas Hawk/Flickr  (CC BY-NC 2.0)

Some multilinguals report that they communicate and respond differently according to characteristics of the language being used. Thomas Hawk/Flickr (CC BY-NC 2.0)


Language allows us to interact and articulate our thoughts about the world, our society and ourselves. The acquisition of language, including learning the structures and vocabulary of a language, is a part of natural development just like learning how to walk. But what about people who pick up more than one language? Does speaking two languages do something special to our brains? In the past, bilingualism was discouraged because it was thought to result in mental disabilities. In recent decades, it’s been touted as a holy grail of brain training that could keep us mentally fit well into our sunset years. While it seems the claims are more tempered now, there’s a lot of interesting stuff going on in the bilingual brain.

The kids are alright

Less than 100 years ago, it was believed that acquiring two languages at the same time would negatively affect young children’s cognitive skills. While there is some evidence that simultaneously learning two languages may delay speech, there’s no reason to delay teaching a second language until the first is mastered. It is true that bilinguals tend to have smaller English naming vocabularies when they’re very young, but this disparity disappears by the age of five if the child has at least one English-native parent. Interestingly, children with two non-native parents do not develop the same accent as their parents if they learn the second language at school. 

Young bilinguals know their audience and will not mix languages, or 'code-switch,' when speaking with monolinguals. Code-switching is not a fault, and it follows grammatical and social rules. Perhaps due to this switching, bilinguals are said to better understand different perspectives, although even mere exposure to multiple languages improves interpersonal understanding in monolingual infants. 

Some studies claim a myriad benefits of learning two or more languages.   IM Swedish Development Partnerl/Flickr  (CC BY-NC-ND 2.0)

Some studies claim a myriad benefits of learning two or more languages. IM Swedish Development Partnerl/Flickr (CC BY-NC-ND 2.0)


Bilingual children also better understand how languages function and have a better grasp of what constitutes a proper sentence and what does not. They also tend to have greater verbal fluency than monolingual children, meaning they can list more relevant words when given a prompt. Although controversial, bilinguals may possess enhanced executive control, which has been linked to doing better in school. This could be due to having to inhibit one language while they are speaking the other. While 80% of studies have not found improved executive functioning in bilinguals, some research indicates that speaking two languages is like a mental workout that results in superior cognitive flexibility

Bilingual baby brains

Regardless of whether bilingualism confers neurological benefits, it is still remarkable what happens when the brain simultaneously houses multiple languages. Our experiences with language in our first few years determine which sounds our brains can perceive as language. Babies can perceive and discriminate between differences in all sounds, called phonemes, that make up human speech. However, by just six months of age, babies preferentially respond to sounds of their native languages. As an aside, it’s worth mentioning that deaf children who are exposed to signing languages begin to ‘babble’ with their hands around the same time a hearing infant babbles audibly. 

Although monolingual infants’ perception decreases by the time they are eight to 10 months old, one-year-old bilingual babies still perceive differences between languages. It doesn’t take much exposure to combat this loss, as just a dozen sessions of listening to a native speaker extends the length of time monolingual English babies can perceive Mandarin speech. However, listening to recorded Mandarin did not give the same benefit, suggesting that social interaction is important for language acquisition.

Early exposure leaves an indelible mark on the brain, even years later. When researchers looked at brain patterns of children who were French monolinguals, Chinese/French bilinguals, or “forgotten Chinese”/French monolinguals, they found that the latter group’s brain patterns matched the Chinese/French bilinguals’, not the French monolinguals’. Although the children hadn’t been exposed to Chinese for over a decade, their brain still maintained early neural patterns.

Language learning in later life: A lost cause?

Researchers have also tested simultaneous and sequential bilinguals, those who learned two languages concurrently or one after the other. All of the sequential bilinguals learned their second language after the age of five. Simultaneous bilinguals had better connectivity between the two hemispheres of the brains, while sequential bilinguals used the left hemisphere more. Clearly, language learning is not only for babies.

