Speaking of Psychology - What moral psychology has to say about charitable giving, with Joshua Greene, PhD

Episode Date: December 10, 2025

It’s December, which means it’s peak season for charitable donations. But how do you decide which organizations to support? Joshua Greene, PhD, discusses how people make moral choices and the implications for where they donate their money; how people can donate using their head and their heart; and how moral psychology can offer avenues to help people cooperate across partisan divisions in a polarized world. Learn more about your ad choices. Visit megaphone.fm/adchoices

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GoogleFi Wireless is not subject to data traffic deprioritization during times of high network usage. It's December, which means it's peak season for charitable giving. If you're planning to donate money to charity this year, here's a question for you. How do you decide which organizations to support? How do you weigh the relative worthiness of, say, a children's arts program, a local food bank, or an anti-malarial campaign on another continent? Do you focus on causes that are personally meaningful to you?

Or do you try to donate to organizations that spend their money most effective? For psychologists who study moral thinking, questions like this offer a tangible illustration of how people make moral choices. Today we're going to talk to a psychologist who studies moral thinking and has turned his research into a platform that he hopes will encourage people to donate more effectively. So what is moral psychology? When people are making moral decisions, do they lean on their emotions, their rational thinking, or both?

happening in the brain when people consider moral choices? And what implications does this have for practical questions from where people donate money to how people and groups cooperate in a polarized world? Welcome to Speaking of Psychology, the flagship podcast of the American Psychological Association that examines the links between psychological science and everyday life. I'm Kim Mills. My guest today is Dr. Joshua Green, a professor of psychology at Harvard University, where he uses behavioral and neuroscience methods to study how people make moral judgments. He's also the co-founder of Giving Multiplier, a research-based donation platform that aims to increase the impact of charitable giving. Dr. Green is author of the book Moral Tribes, Emotion,

Reason, and The Gap Between Us and Them. He's published dozens of peer-reviewed journal articles, and his work has been covered by media outlets, including NPR, The Atlantic, and The Washington Post. Dr. Green, thank you for joining me today. Thank you. Delighted to be here. I introduced this episode by talking about charitable giving, and we're going to talk about that, but I want to start with something else that our listeners may have heard of. And that's the trolley problem.

For those who don't know, could you explain what is the trolley problem and what can it tell us about how people make moral decisions? Well, so the trolley problem has been a kind of obsession of mine since I was an undergrad, and I'm now in my 50s to give you an idea of how long this has been. And I introduced this into research in moral psychology and the then burgeoning field of cognitive neuroscience of morality now over 20 years ago. The gist of it is that these moral dilemmas

are nice little fruit flies for understanding dissociable and sometimes competing mechanisms in our brains when we're making moral decisions. So the two sort of classic, versions of the trolley problem, which will be familiar to many of your listeners, but not everybody, go like this. So in one version, which we'll call the switch case, the trolley is headed towards five people, and you can save those five people, but you have to hit a switch that will turn the trolley onto a different track, where in the canonical case, it will run over one person

instead. Now, this is the version that's gotten super memeified. So a lot of this is often been used as a kind of platform for just, what do you like more, or what do you hate more? Who or what Would you rather run over with the trolley? And, you know, I appreciate the memes, but from a psychology standpoint, the really interesting thing here is the contrast between that classic switch case and what I call the footbridge case. So in the footbridge case, the trolley is again headed towards five people. And the only way you can save them is to block the trolley. So you're on a footbridge over the tracks in between the oncoming trolley and the five people.

and the only way you can save them is to push this other person, let's say it's a person with a very big backpack, onto the tracks, and you can use them as a trolley stopper, and that will kill that person, unfortunately, but it will save the five people, and no, you can't jump yourself because you are not wearing a big backpack and not able to stop it. And yes, we're going to assume that this will actually work.

You've been to the movies, you know how to suspend disbelief. Even with all of those assumptions realistic or unrealistic, most people say, yeah, it's okay, to hit the switch in the first case, turn the trolley away from the five and on to the one. But they either say it's wrong or they feel much more uneasy about using somebody as a trolley stopper in that way,

pushing somebody off of the footbridge to save five. And now after 25 years, we know a lot about what's going on in these different cases. And we could spend two hours just talking about all the evidence here. But the key thing is that there's a kind of emotional response that you get to pushing the person off of the footbridge, that you don't get to hitting that switch. What does it?

Again, this could be a whole episode, but it has to do with the fact that in that case, the harm is not only active, but it is intentional in the sense that you're using the person as a means to your end and that it's more direct. You're pushing with your muscles as opposed to hitting a switch.

