SHANKAR VEDANTAM, HOST: This is HIDDEN BRAIN. I'm Shankar Vedantam.(SOUNDBITE OF MUSIC)VEDANTAM: Here's a question we get asked all the time - how do you change someone's behavior?(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #1: How awesome would it be if you, the victim, decided to not get upset?VEDANTAM: Experts trying to change the way we live our lives.(SOUNDBITE OF ARCHIVED RECORDING)AL GORE: The biggest single cause of global warming, along with deforestation, which is 20 percent of it, is the burning of fossil fuels. Oil is a problem, and coal is the most serious problem.VEDANTAM: Presidents trying to reshape our culture.(SOUNDBITE OF ARCHIVED RECORDING)BARACK OBAMA: For we have a choice in this country. We can accept a politics that breeds division, or we can come together and say not this time.VEDANTAM: We like to think we change people's behavior through information, through education, through persuasion. Now, these things often don't work, but we keep doing them because we have an unshakable faith in a core assumption about human nature. If you want to shape how people behave, you must first change the way they think.Today, we look at a very different approach, one that will take us on a journey from the outskirts of Budapest in 1944 to the hills of Rwanda a half-century later.(SOUNDBITE OF MUSIC)VEDANTAM: This week on HIDDEN BRAIN - how to change behavior. It's not what you think.(SOUNDBITE OF MUSIC)VEDANTAM: When Ervin Staub was a small child, his family had a live-in caretaker named Maria Gogan. Ervin had his own name for her.ERVIN STAUB: We called her Macs, which is an abbreviation of the Hungarian word macska, which means cat.VEDANTAM: That's because Macs told Ervin and his sister bedtime stories, and sometimes, as she told the stories, she'd curl up at the foot of the bed and fall asleep. Outside that cozy house, things were very different. Ervin faced a dangerous world. You see, Ervin was not just a 6-year-old child but...STAUB: A 6-year-old Jewish child, of course.VEDANTAM: Hungary was not a friendly place to be Jewish. Since the 1920s, the Hungarian government had passed a series of anti-Jewish laws restricting Jews from certain occupations, stripping them of the right to vote, prohibiting intermarriage with non-Jews. When World War II erupted, Ervin and his family were in grave danger. Ervin remembers walking with Macs, pushing his little sister down the street in a baby carriage. He heard a massive rumbling and turned to see German tanks rolling down the street.In 1944, Germans occupied the country. With the help of hundreds of thousands of Hungarian citizens, they rounded up the country's Jews. As nearly half a million people were dragged off to places like Auschwitz, most Hungarians did nothing to help. They simply watched as their friends and neighbors disappeared. Ervin's father was captured. Young Ervin might've faced the same fate, but someone intervened to help. It was Maria, or Macs.STAUB: She took my sister and me into hiding with a Christian family.VEDANTAM: To feed the children and their mother, Macs would carry large amounts of dough in the baby carriage to the bakery and then come back with freshly baked loaves. But one day, Hungarian Nazis saw all the bread that she was carrying, and they got suspicious. They stopped her.STAUB: They told her that if she is going to hide Jews, she will be killed, had her stand at the wall with her hands up for a very long time.VEDANTAM: Eventually, a man from the neighborhood, a well-respected Hungarian Nazi, saw what was happening, and he told the others to stop. One might think that after such a terrifying experience, Macs might have stopped helping the Staub family, but she kept on.STAUB: And she continued to do the same thing for the rest of the time.VEDANTAM: Macs also found out where Ervin's father was being held in a forced labor camp. She went there and approached the wire fencing. She asked someone to summon Ervin's dad. Through the fence, she told him where she had taken the children.STAUB: So when the whole group from this forced labor camp was taken to Germany, they had a stopover in Budapest. And during that stopover, my father escaped.(SOUNDBITE OF MUSIC)VEDANTAM: His father found the house with Ervin and his sister. They all hid together and managed to survive the war. Ervin is very sure that Macs saved his life and the lives of his immediate family. Other relatives who didn't have someone like Macs to help them perished.STAUB: My father's sister and her two children were killed in Auschwitz. My mother's sister's husband, my uncle, died in a forced labor camp.VEDANTAM: As Ervin grew up, he found himself dwelling on the question, why do people do terrible things to one another? And is it possible to stop them?Ervin eventually got a Ph.D. in psychology from Stanford and taught clinical psychology at Harvard University. All the while, he kept researching how the Nazis dehumanized the Jews as a stepping stone to genocide. He studied the factors that led to Hitler's rise and Nazi ideology.Evil leaders can get people riled up, but the spark of hate usually doesn't turn into a fire unless people are also experiencing difficult life conditions.STAUB: So if Germany had not been in the terrible state that it was in - losing a war, a revolution, people in groups fighting on the streets for years at tremendous depression - if Germany hadn't had that combined with a history of devaluation of Jews, then it is unlikely that Hitler would have been heard. It's unlikely that Hitler's maniacal intense but