Fifty-fifty when you're fluent in two languages, it can be a challenge to switch back and forth smoothly between them. It'south common to mangle a carve up verb in Spanish, use the wrong preposition in English, or lose sight of the connection between the beginning and end of a long German language judgement. So — does mastering a second linguistic communication strop our multitasking skills or merely muddle us up?

This debate has been pitting linguists and psychologists confronting one another since the 1920s, when many experts thought that bilingual children were fated to suffer cerebral impairments later in life. But the scientific discipline has marched on. In the Almanac Review of Linguistics, psycholinguist Marking Antoniou of Western Sydney University in Australia outlines how bilingualism — as he defines information technology, using at least ii languages in your daily life — might do good our brains, peculiarly as we historic period. He addresses how best to teach languages to children and lays out prove that multiple-language utilise on a regular basis may assistance delay the onset of Alzheimer'southward disease. This conversation has been edited for length and clarity.

What are the benefits of bilingualism?

I'm interested in the interaction between language-learning and cognition — the mental processes of the brain. The cognitive benefits of bilingualism can begin from experiences very early in childhood and can persist throughout life.

The beginning main advantage involves what's loosely referred to as executive function. This describes skills that allow you to command, directly and manage your attention, equally well equally your ability to plan. It besides helps yous ignore irrelevant information and focus on what's important. Because a bilingual person has mastery of two languages, and the languages are activated automatically and subconsciously, the person is constantly managing the interference of the languages so that she or he doesn't say the incorrect give-and-take in the wrong language at the wrong time.

The encephalon areas responsible for that are too used when you're trying to complete a task while there are distractions. The task could have nothing to exercise with language; it could be trying to heed to something in a noisy environment or doing some visual job. The muscle retentiveness developed from using two languages besides can employ to different skills.

Where are these benefits expressed in the brain?

Executive functions are the virtually circuitous brain functions — the most "man" functions that separate us from apes and other animals. They're frequently observed in parts of the encephalon that are the newest, in evolutionary terms: the prefrontal cortex, which is responsible for avant-garde processing; the bilateral supramarginal gyri, which play a part in linking words and meanings; and the anterior cingulate. Studies evidence that the bilingual experience alters the structure of these areas.

Beginning of all, we see increases in gray matter volume. The brain is made upwards of cells called neurons, which each have a jail cell trunk and little branching connections called dendrites. Gray thing refers to how many jail cell bodies and dendrites in that location are. Bilingual experience makes grey thing denser, so you have more cells. This is an indication of a healthier brain.

Results from a study measuring gray-matter volumes in monolingual or bilingual undergraduates. Red areas indicate where gray-matter volumes were greater in one group versus the other. Study participants who spoke both English and Spanish had greater gray-matter volume compared to participants who spoke only English.

Results from a study measuring grayness-matter volumes in monolingual or bilingual undergraduates. Crimson areas point where grey-matter volumes were greater in 1 group versus the other. In total, report participants who spoke both English and Spanish had greater gray-matter book compared to participants who spoke just English language.

CREDIT: ADAPTED FROM O.A. OLULADE ET AL / CEREBRAL CORTEX 2016

Bilingualism also affects white matter, a fatty substance that covers axons, which are the primary projections coming out from neurons to connect them to other neurons. White matter allows messages to travel fast and efficiently across networks of nerves and to the brain. Bilingualism promotes the integrity of white matter equally you age. It gives you more neurons to play with, and it strengthens or maintains the connections between them then that communication tin can happen optimally.

Can education children two languages delay or confuse their understanding?

These myths about bilingualism appointment dorsum to studies in the U.s. and the UK from the First and Second Globe Wars. They were seriously flawed studies involving children from war-torn countries: refugees, orphans and, in some cases, even children who were in concentration camps. Their schooling had been disrupted for years. They may have suffered traumas, and and so they participated in these studies with tests measuring their verbal linguistic communication abilities.

Unsurprisingly, they scored very poorly on these tests. Did the researchers aspect the poor scores to post-traumatic stress disorder (PTSD)? They probably didn't even know what that was. No, instead they attributed information technology to the children's bilingualism.

It wasn't until the 1960s, when a actually important study was published by Elizabeth Peal and Wallace Lambert at McGill Academy in Montreal, that views started to shift. Their findings showed that not just do bilingual children not have a cognitive filibuster or mental retardation merely that their bilingualism really has some cognitive benefits.

In addition to executive function, bilingual individuals and children show advantages in metalinguistic awareness. This is the power to recollect nigh language every bit abstract units and associations. A good example is the letter H, which is associated with the sound "he" in English, with "n" equally in "nickel" in Russian, and with the vowel sound "eastward" in Greek. There'due south nothing special virtually H that makes it have to have a "he" sound; a bilingual person understands this more readily than a monolingual person does.

A table displaying studies on the effects of learning a language. In general, studies show that learning a language increases the volume and density of gray matter, the volume of white matter, and brain connectivity. In older language learners, some studies show cognitive benefits beyond languages, such as for working memory. Findings for older learners are more mixed than for younger ones, but that research is in earlier stages

Studies show that learning a language increases the book and density of gray matter, the volume of white matter, and encephalon connectivity. In older language learners, some studies testify cognitive benefits across languages, such as for working memory. The findings for older learners have been more than mixed than for younger language learners, but the research is in earlier stages.

What do the skeptics contend?