All those things matter. And then when we look inside the head and even look neuroscientifically, what we see is a stronger emotional response. And we see this in a part of the brain called the amygdala, which you may recognize as, you know, what's going to light up if you show somebody

an angry face or a snake, it's a feeling of sort of there's a threat or there's something I need to orient to, something dangerous that requires my attention. And then that feeds signals to the ventromedial prefrontal cortex, which is the classic Phineas gauge region. This is the part of the brain that was damaged

in that classic psych one case where damage to that part of the brain leaves people able to think kind of in a cold, rational way, but not in a way that's guided by intuition and emotion and instinct. Yeah. That was the guy who got the spike in his head. Exactly. Right. And yeah, so it does a couple hours north of where I am in Cambridge, Massachusetts. And, you know, the interesting thing about the footbridge case, yes, it's artificial. It's kind of like a visual illusion where, you know, you can look at those weird flashing checkerboards and it doesn't look like things you normally see,

but it's a good way to drive the brain in a way that reveals the competing mechanics in the case of visual illusions of different visual processes. And the Footbridge case, in a sense, I think of it as, this is controversial, but I think of it as a kind of moral illusion. That is, it has the superficial features of a prototypically immoral act and in some ways deeper features.

That is, you are harming somebody in a direct, active, intentional, violent way. It's like punching somebody in the face. But, and the weird twist is that this is a case whereby stipulation, you're serving the greater good by doing this. And that's what makes it this sort of strange kind of thing. And this case highlights the tension between emotion and reason in moral decision making,

loosely defined. There's emotion on both sides. There's reason on both sides, but as a first pass. And to sort of foreshadow our discussion today, you know, this is a dilemma that you could debate what's the right answer, but for most people, there's no comfortable solution. You can say, well, better to save five lives, well, you're left with that sense of, but isn't it horribly wrong to use somebody as a trolley stopper? Or you can say, no, it's wrong to use somebody as a trolley stopper. but then you have to deal with the fact that more people are coming out dead than necessary from that choice. In charitable giving, there is a similar dilemma, and that's the main topic of the research that I think we're going to talk mostly about today. But the good news is there is a middle way in the charitable dilemma in a way that there isn't for the footbridge case.

And we will get there, but I want to mention something else because I read an interview where you said something to the effect of only psychopaths and Buddhist monks, choose to push someone in front of the trolley. Right. So why is that? Because these two groups don't have a heck of a lot in common. Why would they come to a moral judgment that most other people have a difficult time making? Right. And of course, I should say as a good scientist, that that's a broad brush based on the

research that we have. But so it's a dual process story, right? It's a story where on the one side, you have automatic intuitive responses. This is like, you know, connemon thinking fast and slow with an emotional element on the intuition side. and you can end up giving the same answer for different reasons that correspond to those two processes. So what we think is going on in the case of the psychopaths, they don't have much of a feeling that makes them say, no, it's wrong to harm somebody in this direct, violent kind of way.

So they just sort of say, I don't know, what sounds like a reasonable response in this conversation? It doesn't mean they really care about saving more lives, but at least that sounds like a rational thing to say. So that's what they're more likely to say. with the Buddhist monks, and this is actually this is an unpublished study done by a remarkable undergrad named Shin Shang, former undergrad.

She did this as her senior thesis who went to Tibet and tested 50 Buddhist monks like in Lhasa up in the mountains and 80% of them approved of pushing the guy off the footbridge. Now, we couldn't get this paper published because people always said, well, we want follows, we want more of this, no, like, sorry, she's not going back to Tibet.

So now it's just podcast lore. But we have this really strong effect. So what's going on with that? Well, we don't have good psychometrics on them, and we didn't put them in brain scanners, but from what we understand of the psychology, is part of what you're getting from training in Buddhism is a kind of awareness of your emotional responses to things

and a kind of detachment from them. That is to say, not that you don't feel it, but you see it for what it is, and you have a sort of choice. And you can imagine, in clinical context, this is incredibly useful that a lot of people who have training in meditation and Buddhist philosophy

go into clinical psychology because it's so useful. That is so much of what people are looking to deal with when they have clinical issues is feelings that they don't want to have and that are making them behave in ways that are either destructive or just the feelings themselves. So being able to step back from your fear or from your anger or whatever it is and then make a kind of rational choice,

that's a very useful thing. And in the Buddhist tradition, in particular the Tibetan tradition, you are trained to be very aware of what you're feeling and to be able to decide, say, okay, do I want to trust with that feeling and go with it? Or do I want to go with something else? Now, if you ask the Buddhist, why did you make that choice? In this relatively small sample,

I think five of them referred to this specific sutra, this teaching, which tells the story of the case of this ship captain who was, you know, the captain of a large ship and there was a bad guy on board who was going to kill everybody. And the captain knew that if the crew found out about this person, they would kill him and that would be bad for them,

comically speaking, but also didn't want the bad guy to do his bad stuff. So the ship captain decides to kill the bad guy. And with the understanding that this would be bad for him in the next life, but he was sort of taking it as a personal sacrifice. But because it was done,

not for personal gain or even for, you know, to protect one's own personal interests like one's friends or family, but purely for the greater good. The result was actually, this was considered a noble act and the captain goes on to become a bodhisattva, an enlightened one who's engaged with the world.

