Original subtitles

Morgan: If you think you see everyone as equal,

you're kidding yourself.

We all have biases.

[ Sighs ]

And no matter how open-minded...

We think we are...

Morgan: Stereotypes color our judgment of others.

[ Gun cocks ]

...and can lead us badly astray.

We live in a society fractured by race, religion,

even our favorite sports teams.

[ Baseball bat cracks ]

Man: Going, going, gone!

Yes! Yes!

Morgan: We divide ourselves into rival tribes.

The political divide between us grows deeper

with every passing year.

When did hate become hard-wired into our brains?

We live in two different americas, one for the rich...

Are we all born to discriminate against our fellow humans?

Are we all bigots?

Space, time, life itself.

The secrets of the cosmos lie through the wormhole.

-- Captions by vitac -- www.Vitac.Com

captions paid for by discovery communications

Have you ever thought about who you instinctively trust

and who you instinctively fear?

Someone's walking toward you down a dark alley...

[ Metallic click ] Holding something in his hand.

Now, I think of myself as an open-minded person.

But scientists tell me I'm kidding myself

and so are you.

We all look at the world with prejudice,

and when you have only a split second to decide,

your own snap judgments may shock you.

Josh Correll grew up solving puzzles for fun,

but now, as a psychologist,

he's trying to solve the puzzle of racism.

And his work is a matter of life and death.

Correll: So, my research was originally inspired by Amadou Diallo.

He came home, went back outside to sit on his front porch,

basically, the stoop of the apartment building.

[ Vehicle approaches, stops ]

Morgan: It was the early hours of February 4, 1999.

[ Car doors open ]

Four New York police officers approached him.

Diallo reached for his wallet

when one of the officers shouted,

"gun! He's got a gun!"

[ Gunfire ]

They fired 41 rounds, killing him at the scene.

The police officers were acquitted of all charges,

sparking a heated national debate.

[ Crowd chanting indistinctly ]

It was a tragedy that has since repeated itself

in the death of Michael Brown in Ferguson, Missouri,

the death of Tamir Rice in Cleveland, Ohio,

the death of John Crawford in Beavercreek, Ohio.

And so, that presented a puzzle.

That presented a question.

How can we determine whether or not race was actually

what drove the officers to shoot?

Some of them will be armed.

Morgan: Josh is about to run an experiment with live ammunition

and with participants who are not policemen.

He asks his white test subject

to treat the simulation as if it is real life.

A potentially lethal person is about to confront him,

and he will have less than one second to make a decision.

There's time pressure. They have to react quickly.

And we can look and see

whether when we change the race of the suspect

from black to white or white to black,

does that influence a person's behavior.

Morgan: The subject will see a scene appear on a screen downrange.

Then, a white man will appear holding either a gun

or a cellphone

or it will be a black man with a gun or a cellphone.

The image of the man is only up for one second.

Time to decide.

Shoot or hold fire?

Mistake the gun for a phone and die.

Mistake the phone for a gun and kill an innocent person.

[ Gun cocks ]

So, what we want to look at is, in that situation

where there's not good, clear information

where people have to respond quickly,

did they use race to inform their decisions?

Morgan: The simulation cycles through dozens of confrontations

equally split between white and black male subjects.

Josh records how long it takes subjects

to make a decision

and whether or not they kill an innocent person

or die themselves.

It's worth noting that, in this game,

people are pretty good.

They don't make a ton of mistakes.

10%, 15% of the time, they make a mistake.

But when we look at those mistakes,

we see racial bias in the errors.

[ Gunshot ]

So they're faster to shoot the armed target

if he's black rather than white.

[ Gunshot ]

When the target's got a cellphone,

they're much more likely to make that decision

to shoot an innocent target when he's black...

Rather than white.

Morgan: Josh has run this experiment on thousands of people.

On average, white subjects are quicker to shoot the black male

and are 30% to 40% more likely to mistake his phone for a gun.

When Josh performs this experiment

with law-enforcement officers,

he finds that their expert training

significantly reduced the occurrence of fatal mistakes.

