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ELIZABETH SPELKE: I want to
start with an observation

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about this summer school.

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There's a lot of development
in this summer school.

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You've got two full mornings
devoted to it-- today

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and on Thursday.

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It also came up pretty majorly
in Josh Tenenbaum's class

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last Friday and I learned
early this morning

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also in Shimon Ullman's
class that I couldn't be here

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for yesterday afternoon.

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And the issues have come up
in many other classes as well,

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including Nancy's, Winrich
Freiwald's, and so forth.

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Now, what's come up is not
only the general questions

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about development, but specific
questions about human cognitive

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development.

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Questions that have
been addressed primarily

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through behavioral
experiments, not

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experiments using neural
methods or computational models.

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And the topic that I'm
going to be trying to--

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that Allie and I will try
to get you to think about

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for this morning is
even narrower than that.

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It's about the cognitive
capacities of human infants.

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And I think a fair
initial question would be,

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why so much focus on
early human development?

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And that question
will get sharper

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if you look at where
major organizations are

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putting their research money.

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They are not putting it
into the kind of work

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that I'm going to be
talking about today.

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There is no-- in the
Obama BRAIN Initiative,

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where they're looking
for new technologies,

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there's no call for
new technologies

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to figure out what
human knowledge is

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like at or near
the initial state

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and how it grows over
the course of infancy.

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And the European
Human Brain Project

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doesn't have development as
a major area in it, either.

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So I think it's fair
to ask, why is CBMM

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taking such a different approach
and putting so much emphasis

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on trying to get you guys
to think about and learn

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about human development?

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And two general
reasons, I think.

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One is, it's
intrinsically fascinating.

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Come on.

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We are the most cognitively
interesting creatures

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on the planet.

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And we're extremely flexible.

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At the very least, we know
that a human infant can grow up

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to be a competent adult in
any human culture of the world

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today and any human culture
that existed in prehistory.

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And that means
extremely varied--

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they've had to learn
extremely different things

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under different
circumstances and have

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succeeded at doing that.

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We also know that by the
time they start school,

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if they go to school at
all, the really hard work

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of developing a common-sense
understanding of the world

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is done.

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That is, it's not explicitly
taught to children.

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Most of it isn't
even very strongly

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implicitly taught to them in
the form of other people trying

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to get them to learn things.

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What you're trying to do
when you have a young kid,

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as those of you who have them
know, or have had them know,

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is you're trying to get them not
to climb off cliffs or explore

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the hot pots on the
stove and so forth.

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You're really not spending
very much of your time trying

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to get them to learn new stuff.

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They're doing that on their own.

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So it's I think a really
interesting question,

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how do we do that?

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Intrinsically interesting
in its own right,

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even if it were of
no other use to us.

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But historically it's
also been recognized

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as being really
important for efforts

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to understand the human mind,
understand the human brain,

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and build intelligent machines.

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So Helmholtz, who came up
in Eero's talk last night,

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was not only a brilliant
neurophysiologist

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and a physicist, he was
extremely interested

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in perception and cognition.

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And he wrote about
fundamental questions

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about human perceptual
knowledge and experience.

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How is it that we experience
the world as three-dimensional?

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He concluded that we
didn't know the answer

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and never could know
the answer, unless we

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could find ways to do systematic
experiments on infants

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of the sort that could already
be done to reveal mechanisms

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of color vision, for
example, as were described

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last night on adults--

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systematic psychophysical
experiments on infants.

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But he looked at
infants and said,

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I don't see any way to do that.

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We can't train them to make
psychophysical judgments and so

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forth.

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But he was aware of
their centrality.

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So was Turing, who
in thinking ahead

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to how one might build
intelligent machines,

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suggested that one aim
to build a machine that

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could learn about the
world the way children do.

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And a side of the
work that's come up

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so many times in the whole
Hubel-Wiesel tradition that

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started in the
late '50s, I think

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one of the most exciting
and important developments

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within that field,
we're not just

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focusing on the response
properties of neurons

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in mature visual
systems, but rather

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on the development
of those neurons

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and the effects of
experience on them.

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When you discover that you
get these gorgeous stripes

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of monocularly-driven
cells in V1,

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it then immediately became
really interesting to ask,

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suppose an animal were
only looking at the world

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through one eye?

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Or suppose they could look at
the world through the two eyes,

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but not at the same time,
or not at the same things

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at the same time?

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What would happen
to those cells?

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And there was gorgeous work
addressing those questions

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from the beginning.

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Now, that work has somewhat
receded from attention.

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I think that's a mistake.

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I think that
there's a great deal

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to be learned from those
kinds of studies now.

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And if I get nothing else
across over this time,

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I hope you'll at
least get the idea

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that this is a field
worth following, looking

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at development in humans,
looking at development

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of perceptual and
cognitive capacities

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in animal models of human
intelligence as well.

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So more specifically,
I think there

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are three questions
about human cognition

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for which studies
of early development

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in general and in human
infants in particular

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can shed light on.

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Two of them I'm not going to
really be talking about today,

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except indirectly.

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One is the question,
what distinguishes us

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from other animals?

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We come into the world with
very similar equipment.

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But look what we do with it.

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We create these utterly
different systems of knowledge

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that no other animal
seems to share.

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What is it about us that
sets us on a different path

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from other animals?

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That's question one.

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And the other question
I won't talk about is--

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well, I'll talk about
it a tiny bit, but not

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directly-- is, where do
abstract ideas come from?

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It seems like we not only
develop systems of knowledge,

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but those systems
center on concepts

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that refer to things that
could never in principle

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be seen or acted on.

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Like the concept "seven,"
or the concept "triangle,"

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or the concept "belief," or
ethical concepts and so forth.

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Abstract concepts
organize our knowledge.

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But since they can't be
seen or touched or produced

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through our actions, how
do we come to know them?

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I think studies of
early development

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can shed light on that as well.

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But the question I want to focus
on today is the third question,

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and it's the one that
Josh raised on Friday.

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How do we get so much
from so little as adults?

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As adults, you look at
one of the photographs

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he showed of just
an ordinary scene

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and you can immediately
make predictions about,

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if you were to bang
it, what would happen?

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What would fall?

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What would roll?

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We seem to get this
very, very rich knowledge

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from this very, very
limited body of information

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at any given time.

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And what that
suggests is that we

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are able to bring to
bear in interpreting

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that scene a whole
body of knowledge

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that we already have about
the world and how it behaves.

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But that raises the question,
what is it that we know

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and how is our
knowledge organized?

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What aspects of the world do we
represent most fundamentally?

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Which of our concepts
are most important to us

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and generate the other
concepts and so forth?

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How can we carve human
knowledge at its joints?

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And now this can be
studied in adults

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and you've seen a number
of examples of this.

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You saw it in Nancy's
talk last Tuesday, right?

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Anyway, last week sometime.

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Studies using
functional brain imaging

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to get at our representations
of human faces.

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You saw it in Josh's talk.

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He was mostly using
data from adults

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to be probing the knowledge
of intuitive physics

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that he was focused on and that
his computational models are

00:09:24.620 --> 00:09:26.210
trying to capture.

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You're going to see
it on Thursday in--

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no, tomorrow in
Rebecca Saxe's talk,

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where she'll talk about human
adults' attributions of beliefs

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and desires and other
mental states to people.

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It's certainly
studyable in adults,

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but it's difficult to
answer these questions.

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It's difficult to answer these
questions in any creature,

00:09:47.540 --> 00:09:49.081
but I think it's
especially difficult

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to answer these questions in
adults for a couple of reasons.

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One is that our knowledge
is simply too rich.

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By the time we get to be
adults, we know so much

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and we have so many
alternative ways

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of solving any
particular problem,

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that it's a real
challenge to try

00:10:02.710 --> 00:10:05.860
to sift through
all our abilities

00:10:05.860 --> 00:10:09.130
and figure out what the really
fundamental, most fundamental

00:10:09.130 --> 00:10:11.314
concepts that we have are.

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And the second
problem with adults

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is we not only know too
much, we're too flexible.

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We can essentially relate
anything to anything.

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We can use information
from the face

00:10:20.800 --> 00:10:24.370
to answer all sorts of
questions about the world.

00:10:24.370 --> 00:10:28.600
And here, I think, infants are
useful for a maybe seemingly

00:10:28.600 --> 00:10:30.070
paradoxical reason.

00:10:30.070 --> 00:10:32.020
They're much less
cognitively capable.

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They know much less about
the world and they're

00:10:34.150 --> 00:10:35.590
far less flexible--

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I'll show you examples of this--

00:10:37.090 --> 00:10:39.010
far less flexible in
the kinds of things

00:10:39.010 --> 00:10:43.330
that they can do with the
knowledge that they do have.

00:10:43.330 --> 00:10:46.960
Nevertheless, they seem to
come into the world equipped

00:10:46.960 --> 00:10:49.540
with knowledge that
supports later learning.

00:10:49.540 --> 00:10:51.760
And because it's
supporting later learning,

00:10:51.760 --> 00:10:55.000
it's being preserved
over that learning.

00:10:55.000 --> 00:10:57.190
It's being incorporated
in all of the later things

00:10:57.190 --> 00:10:58.390
that we learn.

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So it remains fundamental
to us as adults.

00:11:00.560 --> 00:11:02.830
And I think this can
help us, to think

00:11:02.830 --> 00:11:08.470
about how our own knowledge
of the world is organized.

00:11:08.470 --> 00:11:09.270
OK.

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So that's a general overview.

00:11:11.500 --> 00:11:12.580
How do we study infants?

00:11:12.580 --> 00:11:16.600
Now here's where the
tables turn radically.

00:11:16.600 --> 00:11:19.420
We have way better methods for
studying cognition in adults

00:11:19.420 --> 00:11:23.140
than we do in infants,
just as Helmholtz thought.

00:11:23.140 --> 00:11:24.554
They can't talk to us.

00:11:24.554 --> 00:11:26.470
They don't understand
us when we talk to them,

00:11:26.470 --> 00:11:27.820
so we can't give them structure.

00:11:27.820 --> 00:11:33.460
Oh, and unlike willing
trained animals,

00:11:33.460 --> 00:11:35.830
you can't train
them to do things,

00:11:35.830 --> 00:11:39.490
at least not in
any extended sense.

00:11:39.490 --> 00:11:40.480
They can't do much.

00:11:40.480 --> 00:11:42.550
I'm most interested in
infants in the first four

00:11:42.550 --> 00:11:45.100
months of life before they
even start reaching for things,

00:11:45.100 --> 00:11:50.710
much less sitting up by
themselves or moving around.

00:11:50.710 --> 00:11:54.070
The interesting thing is,
from day one, from the moment

00:11:54.070 --> 00:11:57.010
that they're born, they're
observing the world.

00:11:57.010 --> 00:12:00.850
They're looking at things and
they're getting information

00:12:00.850 --> 00:12:03.670
from what they see.

00:12:03.670 --> 00:12:06.580
Now, their observations-- we've
learned over the last half

00:12:06.580 --> 00:12:10.270
century or so that their
observations are systematic

00:12:10.270 --> 00:12:12.970
and they're reflected in very
simple exploratory behaviors,

00:12:12.970 --> 00:12:16.215
like when a sound happens
somewhere in the visual field,

00:12:16.215 --> 00:12:18.340
turning the head and
orienting it toward the sound.

00:12:18.340 --> 00:12:20.830
Even newborn infants
will do that.

00:12:20.830 --> 00:12:24.130
Or if something new or
interesting is presented,

00:12:24.130 --> 00:12:26.975
infants will tend to look at it.

00:12:26.975 --> 00:12:28.600
And these behaviors
I think can tell us

00:12:28.600 --> 00:12:31.000
something about what
infants perceive and know.

00:12:31.000 --> 00:12:34.482
And before getting to the
real substance of what

00:12:34.482 --> 00:12:36.190
I want to focus on
today, let me give you

00:12:36.190 --> 00:12:37.990
a few examples of this.

00:12:37.990 --> 00:12:40.420
What kinds of things
do infants look at?

00:12:40.420 --> 00:12:44.320
Well, if you present
even a newborn infant--

00:12:44.320 --> 00:12:45.880
infants at any age, really--

00:12:45.880 --> 00:12:49.692
with two displays
side by side, and vary

00:12:49.692 --> 00:12:52.150
properties of those displays
and the relation between them,

00:12:52.150 --> 00:12:55.130
you'll see that they look at
some things more than others.

00:12:55.130 --> 00:12:57.160
So they'll look at
black-and-white stripes

00:12:57.160 --> 00:12:59.500
more than they'll look at
a homogeneous gray field.

00:12:59.500 --> 00:13:00.760
That's useful.

00:13:00.760 --> 00:13:03.070
It allowed people to
get initial measures

00:13:03.070 --> 00:13:06.905
of the development of visual
acuity which infants--

00:13:06.905 --> 00:13:10.210
it actually overturned
a somewhat popular view

00:13:10.210 --> 00:13:12.540
that at birth, infants
couldn't see at all.

00:13:12.540 --> 00:13:14.860
We know from these simple
studies that they can.