charismatic capacity to talk to people would have had the kind of effects that it did. So yes, evil people are important but not alone. Bad leaders don't alone create it.VEDANTAM: Ervin developed a theory of how genocide comes about. As leaders spread hateful ideologies and as people get used to ostracizing others, hostility between groups slowly evolves into violence. Ervin came up with a term for this gradual process - the continuum of destruction.STAUB: Violence evolves. There's experimental research that shows that when a person engages in a violent action, they are likely to engage in more and greater violence. In studying a variety of genocide and mass killings, I saw this in every case - that people get devalued, devaluation is justified in terms of their ideology - reference to their ideology - that these people stand in the way of us creating this better world. So this is very important to understand and very important to try to counteract.VEDANTAM: Ervin tried to imagine what might've stopped this march to violence. From his own experience, he knew that active bystanders can have a huge impact in saving the lives of victims. But in any conflict, why do some bystanders choose to intervene while so many others stay silent? Why had Macs taken such great risks to save Ervin and his family?STAUB: I think she did it because she loved us, because she was connected to us, because she saw us as human beings and didn't accept and go along with the devaluation of Jews that was part of the society at that time.VEDANTAM: Close, personal relationships between Jews and Christians could inoculate people against stereotypes and prejudice. The close relationship that Macs had had with him and his family made it possible for her to see Jews as human beings worthy of protection.STAUB: At a very young age, she was sent out to work as a servant in other families, and she made very good connections to children and I think to the people she worked for, and she received a lot of love and care from these children back in return for her love. That was a very important healing experience on her part. So all of these things, I think, contributed to the kind of person she became and her openness and readiness to be altruistic.VEDANTAM: Ervin felt that his personal experiences provided a roadmap to combat hatred. He started to think about how to inoculate people against hate speech and intolerance. He traveled the world, sharing his ideas at academic conferences. He became a renowned expert on the causes of genocide.STAUB: You know, when this process begins, when a society begins to harm some group and devalues it more and justifies it and then creates institutions, and there is this evolution, the only thing that can stop it is active bystanders, people who are witnesses who see what is happening and who feel a responsibility and who begin to take action against it. And unfortunately, much of the time on a whole scale, this doesn't happen. But there are wonderful instances when it does. And there are many examples of even single individuals doing things that changes the course of a society.VEDANTAM: Fifty years after Macs saved Ervin's life, he began hearing about an unfolding disaster in the East African country of Rwanda. A radio station was broadcasting urgent messages to the population of 7 million. Very few recordings of these broadcasts exist today. Here's one.(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #2: (Through interpreter) Rwanda belongs to those who truly defend it. And you, the cockroaches, are not Rwandans. The cockroaches will not escape.(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #3: (Through interpreter) Let us rejoice, my friends. The cockroaches were exterminated. God is never unfair.VEDANTAM: Just as the Nazis portrayed Jews as subhuman, the Rwandan government, dominated by the Hutu group, dehumanized the Tutsi minority. Their weapon of choice - radio - or as some call it, hate radio. The broadcasts had a real effect. One Harvard study calculated that hate radio convinced an additional 50,000 people to murder their neighbors. Human rights expert Samantha Power described the scene this way - killers often carried a machete in one hand and a transistor radio in the other - radio and machete. As the French historian Jean-Pierre Chretien put it, the first to give and receive orders, the second to execute them.(SOUNDBITE OF MUSIC)ANDRE MUSAGARA: I was 29. I had to move by night, you know, fleeing through bushes and whatever.VEDANTAM: This is Andre Musagara. During the genocide, Andre lived in Kigali, Rwanda's capital city. He talked to us on Skype from Rwanda. He told me armed men came to his house and dragged everyone outside.MUSAGARA: During the genocide, I remember they took us outside, holding our hands up. I don't know why they came. We had rods in the doors and the curtains were - they put on.VEDANTAM: Andre fully expected to be killed.MUSAGARA: I don't know what prevented them from killing us because they were having these, you know, traditional weapons and they were given to whatever (ph). Happily, I was not killed.VEDANTAM: I asked Andre how many people came to his house with machetes. He had a hard time answering.MUSAGARA: I couldn't even look at them straight in the eyes. They were so terrible. It's like they didn't want, you know, anyone to identify them, so they would say lay down and whatever - and yeah. It was a hard moment.