Speaker 1: What does political polarization have to do with the brain.
Speaker 1: How does an understanding of the medial prefrontal cortex tell
Speaker 1: us about what propaganda posters have in common across nation
Speaker 1: and time. What does any of this have to do
Speaker 1: with the Civil War or hippies versus soldiers, or border
Speaker 1: ruffians versus free staters or barbarians, or hanging chads or
Speaker 1: pearl harbor, or the shadows side of oxytocin, And why
Speaker 1: education can serve as an immune response to mind viruses.
Speaker 1: Welcome to Inner Cosmos with me David Eagleman. I'm a
Speaker 1: neuroscientist and author at Stanford and in these episodes we
Speaker 1: sail deeply into our three pound universe to understand why
Speaker 1: and how our lives look the way they do. Today's
Speaker 1: episode is one of a couple I'm making on the
Speaker 1: topic of neuropolitics. We are in a polarized era, and
Speaker 1: when I look around, I see a primate brain doing
Speaker 1: lots of things that primate brains do. So today I'm
Speaker 1: going to talk about polarization, and in the next episode,
Speaker 1: I'm going to talk about all the good news, which
Speaker 1: is the flexibility of the brain and what hopes we
Speaker 1: might have to get ourselves out of polarization. I'm also
Speaker 1: going to do another episode about all the other aspects
Speaker 1: of the bigger picture that I'm calling neuropolitics, which is
Speaker 1: the way that the circuitry of our brains leads us
Speaker 1: to the kind of political viewpoints we have, and why
Speaker 1: we often have a difficult time understanding one another and
Speaker 1: why societies fracture along particular lines. Okay, so when I
Speaker 1: think about America, the polarization is high, and this feeling
Speaker 1: we all have is of course easily quantified. As one example,
Speaker 1: you can look at the numbers about how many times
Speaker 1: you have congressmen voting across the aisle. When a society
Speaker 1: is very polarized, like it is now, people hold on
Speaker 1: tight to their team. I'm very interested in viewing this
Speaker 1: all from the perspective of the brain, but first I
Speaker 1: need to do some table setting. A lot of people
Speaker 1: assert that our polarization has everything to do with social media.
Speaker 1: I'm interested in the roles that social media plays, but
Speaker 1: I do need to say that I don't think it
Speaker 1: serves by itself as much of an explanation for our polarization. Why,
Speaker 1: because we've been exactly this polarized many many times before,
Speaker 1: all before the Internet was even a twinkle in anybody's eyes. So,
Speaker 1: for example, America in the late nineteen sixties was very polarized.
Speaker 1: This was easily seen on the streets, in living rooms,
Speaker 1: on television screens. The Vietnam War split the nation. You
Speaker 1: had young people marching against it, while others saw opposition
Speaker 1: as unpatriotic and dangerous. The Civil rights movement was reshaping
Speaker 1: laws and culture, and that was going too fast for
Speaker 1: some and too slow for others. Generational divides ran deep.
Speaker 1: Parents who had lived through World War Two and fought
Speaker 1: in it struggled to understand their children's embrace of counterculture
Speaker 1: and long hair and psychedelic music and radical politics. The
Speaker 1: assassinations of Martin Luther King and Senator Robert F. Kennedy,
Speaker 1: the urban riots, what happened Kent State. All of these
Speaker 1: moments reinforced the sense that Americans were not living in
Speaker 1: one shared country, but in different realities. Trust in government
Speaker 1: plummeted with Watergate in the nineteen seventies, and that further
Speaker 1: hardened the feeling that institutions could no longer be trusted.
Speaker 1: It was a time when the nation's social fabrics seemed
Speaker 1: to be tearing and when, much like today, people questioned
Speaker 1: whether their neighbors were even living in the same world
Speaker 1: that they were. And of course that was just one
Speaker 1: of many polarized eras in this country. The most obvious
Speaker 1: one began in the eighteen forties and led to the
Speaker 1: Civil War. The divide over slavery and states rights sharpened
Speaker 1: decade by decade, inflamed by the Missouri Compromised, the Kansas
Speaker 1: Nebraska Act, the dread Scott decision. You can see the
Speaker 1: way that newspapers and churches and politicians increasingly spoke in
Speaker 1: absolutist terms, and by the way violence erupted well before
Speaker 1: the war did. From eighteen fifty four to fifty nine
Speaker 1: in the Kansas territory, you had pro slavery border Ruffians
Speaker 1: and the anti slavery free Staters, and they would make
Speaker 1: raids back and forth, committing assaults and murders, each retaliating
Speaker 1: for the last. There were at least fifty six political
Speaker 1: killings during that time, and by the next year, eighteen sixty,
Speaker 1: the election of Abraham Lincoln prompted Southern states to secede
Speaker 1: and Civil War followed. Okay, so that was a really
Speaker 1: grim outcome with seven hundred thousand people killed. But there
Speaker 1: have been many, many other periods of polarization that somehow
Speaker 1: had their day, and then the temperature went down without
Speaker 1: war for different reasons, and we're going to dive into
Speaker 1: that next week. For example, in the eighteen seventies, a
Speaker 1: decade after the Civil War, polarization grew again around rapid industrialization.