00:13:14.860 --> 00:13:17.110
And we also know that their
acuity starts out very low

00:13:17.110 --> 00:13:19.150
but gets pretty good
by the time they're

00:13:19.150 --> 00:13:21.040
four to six months of age.

00:13:21.040 --> 00:13:23.857
It doesn't reach full adult
levels until about two years.

00:13:23.857 --> 00:13:25.690
We also know that they
look at moving arrays

00:13:25.690 --> 00:13:28.750
more than stationary
arrays, and they

00:13:28.750 --> 00:13:30.520
look at
three-dimensional objects

00:13:30.520 --> 00:13:34.300
more than
two-dimensional objects.

00:13:34.300 --> 00:13:36.880
In addition to having
intrinsic preferences

00:13:36.880 --> 00:13:40.180
between different
things, they also

00:13:40.180 --> 00:13:42.820
have a preference for looking
at displays that change

00:13:42.820 --> 00:13:45.340
or displays that
present something new.

00:13:45.340 --> 00:13:47.680
So jumping from the '50s
when those first studies were

00:13:47.680 --> 00:13:50.560
done up to the '80s,
there was a whole flurry

00:13:50.560 --> 00:13:57.790
of studies showing babies pairs
of cats on a series of trials

00:13:57.790 --> 00:13:59.500
and then switching
to a cat and a dog.

00:13:59.500 --> 00:14:00.520
And the babies
would look longer--

00:14:00.520 --> 00:14:01.936
these are
three-month-olds-- would

00:14:01.936 --> 00:14:06.760
look longer at the dog than
at a new example of a cat.

00:14:06.760 --> 00:14:09.700
So they're able to
orient to novelty.

00:14:09.700 --> 00:14:12.250
And they also look
longer at a visual array

00:14:12.250 --> 00:14:14.980
that connects in some way
to something they can hear.

00:14:14.980 --> 00:14:18.340
Now, one of the things I spend
a lot of my time studying

00:14:18.340 --> 00:14:22.330
is foundations of mathematics--
numerical and spatial cognition

00:14:22.330 --> 00:14:22.930
in infants.

00:14:22.930 --> 00:14:24.850
I'm not going to talk
about it at all today.

00:14:24.850 --> 00:14:27.280
But I kind of couldn't resist
giving just one example

00:14:27.280 --> 00:14:31.710
of looking at what you hear that
connects to infant sensitivity

00:14:31.710 --> 00:14:32.620
to a number.

00:14:32.620 --> 00:14:35.110
This is a study that
was conducted in France

00:14:35.110 --> 00:14:37.720
by Veronique Izard
and her colleagues

00:14:37.720 --> 00:14:40.450
with newborn infants in
a maternity hospital.

00:14:40.450 --> 00:14:46.670
She played infants
sequences of sounds,

00:14:46.670 --> 00:14:50.560
and each sequence involved
repetitions of a syllable.

00:14:50.560 --> 00:14:54.220
For half the infants, each
syllable appeared four times.

00:14:54.220 --> 00:14:56.500
For the others, it
appeared 12 times.

00:14:56.500 --> 00:14:58.750
And for the ones for which
it appeared four times,

00:14:58.750 --> 00:15:00.340
each syllable was
three times as long.

00:15:00.340 --> 00:15:01.798
So the total duration
of a sequence

00:15:01.798 --> 00:15:03.570
was the same for the
two groups, but one

00:15:03.570 --> 00:15:06.300
involved four syllables
and one involved 12.

00:15:06.300 --> 00:15:10.060
And after they heard
that for a minute,

00:15:10.060 --> 00:15:12.060
the sound continued to
play and now she showed,

00:15:12.060 --> 00:15:14.820
side by side, an
array of four objects

00:15:14.820 --> 00:15:16.800
versus an array of 12 objects.

00:15:16.800 --> 00:15:18.930
And the babies tended to
look at the array that

00:15:18.930 --> 00:15:23.880
corresponded in number to
what they were hearing.

00:15:23.880 --> 00:15:26.970
Now, all of this gives us
something to work with,

00:15:26.970 --> 00:15:30.070
but it raises a nasty problem.

00:15:30.070 --> 00:15:31.740
And the problem
is, what are babies

00:15:31.740 --> 00:15:34.390
perceiving or understanding?

00:15:34.390 --> 00:15:36.250
Today we're not
going to be asking,

00:15:36.250 --> 00:15:37.650
how can babies classify things?

00:15:37.650 --> 00:15:39.090
What do they respond
to similarly?

00:15:39.090 --> 00:15:40.591
What do they respond
to differently?

00:15:40.591 --> 00:15:43.006
We're going to be asking, what
sense do they make of them?

00:15:43.006 --> 00:15:44.280
What are they representing?

00:15:44.280 --> 00:15:49.050
What the content of
the representations

00:15:49.050 --> 00:15:52.050
that they're forming
in each of these cases?

00:15:52.050 --> 00:15:57.090
And these studies as I've just
described them don't tell us.

00:15:57.090 --> 00:16:01.470
Let's take the case of the
sphere versus the disk.

00:16:01.470 --> 00:16:04.800
When this study was
first conducted,

00:16:04.800 --> 00:16:07.950
the author concluded that
babies have depth perception,

00:16:07.950 --> 00:16:10.320
that they perceive
three-dimensional solid

00:16:10.320 --> 00:16:12.180
objects.

00:16:12.180 --> 00:16:13.707
Is that a justifiable
conclusion?

00:16:13.707 --> 00:16:14.790
AUDIENCE: Not necessarily.

00:16:14.790 --> 00:16:16.590
ELIZABETH SPELKE: Why not?

00:16:16.590 --> 00:16:18.590
AUDIENCE: Because they
are not [INAUDIBLE]..

00:16:18.590 --> 00:16:18.990
ELIZABETH SPELKE: Yeah.

00:16:18.990 --> 00:16:19.490
OK.

00:16:19.490 --> 00:16:22.770
So when you present things
that differ in depth,

00:16:22.770 --> 00:16:26.310
you're presenting a host of
different visual features

00:16:26.310 --> 00:16:28.710
that for us as adults
are cues to depth.

00:16:28.710 --> 00:16:31.114
The question is, are they
cues to depth for the infant?

00:16:31.114 --> 00:16:33.030
And the fact that the
infant is looking longer

00:16:33.030 --> 00:16:35.910
at something we would call a
sphere than at something we

00:16:35.910 --> 00:16:38.460
would call a disk, doesn't
tell us whether they're looking

00:16:38.460 --> 00:16:40.920
longer because they're
thinking, "sphere,"

00:16:40.920 --> 00:16:43.837
or "3D," or "solid,"
or something like that,

00:16:43.837 --> 00:16:46.170
or whether they're looking
longer because they're seeing

00:16:46.170 --> 00:16:47.670
a more interesting
pattern of motion

00:16:47.670 --> 00:16:51.994
as they move their head around,
or because as they converge

00:16:51.994 --> 00:16:54.660
on one part of the array they're
getting interesting differences

00:16:54.660 --> 00:16:56.993
in how in-focus different
parts of it are, and so forth.

00:16:56.993 --> 00:16:58.560
All of the different
cues to depth

00:16:58.560 --> 00:17:00.184
could-- what we want
to know is, what's

00:17:00.184 --> 00:17:02.262
the basis of this preference?

00:17:02.262 --> 00:17:03.720
And the existence
of the preference

00:17:03.720 --> 00:17:05.040
doesn't tell us that.

00:17:05.040 --> 00:17:09.540
Similarly for the
cats, and similarly

00:17:09.540 --> 00:17:11.849
for this single
isolated experiment

00:17:11.849 --> 00:17:13.500
that I gave you
on number, right?

00:17:13.500 --> 00:17:16.440
Does this say anything
whatsoever about number,

00:17:16.440 --> 00:17:18.780
or could there be
some sensory variable

00:17:18.780 --> 00:17:21.660
where there's just more going
on in a stream of 12 sounds

00:17:21.660 --> 00:17:25.500
and there's more going on
in an array of 12 objects,

00:17:25.500 --> 00:17:28.980
and babies are matching more
with more, independently

00:17:28.980 --> 00:17:29.480
of number?

00:17:29.480 --> 00:17:31.770
These studies in
themselves don't tell us.

00:17:31.770 --> 00:17:34.260
In order to find out,
what we need to do

00:17:34.260 --> 00:17:37.260
is take these methods and
do systematic experiments.

00:17:37.260 --> 00:17:40.710
And these experiments work best
under the following conditions.

00:17:40.710 --> 00:17:44.730
When you're studying a
function that exists in adults

00:17:44.730 --> 00:17:48.840
and whose properties have been
explored in adults in detail

00:17:48.840 --> 00:17:52.080
systematically, when you have
a body of psychophysical data

00:17:52.080 --> 00:17:55.110
that you can rest on in
your understanding of what's

00:17:55.110 --> 00:18:00.450
happening in adults, and you
can then apply that to infants.

00:18:00.450 --> 00:18:03.140
So one example of that
took as its point of-- this

00:18:03.140 --> 00:18:07.470
is work by Richard Held,
a wonderful perception

00:18:07.470 --> 00:18:11.067
psychologist who worked at MIT.

00:18:11.067 --> 00:18:12.150
Still is active, actually.

00:18:12.150 --> 00:18:14.250
He's retired but still active.

00:18:14.250 --> 00:18:15.840
And he did these
beautiful experiments

00:18:15.840 --> 00:18:18.009
that started with the
sphere-versus-disk phenomenon.

00:18:18.009 --> 00:18:19.800
And first of all, he
tried to take it apart

00:18:19.800 --> 00:18:22.550
and say, let's just focus
on one cue today, OK?

00:18:22.550 --> 00:18:25.500
Binocular disparity at the
basis of stereo vision.

00:18:25.500 --> 00:18:27.810
So he put stereo
goggles on babies.

00:18:27.810 --> 00:18:30.630
These were babies ranging in
age up to about from birth

00:18:30.630 --> 00:18:32.640
to about four months, I think.

00:18:32.640 --> 00:18:35.820
He put stereo goggles on
them and showed them, side

00:18:35.820 --> 00:18:38.590
by side, two arrays of stripes.

00:18:38.590 --> 00:18:42.240
In one of the arrays, the
same image went to both eyes.

00:18:42.240 --> 00:18:44.400
In the other arrays,
the edges of the stripes

00:18:44.400 --> 00:18:47.580
were offset in a way
that leads an adult

00:18:47.580 --> 00:18:50.610
to see them as organized in
depth-- some stripes in front

00:18:50.610 --> 00:18:52.560
of others.

00:18:52.560 --> 00:18:57.270
And he showed that infants
looked longer at the array with

00:18:57.270 --> 00:18:59.880
the disparity-specified
differences in depth than

00:18:59.880 --> 00:19:01.650
the array where it didn't.

00:19:01.650 --> 00:19:03.360
He did not conclude
from that that they

00:19:03.360 --> 00:19:05.460
have depth perception,
but it gave him

00:19:05.460 --> 00:19:08.760
a basis for doing a whole series
of experiments that asked,

00:19:08.760 --> 00:19:11.130
in effect, do you
see this effect

00:19:11.130 --> 00:19:14.340
under all and only the
conditions in which adults

00:19:14.340 --> 00:19:16.350
have functional stereopsis?

00:19:16.350 --> 00:19:19.690
So he showed, for example,
that if you rotate the array

00:19:19.690 --> 00:19:23.130
sideways 45 degrees
so that you still

00:19:23.130 --> 00:19:25.170
have double images
on the stereo side,

00:19:25.170 --> 00:19:27.570
but we wouldn't see depth
because our eyes are

00:19:27.570 --> 00:19:30.820
side by side, not one above the
other, the effect goes away.

00:19:30.820 --> 00:19:32.430
He varied the
degree of disparity

00:19:32.430 --> 00:19:34.560
and showed that you
only get this preference

00:19:34.560 --> 00:19:39.450
within this narrow range where
we have functional stereopsis.

00:19:39.450 --> 00:19:42.940
And he was able to show the
striking continuity between all

00:19:42.940 --> 00:19:44.910
of the properties
of stereo vision

00:19:44.910 --> 00:19:47.370
in adults and in these infants.

00:19:47.370 --> 00:19:51.090
So that study and a bunch of
others using other methods,

00:19:51.090 --> 00:19:53.700
I think have resolved this
question of whether depth--

00:19:53.700 --> 00:19:55.680
when depth perception begins.

00:19:55.680 --> 00:19:57.060
Its beginning very early.

00:19:57.060 --> 00:20:00.755
Stereopsis comes in around
two to three months of age.

00:20:00.755 --> 00:20:02.420
Other depth cues
come in at birth.

00:20:02.420 --> 00:20:03.980
It's beginning very, very early.

00:20:03.980 --> 00:20:05.771
But it didn't come from
single experiments.

00:20:05.771 --> 00:20:08.701
It came from systematic
patterns of experiments.

00:20:08.701 --> 00:20:10.700
In the case of cats versus
dogs, we don't really

00:20:10.700 --> 00:20:13.070
have a psychophysics
of cat perception,

00:20:13.070 --> 00:20:15.950
but steps have been taken to
try to get to what the basis is

00:20:15.950 --> 00:20:19.850
of infants' distinction
between dogs

00:20:19.850 --> 00:20:21.260
and cats in those experiments.

