Professor Paul Bloom:
Two follow-ups on
yesterday's--I'm sorry,
on Monday's lecture.
One is that somebody came up
after class and asked when the
preference for your own language
emerges in development and
fortunately,
studies pretty much exactly
this sort of infant
understanding.
She knew the answer.
There's been studies looking at
newborn babies finding that
pretty much the moment they pop
out they favor their own
language over other
language--over other languages.
And this suggests that they are
listening while in utero,
while in the womb,
to the rhythms of their
language and developing a
preference for it.
A second issue is,
I talked very briefly about a
court case in which the person
was--said at a moment where
someone else was pointing a gun
at a police officer,
"Let him have it!"
and a police officer was killed.
And that person was charged
with murder but I admitted I
didn't actually know how things
turned out and was kind enough
to do extensive research.
Well, he went to Wikipedia and
[laughter]
found out the answer.
The answer is he was tried and
found guilty for murder.
He was then subsequently
pardoned.
In fact, he was pardoned in
1988, which is really nice
except he was executed in 1957.
But they did it into a movie.
So, it's a movie.
Okay.
So, I want to do today,
for the first part of the
lecture, is continue the
language lecture and then move
to perception,
attention, and memory.
And what we had spoken about
was--We first talked about
universals of language,
then moved to some detail about
the different aspects of
language including phonology,
morphology, and syntax.
We discussed the ways in which
language does the amazing things
it does, including the fact that
language has used arbitrary
science or sounds to convey
concepts,
and that languages exploit a
combinatorial system including
recursion to put together these
symbols into a virtually
limitless set of meaningful
sentences.
We then talked about
development and made some
remarks about the developmental
time course – talking about
the emergence of language from
babies to – where babies are
really good at learning language
to you who are not,
whose brains have atrophied,
whose language capacities are
dead.
Final issue is to shift to
animals.
Now that we know something
about language,
we could then ask do animals
use--possess the same sort of
language?
And if not, can they learn it?
Now, there is absolutely no
doubt at all that nonhuman
animals possess communication
systems.
This has been known forever and
is not a matter of controversy.
And if you want to use the term
"language" to mean
"communication," then the answer
is obviously "yes."
Dogs and bees and monkeys have
language.
If you want to use language
though in the more technical,
narrow sense as anything that
has the properties that we
discussed earlier,
using English and ASL and
Spanish and so on as our
background, the answer's almost
certainly "no."
Animal communication systems
fall into sort of one of three
categories.
Either there is a finite list
of calls, so vervet monkeys,
for instance,
have a small list of calls to
convey different warnings like
"attack from a snake" or "attack
from a leopard."
There is a continuous analog
signal.
So, bee dance,
for instance,
works on this way.
Bee dance communicates the
location of food sources but
doesn't do it in any
syntactically structured way.
Rather, the intensity of the
dance corresponds to the
richness of the food source.
And then, you get things like
random variation on a theme such
as birdsong.
But what you don't find in any
real sense is phonology,
morphology, syntax,
combinatorial systems or
arbitrary names.
Now, this much is not
particularly controversial.
There gets to be a lot of
controversy though.
This is the summary about
nonhuman communication systems.
It gets more controversial when
we get to famous cases of
primates trained by humans such
as Kanzi,
Nim Chimpsky,
and other famous primates that
you may well have seen on the
Discovery channel and other
venues.
And this is fairly
controversial.
If you read the Gray textbook,
while nothing in it is
particularly inaccurate,
I think Gray is actually a
little bit too credulous,
too believing in the claims
that have been made about the
abilities of the animals.
So many scientists argue,
for instance,
that animals like Kanzi,
even if they can be said to be
learning words at all,
learn very few of them.
And it takes them extensive
years of training to learn,
unlike a normally developing
child who could learn a word in
a day or a word in an hour.
The utterances often have order
but this order tends to be very
limited and lacks the recursive
properties.
And in fact,
the lack of recursion is not
controversial.
Finally, the utterances of
chimpanzees--trained chimpanzees
are extremely repetitive so what
you often see on TV and in
documentaries is sort of a
sampling.
And the sampling could often be
very impressive but if you take
just what they say at random it
tends to look like this.
This is typical chimpanzee
utterances just taken at random:
"Nim eat, Nim eat.
Drink, eat, me Nim.
Me gum, me gum.
Tickle me, Nim play.
Me eat, me eat.
Me banana, you banana,
me you give.
Banana me, me eat.
Give orange,
me give, eat orange,
me eat orange."
Lila Gleitman once commented
that if any normally developing
child spoke like this,
his parents would rush him
screaming to a neurologist.
There's a broader question
here, which is,
"Why would we ever expect a
chimpanzee to learn a human
language?"
We don't normally expect one
species to have the capacities
associated with another species.
So, bats use echolocation to
get around and some birds
navigate by the stars,
but there's not an active
research program seeing if cats
can use echolocation or dogs
could navigate by the stars.
And I think one reason why you
might be tempted to think,
"well, of course chimps must be
able to learn language" is
because you might be caught in
the grips of some bad ideas
about language.
So, one idea is you might say,
"Look.