So the Buddhists might not put it in sort of, what you might call utilitarian terms. They would focus more on the intention. That is that the intention was to promote the greater good, But you can think of it at the very least as a kind of utilitarian concern detached from the emotional response that might push you in the other direction. So I think what's going on here to sort of come back to your question, why do you get the same answer from two populations that might seem to be moral opposites?

It's because it's a difference on the two different components of the dual process story about the moral psychology. The psychopaths don't have the feeling that says, hey, don't push people off of footbridges. The Buddhist monks have that feeling, but they choose to put it aside in this context where there's a greater good at stake. All right.

Now, we're going to get back to the trolley question in a minute, but I'm going to move back to charitable giving, because as I mentioned earlier, you started a platform called Giving Multiplier that aims to get people to donate money more effectively. So tell our listeners, what does it mean to donate effectively? How does the platform work?

Okay, so this is actually a bit of background that comes from outside of psychology, but that's important here. A lot of people don't know that there is such enormous variation in how effective different charities are. So you might think that the difference in effectiveness in charities is something like the difference in human height. So someone who's really tall might be 50% taller than someone who's really not that tall, right? But in fact, the differences can be more like a hundred times or even a thousand times. If you measure these things using the kinds of measurements that health economists and health psychologists use to measure medical outcomes, like how many lives are you saving per dollar or how much are you improving people's quality of life for every dollar or $1,000 that you spend.

So, for example, in the United States, if you were to help people who are blind, so let's say paying for training a seeing eye dog for a blind person in the United States. training and seeing eye dog it costs about $50,000. It's a long intensive process that requires skilled labor. By contrast, in other parts of the world, people go blind because of a disease called trachoma,

which is an infection in the eye. And there is a simple surgery that can cost less than $100 that can prevent people from going blind from trachoma. So you do the math on that. You can fund over 100, maybe close to 1,000 surgeries that prevent people from going blind

in the first place for the cost of training a seeing eye dog in the United States. Now, does that mean that we should disregard the needs of blind people in the U.S.? That is not what I am saying. But to completely ignore the fact that we can do a hundred times, a thousand times more good

on the topic of blindness prevention or mitigation outside, we shouldn't ignore that either. And that's what I mean by the differences between giving effectively or not. In the domain of global health and poverty, where this is most prominent, we have things like distributing malaria nets,

where the cost of distributing a malaria net all in, this is an insecticidal net that prevents people that you sleep under and prevents people typically in sub-Saharan Africa from contracting malaria, usually children under five who end up dying of malaria. It costs about $5 to distribute a net. If you distribute 1,000 nets in sort of key areas, on average you're likely to save one person's life.

And that means you can save someone's life for something around $5,000. Now, that may be more expensive than a lot of people think, but it is a far more effective than, let's say, things that people often want to fund in affluent countries like cancer research, which is very expensive, and the life save for every $5,000 is nowhere close to that. And then there are other programs like deworming treatments that get rid of intestinal worms for less than a dollar, and then a charity will talk about at greater length, which will give directly, which makes direct cash transfers to people in living in extreme poverty.

And those programs make enormous difference in people's lives in a way that goes far beyond anything we can do helping people in a place like the United States or in Europe because just the money goes so much farther there. So that's one kind of effectiveness. Then there's also things that are related to, let's say, climate change. There are things you can do that don't do a lot of good. And then there are other kinds of technological and lobbying oriented things that have a track record of making an enormous difference. There is things in animal welfare. So, you know, supporting the local animal shelter can make a few animals, typically companion animals that humans feel very close to, have better lives.

But if you support a charity like the Humane League, you can make a difference for thousands of animals that are living in terrible conditions in factory farms. So there are organizations like Give Well, which does an incredible job. They've like a team of something like 20 researchers working full time trying to figure out in the domain of health and poverty what saves the most likely. lives per dollar, what improves the quality of life the most per dollar. You have animal charity evaluators doing similar things for animal well-being. And then you have groups like Founders Pledge that look at things that are kind of more big bets like mitigating climate change and trying

to prevent the next pandemic and making calculations about what's most likely to produce the biggest impact. So all of that is research we're taking is given from organizations that have very smart and well-trained people doing their best to figure out what, What's the most good you can do with $1,000 or a dollar for that matter? And then the question is, okay, if we take their evidence-based recommendations as given, what about the human choice, right? It turns out that what people are most drawn to is typically not the stuff that's most effective. And I say this as one of these people.

I mean, my wife and I, you know, we live here in Massachusetts, and we like to support the local public schools where our kids went to school, the Boston Food Bank, which is feeding people during a difficult time. We feel a very strong pull to support things in our community or that are personally meaningful to us. But we also know that there are these extraordinarily impactful charities. And as much as we love Cambridge Public Schools and the Boston Food Bank, we know that what they do does not have the kind of impact that these other organizations can have.