But no matter what their background or training,

most participants are quicker to shoot at a black target.

Does this mean

that white Americans are inherently bigoted?

An utterly shocking trend with Josh's black participants

suggests that it's much more complicated than that.

[ Gunshot ]

We see that black participants show the same anti-black bias

that white participants do.

Actually when we test

to see if there is a difference in the two groups,

white participants versus black participants,

they are not statistically different from each other.

[ Gunshot ]

So, we think this represents

an awareness of a cultural stereotype,

not that our participants believe necessarily

that black men are more dangerous than white men.

[ Gun cocks ]

But by virtue of the movies that they watch,

the music that they listen to, news reports,

they're getting the idea

that "black male" goes with "violent."

[ Siren wails ]

The group and the idea are linked together in their brains

whether they agree with that stereotype or not.

Why would we make life-and-death decisions

based on stereotypes we don't even believe?

I've always thought

we could overcome these bigoted ideas.

But one neuroscientist says it's not that simple.

Racist stereotypes hijack our subconscious minds.

Neuroscientist Jon Freeman believes

that we all carry around stereotypes in our subconscious.

In fact, the instant you see another person's face,

your brain first perceives them as a stereotype of their race,

gender, or sexual orientation.

So when you first lay eyes on a young Asian student,

she might register as...

The stereotypical Asian overachiever...

But only for an instant.

The way we make snap judgments about others is

nowhere near politically correct.

Whether you like it or not,

a well-groomed man may first trigger

a stale stereotype in your subconscious mind...

[ Whistle blows, upbeat music plays ]

Until your conscious mind corrects you.

Jon wants to understand precisely

why first impressions conjure up clich?s.

Woman: Excuse me. Jon?

I'm a docile white girl.

And he wants to learn if there's a way for us

to see through these clich?s.

Jon: It takes hundreds of milliseconds

for that judgment to sort of crystallize and form,

and a lot happens during that process.

And we are only beginning to understand

what the implications of that might be.

Jon uses brain scanners to determine exactly

what is going on in the brain

during the first fraction of a second of perception,

long before we are consciously aware

of what we're looking at.

The brain is like an office,

where two key desks handle most of the face-analyzing workload,

the fusiform face area...

And the orbitofrontal cortex.

When a visual signal arrives,

they both get to work simultaneously to process it

in their own specialized ways.

Jon: The fusiform face area is

involved in taking visual information

and forming a coherent representation

of the identity and, say, the gender

and the race of the face.

Morgan: But across the way, the orbitofrontal cortex is

focused on associating that face with all the knowledge it has

about the world.

Jon: The orbitofrontal cortex is retrieving

all of the associations spontaneously without awareness.

Morgan: When it sees a black man's face,

the orbitofrontal cortex quickly looks up

all the general information the brain has about black men,

including many stereotypes, and alters the visual signal.

So, some brain regions can sort of convince other brain regions

to be in line with them.

Morgan: Because of this, stereotypes can hijack

the signal from our eyes...

And change what we perceive.

When test subjects look

at a black male with a neutral expression,

their brains immediately light up

as if they are perceiving anger.

And even though they don't realize it,

when they look at a white female with a blank gaze,

their brain's instant reaction is to perceive happiness.

These stereotypes take place in all of the brains Jon studied,

no matter their gender, race, or sexual orientation.

These prejudiced thoughts are quickly snuffed out

by the conscious mind,

but that doesn't mean that they're harmless.

Those stereotypes can actually wind up impacting behavior.

So, for example,

if individuals unconsciously see African-American faces

as being slightly more angry than they are,

that's probably going to impact how much they approach

or avoid that individual at a spontaneous level.

Morgan: If we recognize that we are all prone to these biases,

maybe we can compensate...

[ Gunshot ]

...and avoid unintended acts of prejudice.

But one biologist is attempting to go one step further

to manipulate animal minds...

And override their bigotry.

A stereotype is the brain's way of saving time.

It looks at people or objects

and makes quick decisions about them.

Who'd want to eat this disgusting thing?

