WEBVTT

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Professor Paul Bloom:
What we've been talking about

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so far in the course are human
universals, what everybody

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shares.
So, we've been talking about

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language, about rationality,
about perception,

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about the emotions,
about universals of

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development, and we've been
talking about what people share.

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But honestly,
what a lot of us are very

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interested in is why we're
different and the nature of

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these differences and the
explanation for them.

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And that's what we'll turn to
today.

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So first, we'll discuss how are
people different,

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different theories about what
makes you different in a

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psychological way from the
person sitting next to you,

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and then we'll review different
theories about why people are

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different.
And this is the class which is

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going to bother the most people.

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It's not dualism.

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It's not evolution.

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It's this because the
scientific findings on human

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psychological differences are,
to many of us,

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shocking and unbelievable.

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And I will just try to persuade
you to take them seriously.

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Okay.
So, how are people different?

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Well, there's all sorts of ways.

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Your sexual identity--It is at
the core of your being for

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almost all of us whether you're
male or female.

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How we refer to you in
language, what pronoun we use,

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is indexed on how we--on
your--on how--whether you're

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male or female and related to
that though imperfectly is your

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sexual orientation,
who you're attracted to.

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The question of why some of us
think of ourselves as males and

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others as females,
and the question of why some of

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us would ideally want to have
sex with males,

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others with females,
others with both,

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and then a few others who have
harder to define desires,

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is such a good question that
we're going to talk about it

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after spring break while all the
sexual desire has been spent and

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you could focus on [laughter]
on a scientific discussion of

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this--not that I recommend you
do that on spring break.

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How happy are you?

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This is also such a good topic
it's going to get its own class.

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The very last class of the
semester is devoted to happiness

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and the question of what makes
people happy,

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what makes people unhappy,
and what makes people differ in

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their happiness.
If I asked you to rank how

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happy you are from a scale of 1
to 10, the numbers would differ

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across this room.

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And there's different theories
as to why.

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Your success and failure in
life--This is somewhat

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interesting because you could
study this in more or less

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objective ways.
We don't have to ask people.

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We could look at your
relationships,

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how they begin,
how they end,

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your job satisfaction.

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We could look at your criminal
records.

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Some of you are going to see
time.

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Most will not.
Some of you will get into

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little troubles all through your
life.

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Some of you already have seen
the inside of a police station,

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possibly a lineup.

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Others couldn't go near such a
thing.

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What determines that?

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And at the root of all human
differences are two main

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factors.
And so, I want to talk about

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the two main interesting
factors.

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One is personality.

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The other is intelligence.

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And this is what--These are the
differences I'll talk about

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today first from the standpoint
of how do we characterize them,

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how do we explain them,
and then from the standpoint of

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why these differences exist in
the first place.

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One way to characterize
personality is in terms of

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people's style with dealing
with--in dealing with the world

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and particularly their style
with dealing--in dealing with

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other people.
So, you take a simple character

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you know of and you could talk
about that person's personality.

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You could talk about it in
terms of being impulsive,

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irresponsible,
sometimes lazy,

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good-hearted.
You could compare that person's

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personality with other people's
personalities such as my

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colleague who gave a talk last
class.

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He's wonderful.
He's responsible and reliable

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and very kind [laughter]
and different from Homer.

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And so, this difference is a
difference in personality.

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Now, when we talk about
personality we're talking about

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something else as well.

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We're talking about a stable
trait across situations and

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time.
So, if all of a sudden the

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person next to you kind of
smacks you in the head,

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you might be angry but we
wouldn't call that "personality"

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because that's something that's
a result of a situation.

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We'd all feel that way in that
situation.

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It's "personality" if you walk
around all the time angry.

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That'd be a stable trait.

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That'd be something you carry
around with you and that's what

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we mean by personality.

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Now, how do we scientifically
characterize differences in

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personality?
And it's a deep question.

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There's been a lot of attempts
to do so.

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Any assessment has--Any good
assessment has to satisfy two

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conditions.
And these are terms which are

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going to show up all over
psychological research but it's

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particularly relevant for this
sort of measure.

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One is "reliability."

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Reliability means there is not
measurement error.

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And one crude way to think
about reliability is,

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a test is reliable if you test
the same person at different

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times and you get the same
result.

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My bathroom scale is reliable
if whenever I stand on it,

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it gives me more or less the
same number.

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It's not reliable if it's off
by ten pounds in the course of a

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day.
Similarly, if I give you a

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personality test now and it says
that you're anxious and

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defensive,
well--and then give it to you

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tomorrow and it says you're calm
and open minded,

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it's not a reliable test.

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So, reliable is something you
could trust over time.

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"Validity" is something
different.

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Validity is that your test
measures what it's supposed to

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measure.
So, validity means it's sort of

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a good test.
Forget about how reliable it is.

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Does it tap what you're
interested in?

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So, for example,
suppose I determine your

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intelligence by the date of your
birth.

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I figure out what day you were
born and I have a theory that,

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from that, predicts how smart
you are.

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That's my intelligence test,
the date of your birth.

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Maybe people born in January
are the dumbest,

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people born in December are the
smartest.

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Is that--I was born on
Christmas Eve.

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[laughter]
Is that a reliable test?

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Yes, it's a wonderfully
reliable test.

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I'll test you today;
I'll test you tomorrow;

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I'll test you next year;
I'll test you the day you die;

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I'll get the same IQ score.

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Is it a valid test?

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It's a joke.
It's absolutely not a valid

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test.
It has nothing to do with

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intelligence.
But you noticed these are two

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different things.

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Something can be reliable but
not valid and something can be

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valid and not reliable.

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Now, there are no shortage of
personality tests.

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You could get them all over the
place including on the web.

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So, I took one recently.

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I took "which super hero are
you?"

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[laughter]
And it's a series of questions

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determining what super hero you
are.

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You could take this yourself if
you want to.

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The same web page,
by the way, offers you a test

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in whether you're "hot" or not.

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We'll discuss that later.

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And when I did this [laughter]
it told me I was Batman

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[laughter]
and "you are dark,

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love gadgets,
and have vowed to help the

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innocent not suffer the pain you
have endured."

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Now, the honest-- [laughter]
Now, to be honest though,

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it's neither reliable nor
valid.

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When I first did the test I
came up as "The Incredible

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Hulk."
I then changed my answers a bit

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and was "Wonder Woman."

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[laughter]
And finally,

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out of frustration,
I carefully tailored my answers

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so I would be Batman.

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But the fact that I can do
that, well, raises questions

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about both the reliability of
this measure and its validity.

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Here is an example – a real
world example.

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This is, in black and white
form, a version of the Rorschach

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test, the Rorschach inkblot
test.

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How many people have heard of
the Rorschach test?

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Okay.
Is there anybody here who has

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actually, in any sort of
situation, taken a Rorschach

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test?
Some people scattered in the

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room have taken them.

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It was originally used only for
psychiatric cases but then

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became extremely common.

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About eighty percent of
clinical psychologists claim to

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use it and most graduate
programs in the American

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Psychological Association who
are accredited teach it.

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Catholic seminaries use it for
people who want to join the

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seminary.
It was invented by a guy named

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Herman Rorschach.

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He devoted his entire life to
the inkblot test.

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His nickname when he was a
teenager – I am not kidding

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you – was "Inkblot."

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[laughter]
And the idea is by looking at

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these inkblots and then seeing
what somebody says you get great

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insights into the nature of
their personality,

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into what they are.

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Anybody want to try it?

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Come on.
Yes.

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What do you see?
Student:

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I see two people holding hands
pressed together.

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Professor Paul Bloom:
Two people holding hands pressed

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together.
Very good.

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Anybody have a different
reading?

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Yes, in back.
Yes.

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Yes.
Student: Dancing bears.

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Professor Paul Bloom:
Dancing bears.

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Okay.
Good.[laughter] Good.

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Okay.
I got to write your name down--

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[laughs][laughter]
report you to health-- No.

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Dancing bears, very good.

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Anybody else?
One other.

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Yes.
Student:

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A man in a ski mask.

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Professor Paul Bloom: A
man in a ski mask.

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Well, it turns out that there
are right answers and wrong

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answers to the Rorschach test.

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According to the test,
and this is from a real

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Rorschach test,
"it is important to see the

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blot as two human figures,
usually females or clowns."

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Good work over there.

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"If you don't,
it's seen as a sign you have

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problems relating to people."

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[laughter]
If you want to go for "a cave

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entrance" or "butterfly" or
"vagina," that's also okay.

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[laughter]
Now, the Rorschach test is

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transcendently useless.

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It has been studied and
explored and it is as useless as

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throwing dice.
It is as useless as tea leaves.

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Nonetheless,
people love it and it's used

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all over the place.

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It is used for example in child
custody cases.

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If you have broken up with your
partner and you guys are

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quarreling over who gets to keep
the kids,

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you might find yourself in a
shrink's office looking at this.

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And in fact,
this is why they end up on the

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web.
There are services.

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There are people who have been
kind enough to put on the web

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these inkblots,
including the right answers to

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them.
But they are worthless as

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psychological measures.

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Can we do better?

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Well, we probably can.

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Gordon Allport did a study
where he went through the

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dictionary and took all of the
traits that he believed to be

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related to personality and he
got eighteen thousand of them.

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But what was interesting was
they weren't necessarily

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independent traits.

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So, the traits like "friendly,
sociable, welcoming,

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warm-hearted" seemed to all tap
the same thing.

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So, Cattell and many others
tried to narrow it down,

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tried to ask the question,
"In how many ways are people's

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personalities different from one
another?"

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How many parameters of
difference do you need?

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How many numbers can I give you
that would narrow you in and say

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what personality you are?

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One approach was from Eysenck,
who claimed there were just

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two.
You could be somewhere on the

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scale of
introverted-extroverted,

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and somewhere on the scale of
neurotic and stable.

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And since there's basically two
types of traits with two

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settings for each,
there are basically four types

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of people.
Later on he added another trait

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which he described as
"psychoticism versus

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non-psychoticism" that crudely
meant whether you're aggressive

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or empathetic.
And then you have three traits

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with two settings each giving
you eight types of people.

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Later on Cattell dropped it
down into sixteen factors.