(SOUNDBITE OF NEWS MONTAGE)ROBERT SIEGEL, BYLINE: Upheaval in the African state of Rwanda.UNIDENTIFIED REPORTER #1: Bodies litter the streets of Rwanda today.UNIDENTIFIED REPORTER #2: The Red Cross puts the death toll in the tens of thousands...UNIDENTIFIED REPORTER #3: Almost a half-million Tutsis and moderate Hutus have been massacred...UNIDENTIFIED REPORTER #4: Roving bands of drunk youngsters carrying machetes have...UNIDENTIFIED REPORTER #5: Corpses everywhere.UNIDENTIFIED REPORTER #6: Is it genocide? And what is being done to stop the killing?MUSAGARA: I don't want to remember about this.VEDANTAM: By the time the Rwandan Patriotic Front defeated the Hutu government a few months later, the country was in ruins. As many as a million people had been murdered. The majority of the Tutsi population was dead. Many of their killers were roaming free. And now, the nation had to rebuild.How can a country come back from such devastation? Would it ever be possible to rebuild trust? For Ervin Staub, it all seemed eerily familiar. A genocide had unfolded, and yet again, the world had sat on its hands and done nothing.STAUB: I remember seeing pictures of bodies of people killed floating down rivers. And I do remember being very upset that nobody was doing anything, the community of nations wasn't doing anything, that the United States was stepping aside.VEDANTAM: Many countries weren't just stepping aside. They were actively turning a blind eye.STAUB: In Rwanda when the genocide began, many countries sent in military missions to take their own nationals out.(SOUNDBITE OF NEWS MONTAGE)UNIDENTIFIED REPORTER #7: The evacuation of American citizens is proceeding smoothly.SCOTT SIMON, BYLINE: French troops have entered the capital of Kigali to evacuate French nationals. Belgian troops are reported to be on the way.UNIDENTIFIED REPORTER #7: ...Some 300 U.S. Marines are standing by in Burundi to help with evacuations if needed.STAUB: They flew them out and, in a sense, communicated to the perpetrators that we are not involved. You are free to do whatever you do.(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #4: (Through interpreter) If we completely exterminate the cockroaches, nobody in the world will judge us.VEDANTAM: Ervin had been speaking at conferences around the world about the causes of genocide, the trauma faced by survivors and how to work towards reconciliation. But the news from Rwanda told him it was time to try to put into action the theories he had spent decades developing. Simply giving speeches was not enough. Ervin felt he had to act. He and his partner, trauma specialist Laurie Pearlman, got on a plane and went to Rwanda. There was a real risk that violence could flare up again.STAUB: We definitely clearly went with the intention of creating a program that tries to help, that tries to promote healing, tries to promote reconciliation, so that people live better lives and tries to prevent future violence.VEDANTAM: But what might such a program look like? Once he got to Rwanda, Ervin was introduced to someone who had an answer. Alphonse Bakusi was director of Rwanda's conflict management department. Like nearly every other Rwandan, Alphonse had himself been affected by the genocide. Now, even as he came to terms with his own suffering, he was given the task of trying to heal the wounds of his people. I spoke to Alphonse recently on a scratchy phone line to Kigali.ALPHONSE BAKUSI: That is a kind of dilemma. I have an obligation to connect (ph) my people. And on the other side, I was one of the affected people (laughter). So you are affected, and you are asked to help people.VEDANTAM: So you were affected, but you also have to simultaneously help the people who are affected - other people who are affected.BAKUSI: That is what I'm saying about dilemma.VEDANTAM: As he battled his dilemma, Alphonse dug deep into his past, back to happier days before the genocide. He went back to his time in college and high school, and he remembered one thing that he had loved as a student - the theater.BAKUSI: First of all, in my secondary school, I used to play some grandma (ph). I was an (laughter) - I was one of the sentimental actor in my team.VEDANTAM: It was clear that radio could be used to convince people to be violent. Alphonse was sure the reverse was also possible. The idea they came up with - a radio soap opera.(SOUNDBITE OF MUSIC)BAKUSI: You know, our culture - this kind of soap opera is embedded in our culture. And then there are so many programs on radios here.VEDANTAM: Rwandan officials had successfully used an educational drama to teach people how to practice safe sex. Alphonse and Ervin thought that a radio drama could teach ordinary citizens how to spot and then reverse the early stages of the continuum of destruction. Ervin had about a dozen messages he wanted to sprinkle throughout the show. All were derived from nearly 50 years of research and reflected his own experiences during the Holocaust. First, violence evolves slowly. Genocidal leaders don't always start out planning to commit genocide.STAUB: At the beginning, they are not so committed. The vision that we are going to kill these people is not there. That evolves - part of this evolution.VEDANTAM: Point No. 2 - bystanders matter.STAUB: In conditions that lead to great violence, bystanders have to act early because the later it is, the more leaders and the society gets committed to turning against and harming these people.VEDANTAM: No. 3 - when people form close personal relationships with those from other groups, this provides a barrier to the spread of prejudice. When two people from unfriendly groups marry one another, this can reduce hostility between the groups. Ervin wanted to convey this very simple message.STAUB: The hope that intermarriage would be a positive thing.VEDANTAM: Alphonse Bakusi and other Rwandan leaders assembled a team of writers to develop the right narrative. The brainstorming sessions spanned hours, days, weeks.STAUB: Hours and hours and hours looking over the hills of Kigali, developing this original radio program.VEDANTAM: In 2004, one decade after genocide had devastated the country, the program made its debut. It was called...