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Patricia Kuhl: The linguistic genius of babies

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Patricia Kuhl shares astonishing findings about how babies learn one language over another -- by listening to the humans around them and "taking statistics" on the sounds they need to know. Clever lab experiments (and brain scans) show how 6-month-old babies use sophisticated reasoning to understand their world.

- Language
Patricia Kuhl studies how we learn language as babies, looking at the ways our brains form around language acquisition. Full bio

I want you to take a look at this baby.
00:15
What you're drawn to are her eyes
00:18
and the skin you love to touch.
00:21
But today I'm going to talk to you about something you can't see --
00:24
what's going on up in that little brain of hers.
00:27
The modern tools of neuroscience
00:31
are demonstrating to us that what's going on up there
00:33
is nothing short of rocket science.
00:36
And what we're learning
00:39
is going to shed some light
00:41
on what the romantic writers and poets
00:43
described as the "celestial openness"
00:46
of the child's mind.
00:49
What we see here
00:51
is a mother in India,
00:53
and she's speaking Koro,
00:55
which is a newly discovered language.
00:57
And she's talking to her baby.
00:59
What this mother --
01:01
and the 800 people who speak Koro in the world --
01:03
understands [is] that, to preserve this language,
01:06
they need to speak it to the babies.
01:09
And therein lies a critical puzzle.
01:12
Why is it that you can't preserve a language
01:15
by speaking to you and I, to the adults?
01:17
Well, it's got to do with your brain.
01:20
What we see here
01:23
is that language has a critical period for learning.
01:25
The way to read this slide is to look at your age on the horizontal axis.
01:28
(Laughter)
01:31
And you'll see on the vertical
01:34
your skill at acquiring a second language.
01:36
Babies and children are geniuses
01:38
until they turn seven,
01:40
and then there's a systematic decline.
01:42
After puberty, we fall off the map.
01:45
No scientists dispute this curve,
01:47
but laboratories all over the world
01:50
are trying to figure out why it works this way.
01:52
Work in my lab is focused
01:55
on the first critical period in development --
01:57
and that is the period in which
01:59
babies try to master which sounds are used in their language.
02:01
We think, by studying how the sounds are learned,
02:04
we'll have a model for the rest of language,
02:07
and perhaps for critical periods that may exist in childhood
02:09
for social, emotional
02:12
and cognitive development.
02:14
So we've been studying the babies
02:16
using a technique that we're using all over the world
02:18
and the sounds of all languages.
02:20
The baby sits on a parent's lap,
02:22
and we train them to turn their heads when a sound changes --
02:24
like from "ah" to "ee."
02:26
If they do so at the appropriate time,
02:28
the black box lights up
02:30
and a panda bear pounds a drum.
02:32
A six-monther adores the task.
02:34
What have we learned?
02:36
Well, babies all over the world
02:38
are what I like to describe
02:40
as "citizens of the world."
02:42
They can discriminate all the sounds of all languages,
02:44
no matter what country we're testing and what language we're using,
02:47
and that's remarkable because you and I can't do that.
02:50
We're culture-bound listeners.
02:53
We can discriminate the sounds of our own language,
02:55
but not those of foreign languages.
02:57
So the question arises:
02:59
when do those citizens of the world
03:01
turn into the language-bound listeners that we are?
03:03
And the answer: before their first birthdays.
03:06
What you see here is performance on that head-turn task
03:09
for babies tested in Tokyo and the United States,
03:12
here in Seattle,
03:14
as they listened to "ra" and "la" --
03:16
sounds important to English, but not to Japanese.
03:18
So at six to eight months the babies are totally equivalent.
03:21
Two months later something incredible occurs.
03:24
The babies in the United States are getting a lot better,
03:27
babies in Japan are getting a lot worse,
03:29
but both of those groups of babies
03:31
are preparing for exactly the language that they are going to learn.
03:33
So the question is: what's happening
03:36
during this critical two-month period?
03:39
This is the critical period for sound development,
03:41
but what's going on up there?
03:43
So there are two things going on.
03:45
The first is that the babies are listening intently to us,
03:47
and they're taking statistics as they listen to us talk --
03:50
they're taking statistics.
03:53
So listen to two mothers speaking motherese --
03:55
the universal language we use when we talk to kids --
03:58
first in English and then in Japanese.
04:01
(Video) English Mother: Ah, I love your big blue eyes --
04:04
so pretty and nice.
04:07
Japanese Mother: [Japanese]
04:11
Patricia Kuhl: During the production of speech,
04:17
when babies listen,
04:19
what they're doing is taking statistics
04:21
on the language that they hear.
04:23
And those distributions grow.
04:26
And what we've learned
04:29
is that babies are sensitive to the statistics,
04:31
and the statistics of Japanese and English are very, very different.
04:34
English has a lot of Rs and Ls.
04:37
The distribution shows.
04:40
And the distribution of Japanese is totally different,
04:42
where we see a group of intermediate sounds,
04:44
which is known as the Japanese "R."
04:47
So babies absorb
04:50
the statistics of the language
04:52
and it changes their brains;
04:54
it changes them from the citizens of the world
04:56
to the culture-bound listeners that we are.
04:58
But we as adults
05:01
are no longer absorbing those statistics.
05:03
We're governed by the representations in memory
05:05
that were formed early in development.
05:08
So what we're seeing here
