Return to Video

The linguistic genius of babies

  • 0:01 - 0:04
    I want you to take a look at this baby.
  • 0:04 - 0:09
    What you're drawn to are her eyes
    and the skin you love to touch.
  • 0:09 - 0:13
    But today I'm going to talk to you
    about something you can't see.
  • 0:13 - 0:15
    What's going on
    up in that little brain of hers.
  • 0:16 - 0:20
    The modern tools of neuroscience
    are demonstrating to us
  • 0:20 - 0:24
    that what's going on up there
    is nothing short of rocket science.
  • 0:25 - 0:28
    And what we're learning
    is going to shed some light
  • 0:28 - 0:34
    on what the romantic writers and poets
    described as the "celestial openness"
  • 0:34 - 0:36
    of the child's mind.
  • 0:37 - 0:40
    What we see here is a mother in India,
  • 0:40 - 0:44
    and she's speaking Koro,
    which is a newly discovered language.
  • 0:45 - 0:47
    And she's talking to her baby.
  • 0:47 - 0:48
    What this mother --
  • 0:48 - 0:51
    and the 800 people who speak
    Koro in the world --
  • 0:52 - 0:55
    understands is that,
    to preserve this language,
  • 0:55 - 0:57
    they need to speak it to the babies.
  • 0:57 - 1:00
    And therein lies a critical puzzle.
  • 1:00 - 1:03
    Why is it that you can't
    preserve a language
  • 1:03 - 1:06
    by speaking to you and I, to the adults?
  • 1:06 - 1:08
    Well, it's got to do with your brain.
  • 1:09 - 1:13
    What we see here is that language
    has a critical period for learning.
  • 1:13 - 1:17
    The way to read this slide is to look
    at your age on the horizontal axis.
  • 1:17 - 1:20
    (Laughter)
  • 1:20 - 1:23
    And you'll see on the vertical
    your skill at acquiring a second language.
  • 1:24 - 1:28
    The babies and children are geniuses
    until they turn seven,
  • 1:28 - 1:30
    and then there's a systematic decline.
  • 1:30 - 1:32
    After puberty, we fall off the map.
  • 1:33 - 1:35
    No scientists dispute this curve,
  • 1:35 - 1:37
    but laboratories all over the world
  • 1:37 - 1:40
    are trying to figure out
    why it works this way.
  • 1:41 - 1:45
    Work in my lab is focused on the first
    critical period in development,
  • 1:45 - 1:46
    and that is the period in which babies
  • 1:46 - 1:50
    try to master which sounds
    are used in their language.
  • 1:50 - 1:52
    We think, by studying
    how the sounds are learned,
  • 1:52 - 1:55
    we'll have a model
    for the rest of language,
  • 1:55 - 1:58
    and perhaps for critical periods
    that may exist in childhood
  • 1:58 - 2:00
    for social, emotional
    and cognitive development.
  • 2:01 - 2:03
    So we've been studying the babies
  • 2:03 - 2:06
    using a technique
    that we're using all over the world
  • 2:06 - 2:07
    and the sounds of all languages.
  • 2:07 - 2:09
    The baby sits on a parent's lap,
  • 2:09 - 2:12
    and we train them to turn
    their heads when a sound changes --
  • 2:12 - 2:14
    like from "ah" to "ee."
  • 2:14 - 2:17
    If they do so at the appropriate time,
    the black box lights up
  • 2:17 - 2:19
    and a panda bear pounds a drum.
  • 2:19 - 2:22
    A six-monther adores the task.
  • 2:22 - 2:23
    What have we learned?
  • 2:23 - 2:26
    Well, babies all over the world
  • 2:26 - 2:29
    are what I like to describe
    as "citizens of the world."
  • 2:30 - 2:33
    They can discriminate
    all the sounds of all languages,
  • 2:33 - 2:36
    no matter what country we're testing
    and what language we're using,
  • 2:36 - 2:39
    and that's remarkable
    because you and I can't do that.
  • 2:39 - 2:41
    We're culture-bound listeners.
  • 2:41 - 2:43
    We can discriminate the sounds
    of our own language,
  • 2:43 - 2:45
    but not those of foreign languages.
  • 2:45 - 2:48
    So the question arises:
    When do those citizens of the world
  • 2:48 - 2:51
    turn into the language-bound
    listeners that we are?
  • 2:51 - 2:54
    And the answer:
    before their first birthdays.
  • 2:54 - 2:58
    What you see here is performance
    on that head-turn task
  • 2:58 - 3:00
    for babies tested in Tokyo
    and the United States,
  • 3:00 - 3:01
    here in Seattle,
  • 3:02 - 3:03
    as they listened to "ra" and "la" --
  • 3:03 - 3:06
    sounds important to English,
    but not to Japanese.
  • 3:06 - 3:10
    So at six to eight months,
    the babies are totally equivalent.
  • 3:10 - 3:12
    Two months later,
    something incredible occurs.