But these mental shortcuts can lead us astray.

Mmm.

Delicious.

Can we look beyond appearances

and see people for who they really are?

Neuroscientist Peggy Mason knows

that getting through her daily routine

requires looking at everything as a stereotype.

A basket of freshly plucked vegetables is

a vegetable basket.

Vegetable baskets contain vegetables.

don't they?

Mason: We make expectations about everything,

and they smooth the way.

They're shortcuts.

They make our life happen much faster and much more easily.

Morgan: Without the ability to stereotype,

everything we do would take enormous mental effort

to understand.

We could take nothing for granted.

We have relied on stereotyping for eons

to quickly tell our tribe from outsiders.

For all the hurt that stereotyping causes,

it's fundamental to how our brains work.

So, we're more likely to help those closest to us,

and for complete strangers

that we've never even seen the likes of,

we're not so likely to help them.

Morgan: Peggy wanted to see if there might be a way

to get the brain to overcome these biases.

I think that we humans act in part

due to our shared mammalian biology,

and I think that we can increase social cohesion

in modern society amongst humans.

Morgan: She began with a mammal that has a simpler brain than ours...

[ Rat squeaking ]

Mason: Hey, little guys. How you doing?

You're okay, little buddy.

Morgan: ...The rat, a creature who typically

only aids members of its own strain.

Peggy's experiment involves

temporarily trapping a rat in a plastic tube.

The tube has just one way out,

through a door that can only be opened by another rat.

When another rat from the same strain is added

to the chamber, it's not long

before he works out how to free his imprisoned fellow tribesman.

Mason: These are all albino rats of the sprague dawley stock.

And so, while they are not identical

and they've never met each other,

they also might look like the fifth cousin twice removed.

Morgan: If the rat looks familiar, the other rat helps.

But then Peggy repeats the experiment

with rats of unrelated strains.

Now it's a black capped rat in the tube,

and an albino rat has the option to free him.

Mason: They've never met a black capped rat before.

They don't open for them.

They have no affiliative bond,

and therefore they do not act prosocially

towards these very strange-looking type of rats.

Morgan: But can a rat ever change its ways?

To find out, Peggy exposes a white rat

to a black capped rat.

Mason: We took albino rats.

We housed them with black capped rats

for two weeks.

Then we rehoused them with an albino rat

so they've known one black capped rat.

Morgan: Does this experience make the albino empathetic

to all black capped rats?

To find out, she places him in the arena

with a trapped black capped rat that he's never met before.

[ Rat squeaking ]

The albino rat breaks through the color line.

Mason: What that suggested was that just having a bond

to one black capped rat would allow an albino rat

to generalize all the black capped rats.

They've known one. They've lived with one.

Now they get tested with strangers.

And lo and behold,

they're perfectly helpful to the strangers.

So that was really exceptional to me

because it showed that experience was so powerful.

Morgan: It may not be as hard as you think

for a bigot to have a change of heart.

If any of us has a positive experience

with someone from a different racial group,

biology has the power to make us feel empathy

for a stranger from that group.

In fact, Peggy believes that empathy is a primal instinct

for all mammals.

What rats tell us is that we have a mammalian inheritance

which makes us want to help another in distress.

But the amazing thing that we learn from the rats is

that what the rats need to do is to have an experience

with a different type of rat,

and then that rat can be part of their ingroup, too.

And that's really an amazing and hopeful message, I think.

Empathy has enormous power.

Images of Nelson Mandela behind bars

evoked such compassion from people of all races

that they helped end apartheid in South Africa.

But there's another darker side to the human mind,

one that allows us to take pleasure

in the pain of others

and could make us addicted to bigotry.

Bigotry is as old as human society.

We persecute people of different skin color,

of different religion.

We discriminate between men and women.

But bigotry isn't just about the circumstances of your birth.

Even fans of rival sports teams can learn to hate one another

with all the venom of a bigot.

Harvard psychologist Mina cikara has been thinking

about how human beings move from individuals, to groups

to bitter, violent rivals.

Imagine a group of perfect strangers.