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So, these sixteen personality
factors are sixteen ways people

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would differ.
And so, if I asked you to

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describe your roommate along
these sixteen dimensions,

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you should be able to do so.

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More recently,
people have come to the

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conclusion that two or three is
too few, but sixteen might be

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too many.
And there's a psychological

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consensus on what's been known
as "The Big Five."

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And "The Big Five" personality
factors are these,

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and what this means is when we
talk about each other and use

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adjectives,
the claim is we could do so in

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thousands of different ways,
but deep down we're talking

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about one of these five
dimensions.

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This means that when a
psychological test measures

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something about somebody,
about their personality,

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if it's a good test it's
measuring one of these five

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things.
And it means that,

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as people interacting with one
another in the world,

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these are the five things that
we're interested in.

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So, one of them is "neurotic
versus stable."

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Is somebody sort of nutty and
worrying or are they calm?

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"Extrovert versus introvert."

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"Open to experience versus
closed to experience."

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"Agreeable," which is
courteous, friendly versus non

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agreeable, rude,
selfish.

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And "conscientious versus not
conscientious," careful versus

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careless, reliable versus
undependable.

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A good way to think about these
things is in terms of the word

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"ocean," o-c-e-a-n.

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The first letter captures
openness, conscientiousness,

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extroversion,
agreeableness,

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and neuroticism.
And the claim is those are the

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four--the five fundamental ways
in which people differ from one

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another.
Well, why should we believe

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this?
Why should we take this theory

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seriously?
Well, there's actually some

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evidence for it.
It seems to have some

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reliability in that it's stable
over time.

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So, if you test people over
years--If I test your

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personality now on the five
traits and test you five years

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from now, it will not have
changed much.

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And once you pass the age of
thirty, it's very stable indeed.

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If you think about your parents
and then give Mom and Dad a

16:21.839 --> 16:26.139
mental test on where they stand
on each of the five traits,

16:26.139 --> 16:28.759
ten years from now Mom and Dad
will still be there.

16:28.759 --> 16:33.889
It also seems to get agreement
across multiple observers.

16:33.889 --> 16:39.199
So, if I ask for each of their
five traits--If I ask your

16:39.204 --> 16:43.004
roommate what he or she thinks
of you,

16:43.000 --> 16:47.180
then I ask your professor what
he or she thinks of you and your

16:47.183 --> 16:49.953
mom what he or--what she thinks
of you,

16:49.950 --> 16:53.300
[laughter]
how would--back to gender--How

16:53.304 --> 16:55.154
would they match up?

16:55.150 --> 16:58.200
They tend to overlap a lot.

16:58.200 --> 17:01.000
You walk around and you
leave--and your personality

17:00.997 --> 17:03.847
leaves a trail in the minds of
people around you.

17:03.850 --> 17:07.080
And this trail is characterized
in terms of these five

17:07.078 --> 17:09.928
dimensions.
Finally, it seems to

17:09.926 --> 17:13.316
be--predict real-world behavior.

17:13.319 --> 17:16.519
If this didn't have anything to
do with the real world,

17:16.522 --> 17:19.252
you wouldn't be very happy
calling it valid,

17:19.250 --> 17:21.850
you wouldn't take it seriously
as a test, but it does.

17:21.849 --> 17:25.649
So, conscientiousness--how you
score on a conscientious scale,

17:25.648 --> 17:28.698
relates to how faithful you are
to your spouse.

17:28.700 --> 17:33.270
How openness--open you are on a
psychological personality test

17:33.269 --> 17:37.089
relates to how likely you are to
change your job.

17:37.089 --> 17:41.269
"Extroverts" look people in the
eye more and have more sexual

17:41.271 --> 17:43.921
partners because they're
extroverts.

17:43.920 --> 17:45.950
So, these are real scales.

17:45.950 --> 17:48.300
The "Batman,
Hulk, Wonder Woman" doesn't

17:48.299 --> 17:50.889
correspond to anything in the
real world,

17:50.890 --> 17:54.250
but where you stand on each of
these five dimensions does seem

17:54.248 --> 17:57.538
to capture it.
As an example of the agreement,

17:57.542 --> 18:01.362
by the way, somebody did a
study of several of the

18:01.355 --> 18:06.015
characters on the television
show "The Simpsons" because they

18:06.023 --> 18:10.073
wanted to find characters which
everybody knew.

18:10.069 --> 18:14.969
And they had thirteen subjects
judge these Simpson characters

18:14.966 --> 18:17.656
on each of the five dimensions.

18:17.660 --> 18:20.620
These is "openness,
neuroticism,

18:20.622 --> 18:24.832
conscientiousness,
and extroversion" and they

18:24.826 --> 18:27.976
found considerable agreement.

18:27.980 --> 18:30.950
And this isn't actually--What
I've covered up is the

18:30.951 --> 18:33.841
"agreeableness."
So, for those of you who have

18:33.842 --> 18:37.272
never seen the television show,
this is all going to be

18:37.273 --> 18:40.013
confusing,
but those of you who have,

18:40.006 --> 18:44.696
can you guess which characters
would be particularly agreeable?

18:44.700 --> 18:47.890
Anybody guess.
Yeah.

18:47.890 --> 18:49.480
Student: Flanders
Professor Paul Bloom:

18:49.483 --> 18:51.653
Flanders.
You are right.

18:51.650 --> 18:55.220
The most agreeable people are
Flanders and Marge.

18:55.220 --> 18:58.330
Who would not so agreeable?

18:58.329 --> 19:02.069
Student:
Krusty Professor Paul

19:02.065 --> 19:05.985
Bloom: Krusty is
actually--Krusty is a

19:05.991 --> 19:09.251
complicated case [laughter]
but Mr.

19:09.247 --> 19:12.597
Burns--but also--Where is he?

19:12.599 --> 19:16.249
Oh, he's not--Nelson,
where's Nelson?

19:16.250 --> 19:18.340
Anyway, there's Nelson.

19:18.339 --> 19:23.889
You get strong consensus that
Ned Flanders and Marge Simpson

19:23.885 --> 19:27.825
are highly agreeable people,
6.27 and 5.46,

19:27.834 --> 19:31.974
while Mr.
Burns and Nelson are very low.

19:31.970 --> 19:34.910
Nelson's the little kid that
when trouble happens he goes,

19:34.905 --> 19:37.375
"Ha ha."
And that's a psychological sign

19:37.379 --> 19:38.769
for low agreeability.

19:38.770 --> 19:41.160
[laughter] Okay.
That's all I want to say at

19:41.162 --> 19:44.072
this point about personality and
how we measure it and,

19:44.069 --> 19:46.749
again, we're going to get back
to it later when we talk about

19:46.753 --> 19:48.053
differences in personality.

19:48.049 --> 19:51.589
Now, I want to deal with the
second big difference.

19:51.589 --> 19:53.879
The second big difference is
intelligence.

19:53.880 --> 19:57.840
Now, how do you define
intelligence?

19:57.840 --> 19:59.120
There's no easy definition.

19:59.119 --> 20:01.339
Like personality,
it's kind of difficult to get

20:01.336 --> 20:03.646
your fingers on what we're
talking about here.

20:03.650 --> 20:07.960
In one survey they asked 1,000
experts to define intelligence.

20:07.960 --> 20:10.720
And some answers showed up over
and over again.

20:10.720 --> 20:14.130
So, just about everybody said
intelligence involves abstract

20:14.125 --> 20:17.235
reasoning, problem solving,
and the capacity to acquire

20:17.241 --> 20:20.821
knowledge.
That's at the core of being

20:20.821 --> 20:23.561
smart.
Other people mentioned things

20:23.563 --> 20:26.423
like memory, mental speed,
language, math,

20:26.424 --> 20:30.604
mental speed again,
knowledge, and creativity also

20:30.596 --> 20:33.316
as hallmarks for intelligence.

20:33.319 --> 20:37.129
And again, it might be
difficult to define it but you

20:37.133 --> 20:39.923
have a gut feeling about what it
is.

20:39.920 --> 20:42.830
So, you know Homer is
actually--and this is part of

20:42.828 --> 20:45.618
the show--is actually of limited
intelligence.

20:45.619 --> 20:48.989
My colleague is of very high
intelligence,

20:48.993 --> 20:51.383
a wonderful fellow,
[laughter]

20:51.379 --> 20:55.989
but he's probably not as smart
as that guy who is really,

20:55.986 --> 20:58.866
really smart.
And this guy,

20:58.865 --> 21:02.705
Ralph Wiggum,
is particularly stupid.

21:02.710 --> 21:03.980
[laughter]
And so you have a range.

21:03.980 --> 21:06.580
And it's important to figure
out how to characterize it;

21:06.579 --> 21:09.569
this is what research does,
but there's a gut feeling that

21:09.568 --> 21:12.658
there are some people who are
smart and other people who are

21:12.662 --> 21:15.912
very smart and some people who
are dumb and others who are very

21:15.913 --> 21:17.793
dumb.
What you want to do,

21:17.789 --> 21:21.619
from a scientific standpoint,
is characterize this in a more

21:21.621 --> 21:23.831
robust and interesting fashion.

21:23.829 --> 21:27.139
And the textbook has a nice
review of the history of

21:27.141 --> 21:29.931
attempts to define and measure
intelligence,

21:29.933 --> 21:33.443
but there is a couple of ideas
I want to focus on.

21:33.440 --> 21:38.560
One is an idea developed by
Spearman, which is there's two

21:38.555 --> 21:40.705
types of intelligence.

21:40.710 --> 21:44.290
There is "G" and there is "S."

21:44.289 --> 21:48.229
"S" is your ability on specific
tests.

21:48.230 --> 21:53.280
So, if there is ten tests that
you're given as part of an IQ

21:53.280 --> 21:57.560
test, ten subtests,
you'll get a different score on

21:57.560 --> 21:59.700
each of the subtests.

21:59.700 --> 22:02.820
There'll be a math test and a
reading test and a spatial test

22:02.821 --> 22:04.591
and you'll get different scores.

22:04.589 --> 22:10.049
"G" refers to a general
intelligence.

22:10.049 --> 22:14.779
And the general intelligence is
something you bring to each of

22:14.783 --> 22:16.493
the tests in common.

22:16.490 --> 22:18.600
So, this is diagrammed here.