Chimps should use language
because chimps are so smart."
But the response to this is,
"they are smart but we know
that smart isn't enough."
We know that the human capacity
for language is not totally a
result of smartness.
There are smart children who,
due to some deficit in their
language capacity,
don't speak or understand a
language.
So, the smartness of
chimpanzees does not in itself
demonstrate that they should be
able to learn language.
You might also point out
correctly that chimps are our
nearest evolutionary relatives,
which is right,
so you--one would expect on the
face of it--it's not
unreasonable to expect us to
share a lot of abilities with
them.
On the other hand,
we split from them a long time
ago and plainly humans are
different from chimps.
And there was five million
years either way and that's more
than enough time for a language
capacity to evolve.
Now, none of this is to say
that the study of nonhuman
communication systems isn't
interesting.
From my own--This is my
personal opinion I'll raise
here.
From my own opinion,
the study of the attempts to
try to teach chimpanzees,
or gibbons, or gorillas,
a human language like ASL are
misguided.
It would be as if a team of
monkeys kidnapped a human child
and tried to train him how to
hoot like a monkey.
It might be enjoyable but it
does not seem to give us any
rich insights.
What I think is a lot more
interesting is the study of
these animal communication
systems in the wild.
There's a linguistics of human
language that has delineated the
principles that underlie all
human languages.
It would be as extraordinarily
interesting to attempt the same
linguistic program to the other
communication systems used in
the wild such as the cries of
vervet monkeys and bee dance.
So, this brings the section on
language to a close but I want
to tell you a few things we
didn't talk about.
One of the problems with an
Intro Psych course is we have to
whip through a lot of topics
very fast.
So, if you were to take a
course that focused directly on
language you might learn,
for instance,
more about language in the
brain, something touched about
very briefly in the textbook but
something that has a large
literature associated with it.
Similarly, and related to this,
there's language disorders,
disorders like aphasias and
disorders like specific language
impairment and dyslexia.
There is the study of language
perception and production.
How is it that we do this
amazing feat of understanding
and producing words in a
fraction of a second?
Where does that ability come
from?
There is the study of reading
which is, in many ways,
different from the study of a
language.
Remember when Darwin described
language as an instinct.
He carefully distinguished it
from other things that don't
come natural to us including
reading.
And in fact,
reading is difficult.
Reading is a cultural
invention, not every human has
it.
And unlike language,
reading is acquired with
tremendous difficulty over many
years.
On the other hand,
reading plainly intersects with
language.
It's a new way of conveying
language, moving out from speech
to writing.
And the psychology and
neuroscience of reading is thus
very interesting.
There's bilingualism and
multilingualism.
The questions people in this
room typically are going to be
interested in is does it matter
for how well you learn language
whether you're learning one or
two or three or four.
How is it that a multilingual
encodes all these different
languages inside a single brain?
And so on.
Finally, a very hot issue is
that of the relationship between
language and thought and I'm
actually--A few years ago I
taught an entire seminar called
"Language and Thought" devoted
to precisely this question.
And it's a cool question and it
could break up into two very
general questions.
One is, "Is language necessary
for abstract thought?"
And one way to answer that
question is to look at creatures
without language like babies and
chimpanzees and see how smart
they are.
It might be that they're
not--that they're very smart,
in which case it would suggest
you don't need language for
abstract thought.
On the other hand,
it might be that they have
certain cognitive limitations,
which would suggest that
language is essential for
abstract thought.
Then there's the related
question.
Even once you know a language,
does the structural properties
of the language that you know
affect the way you think?
And the claim that the language
you know affects how you think
is sometimes described as
linguistic relativity or the
Sapir-Whorf hypothesis.
So for instance,
there's a lot of research
looking at speakers of different
languages such as English versus
Korean and seeing whether
structural differences in these
languages affect how you think.
Now, some of this work is
discussed in the readings,
the book--the Gray textbook,
and the selections from The
Norton Anthology. And this
makes up--again,
I've showed this to you on
Monday--your reading response
where you have to address this
question and take your best shot
at answering it.
What are your questions about
language?
Yes.
Student: [inaudible]
Professor Paul Bloom:
The question was raised,
"Some people learn languages
easier than others and how do we
explain this?"
And the answer is you could ask
the question both with regard to
first language learning – so
some children learn language
very quickly,
some are very slow – and also
with regard to second language
learning.
Some of you are breezing
through your second language
requirement here at Yale.
Others are struggling and
miserable.
And there's considerable
variation.
There's the story of Einstein
who was very slow to learn
language and didn't speak at all
until he was four.
And in fact,
he was a--He said his first
words when all of a sudden he
was having supper with his
parents and he put down the
spoon and he said,
"The soup is too hot."
And his parents stared in
astonishment and said,
"You've never spoken before."
And he said,
"Well, up to now everything's
been fine."
[laughter]
It's not a true story.
[laughter]
The question of why and where
these differences come from,
nobody really knows and it's
surprisingly hard.
There's a slight advantage for
being female.
Girls are slightly more
advanced in language than boys
but it's not a big one and you
need a hundred people to just
see it statistically.
There's a big genetic factor.
