For a long time it was believed that speaking two or more languages worsened cognitive abilities and even that it conditioned political tendencies and moral values. However, we now know more in depth the functioning of the bilingual brain and we can affirm that the circumstance supposes more benefits than costs.
Next, we will describe the main findings regarding the functioning and characteristics of the brain of people who speak more than one language; some may have intuited them, others will surprise you.
Individual bilingualism is defined as the ability to use two or more languages (multilingualism) in any situation and with the same communicative effectiveness. In turn, this can be differentiated between simultaneous bilingualism and successive bilingualism. The first refers to the acquisition of two languages from birth. The successive takes place when the person learns a second language after having learned one; for example, receiving classes or living in another country.
More than half of the world’s population is considered bilingual. Depending on the area or country, the percentages of bilingual population vary. In the case of Europe, the prevalence is 56%, 20% in Canada and up to 99% in Luxembourg.
This large number of bilingual people has led to researchers from the field of cognitive psychology have been interested in the underlying processes. Thus, it has been found that monolingual and bilingual people present a development, efficiency and even trajectory of different cognitive performance.
The basis for what interests bilingualism at the cerebral and functional level is neuroplasticity. That is, the ability of the brain to modify itself based on experience. Therefore, since bilingualism is an experience that is mainly determined by the environment and not by individual preferences, it is so exciting for science.
Cognitive characteristics of the bilingual brain
During linguistic development in childhood, there are no significant harmful effects due to learning more than one language. However, bilingualism involves a series of costs and benefits at a functional level.
The bilingual people consider that between the two dominant languages, one of them is dominant and the other secondary although they learn them simultaneously.
Therefore, using the second language is always going to involve a greater cognitive effort than using the dominant one. This effort will be reflected in the performance when speaking the non-dominant language. However, there are also differences between monolinguals and bilinguals when using the dominant language.
Disadvantages for bilinguals
In general, it has been found that the verbal skills of bilinguals in each language are weaker than those of monolinguals. For example, they have less vocabulary, although if the number of words in both languages is taken into account, this result may vary.
It has also been seen that bilinguals are slower when it comes to naming objects, producing words and living more that of “having the word on the tip of the tongue”. When thinking of a word, bilinguals take more time to retrieve it, however this effect is less marked in words or very common sentences, such as “home” or “How are you?”.
The main hypothesis used to explain these disadvantages is that when bilinguals want to say, write or listen to a word, they can not prevent it from being activated in the other language. For example, if someone who is bilingual in Spanish and French wants to thank you, the word merci will inevitably also be activated in your mind.
The same fact that the two terms are activated at the same time, requires a great capacity to be able to select one of them and inhibit the one that we do not want to use. Also, taking into account a whole conversation or speech, instead of naming a single word.
The cognitive capacity that allows doing that is executive control. These executive functions (inhibition, change of set and working memory) are a set of skills that are responsible for processing the information and selecting the one that is really relevant and necessary, avoiding the occurrence of interference.
Thus, there has been a medium and large advantage of executive control in bilingual children and compared to monolinguals. This ability is related to academic achievement and to better mental health and long-term well-being. In addition, it has even been found that this greater advantage increases the cognitive reserve of bilinguals, delaying the onset of cognitive impairment or Alzheimer’s up to four years.
«A man who knows two languages is worth two men.»
In relation to executive control, neuroimaging studies have shown that bilinguals have more activation in certain brain areas, such as the caudate nucleus of the left hemisphere, the dorsolateral prefrontal cortex, the cingulate cortex and the supramarginal gyrus.
The bilingual brain has greater activation in the caudate nucleus of the left hemisphere, the dorsolateral prefrontal cortex, the cingulate cortex and the supramarginal gyrus.
In addition, there is evidence that the bilingual brain has a greater number of neurons, possibly due to prolonged exposure to bilingualism. A study conducted by Michelli and his team found greater density of gray matter in parietal regions in bilinguals of Italian and English, compared to Italian monolinguals.
Allowing for better connectivity between different areas, a greater amount of white matter has also been reported in bilingual adults. This has been seen mainly in the corpus callosum, a structure that allows the connection between the two hemispheres.
Despite the old belief that speaking two languages could be negative and of certain non-significant disadvantages, people who speak two languages have greater cognitive and attentional control.
This cognitive advantage also influences other activities beyond linguistics, increasing cognitive reserve, activation and brain anatomy. In short, speaking other languages allows us to communicate with more people, travel without certain limits and improve our brain.