Most of the time, they had parents who spoke two different first languages at home, and grew up as bilingual children. When I meet these people, I often feel a little jealous. I wish my parents had been bilingual, or had enrolled me in a special bilingual school—or that my hometown even had a bilingual school that I could have attended. Unfortunately, none of this happened. So, when I meet bilingual people, I not only feel a little jealous, but also a little anxious about my own language learning goals.
It seems impossible that my second language ability will ever rise to the level of a truly bilingual speaker.
There are many reasons for this: For one thing, finding the time to study and practice and continue to feel confident about my language learning is difficult. For another thing, it seems like I’m too old. I missed my chance to learn a second language well, and so I should just give up and accept my own limitations.
The question of age and language learning is a big part of linguistics research. Basically, this debate is focused on a hypothesis called the Critical Period Hypothesis (CPH). The CPH was first introduced by Eric Lenneberg in his 1967 book Biological Foundations of Language. The CPH attempts to describe a simple phenomenon that anyone who has tried to learn a second language already knows: after a certain age, it is no longer possible to learn a language like a native speaker.
Children, as we have all seen, seem to learn language naturally without the formal instruction found in language classrooms. This period of natural language acquisition is the “critical period.” Many researches have tried to identify the exact time of the critical period, but generally we can think of it as anytime before puberty.
As we all know, many things change at puberty. Things are awkward and difficult. It’s a time of identity creation and rebellion, but it’s also a time when your brain changes and loses the ability to learn a second language like a child. But what exactly changes?
To begin with, every adult language learner should know that the CPH is a controversial hypothesis. This is because the name “critical period” seems to imply that after this period, it is impossible for a language learner to achieve mastery in a second language. In other words, once we hit puberty, there is a sudden, dramatic change. After that, our ability to master a second language is lost forever.
Intuitively, this seems wrong to many of us.
There are plenty of people who learn a second language effectively, or even masterfully, as adults. I personally have met many second language learners who immigrated to a new country and a new language in high school or later, and now speak their second language perfectly. Because of this, some researchers have proposed that the critical period is not a dramatic change, but a gradual change. After puberty, we become less sensitive to the languages used around us, but we do not lose the ability to learn a second language successfully altogether. Yet, an even more important issue is related to that last sentence—what exactly does it mean to “learn a second language successfully?” What is a successful language learner?
Some people have suggested that “speed of learning” is a good way to measure successful language learning. In other words, children learn languages faster than adults; therefore children are the more successful language learners. However, the majority of research that compares adult language learners to child language learners has found no significant advantages for children over adults. What the research has found, however, is that the way adults learn a second language is different. Adults have to rely on meta-cognitive abilities, and an understanding of rules, patterns and structures in a way that children do not.
Also, as Peter Robinson and Nick Ellis pointed out in their book Handbook of Cognitive Linguistics and Second Language Acquisition, adults essentially have to learn their second language through the perspective of their first language, whereas bilingual children do not. In other words, adults must incorporate their second language into their existing identity, while children develop their identity and their language ability at the same time.
Perhaps because of this, research has also shown that while there is no difference between adults and children in terms of language learning speed in the short term, children eventually learn much faster than adults in the long term. However, this research does not necessarily show that children are better language learners than adults.
Instead, this research suggests that, in addition to needing meta-cognitive skills to learn a second language well, adults must also rely on motivation in a way that children do not. Children do not have to motivate themselves to learn a second language. As discussed above, their learning seems to naturally happen. Therefore, it is possible that, in the long term, adult language learners do not persevere in the same way that children do.