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PROFESSOR: Good afternoon.
Good afternoon.
I want to remind you that a week from today
is the second exam.
The format is identical to what you had, 50 multiple
choice questions; 30 from the book, Chapters 5 to 7; 20 from
Sacks and the lectures; short answers.
So talking about tests, why do we have tests?
You live in a world of tests.
Everything from SATs to, on your horizons, maybe GREs or
MCATs or LSATs.
So why do people have tests, besides making it miserable to
be under 30?
It's the revenge of the older people.
Why do people have tests?
Yeah?
AUDIENCE: [INAUDIBLE].
PROFESSOR: One of them is just verify
that you know something.
And people will call it sort of have you learned stuff?
And the test is meant to be an estimate of
what have you learned?
But a second form of testing, what people sometimes will
call high-stakes tests in a slightly different way, are
ones about selection and prediction, which sometimes
involve achievement or aptitude, things
like SATs or GREs.
So achievements are meant to be estimates of what you know,
advanced placement tests, how much math you know or physics.
Content in a given area.
And sort of a broader sense of aptitude, SATs or GREs.
Now, one thing that's different about today's
lecture on intelligence, it'll be a little similar when we do
personalities, up until now, to a first approximation, most
of the time we've talked about what we view as general
principles of the human mind and brain across everybody.
How vision works across everybody, memory across
everybody, thinking across everybody.
And now, we're switching to a domain.
And it doesn't have to be this way, but this is the way the
world has done it, where we emphasized
differences between people.
So when people take tests, it's not to see that everybody
took the test.
What they're going to do is, you get an A, or a B, or a C,
or you get a high SAT or a medium SAT, and schools use
the differences to think about you.
And so one question is, from an empirical sense, are these
tests pretty good at predicting things?
And the answer is they're decent.
They're not terrific.
So the tests survive, like SATs or GREs, because there's
correlations between these kinds of tests before you get
to graduate school for example, and how faculty rates
students or how productive people are in terms of
research or as a graduate student in this case, or the
GPAs, or things like that.
And the correlations are about 0.3 to 0.4.
To give you an intuitive sense, the correlations
between sex and height, whether you're a man or a
woman and height, is about 0.4.
So of course lots of women are taller than lots of men.
On average, men are taller than women.
It's a 0.4 correlation.
So this is in that range.
So tests are pretty good predictors.
Everybody says that for things like predicting college
performance or graduate school performance, a combination of
tests and grades are better.
The difference is grades take a lot of years to produce.
Tests are one traumatic outing.
So tests are just a part of our life
in selection processes.
So now what is intelligence?
And it's a loaded word.
I mean memory is kind of a neutral word.
Attention is a neutral word.
Intelligence is a loaded word.
I mean nobody wants to be low on intelligence.
And so psychologists have come out of this way.
But it's kind of funny, because there's not going to
be a really deep definition.
Maybe it's a lot of different things and how they average up
or something like that.
But people have said well, it's something about the
ability to solve problems, to understand and learn complex
material, to adapt to the environment, mental quickness.
Those are all senses you might have of something that you
think of as intelligence in a person.
But whether they're one thing, many things, it's very hard to
pull that out.
And we don't know too much about that really.
And also I want remind you of something we talked about, but
it's especially important in this field.
We talked about an experiment versus correlations.
An experiment, you have to have a dependent measure,
something you measure.
But critically and uniquely, you have an independent
variable, something that you vary.
That's what makes a study an experiment, as opposed to a
correlation.
So studies of intelligence of every kind are almost always
correlational and almost never experimental.
That means they're always subject to lots of
interpretation and many factors in the world.
And that's very important to keep in mind.
And again, they tend to focus on variation in people, rather
than what is intelligence itself.
And again, here's another correlation
of height and weight.
That's a stronger correlation.
So where did intelligence start with?
It's a fascinating story.
And by the way, let me tell you the SAT story, on the
sidebar, for a moment.
So SATs, nowadays do people, some people get ready a lot
for SATs by courses you take and things like that?
I read about that.
When I took it, people weren't that organized.
But getting into college wasn't that competitive.
And the original goals of SATs was what, do you know?
It's really interesting.
Because it ends up being the thing, they say well, because
people who are maybe under more supported circumstances,
more financially advantageous circumstances, get more help
to get ready for the SAT.
Those things might amplify SAT differences in a way that's
not really about the person to start with.
The original goal of the SATs was to have a national test
that was fair for everybody, so that schools like Harvard,
for example, that tended to admit the same kind of
students from the same small set of
schools in the Northeast.
So now, we have a test for everybody across the country.
And we can admit people on their merit, rather than on
small, social connectivity networks.
Does that make sense?
And yet, SATs are now viewed as a suspicious
tool in that regard.
It was originally meant to be democratizing.
It's like everybody in the country takes the same test.
It's not whether you have a connection through a network,
to our university.
IQs have the same story.
For good reasons, and we'll talk about that, IQ tests and
interpretations of IQ don't have a good history.
But the original goal was pretty reasonable.
So in France in 1904, they began universal elementary
education, that every child goes to class.
And Alfred Binet, a physician, wanted an objective way to
identify children who needed extra help.
A perfectly good idea.
A child comes to school.
Some children are ready to go.
Some children need a lot of extra help because they have a
difficulty.
So he developed a set of tests where he probed many different
abilities, like copying a drawing, repeating digits,
recognizing coins, explaining why a statement
did not make sense.
They wanted to probe different little areas of abilities, so
if a child is terrible at something, or two things, the
teacher knows this child needs some extra help to get going.
So that's a good use of testing, I think by
everybody's criterion.
But then testing sort of took off, IQ testing.
IQ stands for intelligence quotient.
It's a test to give typical children.
They give it often for the most commonly used IQ tests,
at many different ages.
They'll test a large number of individuals.
And they'll compare what nowadays what they think of as
your mental age to your chronological age.
So your chronological age is how long you've lived.
And your mental age is how well you score on a test.
The most famous IQ test, the most widely used, takes about
two hours of testing.
It comes from David Wechsler, the Wechsler Adult
Intelligence Scale.
One for children.
And within that test, what's within that test?
Because when people talk about tests I think, whatever kind
of test it is, it can only about as good as the test
design itself, to the extent that it's any good.
A ridiculous test is a ridiculous test, even if
society gives it to you.
But tests can be better than that.
So what is inside the most widely used IQ tests,
especially in clinical environments?
So let's talk about one of them.
It has a bunch of little tests.
One is vocabulary.
They ask you to define words, similarities.
They'll ask you a series of questions, like how are an
airplane and a car alike?
Very simple arithmetic operations.
Digit spans, how many digits can you remember.
Information, they'll give you a series of questions, like
who was Martin Luther King, Jr.?
Comprehension, they'll ask you things about the world, like
why are there taxes and things like that.
And you give an answer.
Somebody scribbles down when you say.
And they score you.
You get two points or one point.
We'll talk about that.
And then they add up these scores in the subtests.
So in the nonverbal verbal tests or the performance
tests, they'll show you a picture with a thing missing.
Have you did that a kid?
