we tend to think about stupid and evil people

doing stupid and evil things.

And this idea is nicely summarized

by the British critic William Hazlitt,

who wrote, "Prejudice is the child of ignorance."

I want to try to convince you here

that this is mistaken.

I want to try to convince you

that prejudice and bias

are natural, they're often rational,

and they're often even moral,

and I think that once we understand this,

we're in a better position to make sense of them

when they go wrong,

when they have horrible consequences,

and we're in a better position to know what to do

when this happens.

So, start with stereotypes. You look at me,

you know my name, you know certain facts about me,

and you could make certain judgments.

You could make guesses about my ethnicity,

my political affiliation, my religious beliefs.

And the thing is, these judgments tend to be accurate.

We're very good at this sort of thing.

And we're very good at this sort of thing

because our ability to stereotype people

is not some sort of arbitrary quirk of the mind,

but rather it's a specific instance

of a more general process,

which is that we have experience

with things and people in the world

that fall into categories,

and we can use our experience to make generalizations

about novel instances of these categories.

So everybody here has a lot of experience

with chairs and apples and dogs,

and based on this, you could see

unfamiliar examples and you could guess,

you could sit on the chair,

you could eat the apple, the dog will bark.

Now we might be wrong.

The chair could collapse if you sit on it,

the apple might be poison, the dog might not bark,

and in fact, this is my dog Tessie, who doesn't bark.

But for the most part, we're good at this.

For the most part, we make good guesses

both in the social domain and the non-social domain,

and if we weren't able to do so,

if we weren't able to make guesses about new instances that we encounter,

we wouldn't survive.

And in fact, Hazlitt later on in his wonderful essay

concedes this.

He writes, "Without the aid of prejudice and custom,

I should not be able to find my way my across the room;

nor know how to conduct myself in any circumstances,

nor what to feel in any relation of life."

Or take bias.

Now sometimes, we break the world up into

us versus them, into in-group versus out-group,

and sometimes when we do this,

we know we're doing something wrong,

and we're kind of ashamed of it.

But other times we're proud of it.

We openly acknowledge it.

And my favorite example of this

is a question that came from the audience

in a Republican debate prior to the last election.

(Video) Anderson Cooper: Gets to your question,

the question in the hall, on foreign aid? Yes, ma'am.

Woman: The American people are suffering

in our country right now.

Why do we continue to send foreign aid

to other countries

when we need all the help we can get for ourselves?

AC: Governor Perry, what about that?

(Applause)

Rick Perry: Absolutely, I think it's—

Paul Bloom: Each of the people onstage

agreed with the premise of her question,

which is as Americans, we should care more

about Americans than about other people.

And in fact, in general, people are often swayed

by feelings of solidarity, loyalty, pride, patriotism,

towards their country or towards their ethnic group.

Regardless of your politics, many people feel proud to be American,

and they favor Americans over other countries.

Residents of other countries feel the same about their nation,

and we feel the same about our ethnicities.

Now some of you may reject this.

Some of you may be so cosmopolitan

that you think that ethnicity and nationality

should hold no moral sway.

But even you sophisticates accept

that there should be some pull

towards the in-group in the domain of friends and family,

of people you're close to,

and so even you make a distinction

between us versus them.

Now, this distinction is natural enough

and often moral enough, but it can go awry,

and this was part of the research

of the great social psychologist Henri Tajfel.

Tajfel was born in Poland in 1919.

He left to go to university in France,

because as a Jew, he couldn't go to university in Poland,

and then he enlisted in the French military

in World War II.

He was captured and ended up

in a prisoner of war camp,

and it was a terrifying time for him,

because if it was discovered that he was a Jew,

he could have been moved to a concentration camp,

where he most likely would not have survived.

And in fact, when the war ended and he was released,

most of his friends and family were dead.

He got involved in different pursuits.

He helped out the war orphans.

But he had a long-lasting interest

in the science of prejudice,

and so when a prestigious British scholarship

on stereotypes opened up, he applied for it,

and he won it,

and then he began this amazing career.

