• Question: Is there a difference between what you see in the brain of a child and what you see in the brain of an adult? It is said you can't teach old dogs new tricks, and the best to learn a new language as young as possible - is this backed up by your data?

    Asked by Anon to Sarah, Matt D, Matt, Joe, Iroise, Ellie, Catriona on 29 Apr 2015.
    • Photo: Matt Davis

      Matt Davis answered on 29 Apr 2015:

      There’s good evidence that for learning a second (or third!) language
      the earlier you start the better. The most proficient bilinguals learn two languages from birth, such as when mum speaks one language and dad another.

      When learning a second language, we know from studying migrants that move to a new language community that those that move when aged 10 years or younger typically learn to speak their new language with a native accent. Those that move country in their teens or later may not achieve this level of proficiency. So, if you want a native accent, then learning a second language before your teens is best. The same might be true for learning grammar (evidence is mixed), but for learning words there doesn’t appear to be as much evidence for an equivalent ‘critical period’.

      Based on this evidence, then, the ability to learn a second language to fully-native proficiency seems to decline during the teenage years. However, we don’t know exactly when or why. There are various changes that occur in the brain during the teenage years but as far as I know none of these changes have been linked to changes in language learning. More research is needed!

      However, you shouldn’t take these changes to mean that you can’t learn language effectively after your teens. Language is for communication and as long as your words are intelligible listeners can usually make sense of what you’re saying regardless of accent or syntax.

    • Photo: Iroise Dumontheil

      Iroise Dumontheil answered on 1 May 2015:

      To respond to your question more broadly, yes there are differences between the brain of a child and the brain of an adult. The brain of a child will have differences in the structure of the brain:
      – more grey matter, the cortex, which is thought to reflect that they have more connections between neurons (which are gradually pruned away to remove the connections that are not useful/needed but cost energy),
      – less white matter, which is below the surface of the brain and contains the fibers tracts that connect different parts of the cortex to each other; the tracts become covered in a fatty substance called myelin during development (which increase the volume of white matter in the brain). This is thought to permit a speedier transmission of eletrical signals from one part of the brain to another.

      Children and adults also differ in terms of patterns of brain activation. In general children show more widespread activation, and greater increases in activation, when they are doing cognitive tasks that are demanding, compared to adults, who instead show activations that are more limited to key regions specific to the particular tasks. This is thought to reflect that brain regions seem to become more specialised to support particular aspects of thinking during development.

    • Photo: Joseph Devlin

      Joseph Devlin answered on 2 May 2015:

      I like both Matt and Iroise’s answers — they’re both spot on. The problem is that sometimes these two different types of information get combined inappropriately. That is, we know quite a bit about brain differences from children to teens to adults and we also know that there are time periods of during which language acquisition is more successful than others, but what we do not know is how they relate. For instance, we cannot assume that neuritic pruning or white matter development is the reason that language learning is more successful in kids. There are three possibilities here. First, it may be that one (or several) of these biological processes are necessary for good language learning. Second, one (or more) of these maybe actually be a result of language learning. Finally, they could just be happening at the same time for totally different reasons. My only point here is that sometimes solid empirical data about specific aspects get inappropriately linked when people (the media?) try to draw a common story thread linking them all together.

Comments

  • Photo: Steven Rose

    Steven Rose commented on :

    Yes there are differences; it isn’t just a matter of size. Different brain regions mature at different rates, and different capacities similarly mature differentially. Hormonal surges during development also affect brain processes. The frontal lobes of ‘teenage brains’ are still not fully developed, hence the claims that teenagers show more impulsive behaviour than adults (‘high horsepower, poor steering’). The law has always recognised this in setting the age of criminal responsibility.