00:20:21.260 --> 00:20:23.900
And interestingly, what's
popped out are faces.

00:20:23.900 --> 00:20:26.780
Turns out, you can occlude the
cat and the dog's whole bodies,

00:20:26.780 --> 00:20:29.197
and if you leave their
faces, you get these effects.

00:20:29.197 --> 00:20:31.280
If you occlude their faces
and leave their bodies,

00:20:31.280 --> 00:20:34.460
you mostly do not,
unless you cheat and give

00:20:34.460 --> 00:20:36.860
other obvious features, like
all the dogs are standing

00:20:36.860 --> 00:20:40.170
and all the cats are sitting,
or something like that.

00:20:40.170 --> 00:20:42.830
But in the normal case,
faces are coming out

00:20:42.830 --> 00:20:46.696
as an important ingredient
of that distinction.

00:20:46.696 --> 00:20:48.320
In the case of abstract
number, there's

00:20:48.320 --> 00:20:52.100
also a lot of work in
adults on our ability

00:20:52.100 --> 00:20:55.850
to apprehend at a glance
approximate numerical value

00:20:55.850 --> 00:21:00.500
of sounds in a sequence
or visual arrays.

00:21:00.500 --> 00:21:03.320
We've learned a lot about the
conditions under which we can

00:21:03.320 --> 00:21:06.120
do that and the conditions
under which we can't.

00:21:06.120 --> 00:21:10.070
That's not my topic for today,
but Izard and her collaborators

00:21:10.070 --> 00:21:12.200
have been testing for
all of those conditions

00:21:12.200 --> 00:21:13.280
in newborn infants.

00:21:13.280 --> 00:21:14.670
And so far, so good.

00:21:14.670 --> 00:21:17.540
It looks like there
is a similar alignment

00:21:17.540 --> 00:21:19.140
between the patterns of--

00:21:19.140 --> 00:21:22.310
the factors that influence
infants' responses

00:21:22.310 --> 00:21:24.140
in those studies
where they hear sounds

00:21:24.140 --> 00:21:26.540
and see arrays of
objects and the factors

00:21:26.540 --> 00:21:31.720
that influence our abilities to
apprehend approximate number.

00:21:31.720 --> 00:21:32.420
OK.

00:21:32.420 --> 00:21:35.656
So this gives us some good
news and some bad news.

00:21:35.656 --> 00:21:37.280
The good news is that
I think questions

00:21:37.280 --> 00:21:42.410
about the content of infants'
perception and understanding

00:21:42.410 --> 00:21:44.960
of the world can be addressed.

00:21:44.960 --> 00:21:48.440
The bad news is that we
can't do it very fast.

00:21:48.440 --> 00:21:51.390
You can't do it with a single
silver-bullet experiment.

00:21:51.390 --> 00:21:53.990
You have to do it with a
long and extensive pattern

00:21:53.990 --> 00:21:55.070
of research.

00:21:55.070 --> 00:21:58.550
In the past, research on infants
has gone extremely slowly.

00:21:58.550 --> 00:22:00.350
Basically, the
methods that we have

00:22:00.350 --> 00:22:03.890
allow you to ask each baby who
comes into the lab maybe one,

00:22:03.890 --> 00:22:06.260
or if you're lucky, a
couple of questions,

00:22:06.260 --> 00:22:08.070
but not more than that.

00:22:08.070 --> 00:22:11.600
So it takes a long time
to do a single experiment.

00:22:11.600 --> 00:22:14.990
I do think, though,
that this work is

00:22:14.990 --> 00:22:20.300
poised to accelerate
dramatically

00:22:20.300 --> 00:22:21.980
and that we're poised to--

00:22:21.980 --> 00:22:24.440
this is a good time to be
thinking about infant cognition

00:22:24.440 --> 00:22:27.000
because I think we're soon going
to be in a different world,

00:22:27.000 --> 00:22:29.333
where we can start asking
these questions at a much more

00:22:29.333 --> 00:22:30.230
rapid pace.

00:22:30.230 --> 00:22:32.990
That's for at least two reasons,
both of which, by the way,

00:22:32.990 --> 00:22:38.490
are being fostered by the Center
for Brains, Minds and Machines

00:22:38.490 --> 00:22:41.630
and undertaken by people
who are part of that center.

00:22:41.630 --> 00:22:45.230
One is, there are now efforts
underway to be able to test

00:22:45.230 --> 00:22:46.580
infants on the web.

00:22:46.580 --> 00:22:48.770
These basic simple
behavioral studies, you

00:22:48.770 --> 00:22:52.430
can assess looking
time using the webcam

00:22:52.430 --> 00:22:58.520
in an iPad or a laptop, and
you can test babies that way.

00:22:58.520 --> 00:23:00.120
And there's attempts
to do that, which

00:23:00.120 --> 00:23:01.994
would make it possible
to collect data doing

00:23:01.994 --> 00:23:03.410
the same kinds of
experiments that

00:23:03.410 --> 00:23:06.220
have been done in the past,
but much more quickly.

00:23:06.220 --> 00:23:09.530
Two, as Nancy already
mentioned and Rebecca

00:23:09.530 --> 00:23:11.900
may talk about
tomorrow, there are

00:23:11.900 --> 00:23:15.470
efforts underway to use
functional brain imaging

00:23:15.470 --> 00:23:19.080
to get at not only
what infants look at,

00:23:19.080 --> 00:23:22.370
but what regions of the brain
are activated when they look

00:23:22.370 --> 00:23:23.930
at those things,
which will give us

00:23:23.930 --> 00:23:26.570
a more specific signal of
what infants are attending

00:23:26.570 --> 00:23:31.500
to and processing, someday,
hopefully, in the near future.

00:23:31.500 --> 00:23:35.397
And we just had a
retreat of CBMM,

00:23:35.397 --> 00:23:36.980
where there was a
lot of brainstorming

00:23:36.980 --> 00:23:38.540
about new technologies
to try to get

00:23:38.540 --> 00:23:40.831
more than just simple looking
time out of young babies.

00:23:40.831 --> 00:23:43.316
So maybe some of that
will work as well.

00:23:43.316 --> 00:23:44.690
But what I want
to focus on today

00:23:44.690 --> 00:23:47.390
is that even this
slow, plodding research

00:23:47.390 --> 00:23:49.360
has gone on for long
enough at this point

00:23:49.360 --> 00:23:52.400
that I think we've learned
something about what infants

00:23:52.400 --> 00:23:55.820
perceive and what they know.

00:23:55.820 --> 00:23:59.310
And I tried to put what I think
we learned into two slides.

00:23:59.310 --> 00:24:00.950
Here's the first one.

00:24:00.950 --> 00:24:03.710
I think that very
early in development,

00:24:03.710 --> 00:24:06.650
baby in the newborn
period, but anyway,

00:24:06.650 --> 00:24:08.990
before babies are starting
to reach for things

00:24:08.990 --> 00:24:13.280
and move around on
their own, they already

00:24:13.280 --> 00:24:18.290
have a set of functioning
cognitive systems,

00:24:18.290 --> 00:24:21.410
each specific to a
different domain.

00:24:21.410 --> 00:24:25.700
One is a system for representing
objects and their motions,

00:24:25.700 --> 00:24:28.980
collisions, and
other interactions.

00:24:28.980 --> 00:24:31.310
Another is a system
for representing people

00:24:31.310 --> 00:24:34.880
as agents who act on
objects, and in doing so,

00:24:34.880 --> 00:24:39.620
pursue goals and cause
changes in the world.

00:24:39.620 --> 00:24:42.290
A third is a system
for perceiving people

00:24:42.290 --> 00:24:46.250
as social beings who can
communicate with, engage

00:24:46.250 --> 00:24:50.630
with other social beings
and share mental states.

00:24:50.630 --> 00:24:53.372
And then three other systems
that I won't talk about today.

00:24:53.372 --> 00:24:54.830
One system of
number, which I think

00:24:54.830 --> 00:24:58.370
is being tapped in that
first Izard experiment.

00:24:58.370 --> 00:25:01.800
And two systems capturing
aspects of geometry,

00:25:01.800 --> 00:25:06.120
one supporting navigation of the
sort that Matt Wilson studies,

00:25:06.120 --> 00:25:11.630
the other supporting visual form
perception of the sort that IT

00:25:11.630 --> 00:25:17.100
and occipital cortex represent.

00:25:17.100 --> 00:25:20.880
I think each of these
systems operates as a whole.

00:25:20.880 --> 00:25:22.980
In Josh's terms
from last Friday,

00:25:22.980 --> 00:25:25.410
it's internally compositional.

00:25:25.410 --> 00:25:27.810
Infants don't just come
equipped with a set

00:25:27.810 --> 00:25:31.050
of local facts about how objects
behave, they come equipped

00:25:31.050 --> 00:25:34.080
with a set of more general rules
or principles that allow them

00:25:34.080 --> 00:25:36.300
to deal with objects
in novel situations

00:25:36.300 --> 00:25:40.360
and make productive inferences
about their interactions

00:25:40.360 --> 00:25:43.420
and behavior.

00:25:43.420 --> 00:25:45.030
Each of these
systems is partially

00:25:45.030 --> 00:25:47.250
distinct from the other systems.

00:25:47.250 --> 00:25:48.990
It's distinct in three ways.

00:25:48.990 --> 00:25:51.240
First, each of them operates
on different information.

00:25:51.240 --> 00:25:54.010
It's elicited under
different conditions.

00:25:54.010 --> 00:25:59.070
Second, it gives rise to
different representations

00:25:59.070 --> 00:26:00.660
with different content.

00:26:00.660 --> 00:26:04.240
And third, most deeply, it
answers different questions.

00:26:04.240 --> 00:26:06.600
So for example, we
have two-- infants

00:26:06.600 --> 00:26:09.360
have two systems for
reasoning about people,

00:26:09.360 --> 00:26:11.560
but each system is answering
a different question.

00:26:11.560 --> 00:26:13.481
The agent system is
answering the question,

00:26:13.481 --> 00:26:14.480
what is this guy's goal?

00:26:14.480 --> 00:26:15.813
What is he trying to accomplish?

00:26:15.813 --> 00:26:19.380
What changes is he
affecting in the world?

00:26:19.380 --> 00:26:22.080
The social system is asking,
who is this guy related to?

00:26:22.080 --> 00:26:23.400
Who is he connected to?

00:26:23.400 --> 00:26:27.360
Who is he communicating with?

00:26:27.360 --> 00:26:31.500
Each of the systems are limited,
extremely limited relative

00:26:31.500 --> 00:26:33.360
to what we find in adults.

00:26:33.360 --> 00:26:35.640
Each captures only
a tiny part of what

00:26:35.640 --> 00:26:39.690
we as adults know
about objects or agents

00:26:39.690 --> 00:26:41.209
or social interactions.

00:26:41.209 --> 00:26:42.750
Each of them, I
think, interestingly,

00:26:42.750 --> 00:26:44.490
is shared by other animals.

00:26:44.490 --> 00:26:47.040
I didn't expect
that to be true when

00:26:47.040 --> 00:26:48.870
we started doing this research.

00:26:48.870 --> 00:26:53.040
But as far as we can see so far,
it's hard to find anything that

00:26:53.040 --> 00:26:56.490
a young human infant can do
that a non-human animal can't.

00:26:56.490 --> 00:26:59.140
And I'll give you
examples of that, too.

00:26:59.140 --> 00:27:02.610
And finally-- and I won't talk
about this much, unfortunately.

00:27:02.610 --> 00:27:04.500
I think each of these
systems continues

00:27:04.500 --> 00:27:07.080
to function throughout life
and supports the development

00:27:07.080 --> 00:27:09.990
of new systems of knowledge.

00:27:09.990 --> 00:27:12.150
So when we think thoughts
that only humans think,

00:27:12.150 --> 00:27:14.260
we engage these
fundamental systems

00:27:14.260 --> 00:27:17.880
that we've had since infancy
and other animals share.

00:27:17.880 --> 00:27:19.770
I also think this
research tells us

00:27:19.770 --> 00:27:21.300
something about how we do that.

00:27:21.300 --> 00:27:24.120
I think that in
addition to having

00:27:24.120 --> 00:27:26.280
these basic early
developing systems,

00:27:26.280 --> 00:27:29.520
we have a uniquely
human capacity

00:27:29.520 --> 00:27:31.830
to productively
combine information

00:27:31.830 --> 00:27:36.510
across these systems, and
through those combinations,

00:27:36.510 --> 00:27:39.900
to construct new concepts.