22:18.600 --> 22:20.380
You have these six tests.

22:20.380 --> 22:24.850
For each of them there is an
"S" and then above that there is

22:24.853 --> 22:27.583
a "G."
Now, "G" is a very important

22:27.581 --> 22:29.601
notion.
The term "G" is used by

22:29.598 --> 22:32.598
psychologists a lot even in
casual conversation.

22:32.599 --> 22:34.589
People say, "So,
what do you think of him?"

22:34.590 --> 22:38.710
"I think he is high 'G.'"
And what you mean is he's a

22:38.707 --> 22:41.787
smart guy.
Why do you need "G?"

22:41.789 --> 22:44.489
Well, you wouldn't need "G" if
your performance on each of

22:44.488 --> 22:46.758
these tests had nothing to do
with each other.

22:46.759 --> 22:51.339
If the tests were genuinely
separate, there'd be no general

22:51.344 --> 22:54.124
intelligence.
But what people find over and

22:54.123 --> 22:57.093
over again is that when it comes
to explaining people's

22:57.091 --> 22:59.621
performance on multiple
intellectual tasks,

22:59.620 --> 23:01.230
there's two things going on.

23:01.230 --> 23:05.070
There's how good there is--they
are on the specific task,

23:05.070 --> 23:09.320
but then there's also a sort of
general correlation that people

23:09.322 --> 23:10.902
bring to the tasks.

23:10.900 --> 23:13.770
And I could express this with
an athletic analogy.

23:13.769 --> 23:18.119
Imagine I'm running a gym and
we have all of these different

23:18.117 --> 23:21.537
athletic tests.
So, we have a running test,

23:21.537 --> 23:25.627
we have a basketball shooting
test, a swimming test,

23:25.630 --> 23:28.360
fencing, a list of ten of them.

23:28.359 --> 23:31.669
Now, each of you go through
each of the tests and then

23:31.669 --> 23:33.479
you'll each get ten scores.

23:33.480 --> 23:38.850
But what we'll discover is that
the scores are not independent

23:38.852 --> 23:42.072
of one another.
People who are good at one

23:42.068 --> 23:44.908
athletic thing tend to be good
at another.

23:44.910 --> 23:47.970
If there's somebody who's
really good at running and

23:47.970 --> 23:50.910
swimming, odds are they're
probably pretty good at

23:50.910 --> 23:53.490
climbing.
And the same thing holds for

23:53.490 --> 23:57.350
IQ, which is above and beyond
how good people are at specific

23:57.349 --> 24:00.949
things there seems to be a
factor as to how well they are

24:00.951 --> 24:04.671
in general.
And this factor is known as "G."

24:04.670 --> 24:08.660
Now, there's,
again, an extensive history of

24:08.663 --> 24:14.333
modern intelligence tests and
what's really interesting is the

24:14.329 --> 24:17.269
tests now.
What you need to know about the

24:17.265 --> 24:19.315
modern tests,
the Wechsler test for both

24:19.323 --> 24:21.753
adults and children,
is how they're scored.

24:21.750 --> 24:24.910


24:24.910 --> 24:29.990
The way they are scored is that
100 is average.

24:29.990 --> 24:33.050
So, it's just automatic.

24:33.050 --> 24:35.030
Whatever the average is is 100.

24:35.029 --> 24:37.459
It's as if I did the
Midterm--graded the Midterm,

24:37.458 --> 24:39.838
computed the average,
gave everybody who got the

24:39.836 --> 24:41.856
average 100, said your score is
100.

24:41.860 --> 24:43.370
It's just the average.

24:43.369 --> 24:50.549
It works on the normal curve
and what this means is that it

24:50.548 --> 24:57.598
works so that the majority,
68%, get between 85 and 115 on

24:57.602 --> 25:02.642
their IQ test.
The vast majority,

25:02.644 --> 25:07.184
95%, get between 70 and 130.

25:07.180 --> 25:10.550
If you are, say,
above 145 IQ,

25:10.553 --> 25:15.553
which I imagine some people in
the room are,

25:15.554 --> 25:20.444
you belong to 0.13% of the
population.

25:20.440 --> 25:22.470
That's the way IQ tests work.

25:22.470 --> 25:25.250
Now, this is about IQ tests.

25:25.250 --> 25:29.210
We could now ask about their
reliability and their validity.

25:29.210 --> 25:30.410
What do they mean?

25:30.410 --> 25:34.980
Well, this has turned out to be
a matter of extreme debate.

25:34.980 --> 25:37.760
This just reiterates what I
just said.

25:37.759 --> 25:42.079
A lot of the debate was spawned
by the book by Herrnstein and

25:42.077 --> 25:46.467
Murray about--called The Bell
Curve. And in The Bell

25:46.467 --> 25:50.497
Curve these authors made the
argument that IQ matters

25:50.498 --> 25:54.958
immensely for everyday life and
that people's status in society

25:54.959 --> 25:59.279
– how rich they are and how
successful they are – follows

25:59.277 --> 26:03.377
from their IQ as measured in
standard IQ tests.

26:03.380 --> 26:07.950
Now, this book made a lot of
claims and it's probably before

26:07.950 --> 26:12.830
many of you--many of your time,
but spawned huge controversy.

26:12.829 --> 26:16.149
And as a result of this
controversy some interesting

26:16.148 --> 26:19.418
papers came out.
One response to the Herrnstein

26:19.423 --> 26:22.793
and Murray book was by the
American Psychological

26:22.788 --> 26:25.468
Association,
which put together a group of

26:25.465 --> 26:28.715
fifty leading researchers in
intelligence to write a report

26:28.717 --> 26:31.907
on what they thought about
intelligence--what they thought

26:31.913 --> 26:34.143
about,
"Does IQ matter?

26:34.140 --> 26:35.800
How does IQ relate to
intelligence?

26:35.799 --> 26:38.529
How does--what's the
different--why are people

26:38.530 --> 26:40.230
different in intelligence?

26:40.230 --> 26:42.950
Why do different human groups
differ in intelligence?"

26:42.950 --> 26:44.920
and so on.
At the same time,

26:44.917 --> 26:48.047
there was also another group of
IQ researchers,

26:48.051 --> 26:52.141
not quite the same as the first
group, got together and wrote

26:52.137 --> 26:55.067
another report.
And if you're interested in

26:55.073 --> 26:58.633
this, the links to the reports
are on the Power Point slide.

26:58.630 --> 27:01.180
Well, what did they conclude?

27:01.180 --> 27:06.530
The conclusions were slightly
different but here's the broad

27:06.528 --> 27:11.418
consensus by the experts
regarding the importance of IQ

27:11.423 --> 27:14.303
tests.
And the claim is IQ is strongly

27:14.297 --> 27:17.727
related more so--probably more
so than any other single

27:17.725 --> 27:21.275
measurable human trait to many
important educational,

27:21.279 --> 27:24.229
occupational,
economic, and social outcomes.

27:24.230 --> 27:27.670
In some cases,
the correlation is very strong

27:27.674 --> 27:32.454
such as success in school and
success in military training.

27:32.450 --> 27:35.450
In other cases,
it's moderate but robust such

27:35.447 --> 27:37.147
as "social competence."

27:37.150 --> 27:40.410
And in other cases it's smaller
but consistent,

27:40.411 --> 27:44.101
"law abidingness," and they
conclude whatever IQ test

27:44.097 --> 27:48.277
measure it is of great practical
and social importance.

27:48.280 --> 27:50.940
So, IQ matters.
More particularly,

27:50.942 --> 27:53.982
IQ matters for "social
achievement," for "prestigious

27:53.981 --> 27:55.821
positions,"
and for "on the job

27:55.816 --> 27:58.326
performance" and other
work-related variables.

27:58.329 --> 28:02.329
If I know your IQ score,
I know something about you that

28:02.332 --> 28:04.862
matters.
It's not irrelevant just as if

28:04.861 --> 28:08.101
I know your score on a
personality test of The Big Five

28:08.104 --> 28:11.654
I would know something about you
that actually would tell me

28:11.647 --> 28:14.947
something interesting about you
in the real world.

28:14.950 --> 28:18.490
On the other hand,
there's a lot of controversy

28:18.488 --> 28:21.178
about why this connection
exists.

28:21.180 --> 28:25.340
So, to some extent,
people have worried that the

28:25.343 --> 28:29.953
effectiveness of IQ is a
self-fulfilling prophecy.

28:29.950 --> 28:35.670
And here is why.
If society takes IQ tests

28:35.669 --> 28:39.879
important--seriously,
they become important.

28:39.880 --> 28:44.450
So, it's true that your IQ is
very related to your success in

28:44.449 --> 28:47.419
getting into a good school like
Yale.

28:47.420 --> 28:50.370
But the reason for this,
in large extent,

28:50.369 --> 28:54.059
is because to get to Yale they
give you an IQ test,

28:54.055 --> 28:57.235
the SAT.
So, the same for graduate

28:57.243 --> 28:59.083
school.
There is the GRE,

28:59.079 --> 29:01.019
which is yet another IQ test.

29:01.019 --> 29:03.779
So, to some extent,
it's a self-fulfilling

29:03.779 --> 29:06.329
prophecy.
I could make--Society could

29:06.326 --> 29:09.936
choose to make how tall you are
extremely important for

29:09.940 --> 29:11.480
educational success.

29:11.480 --> 29:14.840
They could say nobody under six
feet tall gets into Yale.

29:14.839 --> 29:17.359
And then some psych professor
would stand up and say,

29:17.357 --> 29:19.387
"Of course, height is
profoundly related to

29:19.390 --> 29:23.010
educational accomplishment,"
and it would be because people

29:23.011 --> 29:25.521
made it so.
So, to some extent,

29:25.521 --> 29:30.831
the society that draws highly
on IQ tests regarding promotion

29:30.830 --> 29:36.320
and educational achievement and
military status and so on--it's

29:36.316 --> 29:41.356
just going to follow that IQ
then becomes important.

29:41.359 --> 29:44.629
At the same time,
however, the role of IQ is

29:44.627 --> 29:48.577
pretty clearly not entirely a
social construction.

29:48.579 --> 29:53.379
There is some evidence that
your IQ score relates to

29:53.381 --> 29:58.841
intelligence in an interesting
sense including domains like

29:58.842 --> 30:01.952
mental speed and memory span.

