People really underrate the difficulty of learning not a language but language itself. Concepts learned in one language can transfer over to other languages, but when you learn your first language, you have to learn the concepts for the first time in addition to the word. Personally, I am of the opinion that the critical period in learning is mostly a biproduce of learning over time and less a special feature of a brain’s age. The cortex naturally will organize around the incoming sensory information coming in, so over time the “increased plasticity” of newborn brains will reduce as it becomes increasingly more fitted to their experiences.
Is it difficult if it’s also inevitable? In a social setting, a child will either learn a language or develop one — two wild children would develop a rudimentary language that would evolve in complexity as it’s passed down generation by generation. I wonder if a feral child, who matured alone and without social interaction, could learn a language later in life. Or, if it could, how difficult it would be.
What do you mean by the critical period in learning being a byproduct of learning over time as opposed to a special feature of the brain’s age? I don’t think I grasp it. Are you saying that it’s not really the brain’s age, but rather that it hasn’t learned a lot yet? Which are distinct but highly correlated.
A large foundation for the belief in critical periods for language are based on Genie, a feral child who was entirely unable to learn a spoken language despite significant efforts. Today, she can use some sign language but cannot speak.
https://en.m.wikipedia.org/wiki/Genie_(feral_child)
So the answer is largely believed to be: No. You cannot learn a spoken language if you missed the critical period.
It’s also literally impossible to test/study ethically, so nobody actually knows.
Just from the overview of that wikipedia page, it’s clear she has been subjected to a horrific amount of abuse and emotional turmoil, both as a child and later as an adult. It seems extremely dubious whether you can really draw any general conclusions from such an extreme case study.
I don’t have a source handy, but from what I remember: yes, a feral child can learn language later, but never to the same level of fluency. It’s more like learning a second language. Also there is extremely limited data because it mostly comes from horrifically abusive situations.
If I remember right, the most interesting data came from a study that gathered deaf children from areas where they had no sign language. The young children rapidly developed sign language, but the older children (teens) had a hard time keeping up and did not reach the same fluency.