From Dilettante to Expert, How Babies Acquire Knowledge: David J. Lewkowicz at TEDxDelrayBeach

Translator: Ivana Krivokuća
Reviewer: Denise RQ What do these beautiful young minds know, and where does this knowledge come from? Well, of course, this is the question that philosophers
have pondered for millenia and of course, one of the first
to ponder this question was Plato. And Plato pondered this question and concluded that actually
our senses do not provide sufficient data about our world
to specify it for us, and therefore, that knowledge was innate. And of course, after him, a number of different philosophers
agreed with him. Now, Aristotle, who was Plato’s pupil,
disagreed with his mentor, and after pondering this question,
decided that in fact, our senses do provide sufficient data
to specify our world and therefore,
that knowledge was acquired. And of course, many philosophers
following him agreed with him, like John Locke and David Hume
among others. And of course, this gave rise
to the nature-nurture dichotomy. No one today really subscribes
any longer to the dichotomy as such, but many people think about it in terms of the interaction
between nature and nurture. What I’d like to suggest to you today, that this dichotomy itself
has become outmoded, it is not scientifically plausible, that we need to abandon it,
and we need to instead consider the biological development
of the organism. If we look at the biological
development of organisms, first and foremost, organisms are embedded
in their environments, and they develop and evolve
in those environments. Second of all, organisms are composed of multiple hierarchically
organized systems that increase in complexity
as you go up the scale. And other thing that biology teaches us
and that developmental science teaches us is that the DNA that we possess
does not code anything but protein. Therefore, knowledge
cannot be coded in our DNA. That means that we have to look
elsewhere in the system. And what developmental science
has taught us today is that that elsewhere happens to be the multiple
and bidirectional interactions between all of those systems
of organization that form the organism. And in addition to that, due to the fact that the organism
is completely porous to its environment and therefore, the environment and the organism
interact bidirectionally with one another on an ongoing basis. Of course the brain, the human brain,
which is where our knowledge is situated, is the repository of all
of those developmental interactions. And that therefore means
that knowlegde is really something that emerges from
those developmental interactions. It’s not coded anywhere. If you look at the development
of the nervous system, we find that the brain quadruples in size
during the first six years, and if we look more closely
at the brain mass index, we find that it’s during
the first three years of life that the brain
increases enormously in size. And if we take a slice of cortical tissue
with one month of age and we simply look at those neurons, those are those black bodies
that you see there, and the little processes
that issue from them, they look like spiders, those are the dendrites
that connect to other neurons. You see that those connections
are pretty sparse, but if you then take a slice
at two years of age of the cortex, you see how much more
those connections have grown and how much more dense
that network happens to be. So, what does that buy
the developing organism? Well, what it buys the developing organism is a plasticity
and an openness to experience. Well, let’s look at the experience
of babies and their daily lives. Well, when babies interact
with their caregivers or anyone else, for that matter, they get to see faces,
they get to hear people talking to them, they get touched, they smell things,
they taste things, they are moved. So babies have this very rich
multisensory experiences on a daily basis, and when you combine that with the plasticity and openness
of the nervous system to experience, what you’ve got is the acquisition
of knowledge, in fact. So, let’s start at the beginning and ask
what do babies know at birth? Well, the famous American
philosopher-psychologist suggested, and this is known by everyone,
William James, that the newborn mind basically
experiences blooming buzzing confusion, but today, evolutionary psychologists
actually make the opposite claim, and they actually agree with Plato, and that is that we are born
with core knowledge that we inherit from our ancestors. But, as I’ve already indicated, this view
cannot be biologically plausible because our DNA
does not encode anything but proteins. So therefore, we need
an alternative view to this one. And what I’d like to suggest is a view that many today
in developmental science hold, which is that knowledge comes
from development itself. From all those developmental interactions
that I’ve showed you before. And secondly, I’d like to suggest to you is that actually babies