If your parents learned
language quickly and learned
other languages quickly,
you are more likely to.
But an understanding of the
brain bases of these differences
or the cognitive bases or the
social bases is just--is largely
an open question.
Yes.
Student: What happens
when parents [inaudible]
Professor Paul Bloom:
This is actually more the norm
around the world than the
situation in the United States
where kids are exposed to a
single language.
What happens is children learn
both languages.
Children are very good,
as adults are,
of distinguishing different
languages on the basis of their
sound system and their rhythms
so they don't typically confuse
them.
And then they just learn more
than one language.
And that's actually more the
average state of affairs around
the world.
Yes.
Student: You said that
people who are right-handed
learn languages [inaudible]
Professor Paul Bloom:
The question is about the
hemispheric specialization for
language.
And I don't have actually much
more to say than what I said
before, which I agree is deeply
unsatisfying.
If you're right-handed,
language is probably in the
left side of your brain.
How many people here are
left-handed?
For you we don't know.
It varies.
Some of you have it in the left
side.
Some of you have it in the
right side.
For some of you it's kind of
diffuse.
Now, why is this?
And in fact,
why are some people
right-handed and others
left-handed in the first place?
Those are really good questions.
Yes.
Student: [inaudible]
Professor Paul Bloom:
Yes.
I'll--Yes, that's--I'll answer
that question.
And unfortunately,
it's going to be the last one
and then I'll go to vision.
The question is,
"Does learning more than one
language cause you to learn them
slower than just learning one
language?"
And it would stand to reason
that it would.
There's a finite amount of
mental resources.
If I'm just learning English,
I use all of it for English.
And if I'm learning English and
Spanish I kind of got to split.
And you'd expect them to be
each learned slower.
It's one of the surprises of
the study of language
development that that
common-sense view does not
appear to be true.
Children learning more than one
language seem to show no deficit
relative--in each of their
languages, relative to a child
learning just one language.
In other words,
if I am just learning English
and I'm a kid and you're
learning English and Spanish and
you're a kid,
you'll reach the milestones in
English the same time I will.
Your extra learning of Spanish
doesn't seem to affect you.
There doesn't seem to be any
detriment for learning multiple
languages.
Another question which comes up
is, "Is there any cognitive
deficit?"
In other words,
some people have argued that
learning multiple languages
sometimes harms children in
certain ways.
This is a claim that's been
made in Quebec,
for instance,
over the debate over how
children should be taught
English and French.
It does not appear to be the
case.
There appears to be,
as far as we know,
no down side to learning many
languages when you're young.
Does that answer your question?
I want to move now to the topic
that will take us through today
and through the beginning of
next week – perception,
attention, and memory.
And I'm putting them together
instead of treating them as
separate lectures because
there's a sense in which they're
the same story.
You see a scene.
You see this scene and you're
looking at it and you're
perceiving it.
It's coming through your eyes
and you're interpreting it and
you see something.
You see a man and you see a
house.
If you were to shut your eyes,
you could still hold that scene
in memory.
And a week later,
if I'm to ask you about that,
"What season was it?"
you would do pretty well.
This is the story I want to
talk about – how we do this.
And in the course of this I
want to make a series of claims
that go something like this.
For perception,
I want to first persuade you
the problem of perception's hard
and that successful perception
involves educated and
unconscious guesses about the
world.
For attention,
I want to suggest that we
attend to some things and not
others and we miss a surprising
amount of what happens in the
world.
For memory, there are many
types of memory.
The key to memory is
organization and understanding.
And you can't trust some of
your memories.
How many of you remember where
you were at 9/11?
Many of you are wrong.
And I am never going to
persuade you of this because you
have certain memories.
And you could tell the story.
Everybody could tell the story
where they were when the towers
went down.
But clever psychologists on
September 12 said,
"Let's do a study."
And they asked people,
"Where were you yesterday when
you heard the news?"
And they told them.
And then they went back to them
later, a year later,
two years later,
and said, "Tell me about what
happened September 11."
And they said,
"I remember totally where I
was.
I have a very--" And then--And
often the story was wrong.
There is a lot like that which
we're going to talk about.
And the biggest moral then--so,
I put it really,
in really big print--We are
often wrong about our
experiences, both of the present
and of right now.
So, let's start with perception.
There is a story--I went to
graduate school at MIT and there
was a story there about Marvin
Minsky who is the A.I.
guru.
He--If you've heard the
words--the phrase "artificial
intelligence," that was him.
And if you heard the claim that
people are nothing more than
machines made of meat--also him.
Well, there's a story where he
was doing work on robotics and
he was interested in building a
robot that could do all sorts of
cool things that's like a robot.
And the story goes the robot
had to among--had to write--had
to see the world.
It had to be able to pick up
things and recognize people and
see chairs and navigate its way
and Minsky said,
"That's a tough problem.
It's going to take a graduate
student a whole summer to figure
it out."
And he assigned it to a
graduate student for a summer
project.
Visual psychologists,
perception psychologists,
love that story because the
study of computer vision and
robotics vision and the attempts
to make machines that can
identify and recognize objects
has been a profound failure.
