I’m not a fan of articles where the answer to the lead-in question is carefully nested 3/4 of the way in, so please allow me to clear the air by saying that as adults it is chemically impossible for our brains to pick up new languages the way small children can acquire their first, and even second languages. In addition it is more efficient for adults to learn like adults, and be active agents in their acquisition of language.
I don’t think anyone would be surprised to learn that adults and children acquire languages differently. I also doubt you would be surprised to learn that adults and children use different areas of the brain in order to pick up new words and adapt new grammar patterns. According to the team of neuroscientists lead by UCLA professor Dr. Paul Thompson, children are chemically hard wired to acquire language using the deep motor areas of their brain, a portion of the mind dedicated to controlling unconscious actions. Doctor Thompson describes how our ability to activate this part of the brain “narrowly shuts” as they turn 18. This does not mean that we will be neurologically incapable of learning a language after this point. It only means that the brain will use different, more active areas in order to do so.
Let’s discuss what people often mean by “learning language like a child”. What I find people often mean by this phrasing, is that they intend to absorb a foreign language completely through passive exposure to it. While the intentions of these people are good, I think this way of thinking does both a disservice to the extremely complex minds of both children and adults.
The first myth I would like to address is the idea that children passively master their first language. It is true that infants will be able to distinguish foreign sounds from their mother tongue as young as four months old and soon after begin repeating the words they hear around them, it is hardly a passive phenomenon. While a child does not need to exert a conscious effort to learn language, they will practice the sounds of their language through babbling for months before they may produce any words with intended semantic meaning. It is through interaction and association with caregivers that small children learn the significance of words. If you put a baby next to a radio and leave it on all day, they will not linguistically be better off than any other baby. Likewise, we will not be able to passively learn a language by absorbing native material alone. In the case of Japanese, some of the first words you learned may have been taken from a song or an anime. But it was probably with the added context of subtitles and repeated exposure with those subtitles that taught you the phrase. If you watched hours and hours of Japanese television without subtitles, you could eventually figure out phrases which elicit strong emotional reactions, such as “What the hell!”, “I love you!”, “Stop!”, etc. But how long would it take you to figure out the contents of a news broadcast or a typical conversation? We would be much better off with a textbook to follow, specific recordings with a translation, and then later using these native materials to reinforce what we’ve learned. As adults this is the greatest advantage we have over children. Adults can learn language through more abstract associations than small children, who can only learn via direct interactions with people in their surrounding environment.
It also goes without saying that as adults the concepts we express to one and other are much more complicated and diverse than the conversations of a three year old child, for example. If you were to move to a different country right now, and spend three years consistently studying the language of the place you were living, your functional language ability would likely be much higher than that of a natively-born three year old child born. You could probably sit down for a simple job interview, go buy a phone, or understand the contents of a tv show you were watching. By this time you would probably still be making regular mistakes based on your background in your mother tongue. But that is not to say that small children never make mistakes learning their first language either. The difference is that a child will be quickly corrected by an adult, making sure the child does not grow up with poor speaking habits. A foreign speaker on the other hand, is less likely to be corrected by the people around them when they make a mistake. Unlike a child, it is not the responsibility of surrounding adults to ensure that you acquire correct speaking habits. This makes it all the more imperative that adult language learners seek out correct habits on their own time.
I can understand the appeal of wanting to learn a language without any conscious effort on our behalf. It can be a real slog to dedicate ourselves for years to learning a new language just to find that our abilities are barely that of an early elementary schooler. It’s easy to think: “If only I could have learned the language like they did, I wouldn’t be struggling like I am now”. To learn language the same way as a child also sounds more biologically correct than trying to artificially cram in pages of new vocabulary. From personal experience I’ve gotten a lot of benefit from using passive listening during a structured study session in order to pick up on the natural rhythm and speech patterns of Japanese.
In the end the best way to study a language is the way that will keep you coming back to it every day. It’s a very long road to becoming conversationally fluent, and consistency is the only way to get there. Whether that study is made up of mostly passive listening with some lessons, or a whole bunch of textbook exercises with a bit of passive native material will be dependent on how much you enjoy the resources you use. Your study habits are also likely to change as your knowledge improves. A child’s pace is limited to the surrounding environment and the availability of adults to interact with. Whichever path you choose, consider it to your advantage that you get to choose exactly what to learn, how to learn and when.