30:01.950 --> 30:05.670
So, your score on an IQ test,
for instance,

30:05.672 --> 30:10.642
is to some extent related to
how fast you could think and

30:10.635 --> 30:12.935
your memory abilities.

30:12.940 --> 30:16.420
Now, I want to shift to the
second half of the class and

30:16.423 --> 30:19.153
talk about why.
So, we talked about two

30:19.151 --> 30:21.521
differences, one in
"personality",

30:21.520 --> 30:23.100
one "intelligence."

30:23.099 --> 30:27.239
I want to talk about why people
differ but before I do,

30:27.235 --> 30:29.605
do people have any questions?

30:29.610 --> 30:33.600
Yes.
Student:

30:33.598 --> 30:45.828
About personality--This morning
I took a test--The way the test

30:45.829 --> 30:52.769
was,
they asked you 100 questions

30:52.771 --> 31:01.311
and [inaudible]
Professor Paul Bloom:

31:01.312 --> 31:06.082
It's a good question.

31:06.079 --> 31:10.899
The question is this young man
took--just took a personality

31:10.898 --> 31:13.708
test.
He was accepted into Slytherin,

31:13.714 --> 31:15.964
which is a Hogwarts reference.

31:15.960 --> 31:20.850
I'm hip to that [laughter]
and--but the question is a good

31:20.845 --> 31:23.795
one.
You're a clever man,

31:23.803 --> 31:29.303
high "G," and you wanted to be
in Slytherin.

31:29.299 --> 31:31.479
How do we know you didn't work
the test?

31:31.480 --> 31:34.570
You're going to get these
personality tests all the time

31:34.568 --> 31:37.208
and the personality
tests--You're applying for a

31:37.207 --> 31:40.457
business and one of the tests
says "I like to steal from my

31:40.463 --> 31:42.553
bosses."
Well, I don't think so.

31:42.550 --> 31:44.670
No.
That's a little IQ test right

31:44.674 --> 31:47.104
there.
So, the question is how do you

31:47.099 --> 31:48.459
avoid that problem?

31:48.460 --> 31:53.090
The test constructors have done
so in certain clever ways.

31:53.089 --> 31:56.539
For instance,
there are often catch questions

31:56.541 --> 31:58.661
designed to catch a liar.

31:58.660 --> 32:03.270
Some of these questions pose
very unrealistic phenomena so

32:03.266 --> 32:08.036
you might have a question in
there saying "I have never done

32:08.035 --> 32:10.455
anything I am ashamed of."

32:10.460 --> 32:14.090
Now, some people will say,
"Yes, that's true of me," but

32:14.094 --> 32:15.684
they tend to be liars.

32:15.680 --> 32:19.980
And so, unrealistic questions
tend to catch liars.

32:19.980 --> 32:23.270
Also, you get the same question
asked in different ways across

32:23.273 --> 32:26.463
the one hundred items and they
could use the correlations to

32:26.458 --> 32:27.968
figure these things out.

32:27.970 --> 32:30.750
Again, the proof is sort of in
the pudding.

32:30.750 --> 32:34.480
The reliability and validity of
a test is determined,

32:34.481 --> 32:38.641
in part, by just how well it
does at predicting your future

32:38.644 --> 32:42.954
performance on the test and your
real world performance.

32:42.950 --> 32:47.490
And a test that is easily
fooled--easily tricked by smart

32:47.491 --> 32:51.791
people wouldn't survive long as
a personality test.

32:51.789 --> 32:55.479
So, we know the test you got is
a pretty good test because it

32:55.481 --> 32:57.451
seems to work for most people.

32:57.450 --> 33:01.400
Yes.
Student:

33:01.398 --> 33:04.978
[inaudible]
Professor Paul Bloom:

33:04.983 --> 33:07.193
It's a good question.

33:07.190 --> 33:08.810
The question was about
"Emotional IQ," which is

33:08.814 --> 33:11.044
something I'm actually going to
touch upon a little bit later in

33:11.040 --> 33:12.750
the course,
but people have talked about

33:12.749 --> 33:14.139
different forms of intelligence.

33:14.140 --> 33:18.480
And emotional intelligence,
social intelligence,

33:18.481 --> 33:23.191
is arguably a candidate for
success across different

33:23.191 --> 33:26.961
domains.
The evidence for its predictive

33:26.958 --> 33:32.188
power is not as strong as for
regular IQ tests so you might be

33:32.188 --> 33:34.688
right.
It might turn out to be a much

33:34.692 --> 33:37.702
better predictor but one,
it's not clear that we know

33:37.696 --> 33:39.796
that yet.
Peter Salovey has actually done

33:39.804 --> 33:42.544
some very interesting research
on this and is continuing work

33:42.541 --> 33:43.501
along those lines.

33:43.500 --> 33:46.420
The second thing is emotional
intelligence is actually related

33:46.420 --> 33:48.240
to good, old-fashioned
intelligence.

33:48.240 --> 33:49.990
They kind of pull together a
lot.

33:49.990 --> 33:52.810
So, it's not entirely separate
but that's a good point and I'd

33:52.806 --> 33:55.526
like to return to it a little
bit later on in the course.

33:55.530 --> 33:59.160
Yes.
Student:

33:59.157 --> 34:06.737
[inaudible]
Professor Paul Bloom:

34:06.743 --> 34:11.703
Good question.
How do you determine when--what

34:11.698 --> 34:14.178
a good test is?
And again, it's a real art

34:14.178 --> 34:18.188
going through the details of how
to do that but the broad answers

34:18.185 --> 34:20.435
involve reliability and
validity.

34:20.440 --> 34:23.880
It's a good test if I test you
today and I test you tomorrow

34:23.877 --> 34:25.447
and I get the same score.

34:25.449 --> 34:30.289
It's a really good test if your
score on that test predicts your

34:30.288 --> 34:33.358
grades or, if it's a personality
test,

34:33.360 --> 34:37.490
predicts how many girlfriends
you have or predicts whether

34:37.489 --> 34:39.879
people think you're a nice guy.

34:39.880 --> 34:43.570
So, you have to see both the
replicability of the test over

34:43.571 --> 34:47.201
time but also its relationship
to real world phenomena.

34:47.200 --> 34:48.370
And that's important, again.

34:48.369 --> 34:51.669
Why do we know the Batman,
Wonder Woman,

34:51.672 --> 34:53.792
Hulk test is a bad one?

34:53.789 --> 34:58.459
Well, one answer is because
what I--how I score on that test

34:58.464 --> 35:01.954
isn't going to tell you anything
about me.

35:01.949 --> 35:03.199
It's not going to relate to my
grades.

35:03.199 --> 35:04.789
It's not going to relate to how
well I'm liked.

35:04.789 --> 35:07.289
How do we know the SAT is
useful?

35:07.289 --> 35:13.269
Well, it actually corresponds
with other things like grades.

35:13.270 --> 35:18.200
Yes, in back.
Student:

35:18.201 --> 35:26.501
[inaudible]
Professor Paul Bloom:

35:26.500 --> 35:30.780
Absolutely.
The question is--When I'm

35:30.777 --> 35:33.477
talking about personality I'm
defining it in terms of

35:33.476 --> 35:35.496
something which is stable over
time.

35:35.500 --> 35:37.230
And your question,
which is a good one,

35:37.226 --> 35:39.266
is, "How do we know it's stable
over time?"

35:39.270 --> 35:41.660
Can't it change?
And the answer is "yeah."

35:41.659 --> 35:44.089
A lot of personality does
change over time.

35:44.090 --> 35:48.520
A personality test you give to
a ten-year-old will relate but

35:48.519 --> 35:52.579
not so strongly with that
individual when he's fifty.

35:52.579 --> 35:55.619
On the other hand,
we know that the psychological

35:55.619 --> 35:59.419
claim that there exists such a
thing as personality and it is

35:59.420 --> 36:00.750
stable over time.

36:00.750 --> 36:03.820
It's supported by the fact that
if you're an extrovert now

36:03.815 --> 36:06.715
you'll likely be an extrovert
twenty years from now.

36:06.720 --> 36:08.580
Not perfectly, so you're right.

36:08.580 --> 36:09.460
You could change.

36:09.460 --> 36:12.780
You could become an introvert,
you could become more of an

36:12.780 --> 36:15.870
extrovert, but wherever you
stand now is significantly

36:15.868 --> 36:18.488
related to where you'll be in
the future.

36:18.489 --> 36:21.499
And that justifies talking
about it as a stable trait.

36:21.500 --> 36:24.510
Same with IQ.
Your IQ might change.

36:24.510 --> 36:26.150
It might go up,
it might go down,

36:26.147 --> 36:29.107
but it won't go up and go down
that much and this is why it

36:29.114 --> 36:31.934
makes sense to talk about
intelligence as a more or less

36:31.927 --> 36:33.977
stable trait.
Okay.

36:33.980 --> 36:38.590
Why are we different?

36:38.590 --> 36:42.820
Well, you're different because
of two things:

36:42.823 --> 36:47.353
Your genes and your
environment, your nature and

36:47.346 --> 36:50.706
your nurture,
your heredity and your

36:50.714 --> 36:54.274
experience.
And this doesn't say anything.

36:54.269 --> 36:56.059
This is just defining the
question.

36:56.059 --> 37:00.189
But the question of the role of
genes and the role of

37:00.194 --> 37:04.974
environment in explaining human
differences is an interesting

37:04.965 --> 37:09.015
one and it could be explored in
different ways.

37:09.019 --> 37:11.839
But before talking about it I
have to clear up a common

37:11.835 --> 37:14.315
misconception.
I'm going to talk about the

37:14.315 --> 37:17.845
effects of genes and I'm going
to talk about heredity but I

37:17.850 --> 37:19.070
want to be clear.

37:19.070 --> 37:23.990
I am talking about the role of
genes and also the role of

37:23.988 --> 37:29.348
environment in explaining human
differences, not in explaining

37:29.346 --> 37:31.626
human characteristics.

37:31.630 --> 37:34.890
So, the distinction is we're
interested in the amount of

37:34.889 --> 37:37.199
variation due to genetic
differences,

37:37.199 --> 37:40.829
not the proportion of an
individual's trait that's due to

37:40.831 --> 37:42.611
genes.
So for instance,

37:42.608 --> 37:44.808
you could pull these apart.