There is, at this point,
no machine on earth that could
recognize people and objects and
things at the level of a really
dumb one-year-old.
And the reason why is that it's
a much harder problem than
anybody could have expected.
Well, what makes it such a hard
problem?
Well, one reason why you might
think it's an easy problem is
you say, "Okay.
We have to figure out the
problem of how people see.
Well, here's what we do."
You're in--You're over there
and here's your eye.
And somehow it has to get to
this television monitor and then
you look at it and that'll solve
the problem of how you see.
So, sometimes people say, "Hey.
I hear the eye flips things
upside down.
I guess this guy is going to
have to get used to looking at
things upside down.
That's an interesting problem."
No.
That's not the way to look at
it because that doesn't answer
any questions.
That just pushes the question
back.
Fine.
How does "he" see?
We're not answering anything.
Similarly, although the
Terminator's view of the world
may correspond to that ,
that doesn't solve any problem
of how he actually sees.
So, he has all these numbers
shooting out there.
Well, he has to read the
numbers.
He has to see this.
This is my iTunes.
[laughter] That's inadvertent.
Here's the right way to think
about perception.
You got the eye,
which is very ugly and bloody,
and then around here you have
the retina.
And the retina is a bunch of
nerve cells.
And the nerve cells fire
at--for some stimulus and not
others.
And from this array of firings,
"firing… not firing…
firing… not firing," you have
to figure out what the world is.
So, a better view is like this.
The firings of the neurons
could be viewed as an array of
numbers.
You have to figure out how to
get from the numbers to objects
and people, and to actions and
events.
And that's the problem.
It's made particularly a
difficult problem because the
retina is a two-dimensional
surface and you have to infer a
3D world from a two-dimensional
surface.
And this is,
from a mathematical point of
view, impossible.
And what this means is that
there--For any two-dimensional
image there is an indefinite
number of three-dimensional
images that correspond to it.
So for instance,
suppose you have this on your
retina, an array of light shaped
like that .
What does that correspond to in
the world?
Well, it could correspond to a
thing just like that that you're
looking for or it could
correspond to a square that's
tilted backwards.
And so, you have to figure out
which is which.
And the way we solve this
problem is that we have
unconscious assumptions about
how the world works.
Our minds contain certain
assumptions about how things
should be that enable us to make
educated guesses from the
two-dimensional array on to the
three-dimensional world.
And I purposefully did not make
the slides available for this
class ahead of time because I
don't want people to cheat,
but there are several points
where you could look at the
slides and confirm that some of
the things I'm going to tell you
are actually true.
And I want to give you three
examples.
One is color.
And I'm going to conflate here
color and brightness.
The other is objects.
The other is depth.
First, the problem of color.
How do you tell a lump of coal
from a snowball?
Well, that's a lump of coal and
that's a snowball,
and it's from Google images.
How do you know which is which?
Well, a lump of coal you say is
black and a snowball is white.
How do you know?
Well, maybe you have on your
retina--Your retina responds to
sort of color that hits it.
It's oversimplified,
but let's assume that this is
true.
So, this is black coming out
and that's white and that's how
you tell.
But in fact,
that can't be right.
It can't be right because
objects' color is not merely a
matter of what material they're
made of but of the amount of
light that hits it.
So, as I walk across the stage
I fall into shadow and light,
and none of you screams out,
"Professor Bloom is changing
colors!"
Rather, you automatically
factor out the change in
illumination as this is
happening.
And this could actually be
quite striking.
So, you see this display over
here.
Take a look at those two blocks.
I take it you see this one as
lighter than that one.
You do.
You might imagine this is
because this strip is lighter
than this but it isn't.
They're the same.
And you won't believe me until
you actually print it out and
take a look, but they are in
fact the same.
I'll show it to you.
And you could say I'm tricking
you but this is the way it
works.
There's the close-up.
So, remember we're comparing
this and this.
Now, let's take away other
parts of the environment and
you'll see they're the same.
Now you say, "But hold it.
This can't be the same as this"
but the answer is--goes like
this.
We know shadows make surfaces
darker.
We don't know this like "Here's
something I know."
Rather, we know this in that
it's wired up in our brains.
So when we see a surface in
shadow we automatically assume
that it's lighter than it looks,
and we see it as lighter.
And you could show this by
removing the cues to the shadow.
And you see it as it really is.
And this is an illustration of
how the information to your eyes
is just one bit of information;
the degree of light coming from
a single source is one bit of
information that you use to
calculate certain assumptions
and come to a conclusion.
Here's a different kind of
example: Objects.
You see this and you
automatically and intuitively
segment it into different
objects.
You segment it into a man and a
house and birds and trees.
How do you do this?
It turns out,
to program a computer to
segment a scene into different
objects is hugely difficult and
the question of how we do it is,
to some extent, unknown.
But one answer to this question
is there are certain cues in the
environment that are signals
that you're dealing with
different objects.
And these cues are often
described as Gestalt principles.
So, one example is "proximity."
When you see things that are
close to each other,
you're more likely than not to
assume that they belong to the
same thing.
There's "similarity."
That display could correspond
to an indefinite number of
objects but you naturally tend
to see it as two.