00:27:39.900 --> 00:27:41.910
I think these new
concepts underlie,

00:27:41.910 --> 00:27:44.940
or they tend to be
abstract, and they

00:27:44.940 --> 00:27:48.090
underlie a set of very important
later-developing systems

00:27:48.090 --> 00:27:50.380
of knowledge,
including knowledge

00:27:50.380 --> 00:27:54.630
that allow us to form
taxonomies of objects, of tools,

00:27:54.630 --> 00:27:59.700
of natural kinds like
animals and plants,

00:27:59.700 --> 00:28:01.350
and to reason about
their behavior,

00:28:01.350 --> 00:28:03.660
such that when we
encounter some new thing,

00:28:03.660 --> 00:28:05.970
we already know a lot
about the kind of thing

00:28:05.970 --> 00:28:09.600
that it is and can
use that to infer many

00:28:09.600 --> 00:28:12.150
of its specific
properties, and also

00:28:12.150 --> 00:28:14.190
to direct our learning
very explicitly to fill

00:28:14.190 --> 00:28:16.710
in the gaps in our knowledge.

00:28:16.710 --> 00:28:19.320
Another is the systems
of natural number

00:28:19.320 --> 00:28:20.910
in Euclidean geometry.

00:28:20.910 --> 00:28:24.300
Natural number, children seem to
construct over the first three

00:28:24.300 --> 00:28:25.680
to five years of life.

00:28:25.680 --> 00:28:29.190
Euclidean geometry seems to take
much longer, much, much later.

00:28:29.190 --> 00:28:32.550
Molly Dillon, who's also
here, has been trying to work

00:28:32.550 --> 00:28:35.370
on understanding-- and
so has Veronique Izard--

00:28:35.370 --> 00:28:37.170
how children go from
six years of age,

00:28:37.170 --> 00:28:39.630
where they seem absolutely
clueless about the simplest

00:28:39.630 --> 00:28:43.010
properties of Euclidean
geometry, to 12-year-olds who,

00:28:43.010 --> 00:28:45.510
whether they're in the Amazon
and have never been to school,

00:28:45.510 --> 00:28:51.540
or studying geometry
in school, seem

00:28:51.540 --> 00:28:54.090
to have a basic rudimentary
understanding of points

00:28:54.090 --> 00:28:57.270
and lines and figures
on the Euclidean plane.

00:28:57.270 --> 00:28:59.426
A third is a system of
persons and mental states.

00:28:59.426 --> 00:29:01.050
And I won't talk
about it, but I'm only

00:29:01.050 --> 00:29:03.270
talking for the first
half or so of this time,

00:29:03.270 --> 00:29:05.250
then Alia Martin's
going to take over.

00:29:05.250 --> 00:29:06.780
And you'll touch on--

00:29:06.780 --> 00:29:09.480
you'll get to some
of those issues.

00:29:09.480 --> 00:29:14.160
Now, as Nancy said last week, I
have this out-there hypothesis

00:29:14.160 --> 00:29:16.410
that I don't think anybody
else in the world believes,

00:29:16.410 --> 00:29:18.060
but I still believe it.

00:29:18.060 --> 00:29:21.060
That this productive
combinatorial capacity

00:29:21.060 --> 00:29:24.120
either is or is
intimately tied to what's

00:29:24.120 --> 00:29:26.310
the most obvious cognitive
difference between us

00:29:26.310 --> 00:29:30.390
and other animals, namely our
faculty of natural language.

00:29:30.390 --> 00:29:33.870
In particular, I
think that there

00:29:33.870 --> 00:29:36.330
are two general properties
of natural language

00:29:36.330 --> 00:29:39.930
that make it an ideal medium
for forming combinations

00:29:39.930 --> 00:29:42.790
of new concepts.

00:29:42.790 --> 00:29:46.560
One is that the words
and the rules of--

00:29:46.560 --> 00:29:48.090
well, three
properties, actually.

00:29:48.090 --> 00:29:52.230
One is that the syntactic
and semantic rules

00:29:52.230 --> 00:29:54.600
of natural languages
are combinatorial and

00:29:54.600 --> 00:29:55.300
compositional.

00:29:55.300 --> 00:29:57.780
That is, if you learn
the meanings of words

00:29:57.780 --> 00:29:59.770
and you learn how
to combine them,

00:29:59.770 --> 00:30:02.190
you get the meanings of
the expressions for free.

00:30:02.190 --> 00:30:03.740
You don't need to
go out and learn

00:30:03.740 --> 00:30:05.960
what a brown cow is if
you know what brown is

00:30:05.960 --> 00:30:09.220
and you know what a cow is.

00:30:09.220 --> 00:30:13.490
Second, the words and the
rules of natural language

00:30:13.490 --> 00:30:15.680
apply across all domains.

00:30:15.680 --> 00:30:18.500
They're not restricted to
one domain or another the way

00:30:18.500 --> 00:30:22.010
infants' other cognitive
capacities seem to be.

00:30:22.010 --> 00:30:26.600
So if you learn
how "cow" behaves

00:30:26.600 --> 00:30:29.660
in the expression "brown cow,"
and then you hear "brown ball,"

00:30:29.660 --> 00:30:31.910
or something that a different
domain of core knowledge

00:30:31.910 --> 00:30:35.750
would be capturing,
you can immediately

00:30:35.750 --> 00:30:38.070
interpret that
combination as well.

00:30:38.070 --> 00:30:41.510
And then the last thing about
natural language that I think

00:30:41.510 --> 00:30:44.960
makes it so useful for cognitive
development is that it's

00:30:44.960 --> 00:30:46.520
learned from other people.

00:30:46.520 --> 00:30:48.560
And other people
talk about the things

00:30:48.560 --> 00:30:51.200
that they find useful
to think about, right?

00:30:51.200 --> 00:30:53.720
Word frequency is
a really good proxy

00:30:53.720 --> 00:30:57.740
for what the useful
concepts out there are.

00:30:57.740 --> 00:31:03.980
So a child who has a very
powerful combinatorial system

00:31:03.980 --> 00:31:06.560
that can create a
huge set of concepts

00:31:06.560 --> 00:31:09.590
is going to have a search
problem when they try to apply

00:31:09.590 --> 00:31:11.150
those concepts to the world.

00:31:11.150 --> 00:31:12.670
Something will
happen in the world.

00:31:12.670 --> 00:31:15.380
And if they now have
a million concepts

00:31:15.380 --> 00:31:17.600
that they could bring to
bear, which one are they

00:31:17.600 --> 00:31:18.300
going to use?

00:31:18.300 --> 00:31:20.960
Are they to test them all out?

00:31:20.960 --> 00:31:23.780
Having too many concepts,
too many innate concepts,

00:31:23.780 --> 00:31:26.360
would not necessarily
be a blessing.

00:31:26.360 --> 00:31:29.819
But if you use language to guide
you to the useful concepts,

00:31:29.819 --> 00:31:30.860
I think you'll do better.

00:31:30.860 --> 00:31:32.450
The ones people are going
to talk about around

00:31:32.450 --> 00:31:34.699
you most frequently are going
to be the ones that it's

00:31:34.699 --> 00:31:37.350
going to be most useful for you
to be learning at that point.

00:31:37.350 --> 00:31:41.180
So let's go back to that first
set of questions, which is what

00:31:41.180 --> 00:31:43.980
I want to be focusing on today.

00:31:43.980 --> 00:31:46.610
And as I said, I'll
talk particularly

00:31:46.610 --> 00:31:49.090
about three domains
where infants

00:31:49.090 --> 00:31:51.020
seem to develop
knowledge quite rapidly

00:31:51.020 --> 00:31:52.460
over the course of infancy.

00:31:52.460 --> 00:31:56.300
And I'll spend most of my time
on the first one, objects.

00:31:56.300 --> 00:32:00.350
So object cognition
is really interesting

00:32:00.350 --> 00:32:02.810
and it seems to span
this really big range.

00:32:02.810 --> 00:32:06.280
It seems to involve many
different kinds of processes.

00:32:06.280 --> 00:32:08.510
If you're going to figure
out what the objects are,

00:32:08.510 --> 00:32:11.330
what the bodies are
in a scene, then you

00:32:11.330 --> 00:32:13.760
need segmentation abilities.

00:32:13.760 --> 00:32:15.770
You need to be able to
take an array like this

00:32:15.770 --> 00:32:19.490
and break it down into
units, figuring out

00:32:19.490 --> 00:32:22.890
what different parts of that
array lie on the same object

00:32:22.890 --> 00:32:26.240
and what parts lie
on different ones.

00:32:26.240 --> 00:32:29.720
So early mechanisms
for doing that

00:32:29.720 --> 00:32:33.170
can participate in
object representation.

00:32:33.170 --> 00:32:36.320
But also to perceive
objects, arrays are cluttered

00:32:36.320 --> 00:32:39.200
and objects tend to be opaque.

00:32:39.200 --> 00:32:41.690
And when they are,
it's never the case

00:32:41.690 --> 00:32:43.550
that all of the
surfaces of one object

00:32:43.550 --> 00:32:44.930
are in view at the same time.

00:32:44.930 --> 00:32:46.610
And it's often the
case that you're only

00:32:46.610 --> 00:32:49.430
seeing a little bit of any
given object at a time.

00:32:49.430 --> 00:32:50.900
Yet somehow we're
able to see this

00:32:50.900 --> 00:32:53.600
as a continuous table that's
extending behind everything

00:32:53.600 --> 00:32:58.520
that's sitting on it, and even
sort of as a continuous plate,

00:32:58.520 --> 00:33:00.170
a single plate that's partly--

00:33:00.170 --> 00:33:04.560
that's on the table behind
the vase, and so forth.

00:33:04.560 --> 00:33:06.470
So to represent
objects, we've got

00:33:06.470 --> 00:33:08.540
to be able to take
these visual fragments

00:33:08.540 --> 00:33:11.330
and put them together in
the right sorts of ways.

00:33:11.330 --> 00:33:14.450
Something that's harder
to show in a static image,

00:33:14.450 --> 00:33:17.000
but that of course is
radically true about the world

00:33:17.000 --> 00:33:19.610
is that our perceptual
encounters with objects

00:33:19.610 --> 00:33:20.840
are intermittent.

00:33:20.840 --> 00:33:22.670
We can look away
and then look back,

00:33:22.670 --> 00:33:24.270
or an object can
move out of view

00:33:24.270 --> 00:33:25.940
and then come back
into view, yet

00:33:25.940 --> 00:33:29.270
what we experience is a world
of persisting objects that

00:33:29.270 --> 00:33:31.520
are existing and moving
on connected paths,

00:33:31.520 --> 00:33:35.430
whether we're looking
at them or not.

00:33:35.430 --> 00:33:38.750
And finally, objects
interact with other objects

00:33:38.750 --> 00:33:40.720
and we need to work
out those interactions.

00:33:40.720 --> 00:33:42.470
And the working out
that I'm interested in

00:33:42.470 --> 00:33:44.710
is not what this
little boy is doing,

00:33:44.710 --> 00:33:46.430
but what his younger
sister is doing

00:33:46.430 --> 00:33:48.080
as she's sitting
in her infant seat

00:33:48.080 --> 00:33:50.720
and observing him
acting on these towers

00:33:50.720 --> 00:33:52.591
and wondering what's
going to happen next.

00:33:52.591 --> 00:33:53.090
OK?

00:33:53.090 --> 00:33:57.320
At least that's the problem
on the table for today.

00:33:57.320 --> 00:34:02.840
OK, so a standard view
for a very long time

00:34:02.840 --> 00:34:05.001
has been that different
mechanisms solve

00:34:05.001 --> 00:34:07.250
these different aspects of
the problem of representing

00:34:07.250 --> 00:34:08.080
objects.

00:34:08.080 --> 00:34:10.159
That segmentation
depends on relatively

00:34:10.159 --> 00:34:11.750
low-level mechanisms.

00:34:11.750 --> 00:34:14.176
Completion and
identity through time,

00:34:14.176 --> 00:34:16.550
it's going to depend on how
much time we're talking about

00:34:16.550 --> 00:34:18.860
and how complicated the
transformations are.

00:34:18.860 --> 00:34:20.429
They're sort of in the middle.

00:34:20.429 --> 00:34:24.320
And this is all about
reasoning, about concepts

00:34:24.320 --> 00:34:26.300
that go beyond
perception altogether,

00:34:26.300 --> 00:34:28.489
like the mass of an
object, which we can't

00:34:28.489 --> 00:34:31.944
see directly, and so forth.

00:34:31.944 --> 00:34:33.860
And I kind of believed
that that was true when

00:34:33.860 --> 00:34:36.150
we started doing this work.

00:34:36.150 --> 00:34:39.210
And because I did and wanted to
know where the boundaries were

00:34:39.210 --> 00:34:40.909
of what infants
could do, I started

00:34:40.909 --> 00:34:42.380
by working on these
problems here.

00:34:42.380 --> 00:34:44.360
And that's what I'm going
to talk about today.

00:34:44.360 --> 00:34:46.850
But let me flag at the
outset that I no longer

00:34:46.850 --> 00:34:52.080
believe that the real
representations of objects that

00:34:52.080 --> 00:34:55.210
organize infants' learning
about the physical world, I

00:34:55.210 --> 00:34:57.380
no longer believe
that they're embodied

00:34:57.380 --> 00:34:58.820
in a set of diverse systems.

00:34:58.820 --> 00:35:02.110
I think there's a single system
that's ultimately at work here.