I love those things.
What's missing in the picture and stuff like that.
Blocks, they'll have you rearrange them into various
geometric design.
Picture arrangement, you'll get cartoon panels and you
have to put them in the correct order to tell a story.
And they measure how accurately and quickly you do
these things.
There's nothing amazing about any of these things.
They're probing a variety of little
abilities that you have.
And again, they will take the mental age and chronological
age, divide it, multiply it by 100.
And they'll standardize it, so that 100 is the population
mean in the United States.
Other countries do these things, as well.
Is that OK?
So I mean a test can only be as possibly good as the
content of it.
And what it measures or doesn't measure depends on the
specific conflict of it.
They'll scale the scores out, so you get a normal
distribution, with a peak in the middle.
The raw score is the number you get.
The standardized one is adjusted for your age.
And it's a pretty important concept, because we'll come
back to this in a moment.
The raw score is your actual score.
But then they adjust it for your age.
Because you don't expect a five-year-old to do as well as
a 15-year-old, to do as well as peak 18 to 23-year-olds.
And then bad things happen as you get older.
I'll tell you a bit of them about that too.
2/3 of the people are at plus or minus 1 standard deviation.
They set it for that.
More than two standard deviations up or down, are
about 5% on either end of the distribution of scores.
And they norm it by age.
Again, you don't expect a six-year-old to do something.
But you get some funny things.
Not that you have to worry about this in detail.
But it gives you a sense.
So imagine you're a five-year-old and you take the
test, on the last day you're a five-year-old.
Or imagine you have your birthday today and
you're six years old.
By moving from five to six, from Wednesday to Thursday,
you've moved up a year for the scoring.
Because they go by year, not by day.
So if you would have scored 120 on the IQ test yesterday,
when they say what should you have scored for a
five-year-old, the very same test, the next day,
you would score 100.
Now, that's the extreme case.
But you understand what happens, right?
Because here's how well you did.
That might have been pretty good.
120 is above the average for a five-year-old.
But the next day, if you're a six-year-old, now for a
six-year-old, it's just average.
So age has a big effect on these things.
Here's something sad for aging, but good for you.
Be smart now.
A 40-year-old who scores average
would be a real undergrad.
If I score like you--
no, let me rephrase this.
If you were compared to a 40-year-old, you would have
100 IQ, you would have a 230 IQ.
Because age knocks down the score as well.
So things go up and then things go
down, in this problem.
And usually they think of a score below 70 as clinically
concerning.
And the top 2%, you get to join Mensa and do whatever
Mensa people do.
Which I don't know exactly, but it sounds interesting.
An important thing about tests of any kind, are two huge
concepts, reliability and validity.
So reliability refers to the idea that if you were tested
more than once, you would get the same score.
The better IQ tests work a fair bit to
try to achieve that.
Validity is the deeper question.
Does the test validly measure what it's supposed to measure?
So if we had you flip a coin and said that's your IQ, you'd
say, that's ridiculous.
That's not a valid test.
We could measure your height.
That would be extremely reliable measure.
You'll have the same height today as tomorrow, if we did a
decent job.
That wouldn't be a valid measure of anything about any
mental ability, never mind something like intelligence.
So those are two important concepts in
testing, but very different.
Now, why do people think IQ tests are interesting, besides
just this weird curiosity about intelligence?
Because IQ tests correlate with GPA in high school and
college, job success, salary, stable marriages, staying out
of jail, and how long you live.
Again, it's a correlation.
It could be many different things.
The thing I want to talk you out of is the idea that if you
have a 200 IQ today, you've got something stored up that
will fend off disease.
It's not that, necessarily.
It's that there's lots of things in your life that got
you to that score.
And all those things are likely to persist in your
life: good health, support of education, interest maybe in
taking on challenging tasks.
You had those before.
You had them while you took the test.
You continue to have them after.
Another way to think about it though, which is both a plus
and minus, depending on how you look at it, IQ scores
account for approximately 25% of the
variation on these things.
So that's not huge.
That means there's many, many, many other factors, besides
whatever IQ is capturing.
But it's about as big a chunk as you can get for a couple
hours of testing.
And we know that other things like personality, variation,
education, culture, all those things blend in on how a
person will do on all these outcomes.
So I'm going to go back and forth.
Because on the one hand, we say there's a lot of stuff
besides IQ.
But IQ has some interestingness, otherwise
nobody would talk about it.
And it would just disappear from the world.
So on average, on average, what does 15 IQ points mean?
So on average, a person with 100 IQ in the US will go to
high school and a year or two in a community college.
On average, these are averages over huge variety of people.
You get 15 more IQ points, and on average, you're likely to
finish college and have a white collar job.
Have 15 fewer points, and you're not likely to complete
high school.
And you'd have to have a job that doesn't require
educational background.
So 15 point on averages correlate with things.
Here's another one, because everybody in the end is a
little bit curious.
In your own life, how much of what you're good at or not
good at, of any of us, comes from our genes, from our
environment?
Where does that come from?
What are the things that support us or limit us?
So here's one study that took women from the same family.
So they're all sisters from the same family.
They're trying to control a little bit of the genetics,
because they share genes within the family.
They're not twins.
And definitely shared environment.
They're in the same household.
And within those families, they look at the IQ scores.
So here's the average group, above average, well above
average, a little below average, a lot below average.
And they say that in these women, all coming from the
same household, here's their average income and here's the
average rate of illegitimate births, which is one measure
that people think is kind of a social, on average not a
desired outcome, to have a child without a family
supporting.
It's not going to help a person succeed in the world to
be a single mother.
And so you can see, the salary pretty much moves with the IQ
on average.
And the rate of illegitimate births pretty much
moves with that too.
So again, it's an average.
But there's some relationship between these things.
Now, if you pick up the newspaper today and read about
nuclear disasters in Japan and problems in the Middle East
and other things like that, you would say, it's hard to
say the world is getting smarter.
But you may or may not be surprised to hear of the
so-called Flynn effect.
This was kind of a surprise when it was discovered, which
is basically this.
IQ scores, where they're measured, go up around the
world all the time.
By IQ test scores, it's as if the world is getting smarter
all the time, which is kind of an optimistic thing.
Whether it's getting wiser is a good question.
But by IQ score, smarter all the time.
So that's hidden for many years, because every few years
these tests get renormed for the groups.
Does that makes sense?
So they're given again and 100 is the average.
And they're given again and 100 is the average.
But if they ignore this averaging and just say, across
these tests that only change a little bit, some of them only
change a little bit, if we just take the scores, look at
1930, 1940.
And it just keeps going up.
So Flynn is the person who discovered that the world is
getting smarter by raw IQ tests.
And one of tests they use, I'll show you an example of
this, it's another widely used test called Raven's
Progressive Matrices, IQs go up about three
points every 10 years.
So that if you were born in 1930, a person would have an
IQ of 100, their child 108, and their grandchild, 120,
with a standard deviation higher.
So it's like smarter, smarter, smarter.
I don't recommend to go home and tell your parents that any
debate you have with them is pointless, because you're
smarter than they are.
