[dahart]

While this myth is repeated often, I don’t find it true or obvious at all, I’m not sure where it comes from and I don’t see any actual evidence for it. You need to compare the hours spent learning, not years, in order to compare effort.

What seems “obvious” to me is that the opposite is true - language learning accelerates for people who learn multiple languages; learning a second language takes less time than the first, if you measure the number of hours spent on it. A third one often goes even faster, especially for related languages. The main problem people have is they don’t put in the hours, and that may indeed get harder to find the motivation to do as we age.

Accent is not a metric for proficiency, understanding and communication is. 5 year old native speakers have good accents but have been immersed 100% and often don’t have the vocabulary for adult conversations. The article is someone reaching B2 level from scratch in 1 year, without full immersion. (B2 is the requirement for a foreigner to start a university degree, for example.) It doesn’t take 20 years of intense studying to learn a language, older adults learn them to proficiency in a year or two all the time.

Think of the hours again, a 5 year old has spent 8-16 hours a day (56-112 hours/week) immersed for 5 years, while the author here did like maybe 10-15 hours a week (which is indeed pretty intense and aggressive). Read his notes - ~100 hours of conversation to reach B2, where a 5 year old will have definitely had more than 1,000 hours of conversation and likely closer to ~5,000 hours of conversation. That’s more than 10x, plausibly much more, so it seems clear that in this case the author’s learning is far more efficient than childhood language learning.

[forty]

It is true that learning extra languages makes it easier and easier, but that just makes the learning capacity of babies even more impressive: they are not even learning a language, they are leaning what is a language, what does it mean to make sound with their mouth, etc etc.

Several comments seem to suggest babies are learning to speak full time, but it's very far from it, they have to learn to walk, eat, read physical expression, draw, etc etc, all kind of things we don't even realize. They are just awesome learning machines, which I find fascinating to watch.