Short answer
Children have various advantages when learning a language. Their brains are more flexible than those of adults which makes it easier to store new information. Furthermore, children are less self-conscious about putting their newly learned knowledge into practice and often find themselves in environments that promote learning the new language.
Longer answer
If you’ve ever tried to learn a language as an adult, you might have caught yourself wishing you had started at an earlier age. Indeed, acquiring a second or additional language seems to come naturally to children, while becoming fluent is much harder for adult learners.
There is no consensus on why our language learning abilities diminish as we grow older. However, several explanations have been proposed, and it is likely that several factors are at play here. Firstly, children show greater neural plasticity than adults, meaning that their brains are more flexible and that neural networks reorganize faster in response to new information. This gives them the unique advantage of being able to ‘absorb’ the new language, while adults have to consciously memorize words and grammar rules.
Secondly, children often learn a language through immersion, i.e. living in a community of native speakers, while adults find themselves in a classroom setting. Children of immigrant parents will be exposed to the local language for several hours a day at school or daycare. Their parents, however, might work in an English-speaking environment and only have limited contact with the local language outside of a language course. Research shows that immersion also has a positive effect on adult learners: increased contact with the target language in real-world scenarios boosts learning outcomes.
Additionally, it has been argued that children are less self-conscious than adults when it comes to speaking a foreign language. While adults might carefully plan every sentence before speaking up, children aren’t afraid to make mistakes or look like a fool. Instead, they are driven by a desire to communicate with their peers. In the interaction with other children, they will pick up new words and phrases and effortlessly integrate them into their speech.
In conclusion, young language learners have multiple advantages: Their brains are predisposed to quickly integrate new information, they often encounter the target language in naturalistic settings, and they have less inhibitions. If you are young, learning a language is literally child’s play!
References
Birdsong, D. (2018): Plasticity, Variability and Age in Second Language Acquisition and Bilingualism. Frontiers in Psychology, 9, 81. doi: 10.3389/fpsyg.2018.00081.
Huang, B.H. (2015): A synthesis of empirical research on the linguistic outcomes of early foreign language instruction. International Journal of Multilingualism, 13(3), 257-273. doi: 10.1080/14790718.2015.1066792.