But if push comes to shove, you can look up the Flynn
effect and have a discussion about that.
So somebody who has an IQ today, just flip it around.
If you have a 100, your grandparent would
have a IQ of 82.
By this reasoning, people in 1900 would have
a mean IQ of 70.
And nobody knows why it's going up all over the world.
There's all kinds of ideas about maybe
nutrition is going up.
Maybe reasoning abilities are being pushed.
Maybe educational things.
I mean it's impossible scientifically to know why,
because it's happening in such a global, giant scale.
But some people have said, the tests don't go up uniformly
across the tests.
Which gives us a hint about the way the world is changing
and how intelligence tests in some way become a barometer of
what mental abilities are
increasingly prized by societies.
So there's relatively small gains across years in
vocabulary or general knowledge or arithmetic.
Where there are large gains are what you might call
abstract thinking tasks, like similarities.
So let's focus on that for a moment.
So a similarities question might be like this.
In what way are dogs and rabbits alike?
If you answer both mammals, you get two points.
That's the best you can do.
And that's what we would call an abstract or taxonomic one.
You're abstracting across the two things.
Or you could give an answer like, you use
dogs to hunt rabbits.
That's not a wrong answer.
That's considered a one-point answer.
You kind of seem to know what a dog is, you kind of seem to
know a rabbit.
But you didn't give the best answer by this test criterion.
Because it's a functional description of these things,
not a abstract, conceptual one.
So let's think about different societies, besides the Western
industrialized one that we represent mostly.
In Liberia, they ask people to sort baskets of food, tools,
containers, and clothing.
So most of us, Western educated in a very broad
sense, would put the things of food together, the things of
tools together.
Those are the abstract categories.
The people from this tribe put them in terms
of functional pairings.
They put the potato next to the knife they use to peel the
potato, right?
And here's the fun thing in this study.
They said, what would a fool do with this?
And they said oh, well, a fool would put all the food things
together and all the utensils together.
But that's pointless to do that, because what are you
going to do with all the food things over here, when the
utensils are over here.
You understand?
It's what our society emphasizes as a
useful way of thinking.
So it could be arbitrary.
But it's not arbitrarily rewarded and prized in the
world of education, that we live in here.
So intelligence tests attach value at a specific time and
specific test.
Scores are changing over time.
Different cultures are valuing different things.
It's constantly renormed.
And because of that, here's another example of how the
renorming is.
It used to be for some number of years, that 70 was used as
a cut-off for estimates of, broadly speaking, mental
retardation.
And why that matters is that a person for example would get
certain kinds of medical services provided to them.
When a new version of the WISC, of the Wechsler test,
came out in 1991, so a renormed version, so that
means the scores are going up, if every state in the country
had simultaneously used that new test when it came out,
which they didn't quite, but if they had, the number of
people rated as retarded, diagnosed as retarded, would
have doubled in a single day.
Because the norms aren't pushing the numbers up.
OK?
So the number of people scoring very poorly would have
doubled in a single day because of the renorming.
It's very important to realize that all these things, what's
really in the test, what's valued by a sort of society or
culture, and the norming things are really influencing
a lot of how you get to these numbers.
So ideas about intelligence, roughly in this field, have
come out of what people call
psychometric analysis of subtests.
They give you the scatter of tests.
And the thing that struck many people is how for a given
individual, there's correlations among the tests.
A person who does well on one test, tends to do well on
another test, and tends to do well on a third test.
And a researcher named Spearman gave this correlation
among tests, the letter "g," the name g, to stand for
general intelligence, and "s" for specific intelligence.
And since then, many people have said well really is there
one broad sense of intelligence, are there
multiple separate kinds of intelligence?
And people debate that in the field.
And probably somewhat the answer is it depends what
you're measuring for and the purpose of the measurement.
But a good one to look at, because it's very clear, is
the difference between fluid and crystallized intelligence.
So fluid intelligence is what we think of as
novel problem solving.
You have a situation you were never in
before, what do you do?
Crystallized intelligence are facts you know,
information you know.
So here's the conceptual idea that maybe general
intelligence is a thing.
And then it shows up on different tests, with the
different specific intelligences.
That's like maybe verbal or arithmetic.
But let me show you the fluid and crystallized one.
So the fluid one we said were first mental processes that
apply for a novel situation.
And that declines a lot with age and adulthood.
So these lines going down here, I'm about here and
you're about here.
Who should be grading who in this course, you might ask?
The only reason that I get to grade you is because these
lines keep going up here.
This is how many facts you know.
So the plus of living longer is that you get
to know more stuff.
The risk of living longer is you don't use it as flexibly
under novel situations.
So a pretty strong distinction, at least with
aging, between so-called fluid intelligence and crystallized
intelligence.
Here's another study of exactly the same thing.
It's a striking ski slope of decline in fluid intelligence.
Look at this, ernt, from 20 to 80, it just goes down
relentlessly.
But when it comes to crystallized intelligence,
things like vocabulary, that kind of hangs in there, until
you have some big health problem.
So at least those two kinds seem to
have a different basis.
And people have thought about different ways to think about
intelligence.
And I'll just tell you that in general you get positive
correlations among the tests.
And so often people think about this general
intelligence.
The correlation among the tests is
the best single predictor.
Now, there's lots of responses to ideas about intelligence.
One of them is the study of emotional intelligence.
Peter Salovey is the researcher
most involved in that.
And we know this in everyday life.
We know smart people, what we might call book smart people,
who seem unwise in how they relate to people, how they
perceive emotions, how they facilitate thought with
emotion, how they understand or manage their emotions, how
they relate to other people.
And so it's common sense to think of that as something
that varies across people.
It's very hard to measure that.
I mean, part of the tyranny of tests is what can be measured,
gets measured.
What's hard to measure, is hard to measure.
It's very hard to measure, in a laboratory, in an hour, a
person's emotional intelligence.
People have tried.
It's just hard to do.
Here's another area that's gotten a lot of attention,
from Howard Gardner at Harvard.
Kind of fighting back against this idea of a single form of
intelligence as captured by g, the idea of multiple
intelligences.
And looking at things, the associations in patients and
development.
That we can talk about linguistic intelligence,
spatial intelligence, music intelligence, bodily
intelligence.
Great athletes have great bodily intelligence.
Intrapersonal or interpersonal, it's kind of
like emotional.
Existential.
So he said, there's all these different kinds of
intelligence.
And each person is a profile of these.
You can be really strong in one, and medium in another,
and not so strong in another.
The problem with this whole approach is, yes, it's true
that people have a huge variety of
facets of their humanity.
This whole course, I feel like every lecture we do, we just
turn a person a little bit to study another
facet of their humanity.
But it's hard as heck to measure interpersonal
intelligence or naturalistic intelligence.
Now, maybe somebody will figure out how to do that.
It's just hard to measure those things, even if it feels
like something conceptually that's there.
So this idea, which has had a lot of resonance to people not
liking very simple-minded ideas of intelligence, very
unitary ones, it's still not gained much traction in
practical use.
So let me talk a bit about some of the things that people
have said, well, if we talk about this intelligence, what
might be some mental mechanisms or neural
mechanisms that support or underlie it.