Speaker 1: You had labor strikes and violent clashes like the Haymarket
Speaker 1: riot and the Pullman strike. You had class resentment between
Speaker 1: robber barons and workers. And what you can see then
Speaker 1: as now is that newspapers and politicians portrayed opponents as
Speaker 1: existential threats to the American way of life. Then in
Speaker 1: the nineteen tens and twenties, polarization happened again. World War
Speaker 1: I and its aftermath split Americans over issues of free
Speaker 1: speech and loyalty and communism. The first Red Scare was
Speaker 1: concerned about anarchists and labor organizers who were depicted as
Speaker 1: dangerous reds. There were mass arrests and deportations, and this
Speaker 1: deepened divides, and simultaneously there was a surgeon racial violence.
Speaker 1: The summer of nineteen nineteen saw dozens of race riots
Speaker 1: and the rise of the Second Ku Klux Klan, which
Speaker 1: polarized communities along racial and religious and immigrant lines. Then
Speaker 1: by the Late Night Seen twenties and nineteen thirties, you
Speaker 1: had the Great Depression, the economic collapse that sparked really
Speaker 1: fierce battles over the role of government. FDR's New Deal
Speaker 1: was hailed as salvation by some and it was condemned
Speaker 1: as socialism by others. Far left and far right groups
Speaker 1: clashed bitterly. And it was also the case that the
Speaker 1: country was polarized over whether America should intervene in Europe
Speaker 1: as fascism rose, until the attack on Pearl Harbor, which
Speaker 1: temporarily united public opinion. Okay, then I already mentioned the
Speaker 1: polarization of the civil rights movement Vietnam era. So let's
Speaker 1: jump to the culture wars of the nineteen eighties and nineties.
Speaker 1: Some of you might even recall the Reagan era, where
Speaker 1: the country saw sharp divides over taxation and welfare, and
Speaker 1: abortion and feminism and gay rights. These were the so
Speaker 1: called culture wars, which pitted conservatives and evangelicals against progressives
Speaker 1: in battles over school curricula and art and family values.
Speaker 1: And again you could measure this with polarization in Congress
Speaker 1: steadily growing. Finally, some of you may even remember the
Speaker 1: contested two thousand election of Bush versus Gore. Again, this
Speaker 1: was still pre social media, and the whole race came
Speaker 1: down to just the state of Florida, where Bush seemed
Speaker 1: to lead by a few hundred votes out of six
Speaker 1: million cast there, and officials tried to figure out voter
Speaker 1: intent involving hanging chads, which were in completely punched paper ballots,
Speaker 1: and pregnant chads, which were paper ballots that were dimpled. Anyway,
Speaker 1: this spun all the way up to the Supreme Court,
Speaker 1: who finally ruled the electoral vote in favor of Bush,
Speaker 1: even though Gore had received five hundred thousand more popular
Speaker 1: votes nationwide. Now, not all my listeners were alive or
Speaker 1: watching the news at that time, but boy, that was
Speaker 1: a really highly polarized time as well. Then you had
Speaker 1: nine to eleven, which brought the nation together. But then
Speaker 1: over some years the Iraq War started to sharpen those
Speaker 1: divides again. Now you might be tempted to say, well,
Speaker 1: it's worse than ever now because of social media filter bubbles,
Speaker 1: but I just want to remind us all that echo
Speaker 1: chambers are the oldest story of humankind. We are more
Speaker 1: comfortable with people who agree with us and see the
Speaker 1: world from our angle now. I often hear people say
Speaker 1: things like, yes, but we only had a few news
Speaker 1: sources back in the day, so everyone was pinned to
Speaker 1: the same truth. Walter Kronkite or whoever. This is a
Speaker 1: seductive idea, but it's not true. People got some of
Speaker 1: their info from Kronkite, but also from the newsletters they
Speaker 1: subscribe to in their physical mailbox, and also from all
Speaker 1: their friends and neighbors and co workers. And when people
Speaker 1: would have dinners together or chat in the breakroom or
Speaker 1: drink beers in their backyard with their friends, that's when
Speaker 1: they would really come to consensus agreement about what was
Speaker 1: happening in the world. Just to jump back to the
Speaker 1: Vietnam era, do you think the hippies and the returning
Speaker 1: soldiers were sitting down and watching Walter Cronkite and saying, ah, okay,
Speaker 1: I see the truth. There's no problem. We all agree now.
Speaker 1: So any reading of history shows that polarization is depressingly
Speaker 1: a recurring pattern. Each cycle takes a different shape, whether
Speaker 1: that's slavery or labor or immigration, or race or culture
Speaker 1: or war. But the common thread is the part I
Speaker 1: want to zoom in on. When people begin to see
Speaker 1: each other not as neighbors with families and mortgages and
Speaker 1: lives and desires for a better life, but as existential threats.
Speaker 1: When that happens, the brain circuitry involved in empathy, in
Speaker 1: understanding another person's hopes and dreams, the activity in those
Speaker 1: circuits dials down, and the social fabric begins to frame.
