This summer I came across a fascinating book on my favourite subject – bilingualism. ‘The Bilingual Brain’ by Albert Costa1 seeks to explain how two languages cohabitate in one’s brain and investigates the cognitive effects of bilingualism.
Ode to the book
Written in a down-to-Earth, funny, yet scientific way, this book equipped me with new knowledge, clarified some things and confirmed others I already strived to implement in my bilingual parenting approach. The benefit I felt after reading it made me think that the book deserves to reach more people, hence I decided to write this recommendation and summary.
After reading it, you may decide to read the book yourself, which I strongly encourage you to do. However, the purpose of this post is to bring the book closer to those, who are more like my husband. He started reading the book with enthusiasm, but having read 20 pages he got distracted and lost his stamina.
The book offers a balanced2 approach to the ‘new science of bilingualism’ – the label Costa gives to this subject. The book is full of descriptions of various experiments that have tried to prove different theories around bilingualism, such as the positive correlation between bilingualism and other cognitive functions. Some of these succeeded, while others left unanswered questions. Costa doesn’t hide this from us and points out that further studies need to be done in future.
This summary captures the findings that left the strongest impression on me.
Who is bilingual?
It is worth starting by sharing author’s view on who should be regarded as a bilingual. He takes three important variables related to language: age of acquisition, frequency of use and proficiency to try to fairly include as many people as possible under the umbrella of the term bilingual.
As an example, if the age of acquisition is taken as the only variable, we could say bilinguals are only those who were exposed to two languages from birth. In that case, we ignore a large number of people who have learnt the second language later in life, but they know it well and use it frequently.
Therefore, Costa’s view is to treat each bilingual ‘as one among many points in a continuum of variables, and not as differentiated groups’. However, he points out that when research is done, the three variables in the participants should be as similar as possible.
Chapter one: Bilingual Cradles
In this chapter, Costa talks about the mechanisms with which babies acquire language(s). He further explains how bilingual babies differentiate between languages they hear in their environment.
In general, babies are born with sensitivity to their mothers’ voice and to the language(s) they were exposed to in utero. The sophisticated mechanism with which they learn language(s) is called phonotactics. Phonotactic rules are language specific and refer to the set of rules and constraints regarding how syllables are created3.
The first time I got acquainted with the term phonotactics was while listening to Radio Galaksija podcast, which I have to highlight is in Serbian. In the extremely interesting episode on linguistics and language acquisition4, professor Boban Arsenijević defines phonotactics as ‘a set of features linked to syllables, word length, word accent, word beginning and its end’. Similar to Costa, Arsenijević says that even though babies (in utero and at the very beginning of their lives) do not know the meaning of the words they hear in their mother tongue, they know very well where the word begins and where it ends.
But what happens to babies who are exposed to two languages from the start? Costa says that thanks to phonotactic rules, extremely young bilingual babies are able to classify words into one of the languages they are surrounded with.
He gives the example of bilingual Spanish/English babies who have to learn rules about consonant cluster ‘str’ in both languages. In Spanish, s and t have to be divided by a syllable (as–tro-nau-ta) or word boundary (las trenes). Consequently, in Spanish there are no words that end in -st or begin with str-. In English however, there is a lot of words that start with Str- (strong, strange etc). This is what bilingual babies are able to compute in very early stages of their lives and consequently differentiate between these two languages.
In general, Costa continues, when they are six months old, babies are able to attach the meaning to some words they hear often. This stage is called the recognition stage. The period around 18 months is referred to as the word spurt period and this is when children should be able to produce ten new words per week.
Chapter two: Two Languages, One Brain
Now we get to my favourite part of the book. This is where I learned what happens to one of bilingual’s languages while the other one is in use. The key point here is that language not in use is still very much ACTIVE in the brain and it cannot be switched off.
Take my daughter Klara for example. While she speaks Serbian, her brain constantly needs to block English, which is also active in her brain at the time of speaking, and vice versa. Thankfully, Klara speaks both Serbian and English really well and currently belongs to the category Costa calls true jugglers – she keeps successfully using both languages and switching between them.