37:44.809 --> 37:49.339
The question of--When we ask
what's the role of genes,

37:49.344 --> 37:53.884
what's the role of heredity in
how tall people are,

37:53.880 --> 37:58.380
the question is not asking for
you--what is the role of your

37:58.379 --> 38:01.429
genes in determining how tall
you are?

38:01.429 --> 38:03.409
It's not clear that's even a
sensible question.

38:03.409 --> 38:06.139
The question is there's a
height difference between you

38:06.144 --> 38:07.414
and me and him and her.

38:07.409 --> 38:09.769
How do we explain that
difference?

38:09.769 --> 38:13.069
And I could illustrate why
heredity doesn't mean the same

38:13.066 --> 38:15.476
thing as the contribution of the
genes.

38:15.480 --> 38:21.260
Height is reasonably heritable,
meaning the differences between

38:21.261 --> 38:26.951
people in the population and how
tall they are is due in large

38:26.950 --> 38:28.680
part,
not entirely,

38:28.675 --> 38:30.985
but in large part to their
genes.

38:30.989 --> 38:33.759
What about the number of legs
people have?

38:33.760 --> 38:37.070
Well, the number of legs people
have from zero,

38:37.074 --> 38:41.114
one or two, is actually not
very heritable at all because

38:41.110 --> 38:45.360
almost everybody has two legs
and people who have fewer than

38:45.361 --> 38:50.191
two legs typically have lost one
or both legs in an accident.

38:50.190 --> 38:52.100
It's not due to their genes.

38:52.099 --> 38:55.939
So, of course,
whether or not you have legs is

38:55.942 --> 39:01.152
a very genetic matter but the
differences in number of legs is

39:01.150 --> 39:03.200
not usually genetic.

39:03.199 --> 39:06.269
And so, heredity is a claim
about differences,

39:06.267 --> 39:09.877
not a claim about the origin of
any specific trait.

39:09.880 --> 39:14.120
Well, now we--That's what
heredity, which is genetic--Now,

39:14.120 --> 39:16.650
we could talk about
environment.

39:16.650 --> 39:18.870
And we could break up
environment into two sorts of

39:18.868 --> 39:21.478
environment.
One is shared environment.

39:21.480 --> 39:25.860
And shared environment is the
extent to which the differences

39:25.855 --> 39:29.865
are caused by things--by
phenomena that people raised in

39:29.865 --> 39:31.975
the same household share.

39:31.980 --> 39:36.790
So if one--Suppose some of you
are neurotic.

39:36.789 --> 39:40.589
And suppose we want to say part
of that's due to your

39:40.587 --> 39:43.647
environment.
Well, suppose you're neurotic

39:43.654 --> 39:45.914
because you have lousy parents.

39:45.909 --> 39:49.979
That would be part of your
shared environment because

39:49.978 --> 39:54.518
presumably siblings raised in
the same household would have

39:54.517 --> 39:56.627
the same lousy parents.

39:56.630 --> 39:59.940
This is contrasted with
non-shared environment,

39:59.938 --> 40:01.878
which is everything else.

40:01.880 --> 40:04.980
Suppose I think you're neurotic
because when you were five years

40:04.981 --> 40:07.891
old somebody threw a snowball at
you and it bounced off your

40:07.886 --> 40:10.546
head.
That's non-shared environment.

40:10.550 --> 40:13.620
Suppose you're neurotic because
you won the lottery when you

40:13.619 --> 40:16.219
were twenty-one and all the
money messed you up.

40:16.219 --> 40:18.359
That'd be non-shared
environment.

40:18.360 --> 40:22.500
So, what you have here is
heredity, shared environment and

40:22.504 --> 40:25.854
non-shared environment,
and this equals one.

40:25.850 --> 40:27.230
That's everything.

40:27.230 --> 40:30.930
Non-shared environment is a
sort of garbage can category

40:30.930 --> 40:34.830
that includes everything that's
not heredity and not shared

40:34.833 --> 40:37.533
environment.
Suppose you think you're

40:37.531 --> 40:41.651
neurotic because aliens from the
planet Pluto are zapping your

40:41.652 --> 40:44.542
brain.
Suppose you're right.

40:44.539 --> 40:47.439
Well, that would be non-shared
environment because they're,

40:47.435 --> 40:50.425
presumably, not necessarily
zapping your siblings' brains.

40:50.429 --> 40:53.409
Everything else is non-shared
environment.

40:53.409 --> 40:58.429
It becomes interesting to ask,
for all of these differences,

40:58.431 --> 41:01.751
the physical differences like
height,

41:01.750 --> 41:05.740
but psychological differences
like personality and

41:05.739 --> 41:09.079
intelligence,
how do we parcel it out into

41:09.077 --> 41:12.657
what's genetic and what's
environmental?

41:12.659 --> 41:16.609
This proves to be really
difficult in the real world

41:16.614 --> 41:21.114
because in the real world it's
hard to pull apart genes and

41:21.111 --> 41:25.081
environments.
So, you and me will have

41:25.079 --> 41:27.839
different personalities.

41:27.840 --> 41:30.520
Why?
Well, we were raised by

41:30.515 --> 41:33.505
different parents and we have
different genes.

41:33.510 --> 41:38.510
We can't tell--My brother and
me might share all sorts of

41:38.513 --> 41:44.503
things in common but we have the
same parents and the same genes,

41:44.500 --> 41:45.650
fifty percent of the same genes.

41:45.650 --> 41:48.770
So how do we tell what's
causing us to be alike?

41:48.769 --> 41:53.289
So to do--to pull these things
apart you need to be clever.

41:53.289 --> 41:56.579
You need to use the tools of
behavioral genetics.

41:56.579 --> 42:01.259
And to use these tools you have
to exploit certain regularities

42:01.255 --> 42:03.965
about genes and about
environment.

42:03.970 --> 42:05.920
One thing is this.

42:05.920 --> 42:09.020
Some people are clones.

42:09.019 --> 42:11.939
Monozygotic twins are genetic
duplicates.

42:11.940 --> 42:14.430
They share one hundred percent
of the same genes.

42:14.430 --> 42:16.460
That's kind of interesting.

42:16.460 --> 42:20.250
Dizygotic twins are not clones.

42:20.250 --> 42:22.200
They share fifty/fifty.

42:22.199 --> 42:24.119
They are just like regular
siblings.

42:24.119 --> 42:29.729
And adopted siblings have no
special genetic overlap.

42:29.730 --> 42:34.740
That's zero percent above and
beyond randomness.

42:34.739 --> 42:38.759
Those three groups then become
rather interesting particularly

42:38.762 --> 42:42.652
when we keep in mind that by
definition two people raised in

42:42.653 --> 42:46.483
the same house by the same
parents have one hundred percent

42:46.477 --> 42:48.717
the same shared environment.

42:48.720 --> 42:52.530


42:52.530 --> 42:55.400
So now, we can start to answer
these questions.

42:55.400 --> 42:59.240
Suppose you find that
monozygotic twins are much more

42:59.240 --> 43:01.530
similar than dizygotic twins.

43:01.530 --> 43:05.360
Well, that would suggest that
there's a large role of genes in

43:05.357 --> 43:07.927
those traits that you're
interested in.

43:07.929 --> 43:11.339
It would not cinch the matter
because there are other factors

43:11.341 --> 43:12.751
at work.
For instance,

43:12.754 --> 43:16.464
monozygotic twins look more
alike than dizygotic twins and

43:16.458 --> 43:19.838
maybe they have different
and--they have more similar

43:19.836 --> 43:23.666
environments because of this
similarity in appearance.

43:23.670 --> 43:28.570
Are monozygotic twins just as
similar as dizygotic twins?

43:28.570 --> 43:32.690
If so, then it would show that
that extra overlap in genes

43:32.693 --> 43:34.433
doesn't really matter.

43:34.429 --> 43:38.119
And so, it would suggest a low
role of heredity.

43:38.119 --> 43:42.349
Are adopted children highly
similar to their brothers and

43:42.353 --> 43:45.773
sisters?
If so, then there's a high role

43:45.773 --> 43:47.753
of shared environment.

43:47.750 --> 43:52.160
Suppose the Bloom children,
and there are seven of them,

43:52.156 --> 43:56.956
all have an IQ of 104 and we
adopt three kids and then at the

43:56.963 --> 44:01.693
end of the day those three kids
each have an IQ of 104.

44:01.690 --> 44:05.050
That would suggest that--And we
do this over and over again

44:05.048 --> 44:06.668
across different families.

44:06.670 --> 44:12.000
That would suggest that there's
something about the Bloom family

44:11.996 --> 44:16.136
being raised by me that gives
you an IQ of 104.

44:16.139 --> 44:19.489
On the other hand,
if the IQ of the adopted kids

44:19.489 --> 44:24.049
had no relationship to those of
the biological Bloom children,

44:24.050 --> 44:26.930
it would suggest that being
raised by me has no effects

44:26.932 --> 44:28.002
really on your IQ.

44:28.000 --> 44:29.050
It's sort of separate.

44:29.050 --> 44:35.040
A separate--A second--A final
contrast, which is the thing

44:35.044 --> 44:40.204
that psychologists love,
is identical twins reared

44:40.198 --> 44:42.638
apart.
That's the gold standard

44:42.638 --> 44:45.818
because you have these people
who are clones but they're

44:45.819 --> 44:47.669
raised in different families.

44:47.670 --> 44:52.340
And to the extent that they are
similar this suggests it's a

44:52.335 --> 44:54.545
similarity of their genes.

44:54.550 --> 44:57.710
And in fact,
one of the most surprising

44:57.711 --> 45:01.951
findings in behavioral
genetics--The caption here is

45:01.953 --> 45:05.513
"Separated at Birth,
the Mallifert Twins Meet

45:05.513 --> 45:08.363
Accidentally."
ended up at a patent office

45:08.363 --> 45:09.893
with the same device.

45:09.889 --> 45:13.379
One of the hugely surprising
findings from behavioral

45:13.382 --> 45:17.212
genetics is how alike identical
twins reared apart are.