Speaker 1: By the way, I just want to flag a point
Speaker 1: that I'm going to explore next week, which is that
Speaker 1: most historians interested in this topic linger on how societies
Speaker 1: fall into polarization, but my main interest nowadays is how
Speaker 1: they crawl back out. So next week I'm going to
Speaker 1: examine the factors that seem to pull societies back from
Speaker 1: the brink, because with all those eras that I just named,
Speaker 1: we went to actual war only once, and with all
Speaker 1: the other periods, we managed to pull ourselves back onto
Speaker 1: a straight road. Sometimes this is because of external factors
Speaker 1: and sometimes because of internal work, And this is all
Speaker 1: what we're going to address next week. Okay, So now
Speaker 1: I want to return to the particular issue for today,
Speaker 1: which is how our brains operate with in and out
Speaker 1: groups and what the brain is capable of when it's
Speaker 1: pushed in the wrong direction. So let's start in nineteen
Speaker 1: ninety four in Rwanda. The radio was on in homes
Speaker 1: and shops and bars, and the message that pours out
Speaker 1: every day is relentless. The Tutsis are cockroaches. They must
Speaker 1: be crushed. This was literally the language in this framework.
Speaker 1: The Tutsi were not citizens or neighbors or people with
Speaker 1: families and histories and memories, but they were cockroaches. The
Speaker 1: more often this message was repeated, the more it carved
Speaker 1: itself into people's brains, and eventually the machetes got unsheathed,
Speaker 1: neighbors turned on neighbors. In one hundred days, half a
Speaker 1: million people were killed. And the part that is frankly
Speaker 1: terrifying is that when you think about genocide, you might
Speaker 1: think this gets driven by soldiers or politicians, but that's
Speaker 1: not what was going on here. The engine of what
Speaker 1: happened in Rwanda was regular people who to neighbors who
Speaker 1: had lived side by side with the Tutsi for generations.
Speaker 1: That is the power of dehumanization. Once someone is no
Speaker 1: longer perceived as human, the neural breaks come off. Now,
Speaker 1: it would be comforting if we could view Rwanda as
Speaker 1: a tragic anomaly, but it's not. History gives us no
Speaker 1: shortage of examples of this very same principle. In Nazi Germany,
Speaker 1: the Jewish community was depicted in newspapers like their Sturmer,
Speaker 1: as rodents swarming through sewers. They were painted as vermin
Speaker 1: to be exterminated. And this is precisely the cognitive space
Speaker 1: that you need to get into if you actually want
Speaker 1: to murder your former friends and neighbors. And by the way,
Speaker 1: it's not just the Hutu and the Nazis, but everyone
Speaker 1: does it. So during World War Two, American propaganda posters
Speaker 1: portrayed the Japanese with distorted faces and thick glasses and
Speaker 1: clawed fingers crouched like apes. The caption was this is
Speaker 1: the enemy. And this is the same across history. If
Speaker 1: we step back into the world of ancient Rome, you'll
Speaker 1: see that outsiders were called barbarians. The word comes from
Speaker 1: the Greek barbaros, which was a mocking sound meant to
Speaker 1: imitate the noise of foreign languages. Bar barbar Originally, it
Speaker 1: didn't have a negative connotation. But pretty quickly the terms
Speaker 1: meaning shifted from outsider to a pejorative for being savage
Speaker 1: or uncivilized. And this was because to Roman ears, outsiders
Speaker 1: had meaningless babbel and increasingly reviewed like animals. The Romans
Speaker 1: often described enemies as wild or beasts. Julius Caesar characterized
Speaker 1: the Galls and Germans as quote, living like animals. Tacitus
Speaker 1: described the Britons as quote savages who live like beasts
Speaker 1: in the forests. So across continents and centuries, the pattern
Speaker 1: is exactly the same. When societies prepare for conflict, they
Speaker 1: sharpen their words, and the words are designed for the
Speaker 1: simple task of stripping away the humanity of the other side.
Speaker 1: Now why does this work so well? Why are animal
Speaker 1: metaphors so effective. It's because they reach down into the
Speaker 1: neural machinery and turn a dial. Under normal circumstances, when
Speaker 1: you look at someone else and another person, you have
Speaker 1: regions of the brain that allow you to imagine their
Speaker 1: inner life. Specifically, a region behind your forehead called the
Speaker 1: medial prefrontal cortex gets involved when you consider that this
Speaker 1: person has thoughts and feelings and plans and fears. That's
Speaker 1: what lights up when you see someone else as a
Speaker 1: human reaching out to deal with a bicycle or a
Speaker 1: chair or a coffee machine. This area does not become active.
Speaker 1: It's only active when you're dealing with a human, when
Speaker 1: you're doing what researchers call a social cognition task. But
Speaker 1: some years ago, my colleagues Lasana Harris and Susan Fiske
Speaker 1: at Princeton wanted to see if the amount this area
Speaker 1: is active depends on what you think about a particular group.
Speaker 1: So they put people in the brain scanner fMRI, and
Speaker 1: they showed them photographs of business people and athletes and
Speaker 1: the elderly, and nurses, and drug addicts and people who
Speaker 1: were homeless. And here's what they found. While some pictures,
Speaker 1: like wealthy people, triggered envy, this social region, the medial
Speaker 1: prefrontal cortex was still active. Other photos, let's say a
Speaker 1: very elderly people, triggered emotions of pity, and this social
Speaker 1: region was still active. But when the brain looked at
Speaker 1: pictures and felt discussed, like for pictures of homeless people
Speaker 1: or drug addicts at rock bottom, the brain viewed them
Speaker 1: not as humans with minds, but more like objects. That
Speaker 1: is the humanization, your brain decides, and this is essentially
Speaker 1: all subconsciously that this person does not count as another mind.