So some things that go with it are mental speed.
And you know this, kind of quickness of thought.
OK, not even big thoughts, just quickness feels like it
helps a person solve problems.
So for example there's a moderately high correlation
between IQ, complicated tests, of all those tests, and how
quickly you push a button when the light comes on.
Now, we never say, wow, Sally or Fred is really smart.
They can push a button when the light
comes on really fast.
Let's go to them and get the answers for the problem set.
But that would go with the idea that simply being fast is
kind of a useful thing for acting on the world.
Or how quickly people decide whether two lengths, two
lines, are the same length or a different length.
Very simple thing, just speed.
And another idea is working memory capacity.
How much information you can hold in your head at any one
time that's relevant to the problem or
task in front of you.
So people have tried to explore these in certain ways.
And I'm going to talk to you about a couple of brain
studies that have tried to look at this.
So again, we talked last time about frontal cortex and
different parts of it.
And especially the dorsal-lateral prefrontal
cortex is involved in thinking.
And so people have taken tasks and said, what happens when
you think about them?
So here's one, an easy item on the so-called Cattell
Culture-Fair Test.
So which of these things goes into here.
There's harder ones.
Or here's a slightly adapted version of the Raven's
Progressive Matrices.
I'll let you think about that for a moment.
I don't remember which it is.
So you're told here's some rows and columns.
One of these eight answers logically fits in here.
And it's your job to figure out which one.
Let's see.
How do we like--
three.
I like three too.
Does that three seem OK?
This is a medium-hard item on this kind of a test.
And then they do these kind of map of results.
This is what's fun about the Raven's test, the
item you just saw.
Which is they sort of looked at lots of other tests, so
specifically spatial tests, specifically verbal tests,
specifically math tests.
And they said if we have to give you one test only, one
test only, what test would best predict your performance
on all the other tests?
And the answer is Raven's or IQ tests like that.
So of course if I give you a math test, that better
predicts your math performance.
If I give you a verbal test, that better predicts your
verbal performance.
If I gave you a spatial test, that better predicts your
special performance.
But if I want to give you one test that gives me the best
prediction of your performance on other tests, it's things
like these IQ tests that do that.
And that's just empirical.
That's not arguing about values or what
intelligence is.
A lot of people who work in this field, they don't even
care about these arguments.
They just say, I just want a test that predicts.
It's your job, if you wanted to figure out why it is.
It's the genes, environment, education, whatever.
I just want a test that predicts.
So from that perspective, these tests
have a strong history.
And what turns on in the brain when you solve
this kind of a task.
Well, the frontal cortex a lot.
The parietal cortex.
But especially, frontal cortex.
So it goes with our idea that thinking is very much tied to
prefrontal cortical function.
Here's another example of a study that said, let's compare
what happens in the brain when you have test items that are
hard, which is the outlier one here, that require a lot of g,
or items that are easy, that require very little g.
Will up here in the brain, what happens when you turn on
your g, so to speak?
And again, the prominent areas tend to be, for both spatial
and verbal, prefrontal cortex.
One more.
the n-back task, we use that a lot.
Where your job is, letters come on.
And in this one, one-back, you say, what do I see a letter
that's the same letter as the one before?
So, for example--
two-back, sorry.
So you see, R, R, M, X, this is two-back, because an M
occurred two items ago.
Three-backs are really hard.
Because the letters are going, boom, boom, boom, boom.
And what's hard about it is, the letter in front of you,
you have to say does it match the one I saw three letters
previously, plus remember that, because it's going to be
the target for the one that comes three after.
It's hard.
I can tell you it's hard.
You can be smart.
It's pretty hard.
And for this task in general, the harder it gets, the more
you turn on the dorsal-lateral prefrontal cortex.
And so they did this test with students in Washington St.
Louis, Louis, related it to performance on the Raven's.
And sure enough in the brain, it's again prefrontal cortex.
So a bunch of studies have found all these tests involve
a fair bit of the brain.
But they seem to really draw upon the capacities that you
and I have in prefrontal cortex.
And one more note, in brain imaging when we talk about
things, sometimes it's better to have more activation and
sometimes less activation.
And you have to know the behavior to know that.
So whenever you see somebody saying oh, this person, this
group, or whatever, had more brain activity or less brain
activity, you don't know until you know the rest of the
behavior, whether more is good or bad.
Sometimes when people get really good at something, they
use less of their brain, because they can do it so
efficiently.
So here's an example of people with lower and higher IQ doing
an n-back task.
And you can see that the people with lower IQ have much
more activation than the people with higher IQ.
It's as if these people have to use all their brain
resources to accomplish this.
And these people only have to use some.
It's as if it were that.
So here comes one of the classic topics of
the fate of a human.
How much is your genes at birth and how much is the
environment that you're in.
And if we were really to understand that in a deep,
deep scientific way, we would know the genes are related to
intelligence; the experiential factors in the world, family,
education, emotional support, and so on; how they interact.
All those things, we know practically nothing about.
I'll show you one tiny example.
We know practically nothing about them in
any depth at all.
So we mostly end up using twin studies to make the best
estimates we can.
Which doesn't tell you what the factors are.
It just tells you how much is a twin who is identical more
or less like a twin who is fraternal.
OK, we'll come back to that.
But I do want to tell you sort of an exciting direction
that's slightly getting at the genetic story of this.
So you may know, many of you more
than I do, about genetics.
But single nucleotide polymorphisms are DNA
variations.
These occur relatively commonly.
They're estimated to make up about 90% of
human genetic variation.
And they're constant from generation to generation.
So people have studied a few of these variations among
people and related them to performance.
So let me remind you of something from last lecture,
the Wisconsin Card Sorting Task.
Where you sorted these cards mysteriously and we said that
if you have a frontal lesion, you do poorly on this task.
You get stuck with one kind of problem solving or habit,
answer even when it's wrong, in a new circumstance.
So what people have done is look at one particular gene
that's related to this enzyme that modulates dopamine
function in the prefrontal cortex.
So it's a risk factor for schizophrenia.
It metabolizes dopamine in prefrontal cortex.
We vary with which version of this gene we have.
And here's the performance on the card sorting task.
And let me pick these.
These are healthy people.
If you have this version of the gene or this pairing or
this pairing, your card sorting task is going up.
So this is kind of amazing that we're close to that,
where a single gene is varying.
Now, the score doesn't go up a lot.
It accounts a small percent of the variance.
But it's one gene having an identifiable correlation with
performance on a demanding task.
And you can do this n-back kind of task
we just talked about.
And then you can look in the brain as people are performing
this, divided by which version of this gene they have.
And what you get is more activation in the people with
this complement, than this complement.
Sort of consistent with the idea they're working harder.
There's the same group of people who are performing less
well in the card sorting task.
So there are some genes that have been identified that are
associated with what we may call broadly, intelligence.
But that one gene only accounts for a tiny bit of the
overall score on these kinds of things.
And we don't know much more about it than that.
So how do people even begin to think
about nature and nurture?
And I like to think about this in two ways.
