What part of the brain has been found to be different between psychopaths and super altruists?

Kim Mills: Most of us have heard the term “psychopath” and may have an image of what a psychopath looks like, whether that's Charles Manson or Ted Bundy—or even the fictional Hannibal Lecter. The word itself, psychopath, brings to mind horror movies, serial killers, arson, and other mayhem. But psychopathy isn't just about terrible people who commit heinous crimes. Psychopathy is more common than most people realize. People with psychopathic traits show less empathy and remorse than other people. They may lie, cheat, and steal, but they may also be friendly, smart, and basically unremarkable. In other words, impossible to pick out of a crowd.

Although severe psychopathy affects just about 1% of people, some research suggests that close to 30% of us have some level of psychopathic traits. And we may even know people who fall under this broad umbrella. So what do researchers know about the causes of psychopathy? How is psychopathy related to other mental health disorders? Are psychopaths born? Or are they made by their family life, by their environment? Are there effective treatments for it? Can children show psychopathic traits and if so, how early? And if you recognize psychopathic traits in someone close to you, what should you do? 

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.

Our guest today is Dr. Abigail Marsh, a professor of psychology and neuroscience at Georgetown University. She studies psychopathy as well as its opposite, extreme altruism and pro-social emotions such as empathy, compassion, and remorse. She’s studied both psychopaths and extreme altruists, such as people who donate kidneys to strangers. And she's interested in exploring the emotional processes and the brain differences that can explain both of these extremes of human behavior. In addition to her many scientific publications, Dr. Marsh is author of the award-winning book The Fear Factor: How One Emotion Connects Altruists, Psychopaths, and Everyone In Between.

Thank you for joining us, Dr. Marsh.

Abigail Marsh, PhD: Thank you so much for having me. I'm thrilled to be here.

Mills: So let's start as we often do on this podcast with a definition. There are a lot of misconceptions about psychopathy and psychopaths. I mentioned some of them in my introduction, like the fact that people may think that all psychopaths are violent criminals. What are the traits that define psychopathy and how do they manifest themselves in people's behavior?

Marsh: The most important thing to remember about psychopathy is that it's a personality construct. It's based on a constellation of three kinds of personality traits, which include—at the real core of the construct is callousness, meaning insensitivity to other people's suffering, truly not caring about other people's welfare. In addition to that, people who are psychopathic tend to have bold, sort of dominant, fearless personality styles. And they also tend to be relatively disinhibited, so they have trouble controlling their behavior, trouble managing impulses. And if you have all three of those personality traits, we would say that you're psychopathic, especially if you have them to a really large degree. But they can manifest in all sorts of different ways behaviorally. Sometimes, more often in men than women although not exclusively, they do manifest as aggression and criminal violence.

And people who are psychopathic who do show those behaviors, obviously, we care about understanding them. We want to try to prevent those outcomes if we can. But most people who are psychopathic are not violent criminals, that's actually the exception. It's much more likely to manifest in all sorts of smaller antisocial behaviors in daily life, from being lying and manipulative, to sort of being a bully and threatening people to get what you want, to maybe committing lower level crimes related to theft or con artistry, that sort of thing.

Mills: So psychopathy is not an official diagnosis in the Diagnostic and Statistical Manual of Mental Disorders, right?

Marsh: Exactly. This is one of the many confusing things about it.

Mills: Yes. Why is that?

Marsh: It's a great question. It's one that you—there are slightly different explanations depending on who you ask, because of course the Diagnostic and Statistical Manual is the result of a lot of people working together and making decisions together. The basic idea is that psychopathy is an old construct. It was first formalized, depending on who you ask, in maybe late 1800s, or certainly no later than the early 1900s. Maybe most famously by Hervey Cleckley, the great psychiatrist in his book The Mask of Sanity, which is a fantastic book. If you're interested in psychopathy, I highly recommend it. And he was the first to come up with a list of traits that typify people with psychopathy. And a version of those traits made it into early versions of the DSM, often under other names, something other than psychopathy.

The most recent version of the DSM has a disorder in it called “antisocial personality disorder,” which is sometimes confused with psychopathy. And it overlaps with psychopathy, but it's not the same. It mostly indexes persistent criminal behavior—again, and it focuses much less on the personality features of the patients than psychopathy does. Whereas psychopathy is really strictly about personality, antisocial personality disorder is mostly about behavior. And so you can have lots of people who have antisocial personality disorder who would not qualify as being psychopathic, or at least not highly so, and vice versa is also true. Actually, the closest thing to psychopathy in the current DSM is a diagnosis in children, which is conduct disorder with limited prosocial emotions.

Now if a child qualifies for that diagnosis, we still wouldn't call them a psychopath. And in fact, I try to avoid now using the term “psychopath,” and sticking with person-first language as we do for lots of disorders. But that's not a universal practice in the field certainly. And in any case, we would never call a child a psychopath ever, and we usually try to even avoid calling them psychopathic. We say maybe they're at risk for psychopathy, or they have psychopathic traits.

And a child who has conduct disorder with limited prosocial emotions shows persistent antisocial behavior, including aggression, bullying, making threats, lying, manipulating, delinquency, all the things that you tend to see in children who have psychopathy. And in addition, limited prosocial emotions refers to having an uncaring personality with limited empathy or remorse, and tending not to show strong emotions and particular emotions like fear, sadness, and love. And so if you have a child who qualifies for that diagnosis, they're at very high risk for developing psychopathy.

