Except in rare cases, children are usually able to learn languages with greater ease and to a higher proficiency than adults. However, a new study suggests that the reason for this has less to do with a critical “language learning” time period that closes after youth than with the all the free time and lack of responsibility associated with childhood.

For the study, researchers from the University of Essex in England and the University of Groningen in the Netherlands had 101 volunteers listen to German phrases while undergoing brain scans. Of the participants, 15 were Polish native speakers and 51 were Russian native speakers, all of whom had moved to Germany between the ages of 7 and 36. Although some had learned a bit of German while in school, for the majority, their main immersion in the German language came when they immigrated to the country. The remaining 29 volunteers were native German speakers.

The researchers had the volunteers listen to German recordings that purposely included a specific yet poignant error. German is a gender-sensitive language, meaning that the gender of the article (such as “the” and “this”), must match the gender of the noun in order to make a grammatically correct sentence. In the recordings, nouns were purposely mismatched with articles of the wrong gender. While the volunteers listened to the recording, brain scans revealed how the speakers computed the various German errors on a neurological level.

Results revealed that the brains of native German speakers had a very strong neurological response to the error. On the other hand, the second language learners either had no response to the poor article-noun matching or had a far weaker response, particularly in those who had learned the language later in life. 

One popular linguistic theory states that there is a critical period for language learning and children who fail to learn to speak a given language by puberty will never be able to fully master the language. A handful of cases of feral children, sheltered from human language until far later in life, have suggested there may be truth to this theory. However, when it comes to the case of a critical period for second language learning, things become less clear.

“The debate on whether or not there is some language-specific maturational critical period has been around for a long time, and the controversy has been extraordinarily difficult to solve,”  Monika Schmid, one of the researchers involved in the study, told Medical Daily in an email.

A 1989 study seemed to support the idea that a second language learned after puberty could also never be mastered. For the study, the researchers analyzed the English skills of 46 native Korean and Chinese speakers who arrived in the U.S. between the ages of 3 and 39. In doing so they found that age of language acquisition had a large effect on the speaker’s performance for every single English grammatical structure for which they tested.

However, in this most recent study, Schmid and her team observed that there was no stark difference between how old the participants were when they began to learn German and how well they interpreted the mistake.

“The change was gradual across the entire age range — there was no ‘bump’ — suggesting there is no particular ‘critical period’ and that it’s just a question of not leaving it too late before you start learning,” wrote Schmid, in an essay published on The Conversation.

Instead, Schmid suggested that the reason for children’s excellent language learning skills may be more heavily based in their lifestyle.

“Children can spend more time and effort on learning than adults who have many competing demands,” wrote Schmid.“The motivation for children to fit in is much higher, and the habits of pronunciation and grammar of their first language are less deeply ingrained and thus easier to overcome.”

Correction: This article has been updated to show that the University of Groningen in the Netherlands also took part in the research. It has also been ammended to show that the brain scans used for the study did not reveal specific areas of brain activatation during language listening.

Source: Meulman N, Wieling M, Sprenger SA, Stowe LA, Schmid MS. Age Effects in L2 Grammar Processing as Revealed by ERPs and How (Not) to Study Them. PLOS One . 2016