It takes very little for them to form devout tribal alliances.

Well, one of the most amazing things about humans is

how readily they form groups.

In fact, psychological research has shown

that you can randomly assign people

to red team or blue team,

and that's enough to make them show

what we call ingroup bias.

They prefer their ingroup, they treat them better,

they devote more resources to them,

and, in general, it's just a part of human nature.

Morgan: Since the dawn of humanity,

we have needed the support of others to thrive and survive.

So when two groups come into direct competition,

no matter arbitrarily those groups were formed,

the individuals will put the needs of the group

above themselves.

A line is drawn in the sand.

Out. Nice job.

"Out"? What... give me a break.

All-out violence needs only a little provocation.

You were out.

[ Scoffs ]

A dose of escalation...

And both sides will...

[ All shouting indistinctly ]

Charge.

[ Shouting continues ]

[ Upbeat music plays ]

[ Crashing, thumping ]

In general, people are adverse to treating other people badly.

But that's the thing about competition.

Being a good ingroup member

means being a jerk to the out group.

Aah!

It's not just that you want your own team to do well.

It's that you have to make sure that the other team doesn't.

Aaaaaah!

Aaaah!

Morgan: Mina wants to know why this desire

to persecute the other overrides our better judgment.

Aaaaah!

These two are a couple of stand-up guys.

They certainly would never beat each other into a pulp...

Unless it's game day.

Today Mina is going to scan their brains

as they watch their rival team suffer.

So, what we did was we recruited

18 die-hard Red Sox and Yankees fans.

And the idea was we wanted people to watch plays

where their rivals did poorly against another third team,

the orioles.

[ Crowd cheering ]

The Red Sox fan watches a video

where Alex Rodriguez of the Yankees is pelted

by a 100-mile-per-hour fast ball.

[ Baseball thuds, crowd groans ]

Man: Ooh! That's gonna leave a mark.

Morgan: The Yankees fan gets to enjoy an embarrassing mistake

that cost the Red Sox three runs in a single play.

[ Baseball bat cracks, crowd groans ]

Man: What a disaster.

Ooh, how embarrassing for the Red Sox.

Morgan: Mina discovered

that this feeling of pleasure at our rival's pain,

what the Germans call schadenfreude,

is something our brains learn to crave.

When participants watch their rivals fail,

what we saw that there was activations

of the region called the ventral striatum.

The way that this region purportedly works is

that it basically tags positive information,

rewarding events, so that people then can say,

"oh, I should come back to this in order to get pleasure again."

Morgan: The ventral striatum is at the core of many addictions.

When a smoker sees a cigarette,

their ventral striatum reminds them of its pleasures.

And just as a cigarette a day can soon become a pack a day,

couldn't seeing your rival suffer

make you want to see it happen more and more?

Cikara: So, the question then is

whether or not watching your rival suffer misfortune

makes you then more likely to endorse harm

or actually do harm to the rival team

and affiliated individuals.

Well, we have evidence to suggest that it does.

Morgan: What troubles Mina is

that this line of group-oriented thinking

extends beyond sports teams.

In fact, we see everybody belonging

to one of four social categories.

The first time you meet a new person or a group,

there are two questions you need answered right away.

The first is "friend or foe,"

and the second is, "how capable are they

of enacting their intentions toward me, good or ill?"

Morgan: First, there are the friendly groups.

Bright, young kids and doctors, for example,

we usually see as competent.

Less capable friendly groups, like the elderly and infirm,

usually invoke pity.

Drug addicts or teenage Internet bullies,

we categorize as foe.

But these groups aren't competent enough

to spend much energy hating.

It's the people seen both as foe and highly competent

who stir the strong urges toward bigotry.

This includes investment bankers but also groups like asians

or professional women in domains where men generally dominate.

Morgan: Mina studied hundreds of subjects

who report feeling pleasure when members of these groups suffer.

Cikara: When you ask them who they're most likely to harm,

to just hurt, not actually kill,

they're most willing to harm these competent groups

that are competitive with our own interests.