  • 3:12 - 3:15
    The babies in the United States
    are getting a lot better,
  • 3:15 - 3:17
    babies in Japan are getting a lot worse,
  • 3:17 - 3:20
    but both of those groups of babies
    are preparing for exactly the language
  • 3:20 - 3:22
    that they are going to learn.
  • 3:22 - 3:26
    So the question is: What's happening
    during this critical two-month period?
  • 3:26 - 3:29
    This is the critical period
    for sound development,
  • 3:29 - 3:30
    but what's going on up there?
  • 3:30 - 3:32
    So there are two things going on.
  • 3:32 - 3:35
    The first is that the babies
    are listening intently to us,
  • 3:35 - 3:39
    and they're taking statistics
    as they listen to us talk --
  • 3:39 - 3:41
    they're taking statistics.
  • 3:41 - 3:43
    So listen to two mothers
    speaking motherese --
  • 3:43 - 3:46
    the universal language
    we use when we talk to kids --
  • 3:46 - 3:49
    first in English and then in Japanese.
  • 3:49 - 3:52
    (Video) Ah, I love your big blue eyes --
  • 3:52 - 3:55
    so pretty and nice.
  • 3:56 - 4:02
    (Japanese)
  • 4:02 - 4:06
    Patricia Kuhl: During the production
    of speech, when babies listen,
  • 4:06 - 4:11
    what they're doing is taking statistics
    on the language that they hear.
  • 4:11 - 4:14
    And those distributions grow.
  • 4:14 - 4:19
    And what we've learned is that babies
    are sensitive to the statistics,
  • 4:19 - 4:23
    and the statistics of Japanese
    and English are very, very different.
  • 4:23 - 4:25
    English has a lot of Rs and Ls.
  • 4:25 - 4:27
    The distribution shows.
  • 4:27 - 4:30
    And the distribution of Japanese
    is totally different,
  • 4:30 - 4:33
    where we see a group
    of intermediate sounds,
  • 4:33 - 4:35
    which is known as the Japanese "R."
  • 4:35 - 4:39
    So babies absorb
    the statistics of the language
  • 4:39 - 4:41
    and it changes their brains;
  • 4:41 - 4:43
    it changes them
    from the citizens of the world
  • 4:43 - 4:46
    to the culture-bound
    listeners that we are.
  • 4:46 - 4:51
    But we as adults are no longer
    absorbing those statistics.
  • 4:51 - 4:54
    We are governed
    by the representations in memory
  • 4:54 - 4:56
    that were formed early in development.
  • 4:56 - 4:58
    So what we're seeing here
  • 4:58 - 5:01
    is changing our models
    of what the critical period is about.
  • 5:01 - 5:04
    We're arguing from
    a mathematical standpoint
  • 5:04 - 5:07
    that the learning of language
    material may slow down
  • 5:07 - 5:10
    when our distributions stabilize.
  • 5:10 - 5:12
    It's raising lots of questions
    about bilingual people.
  • 5:13 - 5:17
    Bilinguals must keep two sets
    of statistics in mind at once
  • 5:17 - 5:20
    and flip between them,
    one after the other,
  • 5:20 - 5:22
    depending on who they're speaking to.
  • 5:22 - 5:23
    So we asked ourselves,
  • 5:23 - 5:26
    can the babies take statistics
    on a brand new language?
  • 5:26 - 5:30
    And we tested this
    by exposing American babies
  • 5:30 - 5:31
    who'd never heard a second language
  • 5:31 - 5:34
    to Mandarin for the first time
    during the critical period.
  • 5:34 - 5:38
    We knew that, when monolinguals
    were tested in Taipei and Seattle
  • 5:38 - 5:40
    on the Mandarin sounds,
    they showed the same pattern.
  • 5:40 - 5:43
    Six to eight months,
    they're totally equivalent.
  • 5:43 - 5:45
    Two months later,
    something incredible happens.
  • 5:45 - 5:49
    But the Taiwanese babies are getting
    better, not the American babies.
  • 5:49 - 5:54
    What we did was expose American babies,
    during this period, to Mandarin.
  • 5:54 - 5:57
    It was like having Mandarin relatives
    come and visit for a month
  • 5:57 - 6:01
    and move into your house
    and talk to the babies for 12 sessions.
  • 6:01 - 6:03
    Here's what it looked like
    in the laboratory.
  • 6:03 - 6:08
    (Mandarin)
  • 6:25 - 6:27
    PK: So what have we done
    to their little brains?
  • 6:27 - 6:29
    (Laughter)
  • 6:29 - 6:32
    We had to run a control group to make sure
  • 6:32 - 6:35
    that coming into the laboratory
    didn't improve your Mandarin skills.
  • 6:35 - 6:38
    So a group of babies came in
    and listened to English.
  • 6:38 - 6:39
    And we can see from the graph
  • 6:39 - 6:42
    that exposure to English
    didn't improve their Mandarin.