Speaker 1: This person is neurally speaking, less than human. And by
Speaker 1: the way, I'm linking all the relevant studies to the
Speaker 1: show notes, I encourage you to check those out. So
Speaker 1: let's return to propaganda. When some group of people is
Speaker 1: portrayed as cockroaches or rats or babbling animal, barbarians, or
Speaker 1: a virus or a robot or whatever, the social cognition
Speaker 1: regions like the medial prefrontal cortex get dialed down. The
Speaker 1: brain no longer treats this other group as people with
Speaker 1: a mind. Instead, people of that group become more like objects.
Speaker 1: And when these circuits are not steering your decisions, violence
Speaker 1: becomes psychologically easier. As an example, unless you are a vegetarian,
Speaker 1: you don't really mind murdering a big, beautiful animal like
Speaker 1: a cow or a bowl, because you want that burger,
Speaker 1: and that animal is just an animal to your mind,
Speaker 1: it's not a human, and so your medial prefrontal cortex
Speaker 1: is less active when you look at that cow, and
Speaker 1: so you can take a knife to its throat without
Speaker 1: that keeping you up at night, and that ease of killing.
Speaker 1: Maybe it bothers you a little, but not enough to
Speaker 1: stop doing it. That's what we see throughout history, over
Speaker 1: and over, people murdering their neighbors after a sufficient amount
Speaker 1: of messaging telling them that their neighbors aren't really humans.
Speaker 1: They are less than humans, they're more like cows or worse,
Speaker 1: they carry pestilence and they're dangerous. Now, next month, I'm
Speaker 1: going to have a colleague of mine on the podcast
Speaker 1: who pioneered a lot of these studies, Lassana Harris, So
Speaker 1: we'll go into more detail about the prefrontal cortex then,
Speaker 1: But for today, I just want to make it crystal
Speaker 1: clear that this dehumanization is the oldest trick in the
Speaker 1: playbook of propaganda. Dehumanizing another group doesn't have to be
Speaker 1: about making watertight arguments for convincing people with data. It
Speaker 1: can simply be about bypassing reason entirely and tampering directly
Speaker 1: with the machinery of social cognition. It's really important to
Speaker 1: understand that this is a vulnerability built into the human brain.
Speaker 1: When the wind blows hard enough, the flame of your
Speaker 1: social empathy gets blown out. So when we look at
Speaker 1: Rwanda or Nazi Germany or America during wartime, we're seeing
Speaker 1: a basic lesson about the architecture of our own We're
Speaker 1: seeing how fragile our humanizing can be and how dangerous
Speaker 1: it is when pundits and politicians and online influencers lay
Speaker 1: their hands on the dials. Now, before I go on,
Speaker 1: I want to make really clear why I'm devoting a
Speaker 1: lot of my efforts to this sort of research is
Speaker 1: because I think we can solve this, at least mostly,
Speaker 1: and part of this comes down to education as a population.
Speaker 1: If we can learn to recognize the tricks of the
Speaker 1: trade of propaganda, that renders those tricks mostly impotent. Just
Speaker 1: imagine that all the schools in the nation spent just
Speaker 1: fifteen minutes teaching what I just told you. Then the
Speaker 1: next time a student see some TikTokers say oh, those
Speaker 1: people are like animals, or that group is a disease
Speaker 1: that's infecting our country, a light bulb goes on in
Speaker 1: our kids' minds and they say, wait a minute, we've
Speaker 1: heard that before. That kind of simple recognition is ninety
Speaker 1: percent of the game. That recognition turns all of us
Speaker 1: from passive receivers into active listeners. Having knowledge about this
Speaker 1: topic about how dehumanization works in the brain. Is the
Speaker 1: difference between catching the contagion of hate and mounting an
Speaker 1: immune response against it. So now let's turn to a
Speaker 1: related issue, one which is equally important to the story,
Speaker 1: and again is deeply embedded in our brains, And that's
Speaker 1: our predilection for in groups and outgroups. We are fundamentally
Speaker 1: very tribal. We see this in so many ways, and
Speaker 1: sometimes it doesn't matter, like which football team you root for,
Speaker 1: but when when it comes to politics, it carries cognitive consequences.
Speaker 1: You end up feeling certain that your side of the
Speaker 1: political aisle generally has the right idea and the other
Speaker 1: half of the nation who knows what's infected their brains.
Speaker 1: And I just want to be crystal clear that it
Speaker 1: doesn't matter which side of the aisle you're on, you
Speaker 1: are likely to genuinely feel this about the other side,
Speaker 1: and you'll feel like if they would only listen to
Speaker 1: you and stop being so misinformed or stubborn or wrongheaded,
Speaker 1: everyone would fundamentally come to agree with you. Now, if
Speaker 1: we want to understand why humans divide so easily into
Speaker 1: in and out groups, we have to return to our brains,
Speaker 1: in our psychologies, because long before Instagram or cable news,
Speaker 1: or long before propaganda ministries and political campaigns, and even
Speaker 1: long before there were even such things as nations, we
Speaker 1: were wired for us versus them. If you picture the
Speaker 1: world of our ancestors, you had small bands of maybe
Speaker 1: one hundred or so hunter gatherers traveling together, depending on
Speaker 1: each other for survival. These were people who shared food,
Speaker 1: raised children, collectively, hunted side by side, defended one another
Speaker 1: when predators or rivals approached. In that world, there wasn't
Speaker 1: anything abstract about belonging. To be inside the group was life.