So what's really interesting about these groups is

that, in times of social stability,

people go along to get along with them

because they control resources.

But they're also the first ones to get scapegoated

when social relations become unstable.

Morgan: Being part of a group is

an unavoidable part of being human.

But groupism does more than just block

our natural empathy for others.

When it involves a political agenda,

groupism may actually hack our brains

into perceiving a false reality.

Do you see the world as it really is

or how your political party wants you to see it?

We're a tribal species,

and we all want to be in the winning tribe.

But surely humanity can aspire to rise above this,

to bridge the divide between us.

Democracy was founded in the principle of equality,

that we could reach across the aisle and compromise.

But with every passing year,

political parties seem to be getting

more and more divided.

Maybe it's because conservatives are bigoted

against liberals.

I think you have it backward.

Darren Schreiber is an American political scientist

now working in exeter, u.K.

If there's one thing he's learned

from moving across the pond,

it's that no matter where you go,

liberals and conservatives are not from the same planet.

Do you see yourself as being more liberal

or more conservative?

Definitely more conservative.

I'd see myself more liberal.

Military intervention in the middle east...

How do you feel about that?

I think it's absolutely fundamental.

Each country should be allowed to determine their own future.

What do you think about immigration policy?

The borders need to be slightly more closed.

We should have an open-border policy.

Liberals and conservatives rarely see eye to eye.

Could it be that they have different brains?

Darren decided he would try to uncover the truth

by using an mri brain scanner to see

how the brains of liberals and conservatives handled

decision-making in a simple gambling game.

Today, Darren and his students are re-creating that experiment

but without the mri.

Each test subject is given ?1... About a buck and a half.

They can keep the money, or they can gamble with it.

There's a chance to double the winnings

but also a risk of losing it all.

Do you want to keep that ?1, or do you want to take a risk

at potentially winning or losing ?2?

I will risk ?2.

All right, so open up the envelope

and see what you get.

I've won ?2.

Good. All right.

So here's ?2.

Do you want to keep the ?1,

or do you want to risk potentially winning

or losing ?2?

I think I'll take a risk at winning ?2.

Okay.

I've won ?2.

Whoo-hoo. Congratulations.

So, here's your ?2.

[ Laughing ] I've lost ?1.

You've lost. All right.

Well, you have to give me ?4 now.

Thanks, Sophie.

Darren doesn't care who wins or loses.

His only interest is in how their brains deal

with taking gambling risks,

an act that has no intrinsic political slant.

But to his surprise, liberals and conservatives processed risk

with wildly different regions of their brains.

Conservative brains consistently use the amygdala

to make the decisions to risk everything.

This region is associated with gut feeling

and fight-or-flight responses.

Red brains experienced risk

as a threat with a potential reward.

Liberal brains consistently use the insula when gambling,

a region associated

with perception of one's own feelings.

Blue brains experienced risk as a problem to be solved.

Both brains end up at similar conclusions about taking risks,

but their brains experience it differently.

What it tells us is that being a political liberal

or a political conservative influences

everything that we see,

that we see the world in really different ways,

we use different mental tools when we're processing

even basic things like gambling

that appear to have nothing to do with politics.

And that just blew our minds.

Morgan: So, why is this?

Are we born with our future politics

already fixed in the structure of our brains?

We're unsure about this,

and I actually have a study where we're gonna be looking

to see with a data set that has studied children

from age 4 to 20,

the differences in people's brains

and do they change over time.

But what we know right now is that people,

when they're around 20,

seem to have different sizes of amygdala and insula

depending on whether they're liberals or conservatives.

Morgan: Darren expects that, by the time we are 20,

most of us will have solidified

the color of our political brain.

The possibility of Harmony

between liberals and conservatives is

therefore unlikely.

Politicians and politically active citizens cannot

truly see things from the other side.

Their brains won't let them.

Our intense partisanship is probably here to stay.

But there may be a way to reshape our brains

to Cherish the greater good of all mankind

and open our minds and hearts to one another

if we all play

ultra-violent video games.

[ Gunfire ]

[ Gun cocks ]

The world is full of hate.