00:35:02.110 --> 00:35:03.770
Of course it has
multiple levels to it,

00:35:03.770 --> 00:35:06.090
including low-level of edge
detection, and so forth.

00:35:06.090 --> 00:35:08.640
But that there's a single
system at work that both--

00:35:08.640 --> 00:35:11.150
that tells us what's
connected to what

00:35:11.150 --> 00:35:12.580
and where the
boundaries of things

00:35:12.580 --> 00:35:15.880
are in arrays like this,
how things continue

00:35:15.880 --> 00:35:18.520
where and when they're
hidden, and how they interact

00:35:18.520 --> 00:35:19.330
with other things.

00:35:19.330 --> 00:35:21.670
That's one unitary
system, and I'll

00:35:21.670 --> 00:35:24.790
try to show you what
evidence supports

00:35:24.790 --> 00:35:27.670
that view, though,
of course, jump

00:35:27.670 --> 00:35:31.330
in with questions or criticisms
or alternative accounts.

00:35:31.330 --> 00:35:35.860
OK, so here's an intermediate
case to start with.

00:35:35.860 --> 00:35:40.150
You present a-- it was studied
a lot by Belgian psychologist

00:35:40.150 --> 00:35:45.550
Elvin Meshot back in the 1950s,
I think-- '50s or early '60s.

00:35:45.550 --> 00:35:49.390
Take a triangle, present
it behind an occluder,

00:35:49.390 --> 00:35:55.450
and ask babies, in effect, what
do you see in that triangle?

00:35:55.450 --> 00:35:57.880
Do you see a connected
object or do you see

00:35:57.880 --> 00:36:00.252
two separate visible fragments?

00:36:00.252 --> 00:36:01.960
We did these studies
with four-month-olds

00:36:01.960 --> 00:36:03.751
because they're not
yet reaching for things

00:36:03.751 --> 00:36:05.470
and manipulating objects.

00:36:05.470 --> 00:36:07.120
We used the fact that
they tend to like

00:36:07.120 --> 00:36:08.620
to look at things that are new.

00:36:08.620 --> 00:36:11.590
So we presented this display
repeatedly-- we, by the way,

00:36:11.590 --> 00:36:14.230
is Phil Kellman, now
at UCLA and studying

00:36:14.230 --> 00:36:16.030
all this stuff in
adults primarily, also

00:36:16.030 --> 00:36:18.130
studying mathematics now.

00:36:18.130 --> 00:36:22.390
Anyhow, so we presented
displays like this repeatedly

00:36:22.390 --> 00:36:24.640
to babies until they
got bored with them.

00:36:24.640 --> 00:36:27.670
And then we took the occluder
away and in alternation,

00:36:27.670 --> 00:36:29.680
presented them with
a complete triangle

00:36:29.680 --> 00:36:32.302
and with a triangle that
had a gap in the center.

00:36:32.302 --> 00:36:34.510
And we reasoned that there
were two possible outcomes

00:36:34.510 --> 00:36:35.650
of the study.

00:36:35.650 --> 00:36:41.290
Possibility one is that as
empiricists and the then-very

00:36:41.290 --> 00:36:43.930
influential child psychologist--

00:36:43.930 --> 00:36:46.030
developmental
psychologist Jean Piaget

00:36:46.030 --> 00:36:48.970
argued, for a four-month-old
infant who isn't yet

00:36:48.970 --> 00:36:50.710
reaching for
things, the world is

00:36:50.710 --> 00:36:53.200
an array of visible fragments.

00:36:53.200 --> 00:36:55.840
So they will see
this thing as ending

00:36:55.840 --> 00:37:00.250
at this edge where the occluder
begins, and this display will

00:37:00.250 --> 00:37:02.180
look more similar to
them than this display,

00:37:02.180 --> 00:37:04.444
so they'll be more
interested in that one.

00:37:04.444 --> 00:37:06.610
There was also the theory
from Gestalt psychologists

00:37:06.610 --> 00:37:08.943
and others that predicted the
opposite, that there would

00:37:08.943 --> 00:37:11.050
be automatic completion
processes that

00:37:11.050 --> 00:37:14.080
would lead any creature, whether
they were experienced or not,

00:37:14.080 --> 00:37:16.870
to perceive the simpler
arrangement, which is this one.

00:37:16.870 --> 00:37:19.330
Those, it seemed to us,
were the only two options.

00:37:19.330 --> 00:37:20.921
Baby research is
really fun because it

00:37:20.921 --> 00:37:22.420
can surprise you
even when you think

00:37:22.420 --> 00:37:23.800
you've covered all the bases.

00:37:23.800 --> 00:37:26.000
Neither of those
turned out to be true.

00:37:26.000 --> 00:37:28.690
What happened instead was that
when we took the occluder away,

00:37:28.690 --> 00:37:30.880
you still saw an
increase in looking

00:37:30.880 --> 00:37:33.790
both to the connected object
and to the separate object,

00:37:33.790 --> 00:37:36.700
and those two
increases were equal.

00:37:36.700 --> 00:37:39.610
Now, this could have been for
an extremely boring reason.

00:37:39.610 --> 00:37:41.410
Maybe babies were
only paying attention

00:37:41.410 --> 00:37:44.450
to the thing that was
closest to them in the array.

00:37:44.450 --> 00:37:47.740
So we very quickly tested for
that in the following way.

00:37:47.740 --> 00:37:51.160
Instead of contrasting an array
with a small gap to an array

00:37:51.160 --> 00:37:53.590
that had it filled in,
we contrasted an array

00:37:53.590 --> 00:37:55.900
with a small gap to an
array with a larger gap,

00:37:55.900 --> 00:37:58.000
too large to have fit
behind the occluder.

00:37:58.000 --> 00:38:00.190
And there, babies looked
longer at the array

00:38:00.190 --> 00:38:01.510
with the larger gap.

00:38:01.510 --> 00:38:03.250
So we know it's not
that they're not

00:38:03.250 --> 00:38:06.790
seeing this back form
and its visible surfaces,

00:38:06.790 --> 00:38:09.730
but they seem to be uncommitted
as to whether those surfaces

00:38:09.730 --> 00:38:11.957
are connected behind
the occluder or not.

00:38:11.957 --> 00:38:14.290
They don't see them as ending
where the occluder begins,

00:38:14.290 --> 00:38:16.569
but they don't clearly see
them as connected, either.

00:38:16.569 --> 00:38:18.610
And we showed that this
was quite generally true,

00:38:18.610 --> 00:38:21.580
both for simpler arrays and
for more complicated-- well,

00:38:21.580 --> 00:38:23.905
for richer ones, like a sphere.

00:38:23.905 --> 00:38:25.780
We did this with a bunch
of different arrays.

00:38:25.780 --> 00:38:27.520
And under these
conditions, where

00:38:27.520 --> 00:38:30.136
the arrays are stationary,
that's what we found.

00:38:30.136 --> 00:38:31.510
But there was one
condition where

00:38:31.510 --> 00:38:33.093
we got a different
finding, and that's

00:38:33.093 --> 00:38:35.200
when we took one of
these arrays and moved it

00:38:35.200 --> 00:38:37.780
behind the occluder, never
moving it enough to bring

00:38:37.780 --> 00:38:40.330
the center into view,
but moving it enough such

00:38:40.330 --> 00:38:42.696
that the top and bottom
were moving together.

00:38:42.696 --> 00:38:44.320
And when we did that,
now babies looked

00:38:44.320 --> 00:38:46.000
longer at the display
that had the gap.

00:38:49.160 --> 00:38:52.900
That raised the question, why
is motion having this effect?

00:38:52.900 --> 00:38:54.830
And the immediate
possibility, we thought,

00:38:54.830 --> 00:38:56.830
is motion is calling their
attention to the rod,

00:38:56.830 --> 00:38:59.020
so they're tending to it
more than they otherwise

00:38:59.020 --> 00:39:01.810
would, and it's leading them
to see its other properties,

00:39:01.810 --> 00:39:04.940
like the alignment of its edges.

00:39:04.940 --> 00:39:09.340
So to test that, we gave them
misaligned objects differing

00:39:09.340 --> 00:39:10.810
in color, differing in texture.

00:39:10.810 --> 00:39:12.490
All of the edges--
none of the edges

00:39:12.490 --> 00:39:14.277
were aligned with each other.

00:39:14.277 --> 00:39:16.360
If motion was just calling
attention to alignment,

00:39:16.360 --> 00:39:17.980
it shouldn't do
that in this case.

00:39:17.980 --> 00:39:22.210
But in fact, we found that
after getting bored with that,

00:39:22.210 --> 00:39:24.970
infants expected something like
this, not something like that.

00:39:24.970 --> 00:39:27.215
They looked longer at
the display with the gap.

00:39:27.215 --> 00:39:28.840
So it looks like the
motion is actually

00:39:28.840 --> 00:39:32.530
providing the information
for the connectedness,

00:39:32.530 --> 00:39:36.476
and the alignment is not
playing much of a role at all.

00:39:36.476 --> 00:39:37.850
Now, what could
be going on here?

00:39:37.850 --> 00:39:39.040
This is the kind
of thing I think

00:39:39.040 --> 00:39:41.510
that Josh likes to call a
suspicious coincidence, right?

00:39:41.510 --> 00:39:44.080
That an infant is
looking at this array,

00:39:44.080 --> 00:39:46.120
and isn't it odd that
we're seeing this--

00:39:46.120 --> 00:39:47.740
I'm seeing the same
pattern of motion

00:39:47.740 --> 00:39:50.930
below the occluder as
I'm seeing above it?

00:39:50.930 --> 00:39:53.170
Now that could be two
separate objects that

00:39:53.170 --> 00:39:55.630
just happen to be
moving together,

00:39:55.630 --> 00:39:57.490
but that would be
rather unlikely.

00:39:57.490 --> 00:39:59.680
You're much more likely
to see a pattern like that

00:39:59.680 --> 00:40:02.840
if in fact there's a between it
and it's just one object that's

00:40:02.840 --> 00:40:03.369
in motion.

00:40:03.369 --> 00:40:04.910
I think that's
probably the right way

00:40:04.910 --> 00:40:08.880
to think about what's going
on in these experiments.

00:40:08.880 --> 00:40:12.260
But if it is, notice
that not all coincidences

00:40:12.260 --> 00:40:15.440
that are suspicious for us
are suspicious for infants.

00:40:15.440 --> 00:40:17.330
For us, it's a
suspicious coincidence

00:40:17.330 --> 00:40:19.550
that this edge is
aligned with that edge.

00:40:19.550 --> 00:40:21.092
For infants, it's not.

00:40:21.092 --> 00:40:22.550
I think this is a
case where we can

00:40:22.550 --> 00:40:25.520
see infants can be
useful for thinking

00:40:25.520 --> 00:40:27.710
about our own
cognitive abilities

00:40:27.710 --> 00:40:32.520
because they seem to share some
of our picture of the world,

00:40:32.520 --> 00:40:34.440
but not all of our
picture of the world.

00:40:34.440 --> 00:40:37.550
And that can be a hint as to how
that picture gets put together

00:40:37.550 --> 00:40:39.180
and how it's organized.

00:40:39.180 --> 00:40:40.537
So what kind of motion?

00:40:40.537 --> 00:40:42.120
We've tried a bunch
of different ones.

00:40:42.120 --> 00:40:43.700
One of them is vertical motion.

00:40:43.700 --> 00:40:47.330
That's interesting because
it's also a rigid displacement

00:40:47.330 --> 00:40:48.500
or motion in depth.

00:40:48.500 --> 00:40:51.830
They're both rigid displacements
in three-dimensional space.

00:40:51.830 --> 00:40:54.110
Actually, all of
these three are.

00:40:54.110 --> 00:40:56.480
But in this case, you don't
get any side-to-side changes

00:40:56.480 --> 00:40:57.830
in the visual field.

00:40:57.830 --> 00:40:59.010
I think I animated this.

00:40:59.010 --> 00:40:59.789
Yeah.

00:40:59.789 --> 00:41:01.580
So this is kind of what
the baby is seeing.

00:41:01.580 --> 00:41:04.370
By the way, all of these studies
were done with real 3D objects

00:41:04.370 --> 00:41:06.290
and they had textures
on them, and so forth.

00:41:06.290 --> 00:41:08.090
They've also all
since been replicated

00:41:08.090 --> 00:41:10.880
in other labs using computer
animated displays, which

00:41:10.880 --> 00:41:12.180
we didn't have--

00:41:12.180 --> 00:41:14.734
which weren't available
back in the day.

00:41:14.734 --> 00:41:16.400
And you get the same
result. So I'm just

00:41:16.400 --> 00:41:18.020
doing cartoon
versions of them here,

00:41:18.020 --> 00:41:20.600
but actually babies
showed these effects

00:41:20.600 --> 00:41:22.176
across a range of
different displays.

00:41:22.176 --> 00:41:23.300
So there's vertical motion.

00:41:23.300 --> 00:41:25.287
Here is motion in depth.

00:41:25.287 --> 00:41:27.620
Oh, and by the way, we're not
restraining babies' heads,

00:41:27.620 --> 00:41:29.578
so it's not going to be
anything near as, like,

00:41:29.578 --> 00:41:32.205
simple uniform as
what's at their eye,

00:41:32.205 --> 00:41:33.570
is what I'm showing here.