And so what we do is we do both. And you might say from a certain point of view that's not optimal, why not give everything to the super effective stuff. But it fits with our human psychology, right? And so the insight behind giving multiplier, and this was researched done originally with Lucius Caviola, who I'm now delighted to say as a professor

at Cambridge across the pond in the UK, looking at how people respond to a request to do both. That is, in those initial experiments, in the control condition, we gave people the usual choice, which is pick your favorite, charity and you can give, you know, we're giving you $10, you can direct it wherever you want, just give us the link to your favorite charity. Or here's a super effective charity that, you know,

can deworm 100 children for $100. That's the control condition. And what we find found there is that most people, like 80% of people, will choose to support their favorite charity, even if they've heard what experts have to say about how unbelievably affected this other thing is. In the experimental condition, if you say, well, you can do those two things, or there's a third option, split the money 50-50 between your favorite charity when you get to pick and, let's say, this deworming charity, we found that a little over 50% of people in that first experiment chose to do the split and that more money ended up going to the super effective deworming charity if you offered people the split option than if you force people to choose.

So there is something really powerful about giving people the option to do both. And then we did a lot of experiments to try to figure out psychologically what's going on here and how do we turn this into something we can use and happy to say more about that, but let me pause there. But just to give people a better idea of exactly what this is, there's a website you can go to, right, the giving multiplier, and you can make decisions there. So you plug in the charity you want to give to and then you get some options for other charities and you get a split. And then there's money put on top of that, right? Right. So I'll sort of briefly describe the research leading to this. So first we wanted to understand what's really going on here. And what we really found was that when people support the charity that's close to their hearts, it's not so much about how much you give, but just that you're giving something. If you give $50 or $100 to the cancer charity when your beloved diet of breast cancer and so you want to support that, the amount doesn't matter so much. That means if you have $100 to give, if you give $50 to that charity, you get that feeling of

satisfaction of supporting that charity that means a lot to you personally by giving the 50. And then you have another 50. And if you use that 50 in a way that an expert will tell you have a huge impact, now you feel like not only did you give from the heart, but you also gave in this way that's really smart, people really like that. And so then we thought, okay, well, we could publish a paper saying, hey, make split donations and then no one would do anything. So we'd say, well, what if we add money on top? And that's something we can promote. And we found that people really like it when you say not, if you do this split, we'll add money on top, people say, great, and that adds like another 70% of people who do the

split. But then the question is, well, where's that money going to come from? And then we thought, well, what if we asked people, maybe after the fact, would you support a matching fund to pay it forward for other people so that they can get this kind of bonus on top? Or can you direct the part that you were going to give to the super effective charity that you just learned about to that matching fund instead? And we found us enough people were willing to support the matching fund to cover the matching funds for the people who chose to just take the matching funds. And so we were like, wow, this could really work. So Lucius and his techie friends created a website called Giving Multiplier, which is now in its fifth year. I'll tell you how it works, and then I'll tell

you about what we've, the results. So if you go to the website, what you'll see is, you know, a little description of how it works, you choose a personal favorite charity. So any charity is a little, you know, field that you can fill in where you put in any charity that's registered in the U.S. of 501c3. And then we have a list of 10, super effective charities covering different areas. A lot of them global health and poverty, but some of them animal welfare or climate, things like that. And then we have this cool little slider where you put in the total amount and then you decide how you want to allocate that between the one that you picked and the one that's on our list of super effective charities.

And the way we set it up, the more you give to the ones that are on our super effective list, the more money we add on top up to 50%. We do have a code for list. We do have a code for listeners, but I actually want to mention a different campaign because this year we're doing a campaign with a bunch of podcasts, including this podcast. And this is with one of the charities that we've recommended from the start. This is with give directly. I'll get to that in a sec, but I have to brag a little bit about how well-giving multiplier has worked. So we started this five years ago. We've raised over $5 million for charities in general, and close to $3 million of that has gone to our list of super effective charities.

So this has been over 5,000 donors and over 2,600 people giving to their personal favorite charities. And based on Givewell's estimates just for the health and poverty charity, so like malaria nets and vaccines and things like that, we estimate that the money we've moved has saved about 220 people's lives. So this is a case where psychology can really make a difference

if you get the psychology right. But this holiday season, we have our biggest campaign, We're super excited about this, and this is with podcast partners. And this is specifically with a charity called Give Directly, which I mentioned before. Give Directly takes a different approach. It's actually an interesting story how this was created. There were economists who were interested in trying to figure out what works best when it

comes to charitable giving, and particularly sort of global health and poverty. And they wanted to have a baseline to compare interventions to, you know, what happens if you give people vaccines? What happens if you give people filters for clean water or whatever it is? And they said, well, what happens if you just take the money that you would spend and just give it directly to people? And what they found was that that control condition did incredibly well and often did a lot better than the things that they were looking to compare it against. And more recent evidence has shown that when you give people who are living in extreme poverty, just give them cash directly, it not only helps them and they're able to spend it on things like, food or medical care or repairing a broken roof or investing in themselves. So investing in education,

money that they might need to start a business. Like let's say you want to sell, you want to have a business where you sell things to different villages, but you need a way to get around. So you need a little moped and gas for it, right? That the money can be used not only to take care of immediate needs like food and medical care, but in long-term investments. And recent study have shown that for every dollar that goes in, there's a 2.5 times boost in the local economy, right? So there are things where the measurable and immediate impact may be higher than giving cash directly. But if you think that there's some value in donating in a way where people can choose for themselves, how to spend the money, that kind of agency, if that's important to you, this is a really great charity for that.