You do one with one texture
pattern, the other with the
other texture pattern.
"Closure."
The fact that this is a closed
square here suggests it's a
single object .
"Good continuation."
If you had to judge,
this could just as well be two
shapes, one that runs from A to
C, the other one that runs from
D to B.
But you don't tend to see it
that way.
Rather, you tend to see it as
one that runs from A to B,
the other one that runs from C
to D.
"Common movement."
If things move together they're
a single object.
And "good form."
You see the object over there .
In the absence of any other
information, you might be
tempted to say that's a single
thing, a plus sign maybe.
This , because it has lousy
form, you're more tempted to say
it's two things,
one thing lying on top of each
other.
And these are the sort of cues,
expectations;
none of them are right.
There's cases where they could
all fool you.
But these are useful cues that
guide our parceling of the
world, our segmenting of the
world into distinct objects.
Here they are summarized .
And here's a case where they
fool you .
So you might think,
if you're suggestible,
that there is a triangle here.
And this is a case where there
are certain cues driving you to
think that there's a triangle
here.
There is, however,
no triangle here.
If you cover up these little
Pacmen here, the triangle goes
away.
Similarly, there is no square
in the middle .
There is no square.
It's very Matrix.
And these are illusions because
these are cues that there should
be a square there,
the regularity of form.
Finally, "depth."
You see this and you don't--You
see it on one level as a flat
thing.
Another level you look inside
the picture and you see,
for instance,
the man is in front of the
house.
You look at me and you see the
podium.
And if you have a terrible
neurological disorder you see
this strange creature that's
half podium leading on to a
chest and up to a head that's
sort of--the top of him is
wiggling and the podium staying
still.
If you are neurologically
normal, you see a man walking
back and forth behind a podium.
How do you do that?
Well, this is really a problem
because, I could give you a
technical reason why vision is
hard,
but crudely,
you got a two-dimensional
retina and you have to figure
out a three-dimensional world.
How do you do it?
And the answer once again is
assumptions or cues.
There are certain assumptions
the visual system makes that
aren't always right and in fact,
in cases of visual illusions,
can be wrong but will guide you
to perceive the world in a
correct and accurate way.
So for example,
there is binocular disparity.
This is actually a sort of
interesting one.
This is the only depth cue that
involves two eyes.
If I look at you pretty close,
the image I get here and the
image I get here are somewhat
different while--or I have to
focus my eyes together to get
the same image.
If I look at you in back,
they're almost identical
because the further away,
given the two eyes that are
static, the closer the images
look.
And it's not,
again, that you say to
yourself, "Oh.
Back there an orange.
It's the same image in my right
eye and my left eye.
You must be far away."
Rather, unconsciously and
automatically you make
estimations on how far people
are in depth based on binocular
disparity.
There is "interposition."
How do you know I'm in front of
the podium and the podium's not
in front of me?
No.
How do you know the podium's in
front of me?
Well, from where I'm standing
it's right.
How do you know the podium is
in front of me?
Well, because I'm walking here
and then it cuts into me.
And unless I'm going through a
grotesque metamorphosis,
what's happening is it makes
sense to say I'm moving behind
the podium.
Interposition.
You take the guy.
How do you know the guy is
standing in front of the house?
Well, because there is--you see
all of him and he's blocking a
lot of the house.
There's relative size.
How far away am I?
Well, if you looked at me and
you had to estimate how far away
I am, part of the way you'll
figure that out is you know how
tall a human's supposed to be.
If you thought that I was fifty
feet tall, you would assume I'm
further away than I am.
And so, your judgments on size
dictate your judgments about
distance.
Usually, this cue isn't
necessary but if you look at the
Empire State Building--If you go
into a field and you see a tower
and you look,
your judgment of how far away
the tower's going to be depends
on your knowledge of how tall a
tower should be.
If it's this tall, you say, "Oh.
It must be--" And then you'd be
surprised.
There's texture gradient,
which I'll explain in a second,
and linear perspective,
which I'll also explain in a
second.
Texture gradient goes like this.
Remember the problem we had
before.
How do you know if that thing
is this object or an object in
and of itself?
Well, the answer is things with
textures will show themselves
because the textures will get
smaller from a distance.
Now, logically,
this could still be a single
thing standing upright with just
dots going up smaller.
But the natural assumption is
the reason why the dots recede
in this regular fashion is
because it's receding in depth.
Classic illusion – the
Mueller-Lyer illusion.
People will see this as longer
than this .
It's not.
If you don't believe me,
print it out and measure it.
Related to the Ponzo illusion,
once again people see this one
as--you get illusions named
after you when you discover
these--this one as longer than
this .
Again, it's not.
What's going on here?
Well, the top line looks longer
even though it isn't.
And one explanation for why is,
these other lines in the scene
cause your visual system to make
guesses about distance.
And then you correct for
distance by making assumptions
about size.
If you have two lines--You'll
get--We'll get in more detail in
a second, but if you have two
lines and they take up the same
amount of space on your retina,
but you believe that one is 100
feet away and the other's 50
feet away, the one that's 100
feet away you will see as bigger
because your brain will say,
"Well, if it takes up just this
much space but it's further
away, it must be bigger than
something that's closer and
takes up that much space."