(SOUNDBITE OF MUSEKEWEYA THEME SONG)UNIDENTIFIED PEOPLE: Musekeweya.VEDANTAM: When we come back, we'll hear about the Rwandan love story that captivated a divided country. The question was, would it work? I'm Shankar Vedantam, and you're listening to HIDDEN BRAIN. This is NPR.I'm Shankar Vedantam, and this is...(SOUNDBITE OF MUSEKEWEYA THEME SONG)UNIDENTIFIED PEOPLE: Musekeweya.VEDANTAM: Just kidding. This is HIDDEN BRAIN. The radio soap opera "Musekeweya," which means new dawn, was making its debut. The show follows two fictional villages, Muhumuro and Bumanzi, with a backstory that inevitably leads to conflict. Here's producer George Weiss, who helped launch the program.GEORGE WEISS: We located these two places on two hills opposite one another, and in the middle, there is a field, which is fertile, and through some historic injustice was given to the second village, Bumanzi. And then a little catastrophe happens. A bridge collapses, somebody gets killed, and people start feeling very insecure. This is in parallel to Ervin Staub's - what he calls difficult life conditions.VEDANTAM: Ervin Staub knew from his own experience during the Holocaust that difficult life conditions provide fertile soil for hatred to grow. "Musekeweya" combined Ervin's research into the causes of genocide with Alphonse Bakusi's background in theater. The hope was, in the fictitious conflict between the Muhumuro and the Bumanzi, Hutus and Tutsis in the audience would recognize their own story, and they might learn three concrete ways to move past their divisions. As the Rwandan writers and producers created the drama, one member of the team was...MUSAGARA: Andre Musagara.VEDANTAM: Yes, that's the same Andre who survived the genocide, who didn't know why the men with machetes didn't kill him, who didn't want to be reminded of that traumatic moment. Today, Andre is the director of "Musekeweya."MUSAGARA: The show, to some extent, it opened my mind. And, yeah, now I'm different from the guy I was during the genocide and even before.VEDANTAM: Andre and the other Rwandan writers try to weave psychological messages into their narrative. Violence evolves slowly. Bystanders matter. Intermarriage can reduce conflict.(SOUNDBITE OF ARCHIVED RECORDING)MUSAGARA: (Foreign language spoken).VEDANTAM: Over the past 14 years, there have been more than 700 episodes, each one about 20 minutes long. At a story workshop at the beginning of each season, the writers decide how the plot is going to evolve all while weaving in the messages approved by the academic team they are working with.(SOUNDBITE OF MUSIC)VEDANTAM: Rwandan society has worked hard over the past 25 years to try and erase the divisions between Hutu and Tutsi to ensure that tribal rivalries never again put lives in danger. Here, I'm speaking with show writer Charles Rukundo.Can I ask you? I don't know if this is appropriate to ask you or not, so forgive me if it's not appropriate, but were you from the Hutu community or the Tutsi community?CHARLES RUKUNDO: I'm Rwandan. I'm - (laughter) I'm Rwandan. In Rwanda, it's very difficult to...VEDANTAM: In Rwanda, it's frowned upon to discuss the Hutu or Tutsi past. In some cases, you can even be jailed under a law prohibiting something called divisionism. The official position of the Rwandan government is that there is no ethnicity there; everyone is Rwandan.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED SINGERS: (Singing in foreign language).VEDANTAM: In the soap opera, as hostilities flared between the communities on two opposing hills, the writers needed characters for listeners to identify with. So on those two hilltops, both alike in dignity, they created a pair of star-crossed lovers, Shema and Batamuriza.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #1: (As Batamuriza, speaking foreign language).UNIDENTIFIED ACTOR #2: (As Shema, speaking foreign language).MUSAGARA: People are very interested in love. So by telling them this love story, they are easily connected. And through this story, they could learn that - about the differences. They can find, you know, something to unite them. Yeah.VEDANTAM: Andre explains that "Musekeweya" is a "Romeo And Juliet"-type story where young lovers have to battle the animosity their families feel toward each other. Just like Shakespeare's Montagues and Capulets, the romance causes all kinds of conflict between the two hills.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #3: (As character, speaking foreign language).UNIDENTIFIED ACTOR #4: (As character, speaking foreign language).VEDANTAM: The show was a runaway success. In Rwanda, nearly everyone listens to the radio, and researchers have estimated that most of the population was listening to "Musekeweya." Anyone associated with the show became a big star. And it seemed like the messages were getting through, at least anecdotally.(SOUNDBITE OF MUSIC)VEDANTAM: One of the show's villains is a man named Rutaganira. He's wary of the other side. He thinks they are stealing crops, keeping his village down.