To mark World Brain Day on 22 July, Prof. Dr Patric Meyer from SRH University explains what happens in the brains of bilingual people and what role learning a foreign language plays in later life.
For many multilingual people, switching between languages is a natural part of everyday life: at home, a different language may be spoken to that used at work, whilst with friends, individual words or entire parts of sentences may switch between two languages. What sometimes appears to be a random mix is, from a scientific perspective, a remarkably flexible form of communication. So-called code-switching – the switching between two languages within a conversation or even a single sentence – offers fascinating insights into how our brains work. It demonstrates just how precisely language is adapted to the situation, the person we are speaking to and the purpose of the communication.
“Code-switching is not a speech impediment, nor is it a sign of a lack of competence. It is a flexible form of communication that allows speakers to adapt to their conversation partners, the social situation and the communicative goal,” says Prof. Dr Patric Meyer, Professor of Cognitive Neuroscience on the Bachelor’s and Master’s degree programmes in Psychology at SRH University. “Multilingual people do not simply choose words from two dictionaries. They continuously decide which language is appropriate at any given time.”
What happens in the brain
It is precisely these control processes that are of interest to cognitive psychology. Anyone who regularly uses two languages must activate the appropriate words, control competing linguistic information and switch flexibly between the languages. This requires so-called executive functions – mental processes that direct attention, suppress distracting information and enable the switch between tasks.
However, research also shows that the often-cited phrase ‘bilingualism makes you smart’ does not tell the whole story. On the one hand, bilingual older adults may demonstrate advantages in specific areas such as inhibition – that is, the cognitive ability to control or suppress certain reactions. In other tasks – such as verbal fluency – they may, however, perform less well. What matters, therefore, is not simply whether someone speaks two languages, but how and in which situations they are used.
Advantages – but not across the board
Research by Meyer and his colleagues involving young Turkish-German bilingual adults confirms this nuanced picture. The bilingual participants showed advantages when switching between tasks – in other words, in terms of cognitive flexibility. Monolingual participants, by contrast, performed better in working memory tasks, whilst no significant differences were observed in attention.
“The brain doesn’t simply yield the same benefits across the board,” explains Prof. Dr Patric Meyer. “Multilingualism seems to train or shape certain control processes, but does not automatically improve other areas.”
Researching code-switching in a real-world context
For a long time, code-switching was studied primarily from a linguistic perspective. Today, there is growing interest in which control processes in the brain are involved. A review article by Meyer and his colleagues shows that there are very different forms of code-switching – ranging from the insertion of a single word to dense forms of language mixing. These presumably place different demands on the brain.
For this reason, the study assessed code-switching in Turkish-German bilingualism using an interactive scene-description game. The findings revealed that the frequency with which participants switched between German and Turkish, and the situations in which they did so, were linked to their performance on tasks designed to measure concentration and the ability to cope with distractions. This correlation was particularly evident in a test of attentional control. This, too, argues against simplistic black-and-white conclusions: code-switching is neither fundamentally an advantage nor a disadvantage, but rather draws on different cognitive processes depending on the situation.
Implications for diagnosis and healthy ageing
Multilingualism also plays an important role in neuropsychological diagnostics. In a study involving German, Turkish and Turkish-origin Alzheimer’s patients, Meyer and colleagues demonstrated that education and linguistic background can influence the results of cognitive tests. Culturally sensitive procedures proved to be less susceptible to such influences. In practical terms, this means that test results must be interpreted with particular care in the case of older people with a migration background or experience of multilingualism.
The study also examined foreign language learning in later life. An intensive Spanish course did not generally lead to better cognitive performance. However, individuals with lower baseline cognitive performance showed signs of improvement in response inhibition.
“Learning a new language is not a miracle cure for cognitive ageing,” says Prof. Dr Patric Meyer. “But it is a challenging, real-life and socially significant mental activity. That is precisely why it can be particularly valuable for certain people.”
On World Brain Day, the message is therefore: our brain is not a rigid language computer, but an adaptable system. Multilingualism, code-switching and foreign language learning demonstrate how closely language, attention, memory, social interaction and brain health are interconnected.
Original publications
Özkara, B., Schneider, R., Cedden, G., Von Stutterheim, C., & Meyer, P. (2025). The impact of bilingualism and code-switching on executive function performance. Frontiers in Psychology, 16, 1583441.
Cedden, G., Meyer, P., Özkara, B., & Von Stutterheim, C. (2025). The “code-switching issue”: Transition from (socio) linguistic to cognitive research. Bilingualism: Language and Cognition, 28(5), 1446-1459.
Özkara, B., Cedden, G., Von Stutterheim, C., & Meyer, P. (2025). Code-switching and cognitive control: a review of current trends and future directions. Frontiers in Language Sciences, 4, 1515283.
Grossmann, J. A., Aschenbrenner, S., Teichmann, B., & Meyer, P. (2023). Foreign language learning can improve response inhibition in individuals with lower baseline cognition: Results from a randomized controlled superiority trial. Frontiers in Aging Neuroscience, 15, 1123185.
Degirmenci, M. G., Grossmann, J. A., Meyer, P., & Teichmann, B. (2022). The role of bilingualism in executive functions in healthy older adults: A systematic review. International Journal of Bilingualism, 26(4), 426-449.
Celik, S., Kokje, E., Meyer, P., Frölich, L., & Teichmann, B. (2022). Does bilingualism influence neuropsychological test performance in older adults? A systematic review. Applied Neuropsychology: Adult, 29(4), 855-873.
Celik, S., Onur, O., Yener, G., Kessler, J., Özbek, Y., Meyer, P., ... & Teichmann, B. (2022). Cross-cultural comparison of MMSE and RUDAS in German and Turkish patients with Alzheimer’s disease. Neuropsychology, 36(3), 195.
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