And that's what goes on here.
For the top line,
for the Mueller-Lyer illusion,
we assume that this is further
away and this is closer based on
the cues to distance.
And the cue is factored in.
And because we assume that this
is further away,
we assume it must be bigger to
take up the same space as this
which is closer.
Similarly for the Ponzo
illusion.
There's linear perspective.
Parallel lines tend to recede
in distance.
If this top one is further away
than this but they take up the
same size in your eye,
this one must be bigger and you
see it as bigger.
And the book offers more
details on how these illusions
work.
I'm going to end with an
illusion that I'm not even going
to bother explaining.
I'll just show it to you
because you should be able to,
based on thinking about these
other illusions,
figure it out.
It was developed by Roger
Shepard.
Well, you know that.
And they are called Shepard
tables .
And the thing about it is,
these look like two tables.
If you ask people--You don't
frame in terms of here's a
lecture on visual perception.
You ask people,
"Which of these tables would be
easier to get through a door if
you have a thin door?"
People would say the one on the
left.
This one looks sort of thicker
and harder to get through.
This one looks longer and
leaner.
In fact, they're the same size.
What I mean by that is that
this is exactly the same as this
.
Now, I'm going to prove it to
you by showing you something
which took me--on the computer
which took me about seven hours
to do.
And nobody's going to believe
it because I could have faked
it.
But if you want,
print it out and do it
yourself.
You just take a piece of paper,
put it on here.
Then you move it and the same.
I showed it to somebody and
they called me a liar.
Anyway, you could do it
yourself in the privacy of your
own home or study.
But what I'd really like you to
do after you do it is say,
"Okay.
Fine.
Why does this one look longer
and thinner than this one?"
And the answer is the same
answer that will explain the
Mueller-Lyer illusion and the
Ponzo illusion,
having to do with cues to depth
and the way your mind corrects
the perception of depth.
And that's all I have to say at
this point about perception.
I want to move now to attention
and memory and I'm going to
treat attention and memory
together.
We are fascinated with memory
and, in particular,
it's particularly interesting
when memory goes wrong.
It's particularly fascinating
what happens in cases of
amnesia.
So for example,
I need a volunteer who is
willing to do a little bit of
acting, a very little bit,
an incredibly little bit.
Excellent.
Okay.
So well, you just stay there.
So pretend you have amnesia.
Okay?
What's your name?
Student: I don't know.
Professor Paul Bloom:
Perfect.
I'm really glad you said that.
That's the wrong answer because
you don't have total amnesia.
You still remember English.
Okay.
It's very clever.
Okay.
So you couldn't have lost all
your memories.
You have English.
You --So we'll do you.
What's your name?
Oh.
He looks puzzled but he still
maintains bowel and bladder
control so he hasn't forgotten
everything.
[laughter]
Now, I always lose the third
volunteer in that demo.
So, what I'm saying is that
memory is a hugely broad
concept.
It includes autobiographical
memory, which is what we
standardly think.
That's a perfectly rational
response.
When I say somebody's losing
their memory,
"Oh.
I have a movie about somebody
losing their memory," you don't
imagine a person in diapers.
You imagine the person walking
around, having sex with cool
people and saying,
"Where am I?"
And [laughter]
so what you imagine is you
imagine them losing their
autobiographical memory,
their sense of self.
But of course,
knowing English is part of your
memory and knowing how to stand
and knowing how to chew and
swallow are all things that
you've learned,
that you've--that have been
molded by experience.
There's another distinction
which is going to come in
regarding amnesia,
which is there's broadly two
types of amnesia.
They often run together,
but one type of amnesia is you
lose your memory of the past.
Another type of amnesia--That's
the Matt Damon amnesia.
Another type of amnesia though
is you lose the ability to form
new memories.
And here's a film of a man who
had exactly this problem.
He was a world-renowned choir
director and he suffered viral
encephalitis which led to brain
damage which destroyed most of
his temporal lobes,
his hippocampus,
and a lot of his left frontal
lobe.
It could be--It could have been
worse in that he retains the
ability to talk.
He seems to be--He's not
intellectually impaired.
He just can't form new memories
and so he lives in this
perpetual "now" where just
nothing affects him and he
feels--This has not always
happened.
There's more than one of these
cases and it doesn't always
happen like this,
but he feels continually reborn
at every moment.
And we'll return to this and
then ask what's going on here.
But there's a few themes here.
I want to, before getting into
detail about memory,
I want to review some basic
distinctions in memory when we
talk about memory.
So crudely, you could make a
distinction between sensory
memory, short-term memory,
which is also known as working
memory, and long-term memory.
Sensory memory is a residue in
your senses.
There's a flash of lightning.
You might see an afterimage.
That afterimage is your sensory
memory.
There's somewhat of a longer
echoic memory for sounds.
So as somebody is talking to
you even if you're not paying
attention you'll store a few
seconds of what they're saying,
which is sometimes,
when somebody's talking to you
and you're not listening to them
and they say,
"You're not listening to me."
And you say, "No.