And if you're really thinking long term, the way you pull people out of poverty long term is through economic development, is by giving people the resources so that they can build the kind of society that sustains itself economically, that's a real argument for this. Now, economists go back and forth on what's better to do now with the dollar, but this is at least a strength of this.

So we love Give Directly, and we originally did a promotion with them with our dear friend Lori Santos, who's also a psychologist and hosts the amazing Happiness Lab podcast, and she and her podcasting friends decided to go big on GiveDirectly this year. So we are doing a pods fight poverty campaign

with I think over 20, maybe 30 podcasts, including this one. We're looking to raise a million dollars for GiveDirectly with the goal of supporting three villages in Rwanda, over 700 families, no strings attached, cash transfers, and this could be transformative for the people who live in these villages. And the link for that is give directly.org, That's all one word.

For this podcast, it's slash speak. If you decide to support that, then you'll be logged as a speaking of psychology listener. And then giving multipliers role in this is that we're supplying the batching funds. So while our supplies last, our funds last, we're adding 50% on top of any donations you make as a speaking of psychology listener. So that's give directly.org slash speak. We're going to take a short break. When we return, I'll talk with Dr. Green about what happens when AI systems make moral decisions and whether moral psychology can help guide us as we build this new technology.

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The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for this day. Now, I'm going to change gears yet again. I want to talk about artificial intelligence. And people often bring up the trolley problem in discussions of self-driving cars. And I'm curious to get your take on that. So what happens when AI systems have to make moral decisions? Can moral psychology help guide us as we're building this technology? Yeah, I think it can.

And part of the debate in this field is whether or not the trolley problem is a kind of good guide is useful for thinking about this. And the debate kind of goes like this. So, you know, the original trolley case is one where, for purpose of simplicity, all the outcomes are known, and they follow deterministically from whatever choice you make. So either you kill one person

and save five people, or you allow five people to die, but you save the one person. And, you know, the people who are designing self-driving car technology point out, I think fairly is, rarely, if ever, do you have a situation where you have this stark choice like that.

And the main thing that we want from self-driving cars is to avoid collisions in tire. right, that there are 40,000 road fatalities, and we want to just get to the point where whatever a self-driving car might do in an extremely rare trolley-type situation, the main thing is to have machines doing a better job

than human drivers so that fewer people die or get injured in road fatalities. So on the side of the software engineers and against some AI trolley enthusiasts, I do agree that the most important thing morally at stake here is to reduce road fatalities and injuries. And once the self-driving technology gets to the point where it does that better,

then it really, I think, is a moral wrong to allow humans to continue to, through inattention and bad decision-making, cause people's deaths. We're not there yet. But that's the big prize. With that said, I don't think the trolley stuff is completely irrelevant,

but the way it plays out is more statistical. It's more in terms of apportioning risk rather than do you do this or do that. So let me give you an example. So you probably have the experience of you're driving in your car, and let's say there's a cyclist in front of you, driving in the road, right?

It's a two-lane road, and you have to decide whether or not do I go around the cyclist. But there's oncoming traffic, right? Now, if you choose to go around the cyclist, maybe you're making a really risky judgment there. You're going to just barely miss the cyclist because you have to go fast

in order to get around and in front before that truck is too close to you, right? there's a question there about how much risk are you imposing on the cyclist? There's risk to yourself. There's risk to the person driving the truck, right? And there's sort of three different levels. Let's say the person in the truck's going to be fine because they're going to bowl you over if they hit you.

You might be in a fair amount of trouble, you know, but the cyclist is really in trouble if there's a collision, right? We all know that some people drive nicely and responsibly, and some people drive like jerks. And some people take risks that are unacceptable, both risks to themselves and to other people. There's no way for AI to avoid those questions. Essentially, does the AI drive like a good, responsible, careful driver, does it drive like a jerk? Right. So there has to be a moral component that's going into this, right? If you barely miss a cyclist, is that a win or a loss? When you might say,

well, reinforce that, you managed to pull ahead in traffic and you didn't hurt anybody. Great. Right. And if you're training a machine, you might say, okay, that was a positive example. Or you might say, no, that was terrible. You put that cyclist at risk. You were two inches away, right? When you went by, that's bad, right? Downgrade that. You give negative reinforcement for the algorithm that produced that outcome. So when it comes to the level of training these things, choices have to be made about what counts as a good outcome or counts as a bad outcome. Where I see sort of trolleyology is useful here is it provides a kind of framework for thinking about what kinds of cost-benefit calculations are we willing to make? What kind of constraints do we want to impose?

