In response to yesterday's blog on clever techniques researchers use to get at the goings on of the infant brain, someone asked if the "habituation technique" I described with looking is also used with listening. If you missed that post, click here for a quick primer. The answer of course is YES!
I was going to post an example of a listening habituation study but if you read yesterday's post, you can probably figure out how that would go. Here, instead, is an example of a listening study using a different listening technique called "conditioned head turning". I wanted to include it because it is one of the more famous studies with mind-blowing findings (if you didn't already hear about it in the media), that have come from infant listening work. I hope you agree that it's incredibly cool!
Check it out:
The Scoop: All babies are born with the capacity to acquire language and which one (or ones) they end up using depends on which one (or ones) they are exposed to. So it's not so surprising that young babies can hear and tell the difference between speech sounds that us old folks can no longer hear e.g. Japanese infants can hear and discriminate between the "r" and "l" sounds in the English language more easily than Japanese adults. Interestingly, the paring down of your sound repertoire to the sounds in your language (s) of exposure happens around 10 months of age, just around the onset of language production. It's as though the brain is honing in on what it will need to find our way in the social world.
In fact, the evidence suggests that this "honing in" may apply to social stimuli in general i.e. not just language. Another study showed that young infants can discriminate between different faces of the same race, a phenomenon that holds for different races; Chinese, Caucasian, African etc. But by 9 months of age, they seem to lose that fine tuned ability and are best at discriminating faces of their own race! Read: social input goes a long way to influencing our social perception. Here's a link to one of the relevant papers in case you're really curious.
Notice that the speech and face processing narrowing is happening around the same time? Why? Probably because it's more efficient to be finely tuned to the social environment you have to deal with, the one you need to find your way in, to have your needs met in etc.
I don't know about you, but after reading this stuff I usually have two reactions: 1). Wow! Fascinating! and 2). Holy crap it's so much responsibility raising a child. What is he being exposed to? Do we educate bilingually? Is he getting multiracial/multicultural input? Is that necessarily good or bad or something I should worry about at all? Ughhh! Then I usually realize that time is marching on and stuff is happening anyway, like it or not. There's only so much we can control…