00:41:33.570 --> 00:41:39.170
And then rotational motion,
like that, around the midpoint.

00:41:39.170 --> 00:41:42.830
And what we found is that
babies used both vertical motion

00:41:42.830 --> 00:41:46.070
and motion in depth
about as well as they

00:41:46.070 --> 00:41:50.000
used horizontal motion to
perceive the connectedness

00:41:50.000 --> 00:41:50.870
of the object.

00:41:50.870 --> 00:41:53.300
They did not use rotary motion.

00:41:53.300 --> 00:41:56.810
So I know there's a lot of
interest and projects focused

00:41:56.810 --> 00:41:58.550
on perceptual invariance.

00:41:58.550 --> 00:42:00.560
And I think there's an
interesting puzzle here,

00:42:00.560 --> 00:42:02.976
and it's one that Molly is
very interested in, in the work

00:42:02.976 --> 00:42:05.030
that she's doing on geometry.

00:42:05.030 --> 00:42:08.510
These are all rigid motions.

00:42:08.510 --> 00:42:11.300
But somehow, rotation seems
to be a whole lot harder

00:42:11.300 --> 00:42:17.210
for young intelligent beings
to wrap their heads around

00:42:17.210 --> 00:42:20.690
than translation is--

00:42:20.690 --> 00:42:23.660
including translation in
depth or vertical translation.

00:42:23.660 --> 00:42:26.970
There's something hard
about orientation changes.

00:42:26.970 --> 00:42:29.440
And in fact, I think they
remain hard for us as adults.

00:42:29.440 --> 00:42:33.320
If you think of things like
how the shape of a square

00:42:33.320 --> 00:42:36.500
seems to change if you rotate
it 45 degrees so it's a diamond.

00:42:36.500 --> 00:42:39.221
It's no longer obvious that
it's got four right angles.

00:42:39.221 --> 00:42:40.970
There's something about
orientation that's

00:42:40.970 --> 00:42:42.720
harder than these other things.

00:42:42.720 --> 00:42:45.170
And I think we were
seeing that here.

00:42:45.170 --> 00:42:48.020
When an object-- when a baby
is sitting still and a rod

00:42:48.020 --> 00:42:49.610
is moving behind
an occluder, it's

00:42:49.610 --> 00:42:52.370
moving both relative to
the baby and relative

00:42:52.370 --> 00:42:54.260
to the surroundings,
which of those things

00:42:54.260 --> 00:42:55.650
matters to the baby?

00:42:55.650 --> 00:42:59.360
So Phil Kellman did the
ambitious experiment

00:42:59.360 --> 00:43:01.590
of putting a baby
in a movable chair

00:43:01.590 --> 00:43:03.980
and moving the baby
back and forth.

00:43:03.980 --> 00:43:08.000
In one condition, the baby is
looking at a stationary rod,

00:43:08.000 --> 00:43:11.360
but his own motion is such
that if you put a camera where

00:43:11.360 --> 00:43:14.060
the baby's head is, you'll see
the image of that rod moving

00:43:14.060 --> 00:43:16.640
back and forth behind the block.

00:43:16.640 --> 00:43:18.530
In the other condition,
the motion of the rod

00:43:18.530 --> 00:43:20.060
is tied to the
motion of the baby,

00:43:20.060 --> 00:43:22.880
so it's always staying in
the middle of the baby's

00:43:22.880 --> 00:43:27.500
visual field, but it's actually
moving through the array.

00:43:27.500 --> 00:43:29.700
And it turned out that it's--

00:43:29.700 --> 00:43:32.870
OK, so whether the baby
was still or moving

00:43:32.870 --> 00:43:34.350
didn't matter at all.

00:43:34.350 --> 00:43:36.980
So if the object is--
sorry, I did these wrong.

00:43:36.980 --> 00:43:39.020
This should be still,
that should be moving.

00:43:39.020 --> 00:43:42.620
If the object is still, and
whether the baby is still

00:43:42.620 --> 00:43:44.180
or moving, it doesn't work.

00:43:44.180 --> 00:43:45.680
If the object is moving--

00:43:45.680 --> 00:43:46.850
the diagram is right.

00:43:46.850 --> 00:43:48.770
It was just my
label that's wrong.

00:43:48.770 --> 00:43:50.240
If the object is
moving, it doesn't

00:43:50.240 --> 00:43:52.365
matter whether it's being
displaced in the infant's

00:43:52.365 --> 00:43:53.540
visual field or not.

00:43:53.540 --> 00:43:54.590
It's seen as moving.

00:43:54.590 --> 00:43:56.930
Now, this isn't magic.

00:43:56.930 --> 00:43:58.806
The studies are not
being done in a dark room

00:43:58.806 --> 00:44:01.013
with a single luminous object
where the baby wouldn't

00:44:01.013 --> 00:44:01.700
be able to tell.

00:44:01.700 --> 00:44:04.100
There's lots of surround--
it's in a puppet stage

00:44:04.100 --> 00:44:05.520
and that is stationary.

00:44:05.520 --> 00:44:07.730
So there's lots of information
for the object moving

00:44:07.730 --> 00:44:10.220
relative to its
surroundings in all

00:44:10.220 --> 00:44:12.950
of the conditions of this study,
and I'm sure that's critical.

00:44:12.950 --> 00:44:15.410
But for the point of view
of the infant's connecting

00:44:15.410 --> 00:44:16.994
of the visible
ends of the object,

00:44:16.994 --> 00:44:18.410
the question he's
trying to answer

00:44:18.410 --> 00:44:20.150
is, is that thing moving?

00:44:20.150 --> 00:44:25.040
Not, am I experiencing movement
in this changing scene?

00:44:25.040 --> 00:44:25.970
Retinal movement.

00:44:25.970 --> 00:44:29.180
So if it's the case that--

00:44:29.180 --> 00:44:31.640
what those last
findings suggest is

00:44:31.640 --> 00:44:38.480
that the input representations
to the system that's

00:44:38.480 --> 00:44:42.170
forming objects out of
arrays of visual surfaces

00:44:42.170 --> 00:44:46.160
already capture a lot of the 3D
spatial structure of the world.

00:44:46.160 --> 00:44:48.270
This is a relatively
late process.

00:44:48.270 --> 00:44:52.370
And it allows us to ask, is
it even specific to vision?

00:44:52.370 --> 00:44:54.560
Would we see the
same process at work

00:44:54.560 --> 00:44:58.520
if we presented babies with the
task of asking, am I feeling--

00:44:58.520 --> 00:45:02.270
are two things that are
moving in the world connected?

00:45:02.270 --> 00:45:05.480
Or are they not, in areas
that I'm not perceiving?

00:45:05.480 --> 00:45:08.480
We can ask that in
other modalities.

00:45:08.480 --> 00:45:12.110
So we did a series of studies--
this is with Arlette Streri.

00:45:12.110 --> 00:45:14.450
We did a series of studies
looking at perception

00:45:14.450 --> 00:45:16.580
of objects by active touch.

00:45:16.580 --> 00:45:21.000
By taking four-month-old babies
and putting a bib over them.

00:45:21.000 --> 00:45:22.950
Now I said they can't
reach for objects,

00:45:22.950 --> 00:45:25.640
but if you put a ring in a
baby's hand, even a newborn's

00:45:25.640 --> 00:45:27.080
hand, they'll grasp it.

00:45:27.080 --> 00:45:29.060
So we put rings in
their two hands.

00:45:29.060 --> 00:45:31.750
And in one condition, the
rings were rigidly attached,

00:45:31.750 --> 00:45:34.250
although the array was set up
so that they couldn't actually

00:45:34.250 --> 00:45:37.557
feel that attachment and
they couldn't see anything,

00:45:37.557 --> 00:45:39.140
about the object,
anyway, because they

00:45:39.140 --> 00:45:42.280
had the screen blocking them.

00:45:42.280 --> 00:45:45.050
But as they moved one, the other
would move rigidly with it.

00:45:45.050 --> 00:45:47.300
In the other condition,
the two were unconnected,

00:45:47.300 --> 00:45:49.250
so they would move
independently.

00:45:49.250 --> 00:45:55.020
And after babies explored that
for-- over a series of trials,

00:45:55.020 --> 00:45:56.990
and as in the other
studies, we then

00:45:56.990 --> 00:45:59.520
presented visual
arrays in alternation

00:45:59.520 --> 00:46:02.540
where the two rings
were connected or not.

00:46:02.540 --> 00:46:05.270
And found that in the condition
where they had moved rigidly

00:46:05.270 --> 00:46:07.640
together, infants
extrapolated a connection

00:46:07.640 --> 00:46:10.719
and looked longer at the
arrays that were not connected.

00:46:10.719 --> 00:46:12.510
In the case where they
moved independently,

00:46:12.510 --> 00:46:14.360
they did the opposite.

00:46:14.360 --> 00:46:16.610
Now, that doesn't
tell us that there is

00:46:16.610 --> 00:46:18.770
a single system at work here.

00:46:18.770 --> 00:46:23.709
It could be that there
are, as Shimon, I believe,

00:46:23.709 --> 00:46:25.250
was saying yesterday
afternoon, there

00:46:25.250 --> 00:46:26.702
are redundancies in the system.

00:46:26.702 --> 00:46:28.160
You have different
systems that are

00:46:28.160 --> 00:46:29.570
capturing the same property.

00:46:29.570 --> 00:46:30.840
That's still true.

00:46:30.840 --> 00:46:32.060
But here's a reason to--

00:46:32.060 --> 00:46:36.120
we went on to ask not
only what infants can do,

00:46:36.120 --> 00:46:37.340
but what they can't do.

00:46:37.340 --> 00:46:39.350
And I think it gives us
reason to take seriously

00:46:39.350 --> 00:46:41.090
the possibility that
there's actually

00:46:41.090 --> 00:46:43.220
a single system at work here.

00:46:43.220 --> 00:46:45.320
What we did-- I haven't
pictured it here--

00:46:45.320 --> 00:46:48.620
is, instead of varying the
motion of the things, we did

00:46:48.620 --> 00:46:52.110
vary their motion, but we also
varied their other properties.

00:46:52.110 --> 00:46:53.780
So their rigidity.

00:46:53.780 --> 00:46:55.940
We contrasted a ring
that was made out

00:46:55.940 --> 00:46:57.620
of wood with a ring
that was made out

00:46:57.620 --> 00:47:00.440
of some kind of spongy,
foam-rubbery material--

00:47:00.440 --> 00:47:04.220
their shape, their
surface texture.

00:47:04.220 --> 00:47:07.160
Asking, do infants take
account of those properties

00:47:07.160 --> 00:47:08.464
in extrapolating a connection?

00:47:08.464 --> 00:47:10.130
Are they more likely
to think two things

00:47:10.130 --> 00:47:11.540
are connected to each
other if they're both

00:47:11.540 --> 00:47:12.920
made of foam rubber
than if one of them

00:47:12.920 --> 00:47:15.128
is made of foam rubber and
the other is made of wood?

00:47:15.128 --> 00:47:17.600
We never found any effect
of those properties,

00:47:17.600 --> 00:47:20.900
just as we didn't
in the visual case.

00:47:20.900 --> 00:47:24.050
So we see not only the same
abilities, but the same limits.

00:47:24.050 --> 00:47:25.850
And while that's
not conclusive, I

00:47:25.850 --> 00:47:29.290
think it adds weight
to the idea that what

00:47:29.290 --> 00:47:32.990
we could be studying here-- we
started in the visual modality.

00:47:32.990 --> 00:47:35.390
But what we could
be studying here

00:47:35.390 --> 00:47:38.660
is something that's more
general and more abstract.

00:47:38.660 --> 00:47:42.316
Basic notions about how objects
behave that apply not only

00:47:42.316 --> 00:47:44.690
when you're looking at things,
but when you're actively--

00:47:44.690 --> 00:47:46.898
when you're feeling them,
actively manipulating them,

00:47:46.898 --> 00:47:50.800
exploring them in
other modalities.

00:47:50.800 --> 00:47:53.750
So I put a question mark because
it's not absolutely conclusive,

00:47:53.750 --> 00:47:56.810
but I think we should take
seriously that possibility.

00:47:56.810 --> 00:47:57.770
OK.

00:47:57.770 --> 00:47:58.460
Only motion.

00:47:58.460 --> 00:48:01.100
Is motion the only
thing that works?

00:48:01.100 --> 00:48:07.580
Or will other changes work, so
if an object changes in color?

00:48:07.580 --> 00:48:11.720
We created a particularly
exciting color change

00:48:11.720 --> 00:48:14.480
by embedding colored
lights within a glass rod

00:48:14.480 --> 00:48:16.190
so it's flashing on and off.

00:48:16.190 --> 00:48:19.090
Succeeded in eliciting very
high interest in that array.

00:48:19.090 --> 00:48:21.620
Babies looked at
it for a long time,

00:48:21.620 --> 00:48:23.960
but only the motion array
was seen as connected

00:48:23.960 --> 00:48:25.100
behind the occluder.