You were talking about--" and
pick up the last couple of
seconds from echoic memory.
There's short-term memory.
Anybody remember what I just
said?
If you did, that's short-term
memory--spans for a few minutes.
And then there's long-term
memory.
Anybody know who Elvis is?
Do you know your name?
Do you know where you live?
Your long-term memory store
that you walk around with and
you're not going to lose right
away.
When we think about amnesia in
the movie sense,
we think of a certain loss of
long-term memory associated with
autobiographical personal
events.
There is a distinction between
implicit and explicit,
which we'll talk about it in
more detail.
But explicit,
crudely, is what you have
conscious access to.
So, what you had for dinner
last night.
You could think back and say,
"I had this for dinner last
night."
Implicit is more unconscious.
What the word--what certain
word--what the word "had" means,
how to walk,
how to ride a bicycle,
that you might not be able to
articulate and might not even be
conscious of but still have
access to.
There's a distinction between
semantic memory and episodic
memory.
Semantic memory is basically
facts, what a word means,
what's the capital of Canada,
and so on.
Episodic is autobiography,
is what happened to you.
That Yale is in New Haven is
semantic.
That you went on vacation away
from New Haven last week,
it would be episodic.
There is encoding stores and
retrieval, which refers to
different levels of what happens
in memory.
Encoding is getting the memory
in, as when you study for a test
or you have an experience.
And storage is holding the
memory.
And retrieval is getting the
memory out.
Finally, retrieval is often
broken, conveniently,
into recall versus recognition,
where recall is when you just
pull it out of memory and
recognition is when you
recognize what corresponds to
something in the past.
Anybody remember what color tie
I had on two days ago?
Oh.
Okay.
Well, that would be impossible
to remember but if I asked you,
"Is it purple or is it orange?"
that would be much easier.
[laughter]
Now, you could break up,
crudely, the memory into
stages.
So you start that sensory
memory is just the stuff that
comes in leading to short-term
memory, leading to long-term
memory.
And this stage theory is
something which we'll discuss in
more detail.
But this leads us to the issue
of attention.
How do you get memory from your
sensations, from what you're
hearing?
I'm speaking to you.
You're hearing me.
How does it ever get in to the
other systems?
What decides what's remembered
and what's not?
There's all sorts of things
happening to you now.
The seat of your chair is
pressing against your butt.
You wouldn't say, "Oh.
I want to remember this forever.
The seat's pressing against my
butt."
[laughter]
Your neighbor is exuding a
certain sort of smell.
You're thinking about something.
Your eyes follow him.
Not everything gets in memory.
You'd go mad if you tried to
remember everything.
You can't.
So, what determines what gets
into memory?
Well, one answer is "attention
does."
And attention is--could be
crudely viewed as a flashlight,
a spotlight on experience that
willingly zooms in on something
and makes it memorable.
Attention has certain
properties.
Some things come from
attention--to attention
effortlessly and automatically.
Here's an example.
You're going to see an array of
letters here.
One of them's going to be green.
When you see the green one,
please clap.
[laughter]
No, not this green one.
[laughter]
There's going to be another
slide.
Okay.
You're ready now.
but there's going to be an "o."
When you see it clap.
Okay.
Sometimes it's work.
Find the red "o."
[laughter] It's harder.
Sometimes attention is
involuntary.
I need a volunteer.
And all I want to do is I want
to show you colors on the screen
and I'd like you to name the
colors as they come out.
Do you want this?
Student 1: I'm
colorblind.
Professor Paul Bloom: Oh.
[laughter]
The first one is easy.
See.
This is--You have to just go
down the colors .
Anybody?
Okay.
Student 2: Red,
green, blue,
black, green,
blue, red, blue,
black, red.
Professor Paul Bloom:
Excellent.
[applause] Okay.
Now these.
These will be words but just
name--Okay, you.
Just name the colors.
Student 3: Green,
red, blue, black,
blue, red, green,
black, red, blue.
Professor Paul Bloom:
Perfect.
Now, we'll go back to you,
same deal, words.
Student 4: Red,
blue, green -- Professor
Paul Bloom: No,
no, no.
Huh uh.
Don't--I know you can read.
The colors.
Student 4: Okay.
Sorry.
Okay.
Blue, green,
red, green, black,
green, blue,
black, red, Professor Paul
Bloom: Very good actually.
[laughter]
That's known as the Stroop
effect.
Being an expert reader,
as you are, your knowledge of
reading, your attention to what
the words meant,
subverted your desire to do the
task.
You couldn't make that go away
even if you wanted to.
If somebody gave you $1,000 to
read this as fast as you read
this, and as fast as you read
this, you'd be unable to.
You can't block it.
There is some work--There are
some interesting discoveries
about attention.
I have a demonstration here.
I'd like people actually--It's
important--Some of you may have
seen this before.
It's important for you to be
silent throughout it.
What you're going to see is
you're going to see two teams of
basketball players.
One of them is going to have
white T-shirts.
The other one will have black
T-shirts.
They'll be passing balls back
and forth.
What I'd like you to do is
count in your head how many
passes the white team does with
the ball.
[laughter]
What number did people get?
Okay.