45:17.210 --> 45:20.450
They seem to have similar
attitudes to the death penalty,

45:20.445 --> 45:22.405
to religion and to modern
music.

45:22.409 --> 45:25.349
They have similar rates of
behavior in crime,

45:25.345 --> 45:26.875
gambling and divorce.

45:26.880 --> 45:30.950
They often have been found to
have bizarre similarities.

45:30.949 --> 45:34.549
They meet after being separated
at birth and they meet at age

45:34.550 --> 45:38.030
thirty and then it turns out
that they both get in to a lot

45:38.030 --> 45:41.570
of trouble because they pretend
to sneeze in elevators.

45:41.570 --> 45:45.100
There was one pair of twins
studied by behavioral genetics

45:45.103 --> 45:48.763
who were known as the "Giggle
Twins" because they were--both

45:48.762 --> 45:51.842
would always giggle,
they'd burst into giggles at

45:51.842 --> 45:55.142
every moment even though it
couldn't be environment because

45:55.140 --> 45:56.960
they weren't raised together.

45:56.960 --> 46:01.390
More objectively,
the brain scans of identical

46:01.394 --> 46:07.114
twins reared apart show that
their brains are so similar in

46:07.110 --> 46:11.940
many cases you can't tell whose
brain is who.

46:11.940 --> 46:15.550
I could tell your brain from my
brain from a brain scan and my

46:15.545 --> 46:18.495
brother's brain from my brain
from a brain scan.

46:18.500 --> 46:21.350
But if I were to have an
identical twin it would be very

46:21.351 --> 46:24.201
difficult to tell whose brain is
whose even if we had no

46:24.202 --> 46:25.552
environment in common.

46:25.550 --> 46:29.160
So, this leads to two
surprising findings of

46:29.155 --> 46:30.995
behavioral genetics.

46:31.000 --> 46:33.090
This is the first one.

46:33.090 --> 46:37.720
There is high heritability for
almost everything.

46:37.719 --> 46:40.509
For intelligence,
for personality,

46:40.513 --> 46:44.833
for how happy you are,
for how religious you are,

46:44.829 --> 46:48.599
for your political orientation,
there--for your sexual

46:48.601 --> 46:51.591
orientation, there is high
heritability.

46:51.590 --> 46:55.330
There's a high effect of genes
for just about everything.

46:55.329 --> 46:59.619
Now, that's actually not the
controversial thing I'm going to

46:59.622 --> 47:02.002
tell you.
But before getting to the more

47:02.000 --> 47:05.180
controversial thing I want to
raise another issue which often

47:05.181 --> 47:08.311
gets discussed and has a good
treatment in the textbook.

47:08.309 --> 47:12.299
This suggests that individual
differences within this--within

47:12.296 --> 47:14.286
a group have genetic causes.

47:14.289 --> 47:17.889
Does that mean that group
differences are largely the

47:17.890 --> 47:19.760
result of genetic causes?

47:19.760 --> 47:24.000
So, we know that there are
clear differences in IQ scores

47:23.999 --> 47:28.159
among American racial groups,
between whites and Asians,

47:28.163 --> 47:31.043
African Americans,
Ashkenazi Jews.

47:31.039 --> 47:34.269
There's clear and reliable IQ
differences as well as some

47:34.267 --> 47:35.417
other differences.

47:35.420 --> 47:39.260
Now, to some extent,
these groups are partially

47:39.260 --> 47:41.180
socially constructed.

47:41.179 --> 47:45.119
And what this means is that
whether or not you fall into a

47:45.121 --> 47:48.511
group it's not entirely
determined by your genetic

47:48.509 --> 47:50.949
makeup.
It's often determined by social

47:50.945 --> 47:53.595
decisions.
So, whether or not you count as

47:53.596 --> 47:56.976
a Jew, for instance,
depends not entirely on genetic

47:56.979 --> 48:00.889
factors but also on factors such
as whether you're reform or

48:00.893 --> 48:04.813
orthodox and whether you--so
whether you would accept that a

48:04.807 --> 48:08.917
child of a Jewish man and a
non-Jewish woman is Jewish.

48:08.920 --> 48:12.700
Similarly, categories like
African American and white and

48:12.696 --> 48:16.196
Asian often overlap broad
genetic categories and they

48:16.202 --> 48:19.172
don't make fully coherent
genetic sense.

48:19.170 --> 48:23.120
At the same time though,
there is plainly some genetic

48:23.123 --> 48:27.083
differences across human groups
and say with regard to

48:27.076 --> 48:29.236
vulnerability to disease.

48:29.239 --> 48:32.659
Ashkenazi Jews for instance are
vulnerable to Tay-Sachs.

48:32.659 --> 48:35.109
And the fact that you could
have this sort of genetic

48:35.109 --> 48:37.889
vulnerability suggests that
there is some sort of reality to

48:37.889 --> 48:40.489
these groups.
So, you have to ask the

48:40.492 --> 48:43.712
question now,
to what extent does the high

48:43.705 --> 48:48.715
heritability in individuals mean
that there has to be a heritable

48:48.720 --> 48:51.150
explanation across groups?

48:51.150 --> 48:53.810
And the answer is "not at all."

48:53.809 --> 48:56.959
I'm not saying that this means
that there's no genetic

48:56.956 --> 48:59.446
explanation for human group
differences.

48:59.449 --> 49:03.089
All I'm saying is the question
of the phenomena

49:03.087 --> 49:07.357
of--within-group genetic
differences does not mean that

49:07.357 --> 49:10.597
there is across-group
genetic--sorry,

49:10.599 --> 49:13.439
between-group genetic
differences.

49:13.440 --> 49:17.250
There is a nice example by
Richard Lewontin,

49:17.248 --> 49:20.968
the geneticist,
where he imagines two plots

49:20.968 --> 49:24.598
of--what are you--some sort of
wheat,

49:24.599 --> 49:29.539
yeah, two plots of land and
each one has a set of seeds

49:29.539 --> 49:31.559
and--Oh, no.
They're over there.

49:31.560 --> 49:33.990
No.
Anyway, one of them you

49:33.987 --> 49:36.837
fertilize a lot.
The other one you fertilize a

49:36.842 --> 49:39.722
little.
Now, within each plot how much

49:39.722 --> 49:43.912
the seed grows is actually
largely determined by the

49:43.909 --> 49:45.879
genetics of the seed.

49:45.880 --> 49:49.380
And so, you'd find high
heritability for growth in the

49:49.381 --> 49:52.441
seeds.
But the difference between

49:52.438 --> 49:55.938
groups has no genetic cause at
all.

49:55.940 --> 49:59.060
It's caused by which groups you
fertilize more than others.

49:59.059 --> 50:02.549
Here's another way to do the
logic.

50:02.550 --> 50:06.680
Suppose from the middle down
here, you guys,

50:06.684 --> 50:11.694
I hate you, I really hate all
of you, and I like you,

50:11.685 --> 50:14.565
so I make up two Midterms.

50:14.570 --> 50:16.840
You probably didn't notice but
there were two Midterms.

50:16.840 --> 50:20.920
This Midterm was fiercely hard,
savagely hard.

50:20.920 --> 50:23.780
It took many of you until the
end of class to do it.

50:23.780 --> 50:27.190
This Midterm was,
"Which is bigger,

50:27.185 --> 50:29.585
a dog or an elephant?"

50:29.590 --> 50:31.480
[laughter]
because I like you and I want

50:31.481 --> 50:32.501
you all to succeed.

50:32.500 --> 50:36.290
So, you have two different
groups, you guys and you guys.

50:36.289 --> 50:39.559
Within each group some people
are going to do better than

50:39.555 --> 50:41.465
others.
The explanation for that might

50:41.472 --> 50:43.192
actually have to do with your
genes.

50:43.190 --> 50:45.300
It might have to do with your
environment, how much you study,

50:45.302 --> 50:46.552
but all sorts of reasons for
that.

50:46.550 --> 50:49.950
Within each group some of you
will do better on the hard test

50:49.949 --> 50:53.179
than others on the hard test,
some better on the easy test

50:53.179 --> 50:55.049
than others on the easy test.

50:55.050 --> 50:57.390
But how do we explain the group
difference?

50:57.389 --> 50:59.039
Well, it has nothing to do with
genes.

50:59.039 --> 51:01.729
The group difference,
the fact that you will do much

51:01.731 --> 51:03.901
worse than you,
has to do with the exams I

51:03.895 --> 51:05.285
give.
My point, again,

51:05.285 --> 51:07.915
is that there is a logical
difference between a

51:07.915 --> 51:11.475
within-group difference,
within this half of the class,

51:11.477 --> 51:14.977
and a difference between
groups, within--between this

51:14.975 --> 51:16.585
group and this group.

51:16.590 --> 51:19.500
What do we know about--;So,
that just shows they're not the

51:19.501 --> 51:21.861
same thing but what's the fact
of the matter?

51:21.860 --> 51:25.500
What do we know about human
differences between different

51:25.496 --> 51:28.546
human groups?
Again, the textbook has a good

51:28.552 --> 51:32.722
discussion of this but I'm going
to give two reasons from the

51:32.718 --> 51:36.678
textbook that at least group
differences are at least to a

51:36.675 --> 51:40.005
large extent due to
environmental and not genetic

51:40.008 --> 51:42.848
causes.
One is that the differences we

51:42.848 --> 51:46.268
find in IQ seem to correspond
better to socially defined

51:46.274 --> 51:48.894
groups than genetically defined
groups.

51:48.889 --> 51:52.239
They seem to correspond to
groups defined in terms of how

51:52.241 --> 51:55.831
people treat you and how people
think about you as opposed to

51:55.832 --> 51:58.552
your DNA.
And to the extent that turns

51:58.545 --> 52:02.615
out to be true that would mean
that a genetic explanation is

52:02.624 --> 52:05.394
not reasonable for those
differences.

52:05.389 --> 52:12.279
A second factor is that we know
IQ can differ radically without

52:12.275 --> 52:15.935
any genetic differences at all.

52:15.940 --> 52:20.680
And the most dramatic evidence
of that is the Flynn effect.

52:20.679 --> 52:24.149
The Flynn effect is one of the
freakier findings.