Eliminating bigotry seems hopeless.

But there may be a way...

Pure, unadulterated violence in an alternate reality.

[ Gunfire ] Man: Aah!

Professor Matthew grizzard has spent a lot of time

playing video games.

[ Gunfire ]

But as a communications researcher,

these mediated realities are more than just entertainment.

[ Gunfire ]

We don't necessarily distinguish very much

between mediated reality and real reality.

We see visual elements.

We hear things, auditory elements.

And our bodies respond to those elements

as if they were real.

Morgan: Immersed in a game,

Matthew can feel his pulse pounding

and his stomach churning from the intensity of the experience.

[ Gunfire ]

But one day, a level in a game downright disturbed him.

Grizzard: So, I'm in an elevator.

And I'm looking around,

and there's a lot of armed men in military fatigues with me.

At that point, elevator doors open.

[ Elevator bell dings ]

And we step out into what appears to be a crowded airport.

[ Intercom chatter, [ Indistinct conversations ]

And at that point, the order is given,

and we raise our guns to point at innocent civilians

surrounding this airport.

[ Gun cocks ]

And then, we start firing.

[ Gunfire, people screaming ]

[ People moaning, sobbing ]

Morgan: Matthew felt guilty

for murdering so many innocent pixels.

But as a social psychologist, he knows that guilt is a feeling

that can profoundly change our behavior.

Grizzard: We wanted to see if this guilt

that was elicited from virtual environments

could cause people to think more about real-world morality

and could actually increase their moral sensitivity

to real-world issues.

Morgan: Media pundits often accuse violent video games

of destroying the morality of our youth.

Is that really true?

Matthew has a series of test subjects play a game

where they can hurt simulated human beings.

So, Matthew gives the order

to commit blatant crimes against humanity.

So, we set up a situation where people are gonna play

a violent first-person shooter

where they're engaging in terrorist behaviors,

where they're committing genocides

and they're killing innocent civilians,

they're bombing areas, they're gauging in things

that would be considered morally reprehensible in the real world.

Morgan: Matthew's subjects surrender

to the alternative reality of the game.

[ Gun cocks ]

Inside their minds...

[ Gun cocks ]

They are living through the experience

of being a mass murder.

The game is guilt-inducing... [ Gun cocks ]

To say the least.

So we also had a control group because we wanted to see

and distinguish video-game-induced guilt

from real-world guilt.

So we had individuals remember a situation

in which they felt particularly guilty.

Morgan: Writing this out is emotionally taxing.

It brings back painful memories,

perhaps of the time they cheated on a lover

or lied and got someone else in trouble

or sabotaged a friend for selfish gain.

In every case, real people were really hurt.

Matthew compared this group to the murder-simulator group.

So, our findings showed that individuals recalling

a real-world guilty experience actually felt more guilt

but that guilt solicited by video game

was positively associated with increased moral sensitivity.

Morgan: Committing virtual mass murder

gave his subjects a stronger sense of morality.

[ Gun cocks ]

It's a surprising result,

but Matthew thinks he knows why it's the case.

The players violated their own personal sense of fairness.

They cannot right the wrongs they have committed,

so they atone with a subconscious desire

to be a better person.

I think that's the real power of video games.

You can think of them as kind of moral sandboxes,

as areas where we can explore different aspects of morality

or even take viewpoints that are opposed

to our very core of morality.

Morgan: But it's hard to imagine everyone agreeing

to play guilt-inducting video games.

And there will always be sociopaths

whose bigotry spreads through society

like a deadly virus.

Could it be that we're just too tolerant of intolerance?

What would really happen if we cut off the worst offenders?

Could we ever do it?

In the past century,

we've broken down a lot of walls that divided us.

More social groups have been accepted into the mainstream.

Segregation and prejudice are no longer the laws of the land.

But there are still those who think they're superior

because of their skin color, their age, or their gender.

There may be a way to deal

with these bigots and their bigotry...

Build walls around them.

Sociologist and physician Nicholas christakis is taking

a bird's eye view of human society.