And how do we sort of navigate higher-level trade-offs between a kind of hard constraint? Like, you must never ever get within 10 inches of a cyclist or a pedestrian or something like that, versus thinking about probabilities in terms of, are you likely to get to your destination on time, or are you likely to harm some other person or something like that? So some version of this moral psychology is going to have to be in the machine. Some aspects of it are going to be kind of trained in a black box sort of way, and some can be programmed as hard constraints. And I am not in this self-driving car business, but from what I understand, people are looking towards moral psychology and sort of the psychology of human decision-making more generally to think

about what is the morally best way to train and constrain these driving systems. So some of your most recent work has focused on getting people to cooperate across political and other divides. Can you tell us about that work and how it relates to your work on moral thinking? Yeah. So, you know, my interest in trolley stuff was really always about the larger sort of philosophical problem and really about the rural world. So I came into psychology as a philosopher. My undergrad degree, my PhD are actually both in philosophy. And I was interested in these trolley problems because they pose a challenge for moral theory. I'm a consequentialist. I don't love the word utilitarian because I think it conjures up the wrong idea. I prefer to call myself a deep pragmatist, which is what I think I really am.

And the goal of sort of studying the moral dilemmas and the psychology is partly just as interesting basic science. And now who knew, you know, it would have applications and things like self-driving cars. but part of it for me was always about the broader philosophical thinking about what's right and wrong and why and how should we organize our societies. Ten years ago or so, I published a book called Moral Tribes, which I have put my sort of philosophical thinking and my and other people's psychological and neuroscientific research altogether to try to answer the question of what should our philosophy be. And, you know, I'm proud of that book, but I also felt like it was a little unsatisfying to me. That is, I felt like you look at a book called Moral Tribes, Emotion, Reason, and, you know, I'm proud of that. and the gap between us and them. And you want a book that's going to tell you,

like, how do we solve tribalism? How do we deal, like, directly with intergroup conflict? And if I had an answer in that book, it was more like, don't trust your emotions quite as much, be a deep pragmatist, but that's not like a program, right? So after that book was published, I did some kind of soul searching and sort of think, okay, well, what would it take to really apply what we know

or what we think we know more directly? And, you know, I thought, all right, well, I'll take a look at what do we know about intergroup conflict, which has not really been my field, or political polarization, which also not been my field. And I sort of looked at the research, and I, you know, I thought, oh, maybe I'll have some big new theory about intergroup conflict or polarization. And when I looked at the research, I thought, you know, a lot of these old ideas seem to be pretty well supported and make a lot of sense. So on the biology side, the answer that comes out of like, what does it take to bring people

together is mutually beneficial cooperation. That is everything that evolves. All complex living systems are sustained through mutually beneficial cooperation. Molecules come together to form cells, cells form organisms, organisms form societies. That's the heart of everything. And then on the social science side, you've got ideas going back at least to the 50s, like Gordon Alport's contact theory in his landmark book, The Nature of Prejudice. And Sharif and Sharif, the classic Robbers Cave study, All of those things point to the idea that what you need to do is bring people together under what I would describe as circumstances that are conducive to cooperation. And so I thought, huh, so if the social science and the life sciences are all pointing to the

same direction that basically what you need to do to bring people together is mutually beneficial cooperation teamwork, like, why have we not solved this already? I mean, these are old ideas. And not only that, they're probably much older than the research we know. I mean, it's pretty intuitive, right? And I came to the conclusion that it was more about engineering than understanding the basic principles, right? And it's not that this doesn't work. I mean, there are historical cases where the circumstances are right and people come together across lines of division and work together and that really forms a bond, right? And we see this, you know, classic historical examples in the U.S. are the integration of the U.S. military. People thought black people and white people would never be able to fight together in the military. And it worked beautifully.

and the military, you know, for all of its flaws, became one of the most successfully integrated, you know, institutions in American life and in the world. Sports is another example that people often bring up in for good reason. And those are cases where there's a war to be one. There are games to be won in baseball, right? And you just want the best players. And when people work together,

it's really hard to dislike the people who you depend on to win, whether that's saving your life and saving your country or winning the ballgame. And really, every modern city is a testament to the idea that people of different races and backgrounds and ethnicities can view each other more as cooperation partners than as dangerous enemies, right? So we know this can happen through history's sort of fortuitous circumstances,

but what we don't know is how do you engineer this wherever you are? And so my thinking was, well, how do we get people on the same team and how do we do it in a way that is scalable so you can really make a dent in the problem, right? So a lot of when people address things like intergroup conflict and climate change, people's first thought is dialogue. Bring people together, have them talk it out, right? And all part, you know,

paid attention to these kinds of things. And there are wonderful programs like Seeds of Peace, which is going on for decades in Israel, which brings Arab slash Palestinian youth and Jewish Israeli youth together to a summer camp in Maine. And they may come in skeptical and they come away best friends who are crying at the end of the summer. And it really works beautifully. But the seed metaphor has a problem, which is the idea is that these people are going to go out and be the seeds. And what happens is it's not that those people don't go out and do good. And it's not, you know, we don't have a controlled experiment here, but I assume that the world would be even, we'd be even worse shape if it weren't for all the people who've been through programs like seeds of peace. But it hasn't solved the problem, right?