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #5: (As Rutaganira, speaking foreign language).VEDANTAM: The name Rutaganira became used in casual conversation when someone was acting like a jerk. Here's producer George Weiss.WEISS: Well, we heard people describe conflict situations by using the names of our characters. You know, oh, don't be a Rutaganira.VEDANTAM: It seemed like the Rwandans were getting the message. But were they really? How could the show creators know for sure? Enter social scientist Betsy Paluck, who is now a professor of psychology at Princeton University.BETSY PALUCK: I was sitting in New Haven at Yale University, and I found a report about this radio soap opera.VEDANTAM: At the time, Betsy was a graduate student trying to figure out a topic for her Ph.D. field research. She knew she wanted to study prejudice and conflict. She knew about the hate radio that had incited so much violence. And here was this program that was trying to reverse it.PALUCK: And I thought, I cannot miss out on knowing what's going to happen next.VEDANTAM: She reached out to the show creators. They agreed to work with her to measure whether the show was changing people's beliefs and making them more tolerant toward each other. Betsy wanted to do something very ambitious - conduct a controlled study in a country that had just been through an incredibly brutal civil war. Remember, the creators of the show wanted to convince Rwandans about three things - violence evolves slowly, bystanders matter, intermarriage reduces conflict. But were the messages getting through? Were Rwandans adopting these new beliefs? Betsy wanted to measure the changes, and she wanted to know whether ordinary people were treating their fellow citizens differently.PALUCK: We ran it like a medical trial in which we assigned certain communities to listen to this reconciliation soap opera and other communities to listen to a different soap opera that was about a different topic - specifically, HIV/AIDS and women's health.VEDANTAM: So once a month for an entire year, the "Musekeweya" group gathered around a portable stereo and listened.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #1: (As Batamuriza, speaking foreign language).VEDANTAM: They listened as Batamuriza's father died and Shema came to pay his respects.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #2: (As Shema, speaking foreign language).VEDANTAM: They listened as Batamuriza fell in love with the forbidden Shema.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #2: (As Shema, speaking foreign language).UNIDENTIFIED ACTOR #1: (As Batamuriza, speaking foreign language).UNIDENTIFIED ACTOR #6: (As character, speaking foreign language).VEDANTAM: They listened as heavy rain destroyed a bridge between the hilltops, as Rutaganira's son died from malnutrition.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #5: (As Rutaganira, speaking foreign language).VEDANTAM: ...And he blamed the other village for the death.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTOR #5: (As Rutaganira, speaking foreign language).VEDANTAM: ...As Rutaganira ran for office and planned to invade the other village.(SOUNDBITE OF RADIO SHOW, "MUSEKEWEYA")UNIDENTIFIED ACTORS: (Cheering).VEDANTAM: As all this happened, people listened. And as is often the case in Rwandan society, they listened together in groups. They weren't just hearing the story on their own. They were seeing the reactions on the faces of their friends and neighbors. They wept together. They laughed together. They shouted out encouragement when Batamuriza was dejected - ihangane sha, meaning, hold on, dear. After one year, Betsy and her team interviewed the volunteers and measured their beliefs. Had they learned the lessons? Had their attitudes toward other Rwandans changed? Betsy asked them about Ervin's three ideas that the Rwandan writers were trying to instill. No. 1 - genocide doesn't happen suddenly.PALUCK: The radio program taught that violence accumulates slowly. It doesn't happen all at once.STAUB: I saw this in every case. Violence progressively evolves. People get devalued.VEDANTAM: There was just one problem. The listeners in the study...PALUCK: They disagreed. We had a number of people who were in our study who said to us at the end, you know, I don't think that's true; the way the genocide happened for me, it came like a sudden rain.VEDANTAM: Lesson No. 2 - bystanders matter. It was one of Ervin's most important guiding principles, the thing he had learned from Macs, the woman who had saved him during the Holocaust.STAUB: When a society begins to harm some group, the only thing that can stop it is active bystanders.VEDANTAM: But here, too, the idea that bystanders can make a difference didn't seem to be getting through to listeners. When asked whether bystanders who remain silent bear some responsibility for the evil actions of others, there was no difference between those who had listened to the soap opera and the control group who hadn't.STAUB: People essentially did not think that bystanders would make any difference.VEDANTAM: And what about lesson No. 3, intermarriage can reduce hostility? That didn't work either. People told Betsy...PALUCK: I don't really believe that ethnic intermarriage will bring peace. I just lived through a genocide where I watched Hutu men kill their Tutsi wives and children. So, you know, I don't personally buy that.VEDANTAM: On all three counts, the soap opera hadn't changed people's beliefs. As entertainment, the show was a hit. But as an experiment designed to change hearts and minds, move two traumatized people towards reconciliation, the show was a failure. "Musekeweya" was nothing more than a fun soap opera. Or was it?