From his perspective,

when bigots flourish in a social network,

it is partly the fault of the group itself.

Christakis: So we're embedded in these networks.

How we act in the world is affected

by how the people we know act

but also even by how people we don't know act

as things ripple through the network

and come to affect us.

Morgan: Nicholas and long-time collaborator James Fowler are

studying how social connections change the behavior

of the group as a whole.

Christakis: When you add these ties between people,

the particular number of ties, the particular pattern of ties

then confers on the group

properties it didn't necessarily have before.

Morgan: Patterns and wiring matter.

Think of the Internet.

It's a highly dynamic network of computers.

If one area goes down,

the data simply move around the blockage.

But the electrical grid is more vulnerable.

One bad node can damage all of its neighboring connections...

Or even bring the whole network down.

Nicholas is performing experiments

to see if he can re-engineer human social networks

to be more like the Internet.

His student volunteers form a single social network

divided into four separate groups.

Every student's goal is to make as much money as possible.

Okay, guys, so here's what we're gonna do.

Each of you has a dollar and a pad in front of you.

In a moment, I'm gonna ask you to write "give" or "take."

You can contribute to the collective,

or you can be a parasite and take advantage

of the collective... "Give" or "take."

Then you'll be asked to reveal your choice

and to contribute your dollar or not towards the middle.

I will double the pot,

and then we'll divide the money equally

amongst everyone at every table.

If everybody shares,

everybody makes a good amount of money.

If nobody shares, nobody makes any money.

So, reveal.

All right. You're all givers.

So make your contributions, as well, accordingly.

And so, what we're gonna do is

we're gonna double that and share.

Morgan: At first, most are nice to each other

and share in the rewards.

But a few players choose not to contribute.

When the pot is doubled, they get more than their peers.

In these rounds,

the students cannot change their society's social wiring.

So you're assigned a position in the network,

and you're told, "these are your neighbors.

These are your friends for the next hour.

And you're stuck now interacting with these jerks."

And you don't like it, but all you can do is control

whether you cooperate or defect, whether you share or take.

And what happens after you've been sharing

and some of the people around you are taking is

you say, "I'm not gonna do that anymore,"

and you switching to taking, as well.

And sharing disappears from the system.

Cooperation goes away.

And what you find is that you have then a society of takers.

Morgan: But now Nicholas adds one important rule.

After each round,

each student has the option of moving seats.

Now you can cut the ties to the people who are defectors,

the people who are taking advantage of you

and preferentially form ties

to other nice people in the network,

to other cooperators.

And if you do that,

if you make that small change in the social order,

what you find is cooperation flourishes in the system.

Morgan: The selfish people haven't gone away,

but the society that everybody now lives in

has a completely different culture.

Nicholas believes humans and societies are

like groups of carbon atoms.

Arrange them one way,

and you get soft, opaque graphite.

But if you arrange those same atoms just right,

you get strong, clear, sparkling diamond.

And so, these properties of softness and darkness

aren't properties of the carbon atoms.

And it's just like that with our social groups.

The same human beings connected different ways

gives the group different properties.

Some corporations are experimenting

with an open social network architecture.

Employees are free to break bonds

with any other employee they don't work well with

and form new ones.

Could a similar strategy work for our national

or even global society?

If we were all free to move around,

would there be less hate?

Christakis: Network science doesn't offer one prescription.

It's not as if there's one network structure

that's optimal for everything.

What I can tell you is that network structure matters

to lots of problems, and understanding the rules

of social network structure and function gives us

a new set of tools to intervene in the world to make it better.

Morgan: We may not find a solution to bigotry soon,

but science is at last exposing its roots...

Our biased, snap judgments of others,

our innate groupism,

our rigid political filters.

For now, our best tool to fight bigotry lies

within ourselves...

The courage to walk away.

We all have bigotry inside us.

Most of us work hard to suppress our innate prejudices.

But some don't.

And their bigotry is infectious.

The solution to bigotry does not start

with governments and laws.

It starts with understanding and neutralizing its source

and with you and me doing our best to change.

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