And one way to think about this is during the pandemic, we learned about the concept of are not. This is the sort of coefficient that describes whether or not the virus spreads. And basically, if R not is greater than one, if it's 1.2, then for every person who gets the thing, 1.2 people get it as a result, and the thing goes viral. And if R0 is 0.9, then for everyone who gets it, fewer people get it in the next round and it's going to, and it dies out. And I think what happens with programs like seeds of pieces, it's not that they don't have positive spillover effects, but they don't go viral, right? They don't grow from seeds to forest. So you need something that's more inherently scalable. And then there's also a self-selection problem that the people who would

come into a program like Seeds of Peace in Israel or dialogue groups like in the U.S., like groups like Braver Angels that bring people together across the red, blue, divide, to talk. Those are the people who are willing to devote their time to cross-partisan dialogue. If everyone were like them, we probably would not be in the situation that we're in, right? So you have this self-selection problem, and you have this scale problem, right? And so what we wanted is, well, how do you take the core principle behind a lot of these things, that is bringing people together in a cooperative context, dial it up so that you're not just being cooperative,

but actually have a mutually beneficial cooperative task, put people on the same team to win something, make it so that it can spread and make it so that it's enjoyable so that it's fun so that it's not just the bleeding heart bridgers who are there trying to talk to each other, but regular people. So our solution to this,

and this was where originally started with grad student, M.D. Philippus, now led by the amazing Lucas Woodley, we had people play this game, which we now call Tango. So it is a cooperative quiz game where you play with a partner, and ideally a partner from across the political divide if we're doing this in the U.S.

So you log out of the game, you answer some questions about yourself. Some of them are kind of, you know, about your politics, liberal, conservative, how much, how little. And some of them are kind of fun facts, like, you know, what are fun things about yourself, like, you know, what kind of superpower

would you most want to have and things like that? You get to know the other person. You come up with a team name together, and then you get into the quiz. And the quiz, I'll talk about the U.S. political version, is designed to have a sort of complimentary knowledge. So Republicans are more likely to know about the show Duck Dynasty. This is not just stereotypes. This is empirically validated. Republicans are more likely to know about that show, whereas Democrats are more likely to know about stranger things or the Queen's Gambit.

Yeah. Yeah. Your laughs are giving you away. I know. Oh, I know. Right. And so, you know, you have that like that. And so people, I know this, you know that. We work together. High five. This is fun.

And, you know, winning points, winning money. And then later in the game, we get into more political stuff. So what percentage of gun deaths in the U.S. involve assault weapons. If you ask liberals, they'll often say something like 30%, 40%. As conservatives, they'll say, no, it's like three or four percent. And in this case, the conservatives are right. That actually assault weapons count for relatively few gun deaths, not that they're not terrible, but it's mostly handguns. But if you ask about rates of crime among immigrants,

conservatives are much more likely to think that it's sky high, whereas liberals will say correctly that actually immigrants commit relatively few crimes and in fact have a lower rate of crime than the native-born U.S. citizens. So you have questions like this where sometimes the liberal hunch is right and sometimes the conservative hunch is right. And what we find is that when people play with someone who's different from them, they're respectful and they work it out and they listen to each other. Sometimes I'm right and sometimes you're right and sometimes we're both wrong and sometimes we're both right. And we have this positive cooperative experience where, you know, we played together. It was fun. We learned some interesting things. We had our assumptions

challenged in ways that are interesting. And it works. And when I say that it works, what I mean is we measure before and after how warm or cold do you feel towards Republicans or towards Democrats. How would you divide $100 between a random Republican and a random Democrat? How much do you respect Democrats? How much you trust Democrats? Same with Republicans. And we find out all these measures, people play the game with someone who's politically different from them. We see big immediate effects on this. So when it comes to like the feeling

thermometer, it's the equivalent of rolling, it's like nine degrees. It's like the equivalent of rolling back 15 years of increased animosity in the United States. And then, of course, It's not magic. It fades over time, but we still can detect effects four months later from playing the game once. The results I just described were just published in our paper. It was in Nature, Human Behavior. It came out this summer.

