[webmaven]

> Can you give a concrete example of something that can only be learned as a child?

The canonical example is fluency in an unfamiliar (spoken) language. Most people lose the ability to internalize a new language to the point of being able to 'think in the language' as opposed to 'translating in your head' past their tweens, although the skill of deliberately acquiring new languages is itself learnable, and of course improves with practice, but the ability to learn to speak a language 'natively' (not merely fluently) is lost by nearly all people even earlier.

However, more to the point of this discussion, this age-linked loss of ability or plasticity does not seem to apply to learning programming languages (it is fairly common that one's first programming language is successfully acquired well past that point, after all). I suspect this has something to do with differences between listening/speaking vs. reading/writing fluency.

[tuukkah]

Yes, programming languages and programming are very limited when compared to natural languages and the range of typical verbal communication.

The fact that at least some older adults do internalise new languages and become undistinguishable from native speakers begs the question why everyone cannot. I'd say plausible explanations include adults being buzy or lazy with their lives, having a fixed mindset towards language learning, bad pedagogy etc. as alternatives to loss of the necessary plasticity. All these can apply to learning programming likewise.