Speaker 1: To be outside might mean death, so you had to
Speaker 1: be sensitive to this distinction. Our brains carry this inheritance,
Speaker 1: and we are natural born categorizers. We draw circles around
Speaker 1: us with them on the outside, and once that circle
Speaker 1: is drawn, things inside feel safer and more trustworthy, and
Speaker 1: things outside feel riskier and more dangerous. So there was
Speaker 1: a good experiment on this in the nineteen seventies. The
Speaker 1: psychologist Henry Tefel wanted to know how little it would
Speaker 1: take to spark the tribal machinery, so he brought in
Speaker 1: volunteers and showed them slides of dots on a screen,
Speaker 1: and he asked them to estimate how many dots there were. Then,
Speaker 1: with a straight face, Taefel divided them into two groups,
Speaker 1: overestimators and underestimators, and that was it. It was just
Speaker 1: a label that represented a meaningless categorization. And yet right
Speaker 1: away people started favoring their own side. They gave more
Speaker 1: rewards to fellow overestimators or to fellow underestimators, and not
Speaker 1: to the other side. They rated their own group as
Speaker 1: more likable and more trustworthy. The thing I want you
Speaker 1: to note here is that there was no deep history
Speaker 1: or ideology here. This was just about dots on a
Speaker 1: slide and more specifically belonging to one team or the other.
Speaker 1: So the brain doesn't require a grand narrative to polarize,
Speaker 1: It doesn't need centuries of grievance. It just needs a category.
Speaker 1: And once the category is there, the neural machinery of
Speaker 1: favoritism for your group weres to life and seeing the
Speaker 1: out group as fully human. That dials down. And even
Speaker 1: earlier experiment on this was from nineteen fifty four. This
Speaker 1: was called the robbers Cave experiment. The psychologist Muzifer Sharif
Speaker 1: recruited two groups of eleven year old boys and took
Speaker 1: them to a summer camp in Oklahoma. Yeah, for the
Speaker 1: first week, the groups didn't even know the other existed.
Speaker 1: Each built their own identity. One group called itself the Rattlers,
Speaker 1: the other the Eagles. They made flags, they sang songs,
Speaker 1: they created rituals, and then once those identities had formed,
Speaker 1: Sharif brought the two groups together and set them into competition.
Speaker 1: There was baseball and tugawar and treasure hunts and so on,
Speaker 1: and Sharif watched as things spiraled turned into food fights.
Speaker 1: Food fights escalated into raids on each other's cabins. Cabin
Speaker 1: raids escalated into rocks hurled across the camp, and by
Speaker 1: the end the hostility was so intense that the researchers
Speaker 1: had to physically intervene to keep the boys safe. What's
Speaker 1: so striking about this is how quickly it happened. These
Speaker 1: were boys who had no prior grudges, no ideological differences.
Speaker 1: The researchers manufactured a divide out of thin air, and
Speaker 1: the brains tribal machinery did the rest. And I wish
Speaker 1: this only said something about psychology labs or summer camps,
Speaker 1: but of course, we see the same story everywhere in
Speaker 1: our society. So first let's take something that's not so terrible.
Speaker 1: We see tribalism on full display every weekend in sports stadiums. Sports,
Speaker 1: in a way are our culture's safe tribalism. They let
Speaker 1: us channel our loyalty and hostility into arbitrary groups. So
Speaker 1: it's Yeas versus Red Sox, or Manchester United versus Liverpool,
Speaker 1: or Cowboys versus forty nine ers. People chant, they paint
Speaker 1: their faces, they wave flags, they curse at their rivals,
Speaker 1: and for a few hours they experience the same surge
Speaker 1: of in group bonding that once held hunter gatherer bands together,
Speaker 1: and when the game ends, most fans go home without bloodshed.
Speaker 1: Sports give us the thrill of us versus them in
Speaker 1: a contained, ritualized form. They act like a lightning rod,
Speaker 1: grounding tribal energy, so it doesn't always arc into violence.
Speaker 1: But outside the stadium, when the same circuitry is recruited
Speaker 1: for politics, religion, race, the consequences aren't so harmless because
Speaker 1: then the stakes are higher and the hostility doesn't turn
Speaker 1: off when the whistle blows. So here's what the neurosigence
Speaker 1: shows us about this. The amigdala, which we often think
Speaker 1: of as a detector of fear, is also a sentinel
Speaker 1: for otherness. It flares up when we see faces from
Speaker 1: outside our group. The salience network orients our attention to
Speaker 1: those differences, telling the brain this matters. Watch closely. Meanwhile,
Speaker 1: the chemicals involved in bonding, like oxytocin. These surge up
Speaker 1: when we're with our in group, rewarding us for loyalty,
Speaker 1: for cooperation, for connection. It feels good to be with us,
Speaker 1: which by implication, makes them feel even more alien. Okay, Now,
Speaker 1: when we're talking about summer camps or sports, that's one thing.