at birth are dilettantes, primarily because
of their neural immaturity and their inexperience with the world. So what is a dilettante? Well, a dilettante,
if you look it up in a dictionary, is a dabbler, someone who has
a lot of broad knowledge but doesn’t really know very much
about anything much. So, what sort of evidence do we have to support
this kind of an alternative view? Well, the first thing that we know is that both adults and babies
are very good at face discriminations, so they can discriminate human faces, they can discriminate
the faces of their own race, and they can discriminate
the speech sounds of their own language. We also happened to know
that both adults and babies as well are able to perceive others
as unitary events, that is to say, that baby, when that baby
is interacting with that person, for that baby, that’s mom. It’s not a separate face
and a separate voice. It’s all integrated. And that’s made possible
by the fact that our brains allow us to perform something that we refer to
as multisensory integration. Our brains actually combine
the sights, sounds, touches, smells into unitary events. And my favorite quote, actually,
that captures this very nicely is, “It matters little
through which sense I realize that I have stumbled into a pigsty.”
Or blundered, I should say. So, we also happened to know
something very interesting. It’s remarkable that young babies
actually happen to be able to discriminate faces
of other species like monkeys, faces of other races,
races other than their own, and they can actually discriminate
speech sounds that are the speech sounds in almost every single language
in this world. In addition to that, in our lab,
we recently discovered that babies can perceive the faces and vocalizations
of other species as unitary. So, here is an experiment that we did, where we showed babies
this video of the same monkey making two different vocalizations
in silence first, and what we do is we simply measure how much time
babies look at each one of those, and then we present this to them. (Video) (Monkey vocalizes) So the monkey is now making a coo sound. And our prediction was that babies
should look longer at that cooing face if they are connecting
the vocalizations they’re hearing with the vocalizations
that they’re seeing. And here’s the baby in our lab,
happily looking at these different videos, and what we do simply is we score how much time
the baby looks to each side. Here are the data. These are the data from newborn babies that we tested
in this particular experiment, and what you can see
is that the orange bar shows you that the babies actually looked longer at the face that was vocalizing
during the vocalization than they looked at that same face
when it was in silence. But here are the data
from eight-month-old babies, and you now see
that there is no longer a difference. Something strange is happening.
That ability goes away. Well, next we asked whether young babies
might respond differently to audio-visual speech
than older babies might do. And to ask this question, what we did is we presented
that baah-waah distinction to babies, and the reason we did this is because we know that we, English speakers,
can discriminate between those sounds, but that Spanish speakers
cannot discriminate between those sounds. So, we set up the following experiment. (Voice in the video) Baah. Babies just listen to this
while they watch that. (Voice in the video) Baah. And after they hear the “baah”,
they watch these two faces and of course, on the left, she says “baah”,
on the right she says “waah”. And of course, they should look at “baah”. And indeed, what we found
was that English learning babies, if you look at that graph again,
at those orange bars, they are looking longer at the face
that matches what they just heard before, than they look at that same face
before they heard the vocalization. So, they’re matching. Now, here are data
from babies tested in Spain, where you can see
that at six months of age, they are matching, they’re looking longer,
but by eleven months of age, it’s gone. They’re no longer making the match. So, here’s a fascinating paradox, right? Despite their immaturity and inexperience, babies who are young
seem to be smarter than older babies. What is going on? Well, what is going on
is that young babies come into this world with a certain kind of primitive knowledge
which is based on the detection of very simple low-level
perceptual features, like the synchrony
between voices and faces, but they don’t really detect
their identity. But by one year of age,
babies become experts. They begin to develop an expertise,
and that is based on the fact that they can now detect
identity information. They can tell that faces are human, they can tell that this is
my own language, and so forth. And what happens in development is that primitive knowledge