52:24.150 --> 52:28.980
The Flynn effect is the finding
that people have been getting

52:28.984 --> 52:34.534
smarter.
You are much smarter on average

52:34.528 --> 52:42.168
than your parents if--and the IQ
tests hide that.

52:42.170 --> 52:43.780
Here is why they hide that.

52:43.780 --> 52:47.850
They hide that because they
always make 100 the average.

52:47.849 --> 52:51.719
So, you come home and you say,
"Dad, Dad, I just did an IQ

52:51.715 --> 52:54.095
test.
I got 120."

52:54.099 --> 52:56.299
And your father says,
"Good work, Son.

52:56.300 --> 53:01.090
I got 122 when I was your age,"
but what neither of you

53:01.093 --> 53:04.913
acknowledge is your test was
much harder.

53:04.909 --> 53:07.379
As people got better,
they had to make the test

53:07.377 --> 53:08.447
harder and harder.

53:08.449 --> 53:10.449
And this is plotted by the
Flynn effect.

53:10.449 --> 53:19.479
One of these lines is American
and one is Dutch.

53:19.480 --> 53:25.380
I don't know which is which but
the gist of it is that somebody

53:25.377 --> 53:31.367
who would have--that if you in
1980 would take the 1950 test,

53:31.369 --> 53:35.949
your average person in 1980
would score 120 on the 1950

53:35.946 --> 53:38.786
test.
What this means is if you take

53:38.791 --> 53:43.221
your person who's average now
and push him back through time

53:43.219 --> 53:45.539
twenty years,
thirty years,

53:45.539 --> 53:48.809
he would do much better than
average.

53:48.809 --> 53:53.209
Nobody knows why people are
getting smarter and there's

53:53.208 --> 53:55.568
different theories of this.

53:55.570 --> 53:58.800
And in fact,
well, wait until you see your

53:58.795 --> 54:00.285
reading response.

54:00.289 --> 54:06.309
But what this illustrates is
that IQ can change dramatically

54:06.314 --> 54:11.934
over the span of a few decades
without any corresponding

54:11.929 --> 54:15.479
genetic change.
And that leaves open the

54:15.484 --> 54:18.314
possibility, in fact,
maybe the likelihood,

54:18.310 --> 54:21.540
that the differences we find in
human groups,

54:21.539 --> 54:23.609
existing human groups,
are caused by the same

54:23.606 --> 54:26.326
environmental effects that have
led to the Flynn effect.

54:26.330 --> 54:28.500
Okay.
This is not the surprising

54:28.499 --> 54:30.629
claim though,
the high heritability for

54:30.631 --> 54:31.811
almost everything.

54:31.810 --> 54:33.730
This is the surprising claim.

54:33.730 --> 54:37.240
Almost everything that's not
genetic is due to non-shared

54:37.239 --> 54:41.209
environments.
The behavioral genetic analyses

54:41.213 --> 54:47.283
suggest that shared environment
counts for little or nothing.

54:47.280 --> 54:51.700
When it comes to personality or
intelligence then,

54:51.700 --> 54:56.930
an adopted child is no more
similar to his siblings than he

54:56.933 --> 54:59.463
or she is to a stranger.

54:59.460 --> 55:01.790
To put it a different way,
the IQ correlation in

55:01.791 --> 55:04.971
genetically unrelated adults who
are raised in the same family is

55:04.965 --> 55:07.855
about zero.
Suppose the Bloom family all

55:07.859 --> 55:10.699
has an IQ of 104 and we adopt a
kid.

55:10.699 --> 55:13.979
What will this kid's--We adopt
him as a baby.

55:13.980 --> 55:15.940
We raise him to be a
twenty-year-old.

55:15.940 --> 55:17.790
What's his IQ?
Answer?

55:17.789 --> 55:22.089
We have no idea because the IQ
of the Bloom family who are

55:22.091 --> 55:25.111
unrelated to him has no effect
at all.

55:25.110 --> 55:28.760
Now, if you think about the
implications of it,

55:28.755 --> 55:32.475
it becomes controversial and
Newsweek,

55:32.480 --> 55:36.480
I think, caught the big issue
when they put in their title the

55:36.484 --> 55:38.524
question "do parents matter?"

55:38.519 --> 55:42.479
And the question--And the issue
is parents are shared

55:42.483 --> 55:46.153
environment.
To say shared environment does

55:46.147 --> 55:51.427
not affect your intelligence or
your personality suggests that

55:51.428 --> 55:56.448
how your parents raised you does
not affect your gene--your

55:56.450 --> 55:59.740
intelligence or your
personality.

55:59.739 --> 56:03.949
This isn't to say your parents
didn't have a big effect on your

56:03.953 --> 56:06.063
intelligence and personality.

56:06.059 --> 56:09.879
Your parents had a huge effect
on your intelligence and your

56:09.882 --> 56:12.152
personality, around 0.5
actually.

56:12.150 --> 56:14.870
They had this effect at the
moment of conception.

56:14.869 --> 56:18.249
From then on in,
they played very little role in

56:18.253 --> 56:20.273
shaping you--what you are.

56:20.269 --> 56:23.519
The case for this which
generated the Newsweek

56:23.516 --> 56:27.256
cover came up in a controversial
book by Judith Harris called

56:27.262 --> 56:31.322
The Nurture Assumption
which has a very long subtitle,

56:31.320 --> 56:34.960
"Why Parents Turn--Why Children
Turn Out the Way They Do,

56:34.964 --> 56:38.874
Parents Matter Less than You
Think and Peers Matter More."

56:38.869 --> 56:43.309
Judith Harris has had an
interesting history.

56:43.309 --> 56:47.969
She was kicked out of graduate
school at Harvard and told that

56:47.968 --> 56:50.258
she wouldn't amount to much.

56:50.260 --> 56:53.210
The person who wrote the letter
saying that she was not going to

56:53.205 --> 56:55.025
amount to much was the
department chair,

56:55.028 --> 56:57.928
George Miller.
In 1997, she won the George

56:57.934 --> 57:01.684
Miller award for her astounding
accomplishments.

57:01.679 --> 57:05.399
And when she wrote the book she
took as a starting point,

57:05.400 --> 57:08.980
her point of disagreement,
a famous poem by the poet

57:08.979 --> 57:12.829
Philip Larkin and many of you
have probably heard this.

57:12.829 --> 57:15.299
The poem goes like this:
They fuck you up,

57:15.303 --> 57:16.453
your mum and dad.

57:16.449 --> 57:18.849
They may not mean to but they
do.

57:18.849 --> 57:23.209
They fill you with the faults
they had And add some extra just

57:23.214 --> 57:26.314
for you.
The last line of the poem,

57:26.314 --> 57:31.274
the last bit of the poem,
ends: "Man hands on misery to

57:31.267 --> 57:34.187
man.
It deepens like a coastal shelf.

57:34.190 --> 57:38.080
Get out as early as you can and
don't have any kids yourself."

57:38.080 --> 57:40.670
It's beautiful.
[laughter]

57:40.672 --> 57:45.512
Harris wrote a rebuttal:
"How sharper than a serpent's

57:45.511 --> 57:49.621
tooth to hear your child make
such a fuss.

57:49.620 --> 57:52.300
It isn't fair.
It's not the truth.

57:52.300 --> 57:56.720
He's fucked up,
yes, but not by us."

57:56.719 --> 57:58.899
[laughter]
Just to show that academic

57:58.898 --> 58:01.738
debates never end,
a British psychoanalyst named

58:01.741 --> 58:05.111
Oliver James,
outraged by Judith Harris' book

58:05.113 --> 58:09.653
The Nurture Assumption,
wrote another book in response

58:09.649 --> 58:12.219
called They Fuck You Up.

58:12.219 --> 58:15.649
[laughter]
Now, how do you tell your

58:15.653 --> 58:18.893
grandparents,
"I wrote a book."

58:18.890 --> 58:19.660
"What's it called?"

58:19.660 --> 58:23.420
"Can't tell you."

58:23.420 --> 58:25.880
[laughter] Anyway, look.

58:25.880 --> 58:28.760
If you're paying attention,
this has to sound wrong.

58:28.760 --> 58:32.230
You must be thinking of course
there must be an effect of

58:32.229 --> 58:33.529
shared environment.

58:33.530 --> 58:35.460
Of course parents have an
effect.

58:35.460 --> 58:39.200
After all, good kids have good
parents.

58:39.199 --> 58:43.169
There is no doubt at all that
this is true.

58:43.170 --> 58:46.090
There is a high correlation
between parent and child for

58:46.089 --> 58:48.199
everything.
If your parents read a lot and

58:48.200 --> 58:51.230
there's a lot of books in your
house, you will become a reader.

58:51.230 --> 58:54.320
If your parents are religious,
you will be religious.

58:54.320 --> 59:01.290
If you're raised by Bonnie and
Clyde, you will be a young thug.

59:01.289 --> 59:02.629
[laughter]
If your parents are poor,

59:02.627 --> 59:03.657
you're likely to be poor.

59:03.659 --> 59:06.229
If your parents are brilliant,
you're likely to be brilliant.

59:06.230 --> 59:09.340
No doubt at all.
It is an extremely robust

59:09.339 --> 59:11.439
correlation.
But the problem is this

59:11.438 --> 59:14.258
correlation could be explained
in different ways.

59:14.260 --> 59:17.460
Everybody thinks it's because
parents do something that

59:17.456 --> 59:18.696
affects their kids.

59:18.699 --> 59:21.509
Your parents are bookish,
they read to their kids,

59:21.505 --> 59:23.275
so their kids become bookish,

59:23.280 --> 59:26.390


59:26.389 --> 59:29.969
but another possibility,
which we know is true,

59:29.972 --> 59:34.182
that almost always parents
share their genes with their

59:34.178 --> 59:36.718
kids.
Another possibility is it's the

59:36.717 --> 59:38.607
parents who are
affecting--sorry,

59:38.614 --> 59:41.404
it's the child who is affecting
the parents,

59:41.400 --> 59:44.530
not vice versa,
and to illustrate this,

59:44.527 --> 59:49.547
these different possibilities,
I want to tell you a little bit

59:49.548 --> 59:52.298
about a study.
And I really find this a

59:52.296 --> 59:53.296
fascinating study.

