Rules and corpora

Over the years, I've watched the ways in which my two daughters acquire language and have come to the conclusion that they do so very differently. Kiera, the seven-year-old, has an unbelievable vocabulary; once she hears a word, it's incorporated into her speech. She's like a sponge, absorbing everything she hears. Kyla, the five-year-old, appears to learn in a more rule-based way, with a deeper understanding of grammar. I believe this because she often makes errors in applying a rule of English language to a case when it doesn't apply, e.g. "I beated* Kiera in the race." She seems to have internalized regular patterns like "add '-ed' to put a verb in the past tense."

Kiera, on the other hand, has never made such errors that I can remember. As a toddler, though, she did frequently confuse the first and second persons, apparently deciding that "you" always referred to her, and "I" to the speaker. She also often refers to herself in the third person, and to me in the third person even when she's addressing me. I suspect it's because she has accumulated sort of a corpus of valid English words and phrases that she draws from. Since she's never heard incorrect forms like "beated", she's never inclined to use them---but she has heard both "you" and "Kiera" to refer to herself, which is why it took her a while to understand that she should use "I" rather than either of those.

I think my own acquisition of language is much more like Kyla's. I have a deep understanding of grammar, which facilitates learning new languages in a structured environment, but makes it harder to pick them up based on immersion alone. While boarding a plane to Mexico after studying Spanish for a year, the flight attendant asked me which row I was in and I absentmindedly answered, "Diez y cinco", invoking a rule that applies only to numbers sixteen and above; I felt a little sheepish when she corrected me, "¿Quince?" And last weekend, at my Mandarin lesson, I was asked to translate the time "eleven-thirty pm" and I said, "yi shi yi dian ban", even though I know that "eleven" is just "shi yi". Subconsciously, I'd misapplied the rule that applies to numbers twenty and over, where the tens digit is explicitly named.