00:48:25.100 --> 00:48:29.540
So it looks like not all
changes elicit this perception.

00:48:29.540 --> 00:48:32.420
It's an open question what the
class of effective changes is.

00:48:32.420 --> 00:48:34.490
Maybe it's broader
than just motions,

00:48:34.490 --> 00:48:37.220
but it doesn't seem
like all changes work.

00:48:37.220 --> 00:48:41.780
Finally, is motion
the only variable

00:48:41.780 --> 00:48:44.420
that influences
infants' perception

00:48:44.420 --> 00:48:47.060
of-- the only property of
surfaces that influences

00:48:47.060 --> 00:48:49.250
infants' perception of objects?

00:48:49.250 --> 00:48:51.830
The answer to that
seems to be no.

00:48:51.830 --> 00:48:55.340
So we studied that in
a different situation

00:48:55.340 --> 00:48:58.370
for which this is just a
very impoverished cartoon.

00:48:58.370 --> 00:49:00.980
We took two block-like objects--

00:49:00.980 --> 00:49:03.080
of different colors and
textures in some studies,

00:49:03.080 --> 00:49:04.760
same color and
texture in others.

00:49:04.760 --> 00:49:06.230
It didn't matter.

00:49:06.230 --> 00:49:08.840
And put one on top of the
other and either presented

00:49:08.840 --> 00:49:13.040
them moving together
or moving separately.

00:49:13.040 --> 00:49:16.630
And then tested whether babies
represented them as connected

00:49:16.630 --> 00:49:17.547
in either of two ways.

00:49:17.547 --> 00:49:19.254
Some of the studies
were done with babies

00:49:19.254 --> 00:49:20.480
who were old enough to reach.

00:49:20.480 --> 00:49:22.100
And then we could ask,
are they reaching for it

00:49:22.100 --> 00:49:23.990
as if it were a single
body or as if there

00:49:23.990 --> 00:49:26.117
were two distinct bodies there?

00:49:26.117 --> 00:49:27.950
I could give you more
information about that

00:49:27.950 --> 00:49:29.157
if you're interested.

00:49:29.157 --> 00:49:30.740
The other was with
looking time, where

00:49:30.740 --> 00:49:34.550
we had a hand come out and
grasp the top of the top object

00:49:34.550 --> 00:49:35.154
and lift it.

00:49:35.154 --> 00:49:37.070
And the question is,
what should come with it?

00:49:37.070 --> 00:49:38.861
Will the bottom object
come with it as well

00:49:38.861 --> 00:49:41.720
or will the top
object on its own?

00:49:41.720 --> 00:49:43.820
When the things had
previously moved together,

00:49:43.820 --> 00:49:45.554
they expected it all
to move together.

00:49:45.554 --> 00:49:46.970
When they'd moved
separately, they

00:49:46.970 --> 00:49:52.170
expected only the top
object would move by itself.

00:49:52.170 --> 00:49:54.140
And when there was
no motion at all,

00:49:54.140 --> 00:49:56.360
findings vary somewhat
from one lab to another,

00:49:56.360 --> 00:50:00.130
but mostly they tend to be
ambiguous in the case where

00:50:00.130 --> 00:50:01.090
there's no motion.

00:50:01.090 --> 00:50:03.590
So there it looks like
motion is doing all the work.

00:50:03.590 --> 00:50:05.680
But if you make one simple
change to this array

00:50:05.680 --> 00:50:07.810
that you can't do in
the occlusion studies,

00:50:07.810 --> 00:50:10.420
you simply change the
size of this object

00:50:10.420 --> 00:50:13.356
and present it such that there's
a gap between the two objects.

00:50:13.356 --> 00:50:15.730
And you can either do it with
this guy floating magically

00:50:15.730 --> 00:50:17.771
in midair, or you can do
it with two objects side

00:50:17.771 --> 00:50:20.560
by side, both stably
supported by a surface.

00:50:20.560 --> 00:50:22.600
If there's a visible
gap between them,

00:50:22.600 --> 00:50:23.920
the motion no longer matters.

00:50:23.920 --> 00:50:26.440
They will be treated as
two distinct objects,

00:50:26.440 --> 00:50:28.510
no matter what.

00:50:28.510 --> 00:50:30.490
So what I think is
going on here is

00:50:30.490 --> 00:50:33.220
that babies have a
system that's seeking

00:50:33.220 --> 00:50:36.610
to find the connected, the
solid connected bodies.

00:50:36.610 --> 00:50:39.550
The bodies that are
internally connected and will

00:50:39.550 --> 00:50:44.350
remain so over motion.

00:50:44.350 --> 00:50:46.390
And that's what's
leading them to see

00:50:46.390 --> 00:50:52.630
these patterns of relative
motion or these visible gaps

00:50:52.630 --> 00:50:57.880
as indicating a place where one
object ends and the next object

00:50:57.880 --> 00:50:58.630
begins.

00:50:58.630 --> 00:51:02.560
I did want to get on to the
problem of tracking objects

00:51:02.560 --> 00:51:06.800
over time, perceiving not what's
connected to what over space,

00:51:06.800 --> 00:51:09.149
but what's connected
to what over time.

00:51:09.149 --> 00:51:11.440
Under what conditions are
the thing that I'm seeing now

00:51:11.440 --> 00:51:13.660
the same thing that I
was seeing at some place

00:51:13.660 --> 00:51:17.050
or time in the past?

00:51:17.050 --> 00:51:24.220
So conceptually, it feels like
continuity of motion over time

00:51:24.220 --> 00:51:28.210
is related to connectedness
of motion over space.

00:51:28.210 --> 00:51:30.820
And it's been tested for
in a variety of ways.

00:51:30.820 --> 00:51:32.500
Here's one set of
studies that we

00:51:32.500 --> 00:51:35.190
did, where we have an
object that moves behind

00:51:35.190 --> 00:51:39.040
a single screen, and then
either is-- and it starts here,

00:51:39.040 --> 00:51:39.790
ends up here.

00:51:39.790 --> 00:51:42.280
And either is seen to move
between the two screens

00:51:42.280 --> 00:51:44.770
or is not.

00:51:44.770 --> 00:51:47.800
And we ask babies
in effect, how many

00:51:47.800 --> 00:51:49.810
objects do they think
are in this display,

00:51:49.810 --> 00:51:51.430
by boring half the
babies with this,

00:51:51.430 --> 00:51:53.740
half the babies with that,
and then presenting them

00:51:53.740 --> 00:51:55.360
in alternation
with arrays of one

00:51:55.360 --> 00:51:57.310
versus two objects,
neither of which

00:51:57.310 --> 00:52:00.070
ever passes through the
center, but the arrays

00:52:00.070 --> 00:52:00.926
differ in number.

00:52:00.926 --> 00:52:02.800
In the one case, it's
either moving over here

00:52:02.800 --> 00:52:06.420
or it's moving over there
on different trials.

00:52:06.420 --> 00:52:09.610
And what we find is
that in this case,

00:52:09.610 --> 00:52:12.790
they expect to see one object
and look longer at two.

00:52:12.790 --> 00:52:15.610
In this case, they
expect to see two objects

00:52:15.610 --> 00:52:17.134
and look somewhat longer at one.

00:52:17.134 --> 00:52:19.550
There's actually an overall
preference for looking at two,

00:52:19.550 --> 00:52:21.790
but you get that
interaction and there's

00:52:21.790 --> 00:52:26.950
a slight preference for looking
at one in that condition.

00:52:26.950 --> 00:52:28.990
Providing evidence,
I think, that babies

00:52:28.990 --> 00:52:33.730
are tracking objects over
time by analyzing information

00:52:33.730 --> 00:52:35.730
for the continuity of--

00:52:35.730 --> 00:52:38.890
or discontinuity of
their object motion.

00:52:38.890 --> 00:52:40.810
Now, Lisa Feigenson
has conducted

00:52:40.810 --> 00:52:43.655
stronger tests of this, I think,
with somewhat older babies.

00:52:43.655 --> 00:52:45.280
When babies get older
and they do more,

00:52:45.280 --> 00:52:47.657
you can do stronger tests.

00:52:47.657 --> 00:52:49.240
So these are babies
who are old enough

00:52:49.240 --> 00:52:52.930
to crawl, old enough
to eat, and old enough

00:52:52.930 --> 00:52:55.600
to like graham crackers.

00:52:55.600 --> 00:53:00.010
So she puts the baby back here,
and in one set of studies,

00:53:00.010 --> 00:53:04.000
she takes a single graham
cracker, puts it in one box,

00:53:04.000 --> 00:53:06.850
and then takes two graham
crackers, one at a time,

00:53:06.850 --> 00:53:09.280
and puts them in the other box.

00:53:09.280 --> 00:53:12.520
And then the baby, who's
being restrained by a parent,

00:53:12.520 --> 00:53:13.330
is let loose.

00:53:13.330 --> 00:53:15.430
And the question is,
which box will they go to?

00:53:15.430 --> 00:53:18.550
And they go to the box with
the two graham crackers.

00:53:18.550 --> 00:53:22.390
My favorite study, though,
in this whole series

00:53:22.390 --> 00:53:27.220
was one that she and Susan
Carey ran as a boring control

00:53:27.220 --> 00:53:27.760
condition.

00:53:27.760 --> 00:53:29.843
I think it's the most
interesting of the findings,

00:53:29.843 --> 00:53:30.360
though.

00:53:30.360 --> 00:53:31.870
In the boring control
condition, they

00:53:31.870 --> 00:53:33.911
were worried about the
fact that maybe babies are

00:53:33.911 --> 00:53:35.860
going to the box
with two because they

00:53:35.860 --> 00:53:38.800
see a hand around that box
for a longer period of time,

00:53:38.800 --> 00:53:40.850
doing more interesting stuff.

00:53:40.850 --> 00:53:42.700
So they did the
following boring control.

00:53:42.700 --> 00:53:44.780
The two condition was
the same as before.

00:53:44.780 --> 00:53:46.990
So a hand comes out with
a single graham cracker,

00:53:46.990 --> 00:53:49.240
puts it in the box,
comes out empty,

00:53:49.240 --> 00:53:51.730
takes a second graham cracker,
returns with a second graham

00:53:51.730 --> 00:53:53.520
cracker, puts it in the box.

00:53:53.520 --> 00:53:55.660
In the other condition,
the hand comes out

00:53:55.660 --> 00:53:58.330
with one graham cracker,
puts it in the box,

00:53:58.330 --> 00:54:01.360
comes out again with
the graham cracker,

00:54:01.360 --> 00:54:04.360
and then goes back into the
box with that graham cracker.

00:54:04.360 --> 00:54:08.470
So you've got more graham
cracker sightings on the left.

00:54:08.470 --> 00:54:12.490
You've got a same amount of
hand activity on the two sides,

00:54:12.490 --> 00:54:14.824
but the babies go
to the box with two.

00:54:14.824 --> 00:54:16.990
They're tracking the graham
crackers, not the graham

00:54:16.990 --> 00:54:19.570
cracker visual encounters.

00:54:19.570 --> 00:54:24.910
They're tracking a
continuous object over time.

00:54:24.910 --> 00:54:28.690
Finally, objects.

00:54:28.690 --> 00:54:30.760
Scenes don't
usually just contain

00:54:30.760 --> 00:54:36.550
a single object that's either
connected, continuously visible

00:54:36.550 --> 00:54:39.100
or not, or connected or not.

00:54:39.100 --> 00:54:41.560
They contain multiple objects
and those objects interact

00:54:41.560 --> 00:54:43.190
with each other.

00:54:43.190 --> 00:54:46.180
Shimon talked yesterday
afternoon about the evidence

00:54:46.180 --> 00:54:48.490
that babies are sensitive
to these interactions,

00:54:48.490 --> 00:54:52.930
at least down to about six
months of age in the conditions

00:54:52.930 --> 00:54:54.190
he was talking about.

00:54:54.190 --> 00:54:56.500
In slightly
different conditions,

00:54:56.500 --> 00:54:58.570
the sensitivity has
been shown as young

00:54:58.570 --> 00:55:00.859
as three months of age.

00:55:00.859 --> 00:55:02.900
Basically, here's a paradigm
that will show that,

00:55:02.900 --> 00:55:05.780
if you have a single object
that's moving toward a screen.

00:55:05.780 --> 00:55:08.250
Another object is stationary
behind the screen.

00:55:08.250 --> 00:55:11.480
But at the right time, the
time at which this object,

00:55:11.480 --> 00:55:14.060
if it continued moving at
the same rate, at the point

00:55:14.060 --> 00:55:15.890
where it would
contact that object,

00:55:15.890 --> 00:55:18.820
this object starts to move
in the same direction.

00:55:18.820 --> 00:55:21.080
And now, after seeing
that repeatedly,

00:55:21.080 --> 00:55:23.000
the screen is taken
away and babies either

00:55:23.000 --> 00:55:25.640
see the first object contacting
the second and the second one

00:55:25.640 --> 00:55:27.560
immediately starting
to move, or they

00:55:27.560 --> 00:55:29.120
see the first object
stopping short

00:55:29.120 --> 00:55:31.250
of the second an
appropriate gap in time,

00:55:31.250 --> 00:55:33.170
and then the second
object starts to move.