However, the more dominant the language a person needs to block, the bigger the delay or difficulty with which the person will speak in their other language. Not simply because they cannot remember a certain word, but because the stronger language keeps interfering. Consequently, the brain needs to work more to control it.
To paint the picture of this statement, I need to use the example of my husband Tom who is currently learning Serbian. Serbian is technically his first foreign language. Up until recently, only one language lived in his brain – English. Now that he is learning Serbian, not only that he needs to learn Serbian vocabulary and grammar, but he also needs to learn how to control his main language (English) and prevent it from interfering. As a result, he is able to produce surprisingly correct sentences in Serbian, but he does it with the speed of a snail currently.
In this chapter, Costa also talks about Bilingual conversations. Up until I read this book, I was not aware this phenomenon had a name, but Klara kept practicing these from a very young age. Bilingual conversations are situations in which a person maintains a conversation in two different languages at the same time, depending on the person they are addressing at that particular moment.
Costa gives his family’s example where both Spanish and Catalan were used at the dinner table. He describes this situation as seemingly hectic, because each person would address the other in a language THEY ARE USED TO USE when speaking with that particular person.
Then he asks the question. Given that they all speak both Spanish and Catalan, wouldn’t it be easier if they agreed on one language and used it over dinner. He then clearly answers no, explaining that once one establishes a language they speak to one person, it is difficult to talk to them in another language. He says switching languages between people is easier than changing the language in which you communicate with each one of them.
And indeed, when she was only two, Klara switched between English and Serbian in the same room between her dad (English), her grandma, uncle and mum (Serbian). Costa’s bilingual conversations brought hope that habit created in the early days will remain, even when my children start school.
Then, he talks about language switching or code switching. Even though some may think this is weakness, Costa says that code switching is very clever and follows grammatical rules of both languages involved. For example, when Klara said ‘woodena igračka’, she showed how familiar she is with both of her languages. She used the English word as a root (wood – drvo) and attached the Serbian suffix –ena to it. With this suffix she created an adjective from the word wood + she matched the adjective with the noun igračka in number and gender in Serbian.
In a book I read after this one, I learnt that the above ‘woodena igračka’ is actually an example of the phenomenon called blending (when one combines both languages in one word). According to that other book, the example of code switching would be: ‘Pitala sa daddy da me vodi u cinema.’
Before I close the review of this chapter, I have to mention one sad thing that left a strong impression on me. There is such thing as forgetting a language, your mother tongue even. This is called first language attritionand Costa says it happens when acquisition of the second language influences the first one.
He gives an extreme example where the first language was, as he says, ‘eaten’ by another one. There was a study done with Korean children who were adopted by French families and then moved to France. At the time of adoption, the children were between three and eight years old and they were all verbal in Korean. When they moved to France, they learnt French. Since they didn’t have any contact with Korean, their mother tongue, they completely forgot it overtime.
Chapter three: How Does Bilingualism Sculpt the Brain
In chapter three, Costa talks openly about the ‘consequences’ of being bilingual. Are you ready?
Some experiments, in which participants are asked to name the object in front of them, show that bilingual speakers have slower and less reliable access to their vocabulary compared to monolinguals. Why slower? Because their other language keeps interfering and a bilinguals need to block it.
Why less reliable? The author explains that a bilingual person can never be regarded as two monolinguals in one. In each of their two languages, bilinguals have a smaller sized vocabulary than monolinguals. However, in total, bilinguals know more words (in both languages combined) than monolinguals (in their single language).
Therefore, bilinguals fall more often into the ‘tip of the tongue’ situations. Costa explains that we all find ourselves in these situations, mainly for words we do not use very often. Now, bilinguals have more of these words in both of their languages because they use each of their languages less often than monolinguals use their single language. Makes sense? It is costly for bilingual’s language A to use language B and vice versa.
Costa claims there is no need to worry about a bilingual’s vocabulary size, simply because our ability to learn new words doesn’t decrease through life. It is, therefore, up to bilinguals themselves (and their parents during childhood, I would argue) to surround themselves with lexically rich sources such as good literature and expand their vocabulary in either of their languages.