One way is narrowly IQ tests, because there's been so much
work in that area.
But it's the deep question of how do we get
to be who we are?
So again, they mostly look at twin studies, so-called
behavioral genetics, and estimated heritability, how
much of variation is due to genetics.
And I'll come back to this height thing.
But to give you a sense, height is thought to be 90%
inheritable in the US.
Tall parents on average will average will have taller kids.
Less tall parents, less tall kids.
And in twin studies, they contrast monozygotic twins,
twins that are identical or have the same genes, with
dizygotic ones, who share some genes, but not nearly as many.
Of course, they share the same environment a lot.
Have you guys seen the two twins talking to each other
video on YouTube?
If you haven't seen it, it's kind of fun.
The two twins are babbling.
But they're so demonstrative, it's as if they were talking
to each other in babble.
It's kind of fun, if you haven't see it.
It's very cute.
Here is it again.
The fraternal twins and here's the identical twins, before
they're born.
This has been studied a fair bit.
Here's the correlations between IQ scores and people
of varying relations.
So let's work down that list.
Unrelated persons, reared together.
So perhaps an adopted person and his or
her sibling or something.
They're correlated at about what, 0.2.
Foster parent and child, it goes up a little bit.
Parent and child living together, so that's a
biological parent and child living together, that goes up
a fair bit.
Brother and sister reared apart, back down.
Brother and sister reared together.
So you could look at this as kind of shared genes.
And this might be something like environment.
Does make sense?
Intuitively.
That's assuming there's no interaction between genes and
the environment, which we know must happen.
So when I do this I'm treating them as if they were additive
and independent.
Everything we know about genes and the environment are
tremendously interactive.
We just don't have insight into that in any
deep way, in humans.
Here's the really stunning one.
Identical twins reared apart, 70.7 correlation.
Identical twins reared apart.
That suggests a huge influence of genes.
Identical twins reared together, 90.9.
So this is the finding that stunned people.
So look at identical twins reared apart.
They're much more like each other than a brother and
sister reared together, who share all the same environment
of education, parental support, and other things.
So I'm going to come back to this.
But as best people can estimate, and these might be
radically replaced as we deepen our understanding of
the actual genes and the actual environmental factors,
but people are estimating it's about half
and half for IQ tests.
And we discussed the bit of arbitrariness in that.
So about half and half.
Let me show you a couple of environmental influences that
have been identified.
And the first two, one suspects has to do on average
with something about the healthiness of the environment
the child was born into.
The third one is kind of fun just to talk about because you
may wonder if you have a sibling or no sibling, what
does it mean that you were first born, or second born, or
third born, at least statistically.
So let's do the first two.
Here's breast feeding, 3,000 people were followed from
birth to young adulthood, who had breast feeding, for at
least six months, correlated with a five to
seven point IQ gain.
So we said, 15 points really seems to mean something in
educational outcome.
So 5 to 7 is half of that.
So that's something.
So let's talk about this for a minute.
You could say, and I can tell you as a parent who fairly
recently had children, all the mothers in the US that I know
were going like, I've got to breast feed and
get my kid to MIT.
Two more months of breast feeding and this kid could go
all the way to tenured faculty.
I can tell you there's a lot of pressure on mothers, if you
don't know this.
Not my mother.
But now mothers hear, do this for your kid, do this for your
kid, do this for your kid, because of results like these.
So one possibility is there's something in breast milk.
That would be the direct mechanism
that's making kids smarter.
Give me another possibility that has nothing to do with
the breast milk?
Yeah?
AUDIENCE: Maybe mothers who breast feed, also tend to be
mothers who are more nurturing to their children.
PROFESSOR: It could be more nurturing to
children in many ways.
They could be mothers who can stay home and spend some time
with the children versus being under very pressured economic
circumstances that prohibit that.
It could be a lot of things.
Does that make sense?
We don't know.
Nobody has shown yet that it is the breast milk that goes
into your brain and pushes up your brain, in any sense.
It's just a correlation.
And of course, if you're a parent, I'll do the breast
feeding and let the scientists figure it out in the future.
Here's another one.
There's the birth weight.
So again, you could say the same thing.
I mean certainly having very low birth weight is a big risk
factor for lots of things.
But birth weight again goes with many factors in the
environment that are supportive for a healthy
pregnancy versus not.
So it doesn't mean that it's the birth weight.
It could be all the other things that were in the
environment during the pregnancy, at birth, and
continue, on average, in the environment of that child,
throughout their childhood and young education.
Does that make sense?
If they're born in a very unsupportive medical
environment, they might have a low birth weight.
And unless their parents win the lottery or something,
they're likely to be in a difficult environment for all
their educational years to come.
So people have tried to make clear, because it's so easy to
get into sort of little mental traps on genes versus
environment, how genetic diversity affects
heritability.
So there's a couple different ways to do it.
Let's do this one.
So imagine you had cloned tomato plants.
That means they all have the exact same genes in this
hypothetical example.
But somebody has poor soil, somebody has good soil.
Well, you'll get big differences.
And the heritability will be zero.
Environment can have huge influences.
But if you have genetically diverse plants, then you're
going to have an interaction.
So some plants will do OK, even in poor soil.
Some plants will do most spectacularly in good soil and
less spectacularly alike.
Environment by genes' interactions.
And you can see this in so many different ways.
So here's one example.
So we said height is 90% heritable within a society.
But Japanese men in the US, or people with Japanese extract,
are three inches taller than people in Japan.
So they still have whatever Japanese genes are.
They have Japanese genes.
But they're in the US getting the US diet of McDonald's.
And it's pushing them up three inches.
Height is heritable.
But environment is a big part of the story.
So it's just both.
Now, here's a fun study.
And a reason that if you're a younger sibling and you
desperately want two IQ points, you might knock off
your older sibling.
I don't recommend this.
This is tongue-in-cheek.
But it's kind of fun study, just thinking about birth
order more in a fun way.
Well, look at the whole thing, we're talking
about from 99 to 104.
So it's five points we're talking there.
But in some countries, they sort of test everybody going
into the military.
And I think this was done in Denmark.
And what they said is.
These are all children.
These are the IQ scores.
And these are the IQ scores that you would have.
But what happens if your older sibling has
passed away, sadly.
You get those points.
And here's a person who has an older sibling.
And the older sibling passed away.
And they moved up those points.
That is, if you're a younger sibling, you have a few lower
IQ points, on average.
But kind of strikingly, if your older sibling passes
away, sadly; you seem to get those IQ points as you move up
the birth order.
Yeah?
AUDIENCE: Is this if they pass away before birth, or --?
PROFESSOR: Yes.
Yeah, when they're young.
It's too late.
Sorry.
For all you in here, too late.
It's only a couple points also.
But this got into Science, because people are always
wondering about--
there's been a huge curiosity about birth order
consequences.
But let's talk a little bit about birth order again.
Because there's a second really interesting point.
So here's Raven's score.
And here is if you're a lone child, the second of two
children, the third of three, the fourth of four, the eighth
of eight, to ninth of nine.
You can see the scores keep going down.
It's not dramatic, but larger families.