00:55:33.170 --> 00:55:35.750
And they look longer
at this display,

00:55:35.750 --> 00:55:38.850
providing evidence
that they inferred

00:55:38.850 --> 00:55:41.720
that the first object contacted
the second at the point

00:55:41.720 --> 00:55:45.860
at which it started to move.

00:55:45.860 --> 00:55:50.630
Interestingly, as in the case
of the occluded object studies,

00:55:50.630 --> 00:55:53.330
if instead of having
the second object move,

00:55:53.330 --> 00:55:57.080
you have it change
color and make a sound,

00:55:57.080 --> 00:55:59.960
so it undergoes a change
in state, but no motion,

00:55:59.960 --> 00:56:04.170
the babies no longer infer
contact in this condition.

00:56:04.170 --> 00:56:05.750
They are attentive
to those events.

00:56:05.750 --> 00:56:08.240
They watch them a
lot, but they're

00:56:08.240 --> 00:56:10.490
uncommitted as to
whether that first

00:56:10.490 --> 00:56:13.040
object-- this is work of Paul
Muentener and Susan Carey

00:56:13.040 --> 00:56:14.245
relatively recently.

00:56:14.245 --> 00:56:15.620
It wasn't done
with cylinders, it

00:56:15.620 --> 00:56:19.790
was done with a toy
car that hits a block,

00:56:19.790 --> 00:56:22.760
I think, or doesn't
hit the block.

00:56:22.760 --> 00:56:25.550
They're uncommitted as to
whether the car contacted

00:56:25.550 --> 00:56:27.830
the second object or
not, if the second object

00:56:27.830 --> 00:56:30.200
changes state but doesn't move.

00:56:30.200 --> 00:56:32.540
Returning to the case
where they succeed--

00:56:32.540 --> 00:56:35.810
namely, this thing went behind a
screen, the other thing started

00:56:35.810 --> 00:56:42.610
to move, infants inferred
that they came into contact--

00:56:42.610 --> 00:56:46.430
that begins to suggest that
maybe babies have some notion

00:56:46.430 --> 00:56:48.440
that objects are solid,
that two things can't

00:56:48.440 --> 00:56:50.340
be in the same place
at the same time,

00:56:50.340 --> 00:56:53.420
that when one moving thing
hits another thing, one

00:56:53.420 --> 00:56:56.330
or the other of them or both,
their motion has to change,

00:56:56.330 --> 00:56:58.790
because they're not going
to simply interpenetrate

00:56:58.790 --> 00:56:59.660
each other.

00:56:59.660 --> 00:57:02.900
And Josh already
very briefly pointed

00:57:02.900 --> 00:57:08.690
to some very old studies
suggesting that babies have--

00:57:08.690 --> 00:57:12.860
make some assumption that
objects are solid as early as--

00:57:12.860 --> 00:57:15.380
I think in the
earliest studies done

00:57:15.380 --> 00:57:18.590
with babies it's about two
and a half months of age.

00:57:18.590 --> 00:57:21.100
These are these studies
that Renee Baillargeon did

00:57:21.100 --> 00:57:25.400
that start with simply
a screen, a flat screen,

00:57:25.400 --> 00:57:28.790
rotating on a table, rotating
180 degrees back and forth

00:57:28.790 --> 00:57:29.990
on a table.

00:57:29.990 --> 00:57:34.550
Then she places an
object behind this wall.

00:57:34.550 --> 00:57:36.920
The screen is lying on the
table with its back edge

00:57:36.920 --> 00:57:38.030
right here at the middle.

00:57:38.030 --> 00:57:41.060
She places an object behind
it, and then the screen

00:57:41.060 --> 00:57:44.076
starts to rotate up
around the back edge

00:57:44.076 --> 00:57:45.950
and the question to the
infants in effect is,

00:57:45.950 --> 00:57:48.680
what should happen
to that screen?

00:57:48.680 --> 00:57:50.570
And the two options
she presents to them

00:57:50.570 --> 00:57:52.970
is it either gets to the
point where it would contact

00:57:52.970 --> 00:57:55.820
this object which is
now fully out of view,

00:57:55.820 --> 00:57:59.030
and stops, and then returns
to its first position, which

00:57:59.030 --> 00:58:01.700
is a novel motion,
but consistent

00:58:01.700 --> 00:58:04.580
with the existence,
location, and solidity

00:58:04.580 --> 00:58:06.950
of that hidden object.

00:58:06.950 --> 00:58:09.950
Or it continues merrily on
its way and the same pattern

00:58:09.950 --> 00:58:11.474
of rotation as before.

00:58:11.474 --> 00:58:12.890
When it does that,
of course, it's

00:58:12.890 --> 00:58:14.540
going to come back
flat on the screen

00:58:14.540 --> 00:58:16.989
and there's not going
to be any object there.

00:58:16.989 --> 00:58:18.530
If there had been
an object, it would

00:58:18.530 --> 00:58:19.700
have had to be compressed.

00:58:19.700 --> 00:58:22.140
Or what I think actually
went on in those studies,

00:58:22.140 --> 00:58:24.800
it was quickly and
surreptitiously knocked out

00:58:24.800 --> 00:58:26.090
of the way.

00:58:26.090 --> 00:58:31.290
And infants looked less at
this event than at this one--

00:58:31.290 --> 00:58:34.670
this one, sorry--
providing some evidence

00:58:34.670 --> 00:58:37.610
that they were representing
these objects, both as

00:58:37.610 --> 00:58:43.100
existing when they were
out of sight, and as solid.

00:58:43.100 --> 00:58:47.000
So this is just a summary,
not a claim about knowledge

00:58:47.000 --> 00:58:50.450
development, about--

00:58:50.450 --> 00:58:53.090
I'm attempting to
characterize here

00:58:53.090 --> 00:58:57.650
with motion over just one
dimension of space and time,

00:58:57.650 --> 00:58:59.030
how infants seem--

00:58:59.030 --> 00:59:02.960
what infants seem to represent
about the behavior of objects.

00:59:02.960 --> 00:59:06.440
Namely that each object
moves on a continuous path

00:59:06.440 --> 00:59:08.300
through space and over time.

00:59:08.300 --> 00:59:09.650
That it moves cohesively.

00:59:09.650 --> 00:59:12.959
It doesn't split into
pieces as it's moving.

00:59:12.959 --> 00:59:14.750
So if you've seen
something move like this,

00:59:14.750 --> 00:59:19.190
then you find it unlikely
that if this were lifted,

00:59:19.190 --> 00:59:21.710
it would go on its own, and
you look longer at that.

00:59:21.710 --> 00:59:23.840
There is no merging,
where two things that

00:59:23.840 --> 00:59:26.820
previously moved independently
now move together.

00:59:26.820 --> 00:59:28.640
So after looking at
this, it would also

00:59:28.640 --> 00:59:30.920
be unlikely, if you lifted
this, for the whole thing

00:59:30.920 --> 00:59:33.230
to jump up at once.

00:59:33.230 --> 00:59:34.430
They move without gaps.

00:59:34.430 --> 00:59:36.650
They move without
intersecting other objects

00:59:36.650 --> 00:59:39.410
other objects on their paths
of motion, such that two things

00:59:39.410 --> 00:59:42.020
are in the same place
at the same time.

00:59:42.020 --> 00:59:45.440
And they move on contact
with other objects

00:59:45.440 --> 00:59:48.140
and not at a distance from them.

00:59:48.140 --> 00:59:51.350
So that's just a
summary of what I

00:59:51.350 --> 00:59:55.490
think these studies show about
four-month-old infants, not

00:59:55.490 --> 00:59:56.467
newborns.

00:59:56.467 --> 00:59:58.550
They also show that infants'
perception of objects

00:59:58.550 --> 01:00:00.340
is really limited.

01:00:00.340 --> 01:00:05.010
There's all these situations
under which we see unitary,

01:00:05.010 --> 01:00:07.620
connected, bounded
objects when they don't.

01:00:07.620 --> 01:00:12.360
And interestingly, research
by Fei Xu and Susan Carey

01:00:12.360 --> 01:00:17.220
shows that even when you present
really quite surprisingly

01:00:17.220 --> 01:00:21.660
old infants, 10-month-olds, with
objects that should be really

01:00:21.660 --> 01:00:25.200
familiar to them, like
toy ducks and trucks,

01:00:25.200 --> 01:00:28.620
they don't assume that these
two objects will be distinct

01:00:28.620 --> 01:00:31.380
if they undergo
no common motion.

01:00:31.380 --> 01:00:33.360
If they're simply
presented stationary,

01:00:33.360 --> 01:00:37.020
the babies seem uncommitted
as to whether there's

01:00:37.020 --> 01:00:38.910
a boundary between them or not.

01:00:38.910 --> 01:00:40.980
So they're using very
limited information

01:00:40.980 --> 01:00:44.130
to be making these basic--

01:00:44.130 --> 01:00:45.870
building these basic
representations

01:00:45.870 --> 01:00:48.390
of what's connected to
what, where one thing ends

01:00:48.390 --> 01:00:51.240
and the next begins.

01:00:51.240 --> 01:00:55.080
Now, this changes very
abruptly between about 10

01:00:55.080 --> 01:00:56.160
and 12 months of age.

01:00:56.160 --> 01:00:58.860
They start treating those
as two separate objects,

01:00:58.860 --> 01:01:03.630
whether they're moving
together or stationary or not.

01:01:03.630 --> 01:01:05.160
Now, infants'
tracking of objects

01:01:05.160 --> 01:01:07.260
shows very similar limits.

01:01:07.260 --> 01:01:09.870
So I told you they
succeed in perceiving--

01:01:09.870 --> 01:01:11.430
representing two
distinct objects

01:01:11.430 --> 01:01:13.020
in a situation like this.

01:01:13.020 --> 01:01:15.930
But up until and including
10 months of age,

01:01:15.930 --> 01:01:18.780
they fail in this situation.

01:01:18.780 --> 01:01:21.980
If a truck comes out on one
side of a single large screen,

01:01:21.980 --> 01:01:23.490
so you're not
getting information

01:01:23.490 --> 01:01:25.890
for the motion
behind that screen,

01:01:25.890 --> 01:01:27.840
and a duck comes out
on the other side,

01:01:27.840 --> 01:01:30.990
and you ask babies, in effect,
how many things are there?

01:01:30.990 --> 01:01:32.460
One or two?

01:01:32.460 --> 01:01:34.620
By removing the screen
and alternately presenting

01:01:34.620 --> 01:01:36.840
those two possibilities,
they are uncommitted

01:01:36.840 --> 01:01:39.780
between those two alternatives.

01:01:39.780 --> 01:01:42.240
In this situation as
in the previous one,

01:01:42.240 --> 01:01:44.850
there's this very abrupt
change between about 10

01:01:44.850 --> 01:01:46.420
and 12 months of age.

01:01:46.420 --> 01:01:49.790
And I can't resist saying,
even though I'm way over time,

01:01:49.790 --> 01:01:54.180
that Fei Xu has shown that that
change is interestingly related

01:01:54.180 --> 01:01:57.870
to the child's developing
mastery of expressions

01:01:57.870 --> 01:01:59.762
that name kinds of objects.

01:01:59.762 --> 01:02:02.220
So she's been able to show,
for example, that if you simply

01:02:02.220 --> 01:02:06.420
ask for individual infants, when
did they start succeeding here,

01:02:06.420 --> 01:02:09.300
their success is predicted
by their vocabulary

01:02:09.300 --> 01:02:11.100
as reported by parents.

01:02:11.100 --> 01:02:14.580
She's also shown that
if you take a younger

01:02:14.580 --> 01:02:15.890
infant who would be slated--

01:02:15.890 --> 01:02:19.620
destined to fail this study,
but as you bring objects

01:02:19.620 --> 01:02:23.160
out on the two sides, either
familiar ones or novel ones,

01:02:23.160 --> 01:02:24.990
starting at about
nine months of age,

01:02:24.990 --> 01:02:27.720
if you name them and you give
them distinct object names,

01:02:27.720 --> 01:02:29.310
they now infer two objects.

01:02:29.310 --> 01:02:31.170
And in fact, they'll
even do it if the two

01:02:31.170 --> 01:02:33.990
things you bring out from
behind a single wide screen

01:02:33.990 --> 01:02:35.130
look the same.

01:02:35.130 --> 01:02:37.620
If you bring one thing out
and say, look, a blicket,

01:02:37.620 --> 01:02:40.120
and put it back in, and then
bring something out and say,

01:02:40.120 --> 01:02:42.410
look, a toma, even
if it looks the same,

01:02:42.410 --> 01:02:43.910
they'll infer two objects.

01:02:43.910 --> 01:02:45.930
So there seems to be
this change that's

01:02:45.930 --> 01:02:48.270
occurring at the end
of the first year

01:02:48.270 --> 01:02:51.030
quite dramatically that's
overcoming this basically meant

01:02:51.030 --> 01:02:54.260
that we're seeing earlier on.