Category Archives: Science

Can You Hear That? Listening Study Yields Amazing Insights About Early Human Language

0-3 months, 3-4 months, 4-5.5 months, 5.5 - 8 months, 8-11 months, Baby Brains, Language development, Science, Studies

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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…

- Tracy

What’s going on in that sweet little head of yours?

0-3 months, 12-17 months, 3-4 months, 4-5.5 months, 5.5 - 8 months, 8-11 months, Baby Brains, Devevelopment in general, Science

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Ever look at your baby and wander what the heck is going on in that head? Ever read those articles in magazines or newspapers or hear stuff on the radio about scientific studies on human infants (non-medical) and wonder "How the heck do they know that?".  Can't exactly ask the baby. Heck, they hardly stay awake long enough to find out anything anyway, even if they could talk.

This week I thought I'd take you behind the scenes of infant research to give you a peek into how scientists get inside that head. In a nutshell? They take advantage of the things that babies already like to do such as suck, listen to and look at new things. Looking has probably been explored the most. And dude, you'd be amazed and what we've learned from theses studies.

Looking studies typically use something called "visual habituation". The set-up looks something like this:Dadandbabycb

 
Mum or dad wears a pair of headphones, so they can't nudge, budge or influence baby's behaviour in any way (like try to make them look especially brilliant- kidding, kidding…). Baby is given something to look at on the screen (image, video etc.). At first the baby is interested and looks intently ("Hey, what's that?!"). But eventually, baby gets bored and starts to look away – "That again, whatever…" We say that the baby has "habituated". Then the display changes and baby sees something new. If they look with renewed interest – "What the…?!" (we call this "dishabituation")- then we know that the baby detected the difference between the old and new thing. That's it.

Ho hum, you say. But get this, sometimes the change between the old and new thing can be VERY subtle (we're talking teeny-weeny). By tweaking these subtle changes – while keeping everything else in the displays the same – we've learned a whole host of things about what 's going on in that noggin'. And we're talking tiny babies (newborns, 1-month olds) right up to toddlers. 

Check out this example: In one study, 6 month olds who were habituated to displays of say 8 black dots on a white screen, looked longer when the display changed to 16 black dots. As the two displays contained the same brightness, density of dots, total area of the dots  (i.e. the amount of black), the researchers concluded that the infants must have detected the difference in number. We're talking 6 month olds here people, they're not counting (at least not the way we do)! Cool huh? 

Infant looking has been used to study everything plus the kitchen sink: we're talking awareness of spatial position, proportion, solidity of objects, understanding gravity, adults' intentions (did they mean to grab that object or just touch it by accident?), discriminating faces of the same race, sensitivity to facial expressions and even to rudimentary addition and subtraction (with some conclusions more hotly debated than others).  And get this: it takes longer for babies of depressed moms to habituate to a happy face compared to babies of non-depressed moms, presumably because it's more novel to them! 

Kinda makes you see that bundle of sweetness in a whole new light doesn't it? So what do you think? Are you surprised by some of these findings? Did you have other ideas about how researchers pried their way into the infant brain?  Wanna know about anything in particular about the baby brain? Send your q's and stay tuned to hear more about ingenious ways of getting at the inner sanctum later this week.