And you can have a million ideas about why that would be.
About why it is the larger your family and the further
you're down on the list, you lose a few IQ points for every
sibling who's older.
So here's one idea from Robert Zajonc, who's a very creative
psychologist.
We're not sure that it's right.
But I think it's really fun to think about.
So here is this idea.
He said, I'm going to make up an idea, which is this.
The first born, maybe he is exposed only to adults.
The adults are talking to them about the views of the day and
all kinds of things.
The second born has two adults, let's say
in a typical family.
But also has an older sibling.
So the intellectual environment will be the
average of two adults and a little child.
The next one, and so on.
So he said, you can do a kind of a formula,
which is like this.
Pretend the two parents are each 30 and you're born.
We'll call your family intellectual stimulating
environment, 30.
Because we'll add up the ages and divide by the number of
people in the family.
Does that make sense?
This is not meant to be a real formula, just
a conceptual plan.
And then he said, now you have the two parents and you have a
four-year-old sibling, because you're the second born.
So now there's four of you.
We divide by 4.
And we'll say the average intellectual thing in the
family is 16.
By the time the next child comes along, a seven-year-old
sibling, three-year-old, divide by five, and the
average intellectual environment is 14.
Here's the idea.
On average, it's better for a child to have lots of
interaction with a parent, that with a little kid.
Because a parent will stimulate you more than a
little kid, although a little sibling might be a lot of fun.
But purely IQ land, two parents talking to you about
stuff, is a more educational environment than two parents
plus a sibling who is two years older than you.
Because the two-year-old can't help.
No matter how smart he or she is, they can't talk with you
like an adult.
This is the thought.
And now, here's the really fun observation.
And again, we don't really know if this is exactly right.
But every year, if you're around issues of education,
there's test scores that different states have.
And the test scores go up.
And you have taken high-tests tests right, in high schools
and grade schools and stuff.
If the test scores goes up, everybody goes, oh, reelect us
because we're awesome administration and our test
scores are going up.
We're doing everything right.
If the test scores go down, they go oh, throw the bums out
of the administration.
Their kids are watching too much MTV, turn off that
computer, and so on.
Everybody gets the test scores.
And they figure out who's good and who's bad, parents,
teachers, school systems, politicians, whatever.
Zajonc says, and this is kind of an interesting thought.
He says no, he can predict whether scores will go up or
down simply by on average in a given year, whether there are
more first borns, or second borns, or third borns.
That if he just takes that population average of every
kid, the moment they're born, he can predict years later
where the scores go.
And so here's the scores in Iowa.
Of the actual scores, they're going up and down.
So you can imagine, scores are going down.
Everybody's really upset about kids who don't study, and
teachers who don't teach, and parents who don't parent.
Scores are going up.
And the kids are awesome, the teachers are awesome, the
parents are awesome.
Because that's who gets the credit.
And he's saying, uh-uh.
This is my prediction here, based simply on for a given
birth year, the average number of older
children in your family.
That's it.
And look how well that tracks.
It's unbelievable.
So it just makes you rethink that so often when we get
information about society of what's going on, this may be
right or wrong.
But we don't really know what's going on.
There's all kinds of huge things out there in the world
that aren't the easiest things to blame or give credit to.
So they're relatively small differences, but they seem to
track interestingly in the number of siblings you have
who are older than you.
And at the same time, this idea of
parental exposure to language.
There's this widely cited study from Hart and Risley.
So they recorded for each month, for 2 and 1/2 years, a
heroic recording, one full hour of every word spoken at
home between parents and children in just 42 families.
But they categorized them as high, medium, or low
socioeconomically.
So in terms of income and education.
OK.
And they're recording lots and lots of
conversations verbatim.
And they code and analyzed every utterance in 1,300
transcripts of 30,000 pages.
The reason why this is not done a lot, it's not very
glamorous work to do.
You can imagine sitting down there.
But they're recording lots of conversations at home in
families who are better off, medium off, or poor.
And they're looking at what is the conversation like, for an
hour a day.
And here's what they find.
That variation in children's IQ and language abilities
related to the amount that the parents
speak to their children.
And that the academic success by age 8 or 9 or 10 is related
a lot to speech at 0 to 3.
Now again, you think causally.
Because you think, parents are talking to you at 0 and 3.
And 9 and 10, you're doing
differential equations, causally.
No.
The parents that are talking to you a lot, 0 to 3, are
talking to you at 4, 5, and 6 a lot, most of the time.
So if these things are not like, you get an injection,
you're done.
Many of the factors that we can measure, continue on
average, for most people in their environment.
But it's very impressive how the environment altogether
influences things.
By age 3, the cumulative vocabulary is 1,100 words in a
professional family as a child, 750 in a working class,
and 500 in a welfare family.
And welfare families, 600 words per hour, working class
750, professionals 2,153.
By age 3, the vocabulary used by children in the high SES
homes, is larger than the vocabulary used by parents in
the low SES.
By age 3, larger vocabulary.
This is just telling you the incredible cumulative power of
strong environmental influences.
Because it's unbelievably multiplicative.
It's every day, all day long.
And if you're in an environment that's supportive
or an environment that's not.
It's not one shot.
It's every day, multiply, multiply, multiply.
300 words more per hour for professional,
than the welfare family.
Extrapolate to a year.
A child in a professional family hears 11 million words,
versus 3 million in a welfare family.
And strong correlation with IQ scores by age 9.
So very huge differences in what children are
exposed to at home.
And they correlate highly with these IQ things.
So the literature is that on average, on average, the IQ
scores that children have around 9 or 10, correlate
pretty well with ones they'll have for the
rest of their lives.
Before that, it extremely jumps around.
We don't know why.
But that's they're finding.
By the time in 9 or 10, whatever you have, on average
tends to hang in there.
If you're 100 at 10, you'll tend to be 100 at 20.
If you're 120 at 10, you'll tend to be 120 at 20.
Does that make sense?
So there's been a lot of interest in evidence about
whether you can change your IQ as an adult.
So here's one study that got a lot of attention, because it
was kind of interesting in that way.
So they did a complicated task like this.
This was an n-back task.
Simultaneously you hear letters and you see little
spatial locations like this.
And every time something matched two items ago, you
would push a button.
So you're hearing them at the same time.
And if you hear a letter that was two letters
ago, you push a button.
Or same spatial location, you push one.
It's pretty hard.
They took 34 adults.
They trained them from eight to 19 days,
so less than a month.
Skipped weekends.
25 minutes a day.
It's only half an hour a day.
They train on this.
And then they tested them on some of these widely used IQ
types of measures.
Here's their performance on the task itself, getting
better and better.
OK, that's not surprising.
And the more they practiced, the higher they got.
So if you practice really hard at something, you get better
at doing it.
That's not the thing they were interested in.
They were interested in this.
Here's the IQ scores before they were trained.
The IQ scores.
They didn't practice the IQ tests.
And here's the IQ ones afterwards.
This is the control group, who did nothing.
This is the group that did the mental practice.
And you can see, they pushed up their IQ scores.
Not a lot.
But it was only 20 minutes a day for less than a month.