Now we get to my yet another favourite part of the book: the ability with which bilinguals learn their third language.
An experiment was done where two groups of early-life bilinguals and one group of monolinguals were each asked to learn a new language. This new language was an invented one to avoid similarity with any of the languages participants were already familiar with. For example, teaching Italian to Spanish/English bilinguals potentially wouldn’t give objective results, because both Spanish and Italian belong to the family of Romance languages and as such carry some similarities. These similarities would potentially make learning of Italian easier for Spanish speakers than to those participants who speak only English. Clever, isn’t it?
The results of this study show that both groups of bilinguals were more efficient at learning new vocabulary than monolinguals. But not only that. Bilinguals have another advantage and that is linguistic control – by being bilingual, they already know how to block the language(s) that are not currently in use. By contrast, a monolingual learning a new language also needs to learn how to control the first language when using the new one. Remember Tom and his Serbian?
Finally, Costa talks about studies that have shown that egocentrism is less present in children who are bilingual. These studies show that bilingual children are able to put themselves in other people’s shoes more easily than monolingual children. This phenomenon is called the theory of mind and refers to the ability to assume that other people do not think the same way we do.
Costa speculates the reason for this is bilingual children’s assumption that their parents do not think the same since they do not speak the same. Consequently, they apply this same assumption to other people. I also like the assumption that bilingual children know there is always at least two ways of looking at the world as there are at least two ways of naming an object/concept5.
Chapter four: Mental Gymnastics
Here, Costa talks about how a language, a cognitive ability of the brain, influences and interacts with other cognitive abilities, especially attention. With experiments that do not test the linguistic cognitive capacity but attentional capacity, it was proven that bilinguals are better at avoiding conflict and blocking out irrelevant information.
For example, multitasking. This is the activity that requires a lot of attention. You may have heard that there is a link between successful multitasking and bilingualism. And indeed, there are studies that show that bilinguals are better at multitasking than monolinguals. They are able to quickly and more efficiently switch between the tasks, similar to what they do with their languages. But Costa warns us that there were other studies that did not prove this same hypothesis.
Towards the end of this chapter, Costa focuses on cognitive decline and bilingualism. Our brains are formed from grey matter and white matter. ‘Grey matter’, Costa explains, ‘are the number of neural bodies and synapses present in a given space of cerebral cortex. White matter, on the other hand, are nerve fibres covered with myelin. These fibres are fundamental for transmitting information between neurons’.
Costa goes a step further to clarify things more: ‘Grey matter computes information, white matter is the cable that takes that information from one place to the other.’
Language learning, as any other learning changes the structure of our brains. Costa calls this space taking. Some studies have shown that bilingualism increases the density of the grey matter, while others have shown that it increases the robustness of white matter.
The study that proves the latter was done on 70-year-old bilinguals and monolinguals while their brains were resting ie participants were not asked to perform any task. What was concluded was that the connection (white matter) between two brain hemispheres was better in bilinguals than in their monolingual counterparts.
Costa says that these results show how constant use of two languages can keep our brains flexible even in the old age. Then he asks the question: can bilingualism save us in some way from cognitive decline?
As we get old, he explains, our brains decrease in size like some other organs. This results in the cognitive decline which can be manifested with weaker attention and memory. However, some people age better than others thanks to the cognitive reserve they have built over time. This means that two people of the same age and same degree of brain deterioration do not have to have the same symptoms. Why? Because some may have more cognitive reserve. Different factors such as education, abundant intellectual and social life positively influence the cognitive reserve in one’s brain.
Having higher amounts of cognitive reserve doesn’t protect you from degenerative diseases like Alzheimer’s. However, it postpones the onset of the disease. This means that the symptoms appear later. The following example pictures the effect of cognitive reserve. Experiments were done with monolinguals and bilinguals with a form of neurodegenerative disease. Participants’ education, cognitive performance and occupational status were similar. Results showed that monolinguals visited the neurologist four years earlier than bilinguals.
Costa warns us, however, that having higher amounts of cognitive reserve is not always a saviour. By the time the symptoms appear, it may be too late to help the patient slow down the speed of the degenerative disease.