(SOUNDBITE OF MUSIC)VEDANTAM: There was one dimension where Betsy found the soap opera did make a positive difference - a big difference. And this dimension was even more important than what people believed. When we come back, why the soap opera was far more successful than it might first appear.(SOUNDBITE OF MUSIC)VEDANTAM: I'm Shankar Vedantam, and you're listening to HIDDEN BRAIN.(SOUNDBITE OF MUSIC)VEDANTAM: I'm Shankar Vedantam, and this is - OK, fine, HIDDEN BRAIN.(SOUNDBITE OF MUSEKEWEYA THEME SONG)UNIDENTIFIED PEOPLE: Musekeweya.VEDANTAM: We're talking about the Rwandan radio soap opera that captivated the country with its stories of love and reconciliation after the genocide. That was the good news. The bad news - despite the hopes of the creators, the show didn't change people's beliefs. But there was one metric much more important than people's own beliefs - actual behavior. As the writers of the radio drama went out into the world to speak with listeners of the show, they came across people who lived on two hills near Kigali very similar to the hills portrayed in the show. Here is director Andre Musagara.MUSAGARA: Arando Mri (ph), on one hill, the majority of the population were Tutsi. And on the other hill, the majority were Hutus.VEDANTAM: If the soap opera was a reflection of real life, this was a reflection of the soap opera. The Hutu and Tutsi inhabitants on the two hills that Andre visited were just like the Muhumuro and the Bumanzi. During the genocide, one group had tried to kill the other.MUSAGARA: There were two hill. During genocide, they went to kill people on the other side, and they looted properties and all that. And after genocide, during this transitional justice process, the Hutu hill was tried.VEDANTAM: He's talking about the Gacaca, a series of community courts held in the years following the genocide. It put about 1 million people on trial. There's debate about the specific numbers, but the vast majority of those tried were found guilty, with crimes ranging from vandalism to murder.MUSAGARA: The crime - it was not very good between these two hills. But there was one listener of "Musekeweya" on one hill, and he went to find his colleague from the other hill. They start to get along. They shared beer. And they said, no, this should not continue this way. And they decided to reunite their hills. And they succeeded.VEDANTAM: Life was imitating art. "Musekeweya" had characters playing the role of active bystanders, peacemakers. Now that was happening in the real hills outside Kigali. Even though "Musekeweya" listeners told Betsy Paluck's research team that bystanders couldn't make a difference, bystanders were stepping up to prevent violence.MUSAGARA: They united. And they were inspired by what they heard from our show, "Musekeweya." We are so proud and - yeah. We are happy, you know, that we are playing a significant role in the reconciliation in Rwanda.VEDANTAM: And it was more than just anecdotal. Betsy's data found that even though listeners' beliefs didn't change, their behavior did. Take the question of intermarriage, for instance. "Musekeweya" listeners told Betsy's team that they didn't think intermarriage would lead to peace. But that's not all they said.PALUCK: They said, however, I do think that now we should allow our children to intermarry. I think that this is the thing that Rwandans are doing. We all think it's a good thing moving forward. This is a good example of a distinction between what you personally believe but what you perceive to be a growing trend.VEDANTAM: What's fascinating here is that you are finding that the message is in fact not changing their own personal opinions, but it's still changing their behavior.PALUCK: That's right. I think if you reflect on your own behavior, it's hard to find a time when, as you were deciding on what to do, you didn't consider someone else, or you didn't consider the reaction that your behavior might draw from someone else.VEDANTAM: When it comes to changing how people behave, it turns out there is a much more powerful driver than people's own beliefs. People don't always do what they believe, but they usually do what they think everyone else believes.(SOUNDBITE OF MUSIC)PALUCK: We are such social people. If we think that our behavior is going to be really going in the other lane, in the other direction from what people who matter to us - from what they're doing, that really restrains our behavior. So we might think one thing but eventually do another - not because we're lemmings, but because we're all trying to kind of move in the same direction with the flock. And if we violate those norms, if we behave in ways that disappoint members of our community, we fear that. And so even if we may believe something different, our behavior will conform to the social norm.VEDANTAM: In essence, Betsy's research demonstrated that even after just one year, the show was working. Even if it didn't change people's beliefs, it was changing social norms, what people thought was expected of them. The same thing happens in other contexts. Take, for instance, same-sex marriage in the United States.(SOUNDBITE OF ARCHIVED BROADCAST)AUDIE CORNISH, BYLINE: Hundreds of people were in front of the U.S. Supreme Court this morning waiting.VEDANTAM: In 2015, the Supreme Court ruled that the U.S. Constitution guarantees the right to marry as a fundamental liberty for both straight and gay couples.