05:11
is changing our models of what the critical period is about.
05:13
We're arguing from a mathematical standpoint
05:16
that the learning of language material may slow down
05:19
when our distributions stabilize.
05:22
It's raising lots of questions about bilingual people.
05:24
Bilinguals must keep two sets of statistics in mind at once
05:27
and flip between them, one after the other,
05:31
depending on who they're speaking to.
05:34
So we asked ourselves,
05:36
can the babies take statistics on a brand new language?
05:38
And we tested this by exposing American babies
05:41
who'd never heard a second language
05:43
to Mandarin for the first time during the critical period.
05:45
We knew that, when monolinguals were tested
05:48
in Taipei and Seattle on the Mandarin sounds,
05:50
they showed the same pattern.
05:53
Six to eight months, they're totally equivalent.
05:55
Two months later, something incredible happens.
05:57
But the Taiwanese babies are getting better, not the American babies.
06:00
What we did was expose American babies during this period
06:03
to Mandarin.
06:06
It was like having Mandarin relatives come and visit for a month
06:08
and move into your house
06:11
and talk to the babies for 12 sessions.
06:13
Here's what it looked like in the laboratory.
06:15
(Video) Mandarin Speaker: [Mandarin]
06:17
PK: So what have we done to their little brains?
06:39
(Laughter)
06:41
We had to run a control group
06:44
to make sure that just coming into the laboratory
06:46
didn't improve your Mandarin skills.
06:48
So a group of babies came in and listened to English.
06:50
And we can see from the graph
06:52
that exposure to English didn't improve their Mandarin.
06:54
But look at what happened to the babies
06:56
exposed to Mandarin for 12 sessions.
06:58
They were as good as the babies in Taiwan
07:00
who'd been listening for 10-and-a-half months.
07:02
What it demonstrated
07:05
is that babies take statistics on a new language.
07:07
Whatever you put in front of them, they'll take statistics on.
07:09
But we wondered what role
07:13
the human being played
07:15
in this learning exercise.
07:17
So we ran another group of babies
07:19
in which the kids got the same dosage, the same 12 sessions,
07:21
but over a television set
07:24
and another group of babies who had just audio exposure
07:26
and looked at a teddy bear on the screen.
07:29
What did we do to their brains?
07:31
What you see here is the audio result --
07:34
no learning whatsoever --
07:37
and the video result --
07:39
no learning whatsoever.
07:42
It takes a human being
07:44
for babies to take their statistics.
07:46
The social brain is controlling
07:48
when the babies are taking their statistics.
07:50
We want to get inside the brain
07:52
and see this thing happening
07:54
as babies are in front of televisions,
07:56
as opposed to in front of human beings.
07:58
Thankfully, we have a new machine,
08:00
magnetoencephalography,
08:02
that allows us to do this.
08:04
It looks like a hair dryer from Mars.
08:06
But it's completely safe,
08:08
completely non-invasive and silent.
08:10
We're looking at millimeter accuracy
08:13
with regard to spatial
08:15
and millisecond accuracy
08:17
using 306 SQUIDs --
08:19
these are Superconducting
08:21
QUantum Interference Devices --
08:23
to pick up the magnetic fields
08:25
that change as we do our thinking.
08:27
We're the first in the world
08:29
to record babies
08:31
in an MEG machine
08:33
while they are learning.
08:35
So this is little Emma.
08:37
She's a six-monther.
08:39
And she's listening to various languages
08:41
in the earphones that are in her ears.
08:43
You can see, she can move around.
08:46
We're tracking her head
08:48
with little pellets in a cap,
08:50
so she's free to move completely unconstrained.
08:52
It's a technical tour de force.
08:55
What are we seeing?
08:57
We're seeing the baby brain.
08:59
As the baby hears a word in her language
09:01
the auditory areas light up,
09:04
and then subsequently areas surrounding it
09:06
that we think are related to coherence,
09:08
getting the brain coordinated with its different areas,
09:11
and causality,
09:13
one brain area causing another to activate.
09:15
We are embarking
09:18
on a grand and golden age
09:20
of knowledge about child's brain development.
09:23
We're going to be able to see a child's brain
09:26
as they experience an emotion,
09:28
as they learn to speak and read,
09:30
as they solve a math problem,
09:32
as they have an idea.
09:34
And we're going to be able to invent brain-based interventions
09:36
for children who have difficulty learning.
09:39
Just as the poets and writers described,
09:42
we're going to be able to see, I think,
09:45
that wondrous openness,
09:47
utter and complete openness,
09:49
of the mind of a child.
09:51
In investigating the child's brain,
09:54
we're going to uncover deep truths
09:56
about what it means to be human,
09:58
and in the process,
10:00
we may be able to help keep our own minds open to learning
10:02
for our entire lives.
10:04
Thank you.
10:06
(Applause)
10:08

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About the speaker:

Patricia Kuhl - Language
Patricia Kuhl studies how we learn language as babies, looking at the ways our brains form around language acquisition.

Why you should listen

Patricia Kuhl is co-director of the Institute for Brain and Learning Sciences at the University of Washington. She's internationally recognized for her research on early language and brain development, and studies that show how young children learn. Kuhl’s work has played a major role in demonstrating how early exposure to language alters the brain. It has implications for critical periods in development, for bilingual education and reading readiness, for developmental disabilities involving language, and for research on computer understanding of speech.

More profile about the speaker
Patricia Kuhl | Speaker | TED.com