Stephen Fry had a TV-show on a while back called Planet Word, in one episode he met a computational linguist who tried to teach his son Klingon as his first language, the kid made pretty impressive progress right up to the point he realized he could, effectively, only use it to communicate with his dad, after that he completely lost interest. It makes sense, I guess, if you can’t see how what you’re learning is immediately benefiting you it makes it so much more difficult to stick with…