Did anybody notice anything
unusual?
[laughter]
Did anybody not notice anything
unusual?
Okay.
Some people did not notice
anything unusual.
Those who didn't see anything
unusual, watch this again and
just watch it.
[laughter]
About 50% of people when
counting, who have never seen
this before don't notice
anything.
But then when you're not
counting it's kind of obvious
what you're missing.
[laughter]
And this is one demonstration
among many of the fact that when
you're attending to something
you have a very small window of
attention and you lose the focus
on other things.
Here's another different
example.
I'd like people to watch a
movie and pay attention very
closely to what happens in the
movie and try to remember this.
How many of you noticed
something odd in that movie?
How many of you didn't?
Okay.
Now, everybody look at the
scarf, the color of the plates
and the food,
among other things.
The phenomena,
in general, has been called
"change blindness."
And what it is is we tend to
be--when there's a focus of
attention focused in a certain
way,
we tend to be oblivious to
other things that go on in the
environment.
Often it is,
in fact, quite difficult when
there's a change in scene to
notice what changes and what
stays the same.
So, in this final demo,
there's just going to be two
pictures flicking.
Could you clap when you see
what's different between the two
pictures?
[applause]
[laughter]
I myself am terrible at these
and so I have a lot of sympathy.
How many people never saw it?
[laughter] Good.
That's very impressive.
[laughter]
One more time with a different
one.
[applause]
Did anybody not see it?
Be honest.
I'll give you another try.
[applause] Okay.
I'll put you out of your misery.
[laughter]
This is work by Dan Simons and
it's part of an extraordinarily
interesting body of work on
what's known as "change
blindness."
And what this means is,
the phenomena is,
we have a very narrow focus of
attention and huge changes can
happen that we are oblivious to.
This is why,
in movies, there are so
many--so much difficulty with
continuity changes.
Dan Simons is also famous for
having brought this outside of
the laboratory in some classic
experiments and I'm trying to
get the film corresponding to
them.
What he did was that he did
this great study in the Cornell
campus where he was--where what
happened is they would get some
unsuspecting person walking
through campus and some guy
would come over and say,
"Excuse me, Sir.
I'm lost.
Could you help me with
directions?"
And have a map and then the
person would say,
"Sure."
And then there'd be two
construction workers holding a
door.
And these guys were going to
rudely bump between these two
characters and then the
experimenter gets switched with
another guy.
So now, when these two guys
walk away, the subject is
standing there with an entirely
different person.
[laughter]
What's interesting is nobody
notices.
[laughter]
They notice if the person
changes sexes.
"Didn't you used to be a woman?"
[laughter]
And they notice if the
experimenter changes races,
but most other changes they're
oblivious to.
There's another experiment.
I think Brian Scholl did this
one but it may have been Dan
Simons where what happens is a
subject comes in to the lab.
They say, "If you're going to
do an experiment with us,
you need to sign the human
subject form."
Hands him the form,
the experimenter.
The subject signs the form.
The experimenter takes the form
and says, "Thank you.
I'll put it down here."
Goes down here and then a
different person pops up.
[laughter] People don't notice.
And there's a certain level on
which we're oblivious to
changes.
What's weird is we don't
see--we don't think we are.
We think we see the world as it
is and we don't know--notice
that when we're attending to
something;
everything else gets blanked
out.
And so about 50% of people who
have never seen this demo
before, the gorilla demo,
they don't notice the gorilla.
And there's--you couldn't
imagine anything more obvious.
The gorilla study was actually
done a very long time ago.
And it was originally done in a
different way but I'll show it
to you just because this is the
original study and now that you
all know what to expect--Oh,
not that one.
Oops.
Nope.
That's actually--If you looked
at that quickly,
it's a current Yale professor.
Oh.
I'm never going to get my DVD
back.
Anyway, I'll show you the other
demo on--next week.
I will.
[laughter]
Any questions about attention
and memory at this point?
Yeah.
Student: [inaudible]
Professor Paul Bloom:
Yeah.
Why does it work that way?
Why is it--Why do things that
become very practiced become
automatic and involuntary?
It's a good question.
I don't know.
We know that they do.
We know that once you--that you
can't not read once you know how
to read.
You also can't not listen.
If I'm talking to you and I'm
extremely boring,
but I'm talking to you,
it's very hard not to listen.
You can't shut off your ears.
You could put your fingers in
them but you can't shut off
your--You also can't shut your
eyes without actually shutting
them.
You can't say,
"This is a disgusting movie.
I'm not going to attend to it."
[laughter]
So, that's not answering your
question.
It's just saying that your
observation is a right one and a
more general one.
When you're good at something
and you're over-practiced,
it becomes involuntary and you
cannot stop it.
Okay.
Well--Oh.
One more in back.
Yes.
Student: [inaudible]
Professor Paul Bloom:
What now?
Sorry.
Over there.
Yeah.
Student: [inaudible]
right before his accident?
Professor Paul Bloom:
Did he remember things before
his accident?
Yes.
He had some amnesia of events
before his accident but he did
remember things.
He knew his name and he knew
other things about his life.
Okay.
I'll see you next week.
 