So that's, again, Lucas Woodley's the lead author on that. And that describes five randomized control trials replicating our finding that these positive effects last up to four months. It could be even longer. We haven't gone out that far. And critically, the modal enjoyment rating, I think even the median enjoyment rating across our experiments, is 10 out of 10. Now, these are people doing research studies, so they're not really expecting to have a great time. So this is, you know, low expectations are working to our advantage here, but people do really enjoy the game. And we get great comments from people saying, wow,

this is so much fun if you're ever doing this again, et cetera, sir. So, okay, so that, you know, we spent years getting those RCTs done. And then for the last year or two, we've been working on getting this out in the field. We've been starting on college campuses. You know, used to be college campuses where you go to get convenience subject, you know, participants. But now college campuses, as you know, are like ground zero for political polarization and challenge, not just about right-left politics, but things like Israel, Gaza, et cetera. So we've been developing tango games that work for the right-left divide on college campuses, but also things that divide people along different axes related to things like the war in the Middle East. And we've been

doing pilot studies with us now at several schools. But most recently, we did tango games with the entire incoming class at Harvard. So the class of 2029, over a thousand students, and we see positive effects on all of our outcome measures. So the one I'm most proud of, or the combination I'm most proud of, you may have heard of this in the news, Harvard does lean liberal. So, you know, about 80% of students identify as some kind of liberal, but about 20% do identify as some kind of conservative. And what we found is that when liberals played with the conservatives at Harvard, the liberals showed a seven-point increase in their feeling of less cold and more warm towards conservative students. And the conservative said that they had a five-point increase in the extent to which they said they felt comfortable voicing controversial opinions at Harvard.

Which is really important as we try to take seriously, you know, we want this to be a place where people can really speak their minds. And we can, you know, universities have to be places where people can be honest and open about their political beliefs and not feel that they're being silenced. So Tango had a great effect on that with a thousand students. We induced them to play. I mean, they had, there was part of orientation, but we also gave away Red Sox tickets. So we had a group of like 20 top performing teams go to the ball game, which was awesome. We also encourage people to meet up in real life. People often ask us, okay, so it's nice that people report these changes on the survey going out,

but does they actually do anything? So we have people say, look, if you give your contact information, do you want to meet your partner, if your partner gives their contact information, we'll connect you and suggest, you know, when you can meet at the dining hall. And we had over 10% of the people who played the game meet up with their partners in the dining hall at equal rates, whether their partner was politically similar or different from them. So we're really excited about doing this on college campuses. We also did orientation for Cornell's three business schools this year, and that went great. If you're out there listening and you want to bring this to your school, you can send it to

me, Josh Green, or you can go to let's tango.org and drop a note on our website. We are working to to build this out on college campuses, and ultimately what we want is we want to get this into businesses. And I think that actually this can be something that can not only work for the sort of problem of political polarization and animosity, but employee engagement. You know, we've got remote workers

who feel a little disconnected from their jobs. If you play this game with people who are fellow employees, and there's a real business case for this, and then we're working on building an online version of this, the challenge there is we need people on at the same time. And until you have really high-volve, people are only going to wait a few seconds for a partner. So we're working on building an AI partner that's trained on our thousands of chat transcripts of real Republicans, Democrats,

liberals, conservatives playing these games. So you can come on and play the game with the voice of a thousand Democrats or the voice of a thousand Republicans. And then while you're playing with the bot, maybe a human will come along and you'll be able to play with a real human or you can sign up for a game with a real human. So that's down the road. Our goal is to have millions of people have this positive cooperative experience with people who are different from them. We want to take the idea behind a program like Seeds of Peace and Braver Angels,

but do something where we can reach millions of people. We've got the evidence that it really opens people up and shifts people's attitudes that increases trust and respect. And I should say, it doesn't try to change people's minds, right? Like this is something important. People sometimes think, well, I don't want you to brainwash me and try to convince me that my views are wrong.

That's not what this is about. I think it's healthy in a different. democracy for people to disagree. We're not telling people that they shouldn't disagree. But the only we're going to make those disagreements productive is if there's a baseline level of respect and trust if we can see the humanity in the people who we disagree with. And that, I think, is our big problem right now. So we are working to get tango out there. And if you're interested in playing or having your organization, your school play, or giving us lots of money to help us scale this up, please get in touch. Dr. Green, this has been a lot of fun. And this is really great.

stuff that you're doing. I really appreciate your taking the time to talk to us today. This was great. Thank you so much. I really appreciate you're giving the opportunity. We're super excited about tango and about give directly.org slash speak for our pods fight property campaign. And I just want to tell our listeners that you can find previous episodes of speaking of psychology on our website at speakingof psychology.org or on Apple, Spotify, YouTube, or wherever you get your podcasts. And if you like what you've heard, you can subscribe and leave a a review. And again, if you want to contribute to the Pods Fight Poverty campaign, you can do so by going to give directly.org backslash speak. That's give directly.org backslash speak. And your donation

will be matched one and a half times. If you have comments or ideas for future episodes, you can email us at speaking of psychology at APA.org. Speaking of psychology is produced by Lee Winerman. Thank you for listening. American Psychological Association. I'm Kim Mills. You can't reason with the sun. Trust us. We've tried. This summer, it's time to put that angry ball of fire on mute.

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