Speaker 1: But now take tribal categories and add decades or centuries
Speaker 1: of history and culture, and toss in some ideology, whether
Speaker 1: political or religious or whatever. Then the effect really deepens.
Speaker 1: So my lab Ryan is study on this. Imagine yourself
Speaker 1: lying on back in a brain imaging machine fMRI. You
Speaker 1: see a screen with six people's hands on it, and
Speaker 1: the computer goes around and randomly picks one of the hands.
Speaker 1: Then you see that hand get stabbed with a syringe needle.
Speaker 1: Now your brain has a very fast and low level response.
Speaker 1: A network of areas comes online and we summarize that
Speaker 1: as the pain matrix. This is the same set of
Speaker 1: areas that would come online if your hand was getting stabbed.
Speaker 1: But the interesting part is that this is not your hand.
Speaker 1: You're watching someone else's hand get stabbed. And this is
Speaker 1: the neural basis of empathy. You see something happen to
Speaker 1: someone else, but your brain runs a simulation about how
Speaker 1: that must feel and how that would hurt. Okay, but
Speaker 1: now the experiment changes. We add a one word label
Speaker 1: to each hand Christian, Jewish, Muslim, Hindu, scientologist to atheists,
Speaker 1: and now you watch the computer pick one of these
Speaker 1: hands at random and get stabbed. And the question is
Speaker 1: does your brain care more when it is a member
Speaker 1: of your in group and doesn't care less when the
Speaker 1: hand is labeled as any one of your outgroups? And
Speaker 1: that is precisely what happens. We tested over one hundred
Speaker 1: people of all different faiths, including atheists, and that's the
Speaker 1: clear picture. When the suffering belongs to a hand labeled
Speaker 1: as your group, the pain matrix has a big response,
Speaker 1: But when the very same pain is inflicted on a
Speaker 1: member of an outgroup, those circuits dim The response is weaker,
Speaker 1: so your brain distributes empathy unequally. It follows the boundaries
Speaker 1: of us and them. Other colleagues of might have found
Speaker 1: exactly the same pattern. For example, my colleague Tanya Singer,
Speaker 1: she studied this with soccer fans. She recruited diehard supporters
Speaker 1: of teams and put them into brains scanners and showed
Speaker 1: them videos of fans receiving painful shocks. Sometimes it was
Speaker 1: fellow fans, sometimes it was rival fans, and when their
Speaker 1: own teams fans suffered, these empathy circuits came online. But
Speaker 1: when the rival fans took the same shock, there was
Speaker 1: less of a response, and in some brains something even
Speaker 1: more surprising appeared, which was activity in the reward circuits.
Speaker 1: The suffering of rivals didn't just fail to evoke empathy,
Speaker 1: it evoked pleasure. So when we talk about polarization, we're
Speaker 1: talking about deep circuits firing in the brain, circuits designed
Speaker 1: long ago for survival and small tribes. And these circuits
Speaker 1: are fast and automatic and they run reliably under the hood.
Speaker 1: So when we look at all these studies together, from
Speaker 1: the circuits that involved looking at fellow humans to the
Speaker 1: circuits that come online when we watch other people and
Speaker 1: pain when you put all these studies together, it's clear
Speaker 1: that empathy is not a light that shines equally on everyone.
Speaker 1: It depends on who is in your in groups and
Speaker 1: who in your outgroups. Now, I want to point out
Speaker 1: two more related aspects of polarization that I think are
Speaker 1: often left out of the conversation. The first has to
Speaker 1: do with identity and the second with belonging. So let's
Speaker 1: start with identity. In twenty sixteen, Jonas Kaplan and Sam
Speaker 1: Harris invited people to participate in an fMRI study, so
Speaker 1: people would lie down in the brain scanner and see
Speaker 1: statements about politics. Some of the statements were neutral, but
Speaker 1: others directly contradicted the participants' core political beliefs. What happened
Speaker 1: was that the amygdala and the insula lit up. And
Speaker 1: these are the same regions we see when the body
Speaker 1: feels physically threatened. In other words, when people encountered ideas
Speaker 1: that clashed with their politics, their brains reacted as though
Speaker 1: under siege. But this is another way. Someone disagreeing with
Speaker 1: your politics is not experienced as oh, that's interesting, you
Speaker 1: have a different opinion. It's experienced as something analogous to
Speaker 1: you are attacking me. When political belief is wired into
Speaker 1: the same threat circuitry as our sense of self. Then
Speaker 1: it's no surprise that debate becomes combat or that political
Speaker 1: disagreement is perceived as aggression. It is no wonder that
Speaker 1: arguments get so heated at the dinner table. It's no
Speaker 1: wonder that threads on social media devolve into shouting matches.
Speaker 1: From the point of view of the brain, in these situations,
Speaker 1: people feel like they're in danger. When some people say
Speaker 1: things like words are violence, that squelch is meaningful thinking
Speaker 1: and is quite frankly spineless. But when I saw this
Speaker 1: study some years ago, I thought, ah, okay, that's why
Speaker 1: they're saying it. This is no defense of shutting down
Speaker 1: free speech, but it sheds light on why people deep
Speaker 1: down really want to maintain free speech for their side
Speaker 1: but shut it down for the other side. So this
Speaker 1: is a very important issue about how beliefs become identity.