that babies possess begins to decline during development, and so their knowledge
of non-native categories declines, some call that process
“perceptual narrowing”. But at the same time, their expertise for native categories
of information increases, and we call that “perceptual broadening”. So, let me show an example
of how we study this in our laboratory, those two processes together,
and how they actually contribute to the development
of expertise and knowledge. (Video) (Woman’s soft voice)
Good morning! Get up! Come on now, if you get up right away,
we’ll have an hour to potter around. DJL: So, while babies
were watching these videos, we have an eye-tracker device
that is below that video, and that eye-tracker device allows us
to determine precisely where babies are looking on that face, and in this photograph, you can
actually see those black little dots. Each of those represents
a single visual fixation. What we do is we add them all up together,
and we put them in a graph, like this. Now, here, anything above that zero line means that babies
are looking longer at the eyes, and anything below means
that they’re looking longer at the mouth. I want you to notice that, first of all, at four months of age,
babies are looking primarily at the eyes. But something remarkable happens
between eight and ten months of age. They shift their looking to the mouth. In other words, they begin
to lip-read right there. And the reason they’re lip-reading, it turns out, is because this is
when babies begin to babble. This is when they’re beginning to learn
the sounds of their own native language, so what better way to do it than to look at someone’s face
and try to replicate that or imitate. Notice another interesting thing
that’s happening at twelve months of age. It appears as if now they’re beginning
to shift their eye gaze back towards the eyes. And we know this because, if we compare
those data to the adult data, it suggests that they’re shifting to the eyes
because we, as adults, do that. And why do they do this? Well, it turns out that this is when they begin to develop
their expertise for their native language. So, by now, they recognize
what they are seeing and hearing, it’s their own native language, “I’ve got it, I don’t need to lip-read
anymore because it’s familiar to me.” Now, just to make sure this was
really related to language acquisition, we did this: (Video) (Spanish)
¡Good morning! Wake up now! Let’s go! If you wake up now,
we have one hour to play around! Now, importantly, these are
all English learning monolingual babies. So now, they’re being exposed
to a language that will ultimately become
foreign to them. So look at what they do. At four months of age,
look at those orange bars, they’re doing the same thing
as they do in response to English, at eight to ten months of age,
they’re lip-reading like they should be, but something interesting happens
here at twelve months of age. At twelve months, it appears
that they continue to lip-read. And why do they do this? Because now Spanish
has become foreign to them. All of a sudden, remember,
these are English learning babies who are being raised in an English
environment, English speaking environment. They’re trying to disambiguate something
that has now become unfamiliar to them. Finally, my colleagues in Spain recently have conducted a study
of babies who are bilingual. That is to say, they are learning Catalan
and Spanish at the same time. And we’ve done exactly those same studies
with them, and what you see here is that big bar there,
which is marked ‘bilinguals’. That’s how much lip-reading bilinguals do
at twelve months of age. So, twelve-months-of-age bilingual babies, who are struggling to keep apart
two languages as separate systems, are now doing
a great deal of lip-reading. So, the journey from dilettante to expert
then consists of leaving behind you a relatively primitive world,
a poorly specified world, to a world that is now familiar to you,
that is well-specified. And evolution, therefore,
prepared us for this journey with a developmental openness
to experience. It didn’t code anything. Knowledge, therefore, emerges
from developmental experience. And what’s so interesting about this
is that sometimes, this developmental process
can lead to truly remarkable results. Thank you. (Applause)


  1. Ewart Bent

    September 29, 2013 at 12:55 am

    I asolutely loved his Research Methods class last Spring! Too bad I didn't do enough studying to be able to pass the exams…

  2. Daniel Messinger

    October 3, 2013 at 7:31 pm

    Awesomely broad argument (with data)!

  3. David Moore

    October 6, 2013 at 1:34 pm

    Amazing example of how to fit a huge–and hugely important–topic into a 15-minute talk, and how to support a broad philosophical argument with empirical observations!

  4. Mickey Vera

    January 28, 2014 at 1:34 am

    ayeee thats my professor!!

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