Not all experiments, however, result in the proof that bilingualism delays the onset of neurodegenerative diseases. The author’s view is that bilingualism in combination with other factors such as socioeconomic status and education can have the beneficial effect on ageing and cognitive decline. Costa says there is a lot of room for more research in this area.
Chapter five: Making Decisions
In the last chapter of the book, Costa explains how the decisions we make are susceptible to the language we use while we are making these decisions.
He starts off by saying that there is a big difference between a language (or languages) that one learns in childhood and later in life. Those languages that are learnt in childhood are learnt in social context through interaction with people, primarily our parents. The meaning of the words in childhood language(s) carries strong emotional weight. When we hear words in our ‘childhood’ language(s), it triggers the feelings and emotions we once attached to these words when we communicated with our parents.
By contrast, language learning later in life usually takes place in academic context. The same words/expressions pronounced in those languages carry less emotional weight.
What happens with decision-making then?
Costa describes two systems that can be put to work when we make decisions. The first system is the intuitiveone and is based on our emotions and past experiences. When this system is put to work, it tends to take ‘shortcuts’. With these shortcuts, one tries to avoid weighing pros and cons of a situation realistically, but tends to make decisions quickly, based on what feels right.
The other system is the logical or reflexive one. Making a decision using this system takes time because we have to dedicate time to thinking. This system tends to avoid shortcuts intuition leads us to take.
When we are faced with the situation in which we need to make a decision, the more emotions we feel the more the intuitive system is put to work. When we feel a surge of emotions, we are less able to think logically.
We have already said that words expressed in the language learnt after childhood carry less emotional weight. Therefore, it could be concluded that making decisions in a foreign language makes it easier for the logical/reflexive system to be switched on instead of the emotional/intuitive system. ‘We will be less biased if we needed to make a decision in our second language.’ – Costa explains.
Finally, Costa asks the sensible question: how is it possible we make better decisions in the language we are less proficient in? Then he explains that when we face a situation where we need to stop and think to actually understand the problem (in the language we are less familiar with), we apply the same thinking mechanism to the problem (logical/reflexive system). On the other hand, similar to what we do with the more dominant language, we BLOCK the intuitive system in decision-making process.
Dear Reader, if you managed to stay with me up until here, well done! This is where we conclude my summary.
I hope scientific evidence from this book equipped you with confidence wherever you are in your bilingual journey. Whether you have already started or you are thinking about starting.
As for me, Costa’s book gave me a strong boost to continue with my mission. Mission to raise my children as bilinguals, but also to share my experience and knowledge with others in similar situation, no matter how nichethis market is.
Hopefully, you’ll find value in this post, like I did in this book.
- Costa, A. (2021). The Bilingual Brain, 2nd edition, Penguin Books. ↩︎
- Jones, T. (2020) ‘The Bilingual Brain by Albert Costa review – enlightening and astonishing’, The Guardian, Tuesday, 11 February 2020. Available at: https://www.theguardian.com/books/2020/feb/11/the-bilingual-brain-albert-costa-language-review (Accessed: 11 December 2022).“Courtesy of Guardian News & Media Ltd” ↩︎
- Nordquist, R. (2020) ThoughtCo: Definition and Examples of Phonotactics in Phonology, 26 August 2020, Available at: https://www.thoughtco.com/phonotactics-phonology-term-4071087 (Accessed: 11 December 2022) ↩︎
- Pavlović, D. (2019) Radio Galaksija #136: Usvajanje jezika (gost: prof. dr Boban Arsenijević) [Podcast]. 7 December 2021. Available at: https://radiogalaksija.buzzsprout.com/708018/9679226 (Accessed: 11 December 2022) ↩︎
- Henley, J. (2019) ‘My son swore in front of his grandparents. I was blamed. It made my Christmas’, The Guardian, Tuesday 26 December 2019. Available at: https://www.theguardian.com/lifeandstyle/2019/dec/26/my-son-swore-in-front-of-his-grandparents-i-was-blamed-it-made-my-christmas?CMP=Share_iOSApp_Other (Accessed: 11 December 2022) “Courtesy of Guardian News & Media Ltd” ↩︎