Judith Rich Harris’ The Nurture Assumption is one of those books which I’ve been leaning on for over a decade, it’s so rich in novel and “counter-intuitive” facts which nevertheless just “make sense” in terms of how the world is as opposed to how we’re taught the world should be. The most important finding isn’t really about the importance of heritable variation in human behavior, though that’s not trivial, it’s that “shared [family] environment” matters so much less than you’d think. Quite a large fraction of the variation in outcomes is “non-shared environment,” which basically means we just don’t know, and so we can’t really control. In The Nurture Assumption it is posited that a large fraction of “non-shared environment” are peer group effects. One of the facts which the author uses to support this model is that the vast majority of people pick up their accents in their native language from their peers, not their parents. The telling is exception are children who are diagnosed as autistic. But I don’t know this literature in psychology well and so I’ve been repeating this fact for years without knowing the primary source. Now I think I’ve found it, Do children with autism acquire the phonology of their peers? An examination of group identification through the window of bilingualism:
Normal children whose parents have different native languages tend to develop an accent which is closer to their peers than to either parent. It was predicted that children with autism, because of their social deficits, might not acquire the accent of their peers, perhaps because of the lack of the normal drive to identify with peers. Bilingualism was used as a window into such social factors in language acquisition. Using audiotaped speech samples, the study found that in a sample of children with autism who were brought up in England and whose mothers were not English, 83.3% acquired their mother’s (non-English) accent. In contrast, among normally- developing siblings of children with autism who were brought up in England and whose mothers were not English, only 12.5% acquired their mother’s (non-English) accent. We suggest that such studies of unusual populations are of value in furthering our understanding of the larger population of children with autism, and the influences on normal social development.
The sample size was less than 100, and I’m very curious if this research has been followed up (using Google Scholar I didn’t stumble on anything very clear, but again, I’m not familiar with this discipline). My point in focusing on accent in the previous post is how we speak is often a social cue, rather than about language acquisition as such. Speaking of which, though it is common sense it is important to reiterate that children are basically savants when it comes to learning languages. Multi-lingualism is common in many parts of the developing world, and presumably it may have been in a more ethnically fragmented ancient world too. It’s a core human competency, not a signal of cognitive exceptionality.