Speaker 1: You always see this in the language that we use.
Speaker 1: People will say things like as a conservative or as
Speaker 1: a progressive, I believe, and the signals that what we're
Speaker 1: about to hear has elements of a self definition. It's
Speaker 1: embedded in their identity. And when identity is threatened people
Speaker 1: double down. In fact, a bunch of studies show that
Speaker 1: when deeply held beliefs are challenged, people often emerge even
Speaker 1: more convinced of their beliefs. This is a cognitive bias
Speaker 1: called the backfire effect, in which a person's beliefs become
Speaker 1: more entrenched and stronger when presented with evidence that contradicts them.
Speaker 1: And it's precisely because it's a form of defense against
Speaker 1: a personal attack. Now, this hopefully makes it clear why
Speaker 1: facts alone so rarely change minds. Present somebody with evidence
Speaker 1: that contradicts their worldview, and you might expect to see curiosity,
Speaker 1: but we rarely see that. We see resistance. The brain
Speaker 1: is protecting what it perceives as the self. Now, just
Speaker 1: to be clear, this isn't about laughing at other people's foibles.
Speaker 1: We've all felt this ourselves at some level. Really, think
Speaker 1: about a time when someone questioned something that you felt
Speaker 1: was core to who you are. Maybe it was your
Speaker 1: religious beliefs, or your political stance, or something about your
Speaker 1: country of origin or whatever. Chances are, your body reacted.
Speaker 1: Maybe you had a quickening heart rate or a flush
Speaker 1: of heat, or a tightening in your chest. Your threat
Speaker 1: circuits were activated. Your amigdala and insula were firing. Your
Speaker 1: brain was preparing to defend itself. Now, not all beliefs
Speaker 1: are fused with identity. If someone challenges your belief about
Speaker 1: the best way to fix the car engine or which
Speaker 1: restaurant has the best tacos, you might say, okay, cool,
Speaker 1: I'll think about that. That's a belief floating freely. It's
Speaker 1: not attached to your selfhood. But if someone challenges your
Speaker 1: belief about your values, your tribe, your politics, that's more
Speaker 1: fused with your identity, and you are more likely to
Speaker 1: defend that with vim and vigor. Now, one of the
Speaker 1: dangers about a period of high polarization is that more
Speaker 1: and more beliefs become fused with who you are, so
Speaker 1: it pretty quickly reaches beyond people disagreeing about academic theories,
Speaker 1: of taxation or healthcare. The political disagreements get bundled up
Speaker 1: with identities. Who you vote for, where you live, what
Speaker 1: media you consume, what brands you buy. A red baseball
Speaker 1: cap or a rainbow flag can suggest to you things
Speaker 1: about a person's politics before a single word is spoken.
Speaker 1: There's also a psychological comfort infused identity, which brings us
Speaker 1: to the second point. It tells you who you are,
Speaker 1: and it tells you who your people are. In other words,
Speaker 1: while it's often tempting to think about polarization as something
Speaker 1: about social media and news stations, underneath all of that
Speaker 1: there's another angle which is belonging. For example, I mentioned
Speaker 1: earlier the hormone oxytocin. This is often called the love
Speaker 1: hormone or the bonding hormone, and that's because it surges
Speaker 1: when we hug, when we kiss, when we fall in love,
Speaker 1: and more generally, it helps bond groups together. It strengthens
Speaker 1: trust between friends. If you could bottle the warmth of
Speaker 1: human closeness, oxytocin would be one of the main ingredients.
Speaker 1: But there's a dark side to the oxytocin story because
Speaker 1: other research has shown that it increases empathy and generosity selectively.
Speaker 1: What it does is it sharpens the line between us
Speaker 1: and them. So, for example, in one experiment, participants were
Speaker 1: given oxytocin and then they played a little economics game
Speaker 1: with each other where they're making trades, and what happens
Speaker 1: is that when they have this extra oxytocin, people become
Speaker 1: more generous towards members of their own group, but less
Speaker 1: generous toward outsiders. The same chemical that makes them extend
Speaker 1: kindness to their in group members turns them against their outgroup.
Speaker 1: It's like you've only got so much ability to bond
Speaker 1: and that all gets funneled to your tribe. And oxytocin
Speaker 1: is one of several chemicals involved. You've heard of dopamine,
Speaker 1: which is involved in the reward system. The research shows
Speaker 1: that dopamine release is higher when we cooperate with in
Speaker 1: group members. Same thing happens with serotonin, which helps regulate
Speaker 1: feelings of trust and belonging. You've also got endorphins, which
Speaker 1: flow during synchronized activities that you do with an in group,
Speaker 1: and this, I suspect is why rituals matter so much.
Speaker 1: I devoted episode fifty four to this question of why
Speaker 1: armies march in step, or why religious congregations chant together,
Speaker 1: or why sports fans do things in unison. Synchronized movement
Speaker 1: and shared rhythms amplify endorphin release, creating a larger sense
Speaker 1: of us. So collectively, these are the biological undercurrents of
Speaker 1: human connection, and they have evolved to feel good to us.
