In her study of human language, the professor and researcher at the University of Cambridge Mirjana Bozic (1976, Zenica, Bosnia and Herzegovina) is not interested in grammar or literature. Through behavioral experiments and neuroimaging techniques, he studies the cognitive consequences of knowing languages. Bozic, who speaks Serbian and English, specifically searches for the neuronal attributes that differentiate brains like his: bilingual brains.
Also Director of studies of Psychology and Behavioral Sciences at King's College, Cambridge, she recently visited Madrid to give a talk on the neurocognitive consequences of bilingualism, invited by the British Council in the context of its collaboration with the Ministry of Education. Both institutions develop the bilingual project that is taught in 145 Spanish centers. In recent decades, several neuroscientific studies point to the existence of a bilingual advantage caused by the way information is processed by those who master more than one language. According to the theory, in these people the ability to selectively service to a stimulus and ignore the interferences. Although Bozic questions the generality of the findings, he points out that the consequences of this effect could be felt in many areas of life, not only when talking.
Question: Is the brain of bilinguals different from that of people who only speak a language?
Answer: That is a very big question. Bilingualism is a demand on the brain. The usual context at birth is that we acquire a set of labels for the objects and concepts that surround us: a language. Bilingualism introduces another set of different labels for the same things you already know. In that sense, it is similar to other demanding tasks that the brain must deal with, such as learning to drive or playing an instrument. When investigating the changes that this exerts on the underlying neural networks, it has been found to be true: bilingualism alters the brain functionally and structurally, affects some connections between regions of the brain and how they communicate.
P: Do these changes in the brain affect the intellectual abilities of bilinguals?
Bilinguals are better at ignoring irrelevant information and, crucially, this extends beyond languages
R: There is a great debate in the scientific literature about this. In the last two or three decades, people have started talking about something called bilingual advantage. Is it true that bilinguals are better at certain tasks than at monolinguals? There are published data that show that it could be like this. To understand this, I have to explain the context first: what has been demonstrated in a robust way is that the bilingual brain activates both languages in parallel. Although one of the languages is irrelevant for communication while the other is used, both are activated and compete. That is why bilinguals have to repress language that is irrelevant in each context. The hypothesis is that this makes bilinguals better able to ignore irrelevant information and that, crucially, this extends beyond languages. For example, if someone speaks to you and there is background noise, you can ignore the interference to focus on your interlocutor. There are quite a few studies that suggest this effect, but there are some drawbacks. I think we have to investigate more.
P: On what experiments are these studies based?
R: A typical experiment is a test of cognitive control or executive function, in which participants must perform tasks that require conflict resolution. For example, if a blue box appears on a screen, they have to press an answer with the right hand, but if a red box appears, with the left. If you show them the blue box on the right side of the screen, the answer is easy, but if you change the colors and show the blue on the left side, you create a conflict. It has been shown in several studies that bilinguals can solve that conflict and give the correct answer a little faster: they use the right hand even though the colors appear changed on the screen. It is an example of the type of test used to study this.
P: But there are problems with the conclusions of those experiments.
The effects of neurocognitive experiments with bilinguals have not been reproduced consistently
R: The effects have not been reproduced consistently. Some studies find this effect and others do not. It may be due to very simple methodological reasons, such as that there is not enough statistical power or enough participants, it is something that is easily solved. But there is also a problem when it comes to matching monolinguals and bilinguals according to relevant contextual variables that can affect behavior in a cognitive test. For example, they should be adjusted by socioeconomic level to ensure that there are no differences that may be due to access to education instead of bilingual status.
P: Do you see a socioeconomic difference between bilinguals and monolinguals?
R: No, I did not mean that there is a direct relationship for that. Rather, imagine that you have to do this experiment in the United Kingdom, France, the United States or Germany, the countries that most carry out this type of scientific research: the bilingual population, statistically, is more likely to be of people who come to the country to work. Then a potential difference appears with the monolinguals. It is not something as direct as a correlation.
P: Does bilingualism have any disadvantages?
Children who speak only one language have more vocabulary
R: Yes. A well-studied aspect is the size of the vocabulary. It has been consistently shown that bilingual children have a more limited vocabulary in their respective languages than monolingual ones in their own, although they can catch up when they are adults. The reason is that if only one language is used, the labels that language has for each concept are constantly accessed. Those who speak two languages have two sets of labels for each concept and access each one less frequently. The links between each label and each concept are weaker than in monolinguals, so they may have less vocabulary in each language and may take a little longer to access it. There is also the phenomenon of having the words "on the tip of the tongue". In a conversation, even if you know what the word is, by what letter it starts or even that it is a long word, you do not remember the label. It's for the same reason: you do not use that label-concept pair as often as a monolingual with your unique language does.
However, bilingual children have greater metalinguistic knowledge, knowledge about the language. There are very elegant studies that show that bilingual children understand better the abstract relationship between "this is what is called something" and "this is that something". They know that the same concept can have different labels in each language.
P: Are the same advantages and disadvantages given in native bilinguals as in bilinguals who have studied a second language?
R: This affects the result. When you compare the brain activity of early bilinguals (who have learned the languages of children), there is not much difference between the neural networks that support the processing of each language. When they speak, listen or read, a brain scan shows an almost coincident activation in both languages. However, with the same task in late bilinguals (who have acquired a second language of young people or as adults), differences in the underlying neural network are observed. It is usually seen that the second language, which they have learned later, activates a more extensive network, especially in the frontal lobe and areas of the brain that support cognitive control and the demands of the task.
P: But people who learn a second language later in life also have the bilingual advantage?
Non-natives also benefit from the 'bilingual advantage'
R: Yes, probably yes. If you think about the background mechanism, it consists of repressing the irrelevant language in each context to use only the appropriate one. It could be argued that in the case of late bilinguals, the native language competition is even stronger because it is more ingrained. It would be necessary to apply an even stronger repression of that language, which can exercise even more [que en los bilingües tempranos] those capabilities.
P: Are the cognitive advantages of bilingualism enhanced if the two languages are very different?
R: It's a good question that people are studying. From what I have read, it seems that the combination of languages does not matter much: the same effect is appreciated. There are even recent studies that find a positive effect when speaking different dialects of the same language. It seems that the type of brain competition that activates each language is irrelevant. However, my team is investigating precisely this question, comparing bilinguals with a couple of similar languages, such as English and Dutch (both Germanic) with bilinguals who speak English and Spanish (Germanic and Romance). We have studied the reorganization of neural networks and subtle differences are observed, but we are still interpreting the results and I do not want to speculate at the moment.
P: Does the neuroscientific study of bilingualism support bilingual education?
The advantages of bilingualism far outweigh the disadvantages
R: Yes, of course I would argue it like that. Questions have been raised in some circles, theories about whether teaching in two languages can cause confusion. The research clearly shows that this is not the case. Scientific literature also suggests that the selection of one language or another depends on tracks subtle social, as who speaks or what is the topic of conversation. This can make bilinguals more receptive to social cues; They could benefit more from interactive teaching methods by extracting information more efficiently in those contexts. In addition, although the cognitive benefits we have been talking about are not considered, bilingualism is useful in the real world. Bilingualism allows to talk with more people, fosters cultural understanding, communication skills, job expectations … all that. Even if there are costs, the benefits far outweigh them.