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By Antonella Sorace & Thomas Bak

The idea that there is a critical period for language learning has been around for a long time, at least since Eric Lenneberg’s 1967 book “Biological Foundations of Language”, which proposed that the acquisition of a first language can be successful only if children are exposed to it in early infancy. The concept was then naturally extended to second language (L2) acquisition, given the much greater variation in outcomes among adult language learners. However, conclusive evidence for the biological nature of child-adult differences and for a well-defined cut-off point has not been found.

At the University of Edinburgh, we study speakers at the very upper end of the L2 proficiency range, who can pass for native speakers at least at some levels: the very existence of these speakers shows that it is possible for adults to be very successful at learning a second language later in life. But why do we find so much more variation? There are many different factors contributing to this, including a shorter time scale and the fact that full immersion in the L2 environment can’t be taken for granted for adults in the same way as it can for children. There is evidence that multilingualism helps: the more languages are known, the easier it becomes to learn more. And recent research also shows that the brain of much older adults responds very well to the challenge of learning a new language, even if high proficiency levels are not reached.

Also, the “critical period” might be different for different aspects of language. It is difficult for an adult to learn new sounds to a level of being perceived as a “native speaker”, in fact, this is the case even within the same language in terms of dialects and local accents. In contrast, the rules of grammar can be learned later and we continue to learn new vocabulary throughout our lives, as new words emerge in all languages. Importantly, the fact that with age it might get more difficult to learn some aspects of language (as is the case with many other activities, such as engaging in sports or playing musical instruments) should not discourage us from doing it. On the contrary, learning languages might be one of the best ways of keeping our mind agile in later life!

Useful links

Here’s when it gets more difficult to learn a new language, according to science

Students should learn second language to prevent dementia in later life