So these kinds of studies really intrigued
people in two ways.
And the more training you got, the more your
IQ score went up.
The more weeks you did this.
Because a), maybe we could push up IQ scores, if that's
important to push up.
This is a big decision.
Even when you're an adult.
What if you did more than 20 minutes a day for three weeks.
And b), maybe we could push up everybody's IQ score, who
needed help in that, with the right kind of
training, at any age.
So a lot of interest in that.
So let me take a step now to sort of harder topics.
Now, one of the reasons that intelligence and IQ topics
have gotten appropriately lots of concern is a terrible
history of racism and sexism associated with IQ tests and
the way people use that to argue basically inferiority of
groups, other than themselves.
So the US Immigration Act of 1924, the official government
talked about biologically weak stocks.
At that time, they were focused or prejudiced against
Italians and Jews from Europe.
Different societies, different times, as you know,
tragically, had biases against different groups in the world.
Unfortunately, it's part of the world we live in.
And even though we know now with certainty that we're all
almost identical genetically in any practical sense across
racial groups, race remains a powerful social category.
It's a very complicated topic.
The experience you've had, is the experience you've had.
But we know it's a social category.
People identify to a certain extent with that.
They recognize other people in that context.
We'll come back to that later in the course.
But it's a sort of fact of life that we often think of
ourselves as belonging to one racial group or another and
somebody else as belonging to one racial group or another.
So I'm going to focus on one thing that's both troubled
people and led to bad things, but has some interesting,
important aspects to think about.
So in the US, when people compare African American and
European American scores, there's a gap of scores that
grows over time.
So in infancy, to the extent you can test these kinds of
things, there's no difference.
By age 4, on average, people who are European American will
tend to score about four or five points
higher on IQ tests.
And as the goes up, it continues to go up.
There's a gap on average.
This is a huge average.
It's across many people across time, as people get
older in the US.
Now, we've strongly believed for many, many reasons
empirically that this is an environmental influence.
And here's one example of many pieces of evidence.
So that children fathered, for example, by Black America GIs
in Germany, brought up by German mothers, have exactly
the same IQs as white American GI
children and German mothers.
That is, in countries where stereotypes were applied in
general, partly because there wasn't a history of African
Americans in Germany at that time, the IQ
scores are the same.
So we think it's overwhelmingly evident that
it's an environmental effect.
But in the US, there's a lot of relationship between, on
average, across the entire country, on average, between
what group you're in and average income.
So here's the average income a few years ago, depending on
which group you identified yourself as belonging to.
So we talked earlier about the relationship between economic
comfort or stability or support and things like the
number of words a parent can speak to or it's time to speak
to their child.
And the habit seems to correlate with all kinds of
advantages.
So here's an incredibly powerful and important idea.
Claude Steele is a researcher at Stanford, who I knew, who
has played a big part in this.
And here's the idea.
So it's called stereotype threat.
It applies to all of us.
But in some ways depending on the world we live in, some of
us can be more vulnerable than others in certain situations.
Here's the idea.
So let me tell you the experiment and then the
interpretation.
The experiment is that he'll bring people in and give,
Claude or his students, black and white participants,
college students.
And they say, it's a laboratory experiment.
And they give them something like an SAT test.
And the groups perform just the same.
Stanford students, black and white, perform just the same.
That's the one group.
Here comes the next group of black and white students, who
are told we're going to give you a test of intelligence.
Now, look what happens.
The scores of African Americans go down.
And it doesn't even have to be the phrase "test of
intelligence," you can have people just tick off, on a
front page, what racial group they belong to and you get
almost the same effect.
So what is this?
This is understood as stereotype vulnerability.
That is, tragically in the US there's a stereotype that
African Americans are not as good
academically as white Americans.
It's a pernicious stereotype.
It's one we can decry morally and say it's a bad thing.
But it's out there.
There's another area where African Americans are thought
of as phenomenal by stereotype, which is sports,
in this country.
It's a weird thing.
The idea is that knowledge of these things, even if this is
your real performance, once that thought enters your mind
that I'm doing something that some people say I'm not going
to do such a good job at, is enough to make you
underperform compared to your true potential.
So the other area where this has been studied a lot is
women and mathematics.
I think that's disappearing.
When I grew up, everybody was worried that women weren't
given as good an academic support as men
or girls and boys.
OK, it's reversed.
In my lifetime, it's reversed.
Because now, by every criteria, women are
outperforming men in the US by every criteria, at least
societally, the number who finish school, your beginning
salaries, everything.
So now they're worried that us boys are
really being left behind.
So these things change because they're cultural inventions.
They're cultural inventions.
And cultural morays change.
And sometimes in good ways, hopefully.
So stereotype threat is that other's judgments or one's own
actions will confirm negative stereotypes about one's group.
Oh, you should do badly on something or you should do
well on something.
So they studied on women on that, old people.
Athletic ability of course runs the opposite.
The experiment was kind of fun.
They had a very athletic African American instructor
come up and start doing push-ups.
And all the white guys started to lapse in their push-ups.
They got tired really fast, compared to an equally
athletic white trainer who came up to the front.
Does that make sense?
It's whatever is the stereotype you have in your
head, if you say OK, oh, oh, I'm not supposed to do so good
in this, you underperform.
Not everybody, all the time of course.
But enough that we have to be concerned about that.
More for academic performance probably than push-ups.
But who knows.
So here's this achievement gap.
And different scores between again, at age 13, between
whites and blacks in the United States, which we know
shouldn't be there.
Many factors are in it.
A huge variation among people, of course.
These are huge averages.
But one that everybody wants to get rid of, in a just
society where everybody has an equal opportunity.
So here's a result that's so unbelievable, that if it
weren't for some subsequent results, I wouldn't even show
it to you, even though it's a well-done experiment.
But the message of it seems so incredible.
So here's what they did.
In this well-controlled study in Science, and there's been
some follow-ups that have exactly done this.
So they took African American students and white students.
And they had them take these various tests.
But some of them, at the beginning of the year, wrote
an affirmation.
They had to choose a value from a list and write an
in-class essay about why the chosen value is
important to you.
The controls chose a value from those same lists and
wrote an in-class essay about why the value might be
important for somebody else.
You're writing a one-time essay about why something
matters to you or matters to somebody else.
So obviously what matters to you is more powerful for you.
And by just doing that, there's a 40% reduction in the
African American students in the study in
their achievement gap.
Their scores went up 40% because they wrote one essay
at the beginning of the year about why values are important
to them and related to education.
One essay did that.
Unbelievable.
And just a reminder about how much one's attitude incredibly
influences your performance.
You have a range of things you can do it.
And what gets you to the top of your range that's in you,
or the bottom of your range, has a lot to do with
attitudes, that can be moved around by a lot of things.
One essay overcame a tremendous amount of the
concerns that on average, African American students have
about academic achievement.
And it's not just that.
So in this course, you only get a couple of tips of things
that are useful to you for courses.
Here's one.
It's the same principle, but it seems
to apply for everybody.
So here's the experiment, also published in Science.
It's really cool.
So they brought in students.