The original findings near bilingual advantages to executive role in the 1960s generated a lot of excitement and media interest. Perhaps the advantages were overstated or misinterpreted. Not every bilingual person is going to have a healthier encephalon than every monolingual person. We're talking about general, population-level trends.

Nosotros run into prove of bilingual advantages in children, just not always. And as we move into young adults, say, in their 20s, information technology becomes more than difficult to detect these advantages. This makes sense in terms of brain maturation: When yous're a child, your brain is still developing, only when y'all achieve young machismo, your brain is at its acme, so bilingualism doesn't give yous much extra.

Learning languages as a child is dissimilar than doing so afterward in life, correct?

It depends. For a long time, information technology was thought that the only way to really learn a linguistic communication was to do information technology early. It was thought that later adolescence, you couldn't acquire a language perfectly. You were always going to exist accented. But we now know that that's not truthful, because in that location are many people who learn languages as adults, and they larn them very well. So this has led united states to reexamine what it is about learning a language during childhood that makes it dissimilar from adulthood.

Is your brain more gear up and more than flexible — what nosotros call more "plastic" — when you're a child, and then it becomes more rigid and fixed as an developed? Or is it that the atmospheric condition of linguistic communication-learning are different when you're a kid, in terms of the amount and type of input you receive, how much slack you're afforded and how much encouragement others give you lot? An adult who is working two jobs and going to linguistic communication classes at 7 o'clock at night has a different type of acquisition than a child constantly receiving input from the female parent, grandmother, father or other chief caregiver.

Ultimately, the divergence between language-learning in children and adults is probably some combination of the two: plasticity and conditions. There are besides private differences. If you lot put different people in the same situation, some people volition flourish and others volition struggle.

Does a bilingual brain age differently than a monolingual ane?

We know from studies that starting at the age of about 25, your brain starts to reject, in terms of working retentivity, efficiency, processing speed, those kinds of things. As you historic period, these declines get steeper. The argument is that as nosotros go into older age, bilingualism puts the brakes on and makes that decline less steep. Bear witness from older adults is the strongest kind supporting a bilingual advantage. (The 2d strongest comes from children.)

When you expect at bilingual individuals who accept suffered neurodegeneration, their brains expect damaged. From their brain scans, you'd call back these people should be more than forgetful, or that they shouldn't exist coping as well every bit they are. Merely that'due south not the case. A bilingual brain can compensate for brain deterioration by using culling brain networks and connections when original pathways take been destroyed. Researchers phone call this theory "cognitive compensation" and conclude that it occurs because bilingualism promotes the health of both grey and white matter.

Graphic of a brain showing parts affected by bilingualism. As bilingual individuals age, their brains show evidence of preservation in the temporal and parietal cortices. There also is more connectivity between the frontal and posterior parts of the brain compared with monolingual people, enhancing cognitive reserve.

As bilingual individuals age, their brains show evidence of preservation in the temporal and parietal cortices. At that place also is more connectivity betwixt the frontal and posterior parts of the brain compared with monolingual people, enhancing cognitive reserve.

Could learning a language subsequently in life go along Alzheimer's at bay?

That is a working hypothesis. Nosotros're doing studies where nosotros teach a strange linguistic communication to people aged 65 and up with the goal of promoting healthy encephalon office, even at such a late point in life. What we're testing is: Can nosotros assistance people in one-time age by using language-learning? Does that requite you some benefit in terms of a "use it or lose it" arroyo to brain wellness?

The initial signs are encouraging. Preliminary data look good. It seems that learning a linguistic communication in later life results in positive cerebral outcomes.

Because language-learning and use is so circuitous — arguably the virtually complex beliefs we homo beings engage in — it involves many levels. Y'all have spoken communication sounds, syllables, words, grammar, sentences, syntax. There's and so much going on; it really is a conditioning for a broad brain network. And those areas of the encephalon overlap with the ones in which aging adult brains show decline or neurological pathological disease. As a result, we argue that learning a second language would exist an optimal activity to promote good for you aging.

Just not enough studies have been washed to settle this in one case and for all. And we don't know any of the details. How much linguistic communication experience is needed? Does it matter which languages you larn? Practise y'all need to reach a certain level of proficiency? We don't accept answers to these questions.

What advice do you have for parents raising bilingual children?

My advice would be to exist encouraging and patient. Bilingual children take a tougher task than those learning only a single language. They're learning two sets of vocabulary and speech sounds. It can be challenging for those of us living in a land with a dominant language to establish a functional purpose for the second language. A child needs to feel that the language is applied and has a use. Grandparents are swell for this, and then is living in a community where there are cultural events or schools where children can be immersed in the second language.

Some other concern parents bring upwards is worrying that their kid might be mixing the languages. Don't worry about what we refer to as "code mixing." It'due south a perfectly normal part of bilingual evolution. They're non dislocated. It's thought to be a sign of bilingual proficiency or competence to mix up the languages.

What other inquiry are you doing in this area?

I'm interested in trying to understand why sometimes we see a bilingual effect, and other times we don't. In ane article, I proposed that possibly the language pairing matters. If you speak two distant languages, like Mandarin Chinese and English, would that result in like types of brain changes as speaking two closely related languages, like German and English?

Maybe if the languages are closely related, they're competing more and you lot have a harder job of separating them, to avoid using the wrong word at the incorrect time. Maybe if they're more than distant, then y'all can't rely on prior cognition from learning the first one to learn the 2d. In that case, you're starting from scratch with the second language, and that's more than effortful at the initial learning stages. But once you've learned the ii languages, mayhap there's less competition.