  • 6:42 - 6:45
    But look at what happened to the babies
    exposed to Mandarin for 12 sessions.
  • 6:45 - 6:48
    They were as good as the babies in Taiwan
  • 6:48 - 6:51
    who'd been listening
    for 10 and a half months.
  • 6:51 - 6:55
    What it demonstrated is that babies
    take statistics on a new language.
  • 6:55 - 6:58
    Whatever you put in front of them,
    they'll take statistics on.
  • 6:58 - 7:00
    But we wondered what role
  • 7:00 - 7:04
    the human being played
    in this learning exercise.
  • 7:04 - 7:08
    So we ran another group of babies
    in which the kids got the same dosage,
  • 7:09 - 7:11
    the same 12 sessions,
    but over a television set.
  • 7:11 - 7:15
    And another group of babies
    who had just audio exposure
  • 7:15 - 7:17
    and looked at a teddy bear on the screen.
  • 7:17 - 7:19
    What did we do to their brains?
  • 7:19 - 7:22
    What you see here is the audio result --
  • 7:23 - 7:25
    no learning whatsoever --
  • 7:25 - 7:26
    and the video result --
  • 7:27 - 7:29
    no learning whatsoever.
  • 7:29 - 7:33
    It takes a human being
    for babies to take their statistics.
  • 7:34 - 7:36
    The social brain is controlling
  • 7:36 - 7:38
    when the babies
    are taking their statistics.
  • 7:38 - 7:41
    We want to get inside the brain
    and see this thing happening
  • 7:41 - 7:45
    as babies are in front of televisions,
    as opposed to in front of human beings.
  • 7:45 - 7:50
    Thankfully, we have a new machine,
    magnetoencephalography,
  • 7:50 - 7:51
    that allows us to do this.
  • 7:51 - 7:54
    It looks like a hair dryer from Mars.
  • 7:54 - 7:59
    But it's completely safe,
    completely noninvasive and silent.
  • 7:59 - 8:01
    We're looking at millimeter accuracy
  • 8:01 - 8:04
    with regard to spatial
    and millisecond accuracy
  • 8:04 - 8:07
    using 306 SQUIDs --
  • 8:07 - 8:10
    these are superconducting
    quantum interference devices --
  • 8:10 - 8:14
    to pick up the magnetic fields
    that change as we do our thinking.
  • 8:14 - 8:20
    We're the first in the world
    to record babies in an MEG machine
  • 8:20 - 8:22
    while they are learning.
  • 8:22 - 8:24
    So this is little Emma.
  • 8:24 - 8:26
    She's a six-monther.
  • 8:26 - 8:31
    And she's listening to various languages
    in the earphones that are in her ears.
  • 8:31 - 8:33
    You can see, she can move around.
  • 8:33 - 8:37
    We're tracking her head
    with little pellets in a cap,
  • 8:37 - 8:40
    so she's free to move
    completely unconstrained.
  • 8:40 - 8:42
    It's a technical tour de force.
  • 8:42 - 8:44
    What are we seeing?
  • 8:44 - 8:46
    We're seeing the baby brain.
  • 8:46 - 8:51
    As the baby hears a word in her language,
    the auditory areas light up,
  • 8:51 - 8:56
    and then subsequently areas surrounding it
    that we think are related to coherence,
  • 8:56 - 9:00
    getting the brain coordinated
    with its different areas, and causality,
  • 9:00 - 9:03
    one brain area
    causing another to activate.
  • 9:04 - 9:09
    We are embarking on a grand
    and golden age of knowledge
  • 9:09 - 9:11
    about child's brain development.
  • 9:11 - 9:14
    We're going to be able
    to see a child's brain
  • 9:14 - 9:18
    as they experience an emotion,
    as they learn to speak and read,
  • 9:18 - 9:21
    as they solve a math problem,
    as they have an idea.
  • 9:22 - 9:25
    And we're going to be able to invent
    brain-based interventions
  • 9:25 - 9:27
    for children who have difficulty learning.
  • 9:28 - 9:31
    Just as the poets and writers described,
  • 9:31 - 9:35
    we're going to be able to see, I think,
    that wondrous openness,
  • 9:35 - 9:38
    utter and complete openness,
    of the mind of a child.
  • 9:39 - 9:42
    In investigating the child's brain,
  • 9:42 - 9:46
    we're going to uncover deep truths
    about what it means to be human,
  • 9:46 - 9:47
    and in the process,
  • 9:47 - 9:50
    we may be able to help keep
    our own minds open to learning
  • 9:50 - 9:52
    for our entire lives.
  • 9:52 - 9:53
    Thank you.
  • 9:53 - 9:56
    (Applause)
Title:
The linguistic genius of babies
Speaker:
Patricia Kuhl
Description:

At TEDxRainier, 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.

more » « less
Video Language:
English
Team:
TED
Project:
TEDTalks
Duration:
09:57

English subtitles

Revisions Compare revisions