And what started his career is an insight

that the way most people were thinking

about the Holocaust was wrong.

Many people, most people at the time,

viewed the Holocaust as sort of representing

some tragic flaw on the part of the Germans,

some genetic taint, some authoritarian personality.

And Tajfel rejected this.

Tajfel said what we see in the Holocaust

is just an exaggeration

of normal psychological processes

that exist in every one of us.

And to explore this, he did a series of classic studies

with British adolescents.

And in one of his studies, what he did was he asked

the British adolescents all sorts of questions,

and then based on their answers, he said,

"I've looked at your answers, and based on the answers,

I have determined that you are either" —

he told half of them —

"a Kandinsky lover, you love the work of Kandinsky,

or a Klee lover, you love the work of Klee."

It was entirely bogus.

Their answers had nothing to do with Kandinsky or Klee.

They probably hadn't heard of the artists.

He just arbitrarily divided them up.

But what he found was, these categories mattered,

so when he later gave the subjects money,

they would prefer to give the money

to members of their own group

than members of the other group.

Worse, they were actually most interested

in establishing a difference

between their group and other groups,

so they would give up money for their own group

if by doing so they could give the other group even less.

This bias seems to show up very early.

So my colleague and wife, Karen Wynn, at Yale

has done a series of studies with babies

where she exposes babies to puppets,

and the puppets have certain food preferences.

So one of the puppets might like green beans.

The other puppet might like graham crackers.

They test the babies own food preferences,

and babies typically prefer the graham crackers.

But the question is, does this matter to babies

in how they treat the puppets? And it matters a lot.

They tend to prefer the puppet

who has the same food tastes that they have,

and worse, they actually prefer puppets

who punish the puppet with the different food taste.

(Laughter)

We see this sort of in-group, out-group psychology all the time.

We see it in political clashes

within groups with different ideologies.

We see it in its extreme in cases of war,

where the out-group isn't merely given less,

but dehumanized,

as in the Nazi perspective of Jews

as vermin or lice,

or the American perspective of Japanese as rats.

Stereotypes can also go awry.

So often they're rational and useful,

but sometimes they're irrational,

they give the wrong answers,

and other times

they lead to plainly immoral consequences.

And the case that's been most studied

is the case of race.

There was a fascinating study

prior to the 2008 election

where social psychologists looked at the extent

to which the candidates were associated with America,

as in an unconscious association with the American flag.

And in one of their studies they compared

Obama and McCain, and they found McCain

is thought of as more American than Obama,

and to some extent, people aren't that surprised by hearing that.

McCain is a celebrated war hero,

and many people would explicitly say

he has more of an American story than Obama.

But they also compared Obama

to British Prime Minister Tony Blair,

and they found that Blair was also thought of

as more American than Obama,

even though subjects explicitly understood

that he's not American at all.

But they were responding, of course,

to the color of his skin.

These stereotypes and biases

have real-world consequences,

both subtle and very important.

In one recent study, researchers

put ads on eBay for the sale of baseball cards.

Some of them were held by white hands,

others by black hands.

They were the same baseball cards.

The ones held by black hands

got substantially smaller bids

than the ones held by white hands.

In research done at Stanford,

psychologists explored the case of people

sentenced for the murder of a white person.

It turns out, holding everything else constant,

you are considerably more likely to be executed

if you look like the man on the right

than the man on the left,

and this is in large part because

the man on the right looks more prototypically black,

more prototypically African-American,

and this apparently influences people's decisions

over what to do about him.

So now that we know about this,

how do we combat it?

And there are different avenues.

One avenue is to appeal

to people's emotional responses,

to appeal to people's empathy,

and we often do that through stories.

So if you are a liberal parent

and you want to encourage your children

to believe in the merits of nontraditional families,

you might give them a book like this. ["Heather Has Two Mommies"]

If you are conservative and have a different attitude,

you might give them a book like this.

(Laughter) "Help! Mom! There Are Liberals under My Bed!"]

But in general, stories can turn

anonymous strangers into people who matter,