59:53.300 --> 59:56.750
It was reported last year and
it was a study shown

59:56.753 --> 1:00:00.913
that--suggesting that family
meals help teens avoid smoking,

1:00:00.911 --> 1:00:03.271
alcohol, drugs.
It involved a phone

1:00:03.272 --> 1:00:06.552
questionnaire where they phoned
up teenagers and their parents

1:00:06.553 --> 1:00:08.063
and said, "Hey,
teenager.

1:00:08.060 --> 1:00:09.990
Do you do a lot of drugs?"

1:00:09.990 --> 1:00:12.620
"Yes."
"Do you have dinner with your

1:00:12.619 --> 1:00:14.159
parents?"
"No."

1:00:14.159 --> 1:00:19.159
And they take it off--and then
they ask other people and they

1:00:19.163 --> 1:00:24.253
find that the kids who are the
good kids have meals with their

1:00:24.249 --> 1:00:27.149
parents,
suggesting this headline.

1:00:27.150 --> 1:00:31.230
I like this study because I
have read--I must have read in

1:00:31.230 --> 1:00:35.530
my career a thousand studies and
this is the worst study ever

1:00:35.526 --> 1:00:38.816
done [laughter]
in the history of science.

1:00:38.820 --> 1:00:43.340
And it's almost--We could
devote a week to discussing

1:00:43.337 --> 1:00:46.027
what's wrong with this study.

1:00:46.030 --> 1:00:48.350
Let's just--But here's the idea.

1:00:48.349 --> 1:00:52.699
It is possible that they are
right.

1:00:52.699 --> 1:00:55.339
It is actually
possible--there's no--I have no

1:00:55.342 --> 1:00:58.572
evidence against it – that
having meals with your kids

1:00:58.572 --> 1:01:02.232
makes them into good,
drug-free, non-promiscuous,

1:01:02.229 --> 1:01:03.769
non-drinking kids.

1:01:03.769 --> 1:01:06.849
Of course, it's equally
possible it's the other way

1:01:06.846 --> 1:01:10.406
around.
If little Johnny is kind of--is

1:01:10.408 --> 1:01:15.748
out there smoking pot and
cavorting with prostitutes and

1:01:15.746 --> 1:01:19.076
stuff like that,
he's not going to come home for

1:01:19.075 --> 1:01:20.935
the family meal.
It's the other way around.

1:01:20.940 --> 1:01:23.470
While if he's a good kid,
he might be more likely to have

1:01:23.467 --> 1:01:25.947
a family meal.
So, the direction--It might

1:01:25.948 --> 1:01:29.728
actually be not family meals
make good kids but rather good

1:01:29.726 --> 1:01:33.566
kids stick around to have--if
they have nothing better to do

1:01:33.569 --> 1:01:35.979
and have meals with Mom and Dad.

1:01:35.980 --> 1:01:38.770
[laughter]
Another possibility is there's

1:01:38.774 --> 1:01:41.084
good families and bad families.

1:01:41.079 --> 1:01:44.299
A good family is likely to have
drug-free kids and a family

1:01:44.301 --> 1:01:46.571
meal.
A bad family is likely to have

1:01:46.572 --> 1:01:48.582
stoned kids and no family meal.

1:01:48.579 --> 1:01:49.259
[laughter]
So, there--maybe there's an

1:01:49.258 --> 1:01:51.368
effect of that.
The parents had nothing to do

1:01:51.366 --> 1:01:52.726
with the family meal.

1:01:52.730 --> 1:01:55.710
Here's the even weirder part.

1:01:55.710 --> 1:01:59.640
They didn't factor out age so
think about this.

1:01:59.639 --> 1:02:02.939
Their sample included children
ranging from twelve to seventeen

1:02:02.941 --> 1:02:05.871
but let me tell you something
about twelve-year-olds.

1:02:05.869 --> 1:02:10.589
Twelve-year-olds don't use a
lot of drugs and are likely to

1:02:10.594 --> 1:02:12.554
eat with their family.

1:02:12.550 --> 1:02:16.490
Seventeen-year-olds are stoned
all the time and they don't eat

1:02:16.488 --> 1:02:17.778
with their family.

1:02:17.780 --> 1:02:20.560
[laughter]
I've just begun on this study

1:02:20.559 --> 1:02:24.549
but the point is when you hear
something like--So now,

1:02:24.550 --> 1:02:27.610
take something which you may be
more likely to believe.

1:02:27.610 --> 1:02:30.450
Maybe you believe that having
parents who read to their kids,

1:02:30.454 --> 1:02:31.834
that's good for their kids.

1:02:31.829 --> 1:02:38.249
Well, maybe it is but most of
these criticisms apply to that

1:02:38.245 --> 1:02:41.545
study too.
A bookish kid is more likely to

1:02:41.552 --> 1:02:43.622
get his parents to read to him.

1:02:43.619 --> 1:02:48.219
A good family--Parents who are
good parents in general are more

1:02:48.215 --> 1:02:52.585
likely to do all sorts of good
things to their kids and have

1:02:52.589 --> 1:02:54.219
good kids besides.

1:02:54.219 --> 1:02:57.099
Take another case,
the so-called cycle of

1:02:57.098 --> 1:02:59.318
violence.
Yes, it's true.

1:02:59.320 --> 1:03:03.450
Parents who smack their kids
tend to have statistically more

1:03:03.449 --> 1:03:06.829
violent kids.
But maybe the causality goes

1:03:06.829 --> 1:03:08.659
the other way around.

1:03:08.659 --> 1:03:11.599
Maybe if you have a kid who is
a troublemaker you're more

1:03:11.603 --> 1:03:12.763
likely to smack him.

1:03:12.760 --> 1:03:15.520
Maybe, which seems to be
entirely likely,

1:03:15.515 --> 1:03:19.505
the propensity for violence is
to some extent heritable.

1:03:19.510 --> 1:03:23.130
And so, even if the kid was not
raised by the smacking parent,

1:03:23.130 --> 1:03:26.510
whatever properties of that
parent caused him--led to that

1:03:26.514 --> 1:03:28.774
violence got inherited by the
kid.

1:03:28.769 --> 1:03:31.909
Now, again, this isn't going to
sit right for you and I've

1:03:31.906 --> 1:03:35.146
had--I put this down because
last year when I gave this talk

1:03:35.153 --> 1:03:37.413
people ran up to me and told me
this.

1:03:37.410 --> 1:03:38.400
They said, "Look.

1:03:38.400 --> 1:03:40.840
I know my mom and dad had a
huge role in my life.

1:03:40.840 --> 1:03:44.030
That's why I'm so happy and
successful," then other people

1:03:44.032 --> 1:03:47.002
said, "That's why I'm so
miserable and screwed up,"

1:03:47.000 --> 1:03:51.850
but either way blame it on Mom
and Dad or thank Mom and Dad.

1:03:51.850 --> 1:03:54.800
And you might think you know.

1:03:54.800 --> 1:03:57.690
When you become famous and you
stand up and you get your awards

1:03:57.689 --> 1:03:59.459
maybe you'll thank your mom and
dad.

1:03:59.460 --> 1:04:02.110
When you go to your therapist
and explain why you're so

1:04:02.112 --> 1:04:03.882
screwed up maybe you'll blame
Dad.

1:04:03.880 --> 1:04:06.030
"He never took me to a baseball
game."

1:04:06.030 --> 1:04:08.410
Well, maybe,
[laughter]

1:04:08.414 --> 1:04:10.694
but you don't know.

1:04:10.690 --> 1:04:14.470
Were you adopted?

1:04:14.469 --> 1:04:16.899
If you weren't adopted,
you can't even begin to have

1:04:16.904 --> 1:04:19.914
the conversation about how your
parents messed you up because if

1:04:19.911 --> 1:04:22.681
you're a lot like your parents
you might be a lot like your

1:04:22.679 --> 1:04:24.779
parents because you share their
genes.

1:04:24.780 --> 1:04:26.610
Of course, you resemble your
parents.

1:04:26.610 --> 1:04:30.500
Moreover, how do you figure out
which is the cause and which is

1:04:30.503 --> 1:04:32.793
the effect?
"Mom smacked me a lot and

1:04:32.794 --> 1:04:35.924
that's why I turned out to be
such a rotten person."

1:04:35.920 --> 1:04:38.440
Well, maybe she smacked you
because you were rotten.

1:04:38.440 --> 1:04:42.090
[laughter]
I don't want to get personal

1:04:42.093 --> 1:04:47.193
but it's very difficult to pull
these things apart.

1:04:47.190 --> 1:04:48.720
A final point on this.

1:04:48.720 --> 1:04:51.970


1:04:51.969 --> 1:04:55.379
One response to Harris' book is
this.

1:04:55.380 --> 1:04:57.550
"Look.
Even if this is true,

1:04:57.554 --> 1:05:01.474
you shouldn't let this get out
because if parents don't mold

1:05:01.471 --> 1:05:05.261
their children's personalities
maybe why should they treat

1:05:05.256 --> 1:05:06.846
their kids nicely?"

1:05:06.850 --> 1:05:08.830
And you might be wondering this.

1:05:08.829 --> 1:05:12.219
You might be thinking,
well, gee, if you don't have

1:05:12.220 --> 1:05:16.090
any effect on how your kids turn
out, why be nice to them,

1:05:16.086 --> 1:05:17.846
but there are answers.

1:05:17.849 --> 1:05:20.719
You might want to be nice to
them because you love them.

1:05:20.719 --> 1:05:23.499
You might want to be nice to
them because you want them to be

1:05:23.499 --> 1:05:25.359
happy.
You might want to be nice to

1:05:25.362 --> 1:05:28.562
them because you want to have
good relationships with them.

1:05:28.559 --> 1:05:31.589
And I have a little bit more
but I'm going to skip it and I'm

1:05:31.588 --> 1:05:33.958
going to move right to your
reading response,

1:05:33.960 --> 1:05:35.760
which is very,
very simple,

1:05:35.764 --> 1:05:37.784
easy to answer,
easy to grade:

1:05:37.777 --> 1:05:39.787
Explain the Flynn effect.

1:05:39.789 --> 1:05:42.829
It's a toughie so just explain
that.

1:05:42.830 --> 1:05:46.950
Okay.
Have a wonderful spring break

1:05:46.950 --> 1:05:49.000
and I'll see you when you get
back.