People love saying that adults cannot learn languages. This is almost always said by adults who have not learned a language to any serious degree. That should already make you suspicious. Why would someone who has never really attempted to learn a language have such a strong opinion on the matter?
What they mean is not that adults cannot learn languages. Adults clearly learn languages all the time; however, what they mean is an unwillingness to endure the potential embarrassment, repetition, ambiguity, and sustained attention required to learn a language. So they would prefer a theory in which failure is predetermined and therefore, not really their fault.
“Adults can’t learn languages” is attractive for the same reason every other cope is attractive: it turns a difficult task into an impossible one and then justifies it with a thin veneer of science.
This is completely true. People say this as though the whole discussion ends the moment someone mentions neuroplasticity. But adults are not merely worse children. Adults can reason, plan, pick better methods, structure their environment, sit still, and pay attention. Children cannot do any of that. They get one advantage for free, and people act as if that cancels everything adults have actually developed.
The comparison is also bad in another way. Children do not “just absorb” language in the abstract. They are surrounded by language all day in situations where understanding matters. They point, guess, demand, fail, try again, and get constant feedback from context, tone, gesture, and repetition. Their whole life is arranged around making sense of language. Adults then give a language twenty distracted minutes through an app and blame their biology when it doesn’t stick.
Many semi-serious language learners are at least somewhat familiar with Stephen Krashen. His “input hypothesis” is simple: people acquire language through sustained exposure to meaningful messages that are mostly understandable. Most adults try to learn by doing duolingo lessons, learning disconnected vocabulary and grammar concepts out of context, and wonder why they aren’t able to understand anything after years of maintaining their app streak. “I wish I learned when I was a child” they say, but in reality what they are doing is the linguistic equivalent of trying to ride a bike by only reading a book about bike riding. They learn facts about the language without ever growing familiar with the language itself.
The answer is to build an environment that gives you a lot of comprehensible input. Approaches like AJATT (All Japanese All the Time) and Refold are built around this idea. The input also has to be at your level. When I started learning Chinese I could not follow Chinese TV at all. Children’s shows and material targeted towards learners (such as graded readers) are the ideal starting point. There are tools like Yomitan that allow you to have a pop-up dictionary to figure out the meaning of the words as you are reading. You can use Anki flashcards as a supplement to reinforce vocabulary that you encounter during immersion.
At this point someone usually says the real answer is to go to a meetup, join a speaking group and “just start talking.” After all, it makes sense right? That’s how babies learn!
Well, the great part about being an adult is that we don’t have to learn like babies.
A beginner who tries to speak before they have enough input ends up translating from their native language in their head, recycling the same stock phrases and reinforcing the same incorrect patterns. Conversation groups are often not much better, usually offering limited speaking time with the added benefit of exposing you to other learners’ mistakes.
Output matters, but it grows from a foundation of hundreds or thousands of hours of input. Speaking practice is good for getting over nerves, or for people who already have a solid foundation. Some people do it just because they enjoy it, and it helps them to stay motivated. But as an early stage learner, do not confuse it with real efficient language acquisition.
That is the truth people are trying not to say.
Adults do learn languages.
We fail for ordinary reasons. Bad methods, inconsistent effort, too much embarassment, not enough input, or giving up before the language has had time to settle in. None of it proves that adults cannot learn languages. It only proves that most of us would rather protect our pride than do the work.
I am not specifically endorsing anything linked here but all of these links are about immersion learning. Some are written specifically for Japanese but are still profitable for other languages.