(SOUNDBITE OF ARCHIVED BROADCAST)CORNISH: An historic victory for gay rights today. The Supreme...VEDANTAM: Betsy followed ordinary Americans at the time to see if the court decision changed their own views. Again, people's personal beliefs didn't change, but their behavior did.PALUCK: What moved everyone in the same direction was this perception of whether other Americans support same-sex marriage and whether it would become more accepted in the future.VEDANTAM: The Supreme Court ruling in effect told people the United States now believes same-sex marriage is OK. You could still think otherwise, but if you acted in ways that showed you didn't agree with the consensus, you risked being left behind.(SOUNDBITE OF MUSIC)VEDANTAM: Even worse - you risked becoming an outcast.PALUCK: And you may remember that time where people's Facebook walls exploded in rainbows.(SOUNDBITE OF ARCHIVED BROADCAST)UNIDENTIFIED CROWD: (Cheering).VEDANTAM: Once the social norm about gay marriage changed, it emboldened supporters, and it prompted many dissenters to shrug their shoulders and accept the new normal. The same principle works in all sorts of places. Take bullying, for example. Betsy has found that norms play a powerful role in encouraging bullying and discouraging it.PALUCK: I've been studying bullying and conflict as it plays out in Americans' public schools. And what kept hitting me was that at some point, certain types of conflict and prejudice become normal to the people who are living there.VEDANTAM: The central insight of this research is that people go along with the flow rather than their own beliefs. Betsy found the same thing in Rwanda. People who listened to "Musekeweya" began supporting intermarriage even if they didn't personally think that intermarriage was a good thing.PALUCK: It all comes back to this idea that what it means to be human is to belong socially to a group. And so we're all trying to figure out the rules of those groups.VEDANTAM: Betsy realized that one unintended way the soap opera had a big effect was that people had listened together. They thought they were just listening to the show, but they were also taking in the reactions of friends and neighbors. When other people expressed dismay as Rutaganira got in the way of the star-crossed lovers, that sent a message - my fellow Rwandans don't like people like Rutaganira.(SOUNDBITE OF MUSIC)VEDANTAM: After the year of testing was over, Betsy's team gave each group a portable stereo and 14 cassette tapes of the radio program. It was ostensibly a reward for volunteering, but it was actually part of the experiment, too. After presenting the stereo, a research assistant suggested that the group could decide how best to share it.PALUCK: In the communities that had been listening to this reconciliation radio program, it was a little bit counterintuitive at first, but they fought more over their common resources that we gave them. And the reason why that was exciting to us is that one of the messages of this radio program was, you should dissent against authority; you should make your voice heard. In the communities that had not been listening in a dedicated way to these reconciliation soap operas, basically, one person proposed, we give it to the local authority; they will decide for us. Everyone said, good, and moved on.VEDANTAM: Among the "Musekeweya" group, the discussion was much more lively.PALUCK: Usually, someone would make the same proposal. This is what is customary to do in Rwandan communities. But then someone would raise their hand and say, I don't know; the local authority hasn't been coming to listen to all these shows with us; why should we sign it over to him? And then maybe someone else would raise their hand and say, I think we should give it to a woman; they are way more responsible than men. And there would be a healthy debate about that. And then people would decide on what to do. So I went back and I said, look, we have caused healthy debate. This is something to celebrate.(SOUNDBITE OF MUSIC)VEDANTAM: When I spoke to the Rwandan leader Alphonse Bakusi recently, it was close to the anniversary of the 1994 genocide. He told me he was incredibly proud of all that Rwandans had accomplished in the intervening quarter century. "Musekeweya," along with many other interventions that Alphonse oversaw, had made a difference. Ervin Staub accomplished what few scholars ever do. He got to see his ideas put into action. More important, he got to see his ideas make a difference. If there's a continuum of destruction, Ervin helped to show there is also a continuum of benevolence. People can learn tolerance by watching what others do, even fictional characters living on make-believe hilltops.Ervin told me he admires Betsy Paluck's study, but he disagrees with some of her conclusions. Betsy found that people's behavior changed not because their beliefs evolved but because their perceptions of social norms did. But Ervin thinks it isn't possible to easily separate personal beliefs from one's perception of social norms.STAUB: Let me just say, there is no argument about the findings, the results. The only difference between her and me is the interpretation of the results. The results are clear. They are there, and they are meaningful and significant.VEDANTAM: One point Ervin makes is that Betsy's study was conducted during the first year of the show. By the end of that year, there were many unresolved issues in the narrative. Ervin thinks that if the study had been conducted