Still, it’s true that young children are more likely than adults to achieve native-like pronunciation and grammatical skills. Children that learn to speak another language by age eight can typically speak without an accent and with correct grammar usage. Afterward, achieving this level of verbal language mastery is much less likely. People who became bilingual in their twenties did not have their language perception slowed down by an incorrect gender marking, while young bilinguals and native speakers did, suggesting their brains do not ‘see’ the mistakes. 

Mastering a second language can prove more difficult later in life.   eltpics/Flickr  (CC BY-NC 2.0)

Mastering a second language can prove more difficult later in life. eltpics/Flickr (CC BY-NC 2.0)


A study of native Spanish speakers in Sweden further identified the critical period for second language acquisition. When the study participants were judged on their Swedish, 62% of those who learned Swedish between the ages of one and 11 passed for native speakers. However, if they learned Swedish between age 12 and 17, only 6% passed, and of those who learned the language after 17, none passed. It’s not all bad news for mature learners though; older children and adults are at an advantage when learning vocabulary and grammar. When we learn sequentially, our first language affects the process of learning the second, and we use sentence constructions and idioms that mimic those in our native language. Interestingly, the newly acquired second language can affect the process of learning a third language and this is called the foreign language effect.

There are many reasons to learn a new language, even as an adult. There is evidence that bilingualism maintains white matter, which typically decreases with age. Even learning another language later in life reorganises white matter. Learning a second language also increases the density of grey matter in certain parts of the brain. Moreover, multilinguals are affected by dementia, on average, 4 years later than monolinguals. There can also be financial benefits to bilingualism. For example, English and French are both official languages of Canada, and bilinguals earn an average of 10% more than English monolinguals and 40% more than French monolinguals. Their unemployment rates are also lower. 

Switch languages to switch yourself

Intriguingly, languages can affect multilinguals’ personalities. For example, Parisian bilingual adults, when asked to recount stories from their lives, more often talked about standing up for themselves in French and bowing to others’ wishes in Portuguese. Language can also influence how we perceive objects. While Japanese speakers generally categorise objects based on material, English speakers typically use size. When Japanese speakers learned more English, their categorization pattern more closely matched that of English monolinguals.

Similarly, we may perceive situations differently because of the language we speak. In one study, German/English bilinguals were asked to describe videos as either having or not having a goal. The researchers wanted to see if language structure had an effect on their characterisation and they found that it did. When shown ambiguous videos, bilinguals speaking German said these videos were goal-oriented 40% of the time, yet the same group of people only categorised 25% as goal-oriented when they spoke English. 

Many children learn to read, write and speak in a second language as part of their early development.   Sarah Horrigan/Flickr  (CC BY-NC 2.0)

Many children learn to read, write and speak in a second language as part of their early development. Sarah Horrigan/Flickr (CC BY-NC 2.0)


There’s evidence that our emotions are closely tied to language. When native Dutch speakers said “I am smiling” in Dutch, they smiled more than when they said the same phrase in English. This emotional embodiment while reading books is stronger in our native language. That may also hold true for writing books. The famous author Vladimir Nabokov first wrote his memoir in English, followed by a translation into his native Russian — to his surprise, writing in Russian unlocked memories and details that had not been available to him when he wrote in English.

For people who learned their second language in a different time and place than their maternal language, the maternal language triggers memories of childhood and the native country while the newly acquired language is more seated in later life experiences. Even swear words from our maternal language affect us more than their equivalents in languages we acquire later. The emotional aspect may also explain why it is easier to lie in a non-native language. And actually, bilinguals didn’t need studies to know all this — two thirds of bilinguals report feeling like a different person when they speak another language. 

Even if it turns out that bilingualism does not endow the speakers with some of the more controversial neurological benefits, there is real social, professional, and personal value in speaking multiple languages. Maybe it’s time to dust off that old language textbook?

Edited by Deborah Kane