special needs seminar

[Guest guest]

What bilingual babies reveal about the brain

Learning two languages at once may boost infants' brain power, researcher says

By Clara Moskowitz, LiveScience Senior Writer

Sometimes immigrant families are told that if they speak their heritage language

that their baby may not learn the dominant language as well, and if they speak

two languages to their children that they're going to be confused.

There just isn’t any really good evidence of language confusion. Of course

there's language mixing. It's called code-switching and it's rule-governed. So

any community of two languages will have rules about how much and when they can

switch. Babies who grow up in this kind of environment, by the time they're 2

1/2 or 3, do the code-switching [going back and forth between the languages]

themselves. If one parent is bilingual, they'll code-switch with them, and if

another parent is monolingual they won't code-switch with them. So these are

kinds of rules that they figure out.

LiveScience: So you have found a perceptual sensitivity in bilingual babies,

where they can not only distinguish between two languages when hearing them, but

also when watching muted videos of the same person speaking two different

languages? What's going on here, and how long does this sensitivity last?

Werker: That's a great question. We've only tested babies on the visual-language

discrimination at 4, 6 and 8 months of age. And 4- and 6-month-olds can

discriminate two languages visually whether they're familiar with only one of

them, or both of them.

But by 8 months, our previous work has suggested that they have to be familiar

with both languages to keep them apart. Whereas our more recent work is showing

that if you're bilingual you can discriminate even two unfamiliar languages [at

8 months old].

We haven’t tested babies after 8 months, so I'm not sure how long it's

maintained. We have tested adults, and what we find is that as an adult, you do

better again if you're bilingual. You can still perform better than chance but

only slightly, so if you're familiar with one of the languages. But, in work we

haven’t published yet, we've shown that you have to have had exposure to one

of those languages by about age 4 or 5 to continue to show even this

slightly-better-than-chance discrimination as an adult.

So we think there's a lasting influence from this early exposure.

LiveScience: OK. But the peak of this visual sensitivity to languages occurs

when they're doing the bulk of this language learning?

Werker: We think the peak of this sensitivity occurs very early.

It's not necessarily the case that an 8-month-old couldn’t learn this. The

fact that adults, when they're trying hard, can do a little bit better than

chance, suggests there's some latent sensitivity there. We think what's going on

is the perceptual system is getting tuned. It becomes more proficient at using

that kind of information that it might require. And if you're growing up in a

monolingual environment, and you haven't been experiencing the variability in

input, well then treating all visual languages the same is probably not

unadaptive, [in other words, wouldn't cause any disadvantage].

LiveScience: So this is the first I'd heard that bilingual children have other

skills besides extra sensitivity to sound – that they, in fact, have

heightened sensitivity to visual cues as well. So what other differences between

bilingual and monolingual babies are known?

Werker: There's some great work by Aggie Kovács and Jacques Mehler that shows

that at 7 and 12 months of age, babies growing up bilingual are better able to

switch rules. So if a baby is taught to turn their head in one direction in

order to hear or see something interesting, they'll do that well. But a

bilingual baby at 7 months can then reverse the rule and learn to turn their

head in another direction better than a monolingual baby can. And similarly, at

12 months they're better [able] to learn two sets of rules.

So it seems that babies who are growing up bilingual are learning the perceptual

properties of each of their languages. They're learning to pay attention to

perceptual cues that might be important for distinguishing things in the world,

beyond distinguishing two languages and that they're able to switch between

paying attention to one kind of property and paying attention to another.

LiveScience: Is there any reason to think these differences could affect other

types of learning, beyond language?

Werker: Well, yeah. I think Aggie Kovács and Jacques Mehler's work suggests it

can lead to more flexibility in learning more generally. In learning one rule,

and then learning a second rule. So that's really interesting.

So I think there is evidence that growing up with two languages confers certain

cognitive advantages. But I wouldn't go so far as to say you have to grow up

bilingual to have those cognitive advantages. I think this is one natural route.

And I think more generally what the work shows is that babies are just as

prepared to learn two languages from birth as they are one, and that if parents

speak two languages in the home they should be comfortable continuing to do so.

LiveScience: Based on what you know, would you tell your friends and family to

try to raise their own children to be bilingual if at all possible?

Werker: I would tell my friends and family that if they have a baby and if they

speak two languages in the home, to feel comfortable speaking both of those

languages. I wouldn't say that they should now start introducing some other

language that they don't really know yet.

LiveScience: What about sending babies to language schools, or hiring foreign au

pairs?

Werker: You know, nobody's done any work on au pairs or even grandparents in the

home, and I think that's a really interesting question. Babies learn the

languages they want to learn. So even if bilingual families maintain the two

languages that they have in the home, and even if babies are learning those two

languages, once they start going even to preschool, if only one language is

being used, they'll often stop using the nondominant language, and they'll even

stop using it at home. And so that's a frustration, I think, for a lot of

families.

So the attempt to introduce a second language in an unnatural fashion, or in a

natural fashion but with somebody who isn't Mom or Dad – more work is needed

to see what kind of impact this has. Does it confer the perceptual advantages

and the cognitive advantages, even though the child might refuse to maintain

that language? That we don't yet know.

LiveScience: What are some of your biggest unanswered questions about how humans

learn language?

Werker: There are so many questions about language learning. I think what really

drives me is I'm really interested in the preparation we have at birth for

language learning. How the perceptual system – cause that's really all that we

have at birth – we don't know any words yet, we don't know any concepts yet,

we don't know sentence structure yet of our native language and so we have to

get it all through listening and watching – and just how we do that is what

really fascinates me.

LiveScience: Why can babies learn second languages without " foreign " accents,

but adults rarely can?

Werker: I think what the research thinking on accents is, is that we've already

established one representational system, the sound properties in both of the

individual consonant and vowel sounds as well as the rhythmical properties of a

first language. And then when we start putting a second language on top of that,

if it's past this kind of sensitive period that people have talked about, it's

more difficult.

I think the debate in the literature now is, is this sensitive period one that

is in the brain – so are there structures or connections that are just

difficult or impossible to change after a certain time – or is it continued

interference with the first language? Because usually when somebody learns a

second language, they're still speaking their first language. And so the

properties of the first language will be influencing and maybe getting in the

way and interfering with the second.

There's some work by Christophe Pallier and others that suggests that if you

remove the first language entirely – so work, for example, with people who

were adopted from Korea at 8 years of age, into different villages in France

where they had no more contact with Korean speakers – suggests that without

any interference from the first language, then more acquisition in an

accent-free fashion might be possible.

It's still up in the air, because there are hardware changes in the brain as

well. It's still an ongoing question.