later - for example, after the villain Rutaganira experiences a change of heart - the study might have picked up changes in people's attitudes, not just their behavior. Now, you might argue that the academics are splitting hairs. I asked Ervin about that. I'm going to play you an extended excerpt from our exchange because it leads up to something really important.As I said, I think the theoretical differences about why the behavior changed are less important than the fact their behavior actually changed in the direction that was intended. And, as you point out, this evaluation was done after one year of a program that lasted now 14 years. And those points are very well made. But do you think, actually, it's important whether the difference comes from norms or beliefs or values? Or is it actually just more important that people's behavior changed, and who cares what the actual mechanism was?STAUB: Well, I think that for this, in our case, after one year, what's really important is that behavior had changed and some thinking has changed. But there is one reason why it is always so important what leads to change. And that is when a society moves towards violence, what we hope is that people understand and can foresee what's going to happen. That was one reason we talked to them about the origins of violence. Now, things evolve slowly. And at each point, a person can say, well, it's just one little thing; I'm not doing anything, and then at the next point, same thing. But if you can foresee where this is going to lead, you are more likely to get involved early.VEDANTAM: Right.STAUB: Now, if your views depend on social norms, as a society begins to move towards violence, the social norm is that you move together with everybody else towards violence. But if you personally believe that you should take action, then you are more likely to go contrary to the direction of your group.VEDANTAM: Ervin wants to believe that the values of ordinary Rwandans changed because he wants to believe that the transformation in Rwanda is here to stay. That if hate radio were to start broadcasting again, ordinary Rwandans would stand up to it because they now have different values. But if Betsy is right, this means that Rwandans began acting in a more tolerant fashion in large part because tolerance became the new social norm.This raises a troubling question. If social norms can change in a matter of months from hate to tolerance, can't they go back just as easily in the other direction? Betsy's study provides an important lesson, and not just for people in Rwanda. The currents that govern human behavior are fickle. If you want to make change and then preserve it, you need to be eternally vigilant.(SOUNDBITE OF MUSIC)VEDANTAM: After several years of will-they-or-won't-they drama, Shema and Batamuriza finally get married. Rwandans got so excited about the wedding, about the forbidden love between these two villages, that they wanted to witness an actual wedding. They demanded that the producers of the radio show hold a wedding in the national stadium so that the whole country could show up to watch. Here's the director Andre Musagara.MUSAGARA: We told them Shema and Batamuriza's wedding cannot take place at the national stadium because they have many friends. So if you want to take part in their wedding, this is the way you are going to do it. You dress very, very well, and you go to someone you are in a conflict with, and you reconcile. And that will have participated in Shema and Batamuriza's wedding. And the day after we received (unintelligible) telling us people reconciled because of that announcement we made about Shema and Batamuriza's wedding.(SOUNDBITE OF MUSEKEWEYA THEME SONG)UNIDENTIFIED SINGER: (Singing in foreign language).VEDANTAM: So we've been playing the "Musekeweya" theme song this whole hour. Here's what it means.JACKSON M'VUNGANYI: Dear friends, peace is a plant that is cross-planted and maintained by people together. It is the fruit of love for your neighbor. Be the first to maintain them. Where there's hatred, they do not grow. Where there's love, they grow and flourish.VEDANTAM: For Andre Musagara and the other creators of the show, the goal is to keep that message going as long as the audience is interested. "Musekeweya" is now in its 14th year and shows no signs of stopping. It's a soap opera. The twists are endless.(SOUNDBITE OF MUSEKEWEYA THEME SONG)UNIDENTIFIED SINGER: (Singing in foreign language).VEDANTAM: Today's show was produced by Matthew Schwartz and edited by Tara Boyle. Our team includes Jennifer Schmidt, Rhaina Cohen, Parth Shah, Laura Kwerel and Thomas Lu. Jackson M'vunganyi did our voiceovers and translations. Our unsung heroes this week are Natasha Branch and Alex Drevenskiz (ph) from NPR's incredible audio engineering team. Natasha and Alex pitched in when we were having some challenges with our audio for this week's show. They quickly helped us troubleshoot the problems, and they did so with remarkable calm and good cheer. Thanks so much for your help, Natasha and Alex.If you liked today's show, check out a recent episode of Invisibilia called "The Other Real World." It tells a story of a reality TV show that sought to change behavior and push back against decades of oppression by extremist groups in Somalia. You can find more HIDDEN BRAIN on Facebook and Twitter. And be sure to listen for more of my stories on your local public radio station. I'm Shankar Vedantam. See you next week. And remember; don't be a Rutaganira. Transcript provided by NPR, Copyright NPR.