Speaker 1: We like to be coordinate with our in groups, but
Speaker 1: The problem is that the stronger the US, the sharper
Speaker 1: than them. All you have to do is study any
Speaker 1: war period or even just highly polarized period to see
Speaker 1: that the stronger the in group bond, the more ferocious
Speaker 1: the outgroup hatred. So all this is to say, part
Speaker 1: of why polarization can feel so intoxicating is that it's
Speaker 1: not just the anger or outrage piece. It's equally the
Speaker 1: belonging piece to be part of aside to march and
Speaker 1: step with others, to chant the same slogans, to share
Speaker 1: the same memes. That is rewarding to the brain and
Speaker 1: even in some ways addictive. So I've told you several
Speaker 1: different aspects of polarization, from dehumanization to propaganda, to in
Speaker 1: groups and outgroups, to issues of identity and belonging. But
Speaker 1: this was all table setting because what I really want
Speaker 1: to do is pose the critical question and what do
Speaker 1: we do about all this? If we understand something about
Speaker 1: the neuroscience that leads to polarization, can we use this
Speaker 1: same knowledge to do something about it. That's what part
Speaker 1: two of this podcast is going to be next week.
Speaker 1: But there's one piece that I want to flag again,
Speaker 1: which is education. To my mind. The most important thing
Speaker 1: we can do is teach people about what's going on
Speaker 1: at the intersection of brains and politics, because that's the
Speaker 1: only way we don't fall for it every time. We
Speaker 1: need to be able to recognize when language collapses humans
Speaker 1: into pests, or when headlines portray opponents as monsters, or
Speaker 1: when memes strip away complexity in favor of ridicule. People,
Speaker 1: especially young people, need to be able to recognize when
Speaker 1: these ancient levers are being pulled. Why because propaganda is
Speaker 1: never going going away. As long as we have brains
Speaker 1: that can be polarized, there will be people who try
Speaker 1: to exploit that for whatever reasons, their own beliefs, or
Speaker 1: they realize it's working to give them power, or it
Speaker 1: gives them a solid sense of belonging. Whatever the reason,
Speaker 1: people will always pull these tricks. And the best defense,
Speaker 1: possibly the only defense, is simply awareness. To understand how
Speaker 1: these tricks work, so we can recognize them from a
Speaker 1: mile away. That way we can at least resist the poll. So,
Speaker 1: in closing today, where does this leave us? My position
Speaker 1: here is that you can't explain polarization only in terms
Speaker 1: of social media or which party is winning the election.
Speaker 1: We also have to understand the brains that we are
Speaker 1: all yoked with. We began with cockroaches on the Rwandan radio,
Speaker 1: rats and Nazi cartoons, apes and American posters. We saw
Speaker 1: how quickly the brain can dial down empathy when the
Speaker 1: right metaphors are deployed. We follow the circuitry into the lab,
Speaker 1: where empathy surges for in groups but dims for rivals.
Speaker 1: We saw children at summer camp turn into enemies in
Speaker 1: a manner of hours. We traced the pull of identity,
Speaker 1: the power of disgust, and the shadow side of the
Speaker 1: hormones and chemicals that bond us. The end result is
Speaker 1: that our threat circuitry is like a smoke detector set
Speaker 1: on high sensitivity. It goes off at the faintest whiff,
Speaker 1: even when there's no fire. And we've seen how history,
Speaker 1: again and again has weaponized these vulnerabilities of the brain.
Speaker 1: But this is all just laying the foundation, and now
Speaker 1: we're ready to see next week. My argument that this
Speaker 1: is not destiny. The challenge for us is not to
Speaker 1: abolish tribalism, because I'm not sure that we can, but
Speaker 1: instead to channel it, to find out that let us
Speaker 1: experience belonging without dehumanization generally to expand the circle of
Speaker 1: who counts as us, and I'll explain how we can
Speaker 1: do that, and to learn to recognize the tricks of dehumanization,
Speaker 1: because somehow every generation falls for them anew like it's
Speaker 1: the first time. We now have more educational firepower than
Speaker 1: we've ever had in global history, and it's time to
Speaker 1: make sure everyone knows the tricks of the trade so
Speaker 1: we can have some immunity against them. When we understand
Speaker 1: the neuroscience of polarization, we have the opportunity to derive
Speaker 1: a little bit of hope because the same brains that
Speaker 1: divide us under different conditions can unite us. The key
Speaker 1: thing about the brain is that it's live wired. It's
Speaker 1: always adapting, it's always reshaping its circuitry. So what we'll
Speaker 1: see next week is that even when tribalism mutes empathy,
Speaker 1: shared goals and cooperation can reignite it. And where propaganda
Speaker 1: can dimn humanness perspective, taking can light it up again
Speaker 1: to see how we might build a better world. Please
Speaker 1: join me next week for part two. Go to Eagleman
Speaker 1: dot com slash podcast for more information and to find
Speaker 1: further reading. Join the weekly discussions on my substack and
Speaker 1: check out Subscribe to Inner Cosmos on YouTube for videos
Speaker 1: of each episode and to leave comments until next time.
Speaker 1: I'm David Eagleman and this is Inner Cosmos.