And they said, look students often are worried about how
they're going to do in a test, especially if it's an area you
think you're not so good in.
So they had them take a test on Gauss's modular arithmetic.
Here's the pre-test.
Everybody did about the same.
Then they said, OK now, they have to create pressure.
Because of course if you take a test in an experiment,
that's not pressured, right?
Pressure is the grade you're going to get, whether it lets
you into medical school, whether you get to become the
head of the American Medical Association.
That's pressure, right?
So they say oh, here's what we're going to do now.
We're going to give you another test, everybody
scoring about the same.
But you can make a fair bit of money with a partner who's
down the hall.
We should tell you that partner has already done a
really good job on the second version of the test.
So if you don't do well, you don't get money and the
partner down the hall doesn't get your money.
If you do well in the second test you're about to take now,
then everybody wins.
So they're trying to make you feel pressured.
On man, I want to win the money.
Plus there's a guy down the hall who already did well and
I'm going to let us down.
They're trying to make you feel as
pressured as you might.
As much as they can in an experiment, like you do in a
regular test, in a regular course.
So trying to create pressure and anxiety.
And then for 10 minutes, the controls just sit there and
think about it.
Oh, I hope I don't mess up now.
The pressure is on.
I hope I don't meet the person, if I don't do a good
job, down the hall.
An expressive group wrote an essay for 10 minutes about
their thoughts and feelings.
Oh, I wrote this.
This is a huge mistake.
This should be "better." I'll fix it up.
Better, better, better.
I did it unrelated, in writing.
So here's what happens.
The group that just sat there did nothing.
Their performance doesn't-- let me get this right.
The performers that wrote the expressive writing, their
score goes up.
Everybody else's scores go down.
Because here, here's where they're beginning.
Now, they get pressured.
And they perform less well.
They're choking.
The group that wrote the essay, their
performance stays up.
And it's kind of ironic, because a theme of comedy is
frequently when they tell you, whatever you do, don't tell
somebody x.
And then my mistake, you tell x.
Have you seen that a comedy show?
So you could have thought, well writing an essay about my
thoughts and feelings about how much anxiety and pressure
I feel, is like the worst thing you can do.
It's like, I don't want face it.
I'd rather clear my mind.
But it turns out that when people write this little essay
about the thoughts and feelings about their anxiety,
their scores rise.
And if they don't write that kind of an essay, the scores
fall, because you've introduced here the stress and
anxiety that we think is a part of regular testing.
Does that makes sense?
I'll fix the slide.
I'm sorry about the typo.
Is that OK?
I'm almost a little afraid to give you advice, because
somebody will write an essay, do bad on the physics test,
and say oh, this is terrible.
I would have gotten a A.
But it seems like writing a little essay about your
thoughts and feelings actually pushes scores up.
I mean that's the scientific evidence.
But again, it's just a reminder of how powerful
feelings and attitudes are, whether they're in us or
visited on us by the world, in how well we perform, within
the range of performance that are within us to start with.
I have two more points.
So we talked a little bit about entity versus growth.
You know people who believe they're like, I'm only so good
at something.
I'm only so good at basketball, I'm only so good
at math, I'm only so good at programming, I'm only so good
of writing, or whatever, versus people who say, the
harder I work, the better I'll get.
And that pretty much, this work from Carol Dweck, that
many people tend to go for one thing or the other.
Is it are we born with talent and that's
pretty much the deal?
Or the harder we work, do we get more
talented at doing something?
And so this is the kind of questionnaire.
And these are literally questions, so she gives
students, you have a certain amount of intelligence and you
really can't change it.
I strongly agree.
That's this trait model.
Or I disagree.
The harder I work, the smarter I can be.
And what she did for example, is give that kind of question
to students.
And then follow them in their performance on a math course.
Here's the ones who believed they could get better.
Here's the ones who said they only have so much math ability
and intelligence.
And look at the ones who thought they could get better,
got better.
So that seems like a really good thing to have, is not
only the positive attitude.
But a real belief that the harder the work, the smarter
you'll get.
Last two slides.
So finally, finally, finally.
And we've had a couple of them, but almost none, a
longitudinal, random assignment study.
Which doesn't sound hugely exciting, but that's the best
science we can ever do.
Randomly assign people to things.
And then follow them over time to understand how life works.
So one of the famous studies is, this is Perry Preschool.
So it followed into adulthood, 123 children from low SES
environments in Michigan.
And they were randomly divided, randomly divided.
And there's no randomness right, in life, mostly.
You're not randomly given genes.
You're not randomly put into a household.
It's always things are super correlated with each other.
And it's very hard to tease them apart.
But here they took kids who were from poor families and
put them randomly into two groups.
One group is a program group, who received a high-quality
active learning preschool program and home visits, to be
supportive as well.
So they got help at home and help in preschool.
And a no-program group, who didn't get any of these.
I can tell you that when you do random assignment studies
in real life like this, some people argue, I don't agreed
with this, that it's unethical, because you should
help everybody all the time.
But if you don't do this, you never figure
out what helps people.
OK It's a little bit of a circular--
you can't figure out what really helps people.
And then in a really rare thing-- so it's random
assignment.
They followed them ages 3 to 11, 14 to 15, 19, 27, and 40.
They follow you through most of your
childhood and adult life.
So what happens?
Here's their IQ scores?
Here's the program people in red and the
no-program people in blue.
And you can see that for a few years, they separate by IQ.
But by age 7, they're pretty much the same.
And when these kind of data came out, because of course
after the preschool, they go back to their
regular local schools.
They're pretty much the same schools.
So people, after that they said, well Head Start is a
kind of a program to help kids who are poor, get a head start
in education and support.
It's no good.
It doesn't do anything.
Because once they get back into schools that not very
supportive, the benefits of the program disappear.
You didn't do anything for the kid, because unless you fix
everything in their lives, that one year just doesn't
make a difference in the long run.
So everybody said, Head Start programs are just, sadly, a
waste of resources, because they don't do anything for
these children over the longer term.
But here's the remarkable thing.
They kept following these kids.
And here's what they found.
For example, in the number of arrests, 36 had five or more
arrests in the program group.
But all the way up to 55, for the no-program group.
That's a big difference, how often you're arrested.
That's a big outcome in life.
Earning $20,000 or more at age 40, program group 60%;
no-program group, 40%.
Completed high school, 45% to 65%.
20% increase in completion of high school, from one year of
help before kindergarten.
Basic achievement at age 14, way up.
Willingness to do homework, way up.
So what's that's telling us is, IQ is a
pretty interesting thing.
And we've talked a lot about it.
It is an interesting thing.
But there's something really deep in the ways you can help
people, that make them succeed in life.
Not get in trouble, avoid bad things, make money, finish
school, do your work.
That one year of school changed these kids for the
rest of their lives, on average.
And imagine if you had done two years or five years?
And IQ in this case doesn't capture it at all.
There's something else in them that changed, that made them
more resilient in life and successful in the long run.
So there's a lot of pieces to who does well and not well in
ways we wish for everybody.
And IQ is a piece of that story.
But there's a lot of pieces.
So thanks very much.