Mills: And you've done quite a bit of work with children who manifest these traits. And I know that it's highly, highly difficult for parents who have such children. How do you help them deal with this? Are there treatments for the children that maybe can nip this behavior in the bud? And then how do you work with the parents?

Marsh: It's a really difficult problem when parents have children who have these traits. Unfortunately, as many people know, there's a real lack of trained child psychologists and psychiatrists to start with. So parents of children with any severe psychological disorder already struggled to find somebody who can provide good treatment. There's a particular lack of people who are trained and experienced in treating children who have serious externalizing behavior disorders. So that's conduct disorder, oppositional defiant disorder, et cetera. I tend to suspect that those are not the kinds of disorders most people go into child psychology or psychiatry to treat. And it can be really hard to feel compassion for people who treat others badly.

I mean, this is a natural human tendency. But I think it's so important to remember that children do choose to have the psychological symptoms and traits that they do. And just as we wouldn't blame a child with autism or a child with anxiety for the symptoms that we show, I think it's wildly inappropriate to blame a child with conduct disorder or oppositional defiant disorder for their symptoms, just because those symptoms do hurt other people. Which doesn't quite fit most people's mental profile of what a psychological disorder is. We think of people who are mentally ill as having maybe disordered thoughts are having lots of anxiety and suffering and distress. That's kind of the prototype, and conduct disorder and psychopathy just don't fit that mold.

The children with these conditions often deny there's anything wrong with them. Because being fairly narcissistic is a big part of the personality profile of psychopathy. And that is also one of the reasons it's very hard to treat. Of course, if you don't think there's anything wrong with you, the problem is with everybody else, you're not going to be super receptive to people trying to change things about you. Unfortunately, psychopathy developed a reputation for being untreatable based on some papers that came out in the late 1900s. But that's not true. It's a personality disorder and personality disorders are notoriously difficult to treat but certainly not impossible, and especially if we can identify children who are at risk for developing psychopathy, it is treatable. But it does require time and a lot of effort and in some cases a lot of resources, which is unfortunate. The most effective treatments tend to be some combination of training aimed at how parents respond to their children.

And I say this with caution because it's too easy for people to assume that if you are addressing parents' behavior to help treat the condition, that it's the parents' behavior that caused the condition. And I think that's a huge myth I'd like to dispel. We know that behavioral therapy, a lot of it administered by parents is a really effective treatment for children with autism. You have to use very specific kinds of interpersonal behaviors to help them develop. But we don't think that parents cause autism, or at least not anymore, right? We used to think that. This used to be just accepted wisdom in psychology that refrigerator mothers cause their children’s autism. Unfortunately, we're still in that place with psychopathy where a lot of people assume it's the parents' behavior that causes it.

So even though that's not true, there are things that parents can do to help, but they're not the sort of behaviors that parents would naturally come up with on their own. Usually, there's a number of different kinds of formalized therapeutic approaches that work. Most of them emphasize how to provide children with extremely clear, consistent, positive reinforcement for doing the right thing and ensuring that they're not reinforced for doing the wrong things. Don't get into the tantrums, don't get into the manipulation. Because if you get into those behaviors, you reinforce them and you make sure that they come back.

They also reinforce not relying on punishments to change children's behavior. One of the really difficult things about psychopathy is the fearless temperament that it seems to be rooted in. And that's how punishment works, is through the fear system. And I don't mean violent punishment necessarily, but anytime you avoid behavior that you think will be punished, that's fear talking. You're like, “I don't want that bad thing to happen, so I won't do this thing I'm not supposed to do.” And children who are psychopathic, many of the ones that I've worked with truly are fearless. They say they have never felt afraid of anything. They didn't report feeling any high autonomic arousal sensations in their body under threat. And they have difficulty describing what fear feels like. And so you can't punish a child into behaving who doesn't feel fear. And P.S., that's not a good parenting strategy for any child.

And the other thing is that children who are psychopathic often seem very resistant to affection, or they don't seem to get a lot out of affection for reasons we don't really understand yet. And so sometimes parents will sometimes not be as outwardly affectionate toward these children, both because they're frustrated by them and both because the child doesn't seem to want it. But there's some evidence to suggest that they should do exactly the opposite, which is counterintuitive, and that they should provide extra big, sort of, social positive cues. More affection, more smiles, more positive physical touches, than seems natural and that the child even seems to want. And we know there's some evidence that parents who use these types of approaches with even very high risk children can see good effects in the long run. But it's challenging, I won't lie.

Mills: So is it possible then to teach a child, and it may be even harder with adults, but to teach a child who has these traits to feel fear, to understand fear and to feel remorse, which they apparently don't?

Marsh: These are really big open questions. One of the real problems with the field of psychopathy is that not enough mental health resources have been devoted to trying to understand or treat it over the years. It's very common—conduct disorder affects, depending on the estimate, up to 7% of children at some point during development. Oppositional defiant disorder even more. And there are as many as 2 to 3% of children have high levels of limited social emotions during development. These are not rare conditions. Psychopathy is at least as common as bipolar disorder or anorexia or some other disorders that we think of as not that rare. And yet very, very few resources have been devoted to trying to understand how to treat it. And so there's a lot of things we don't know.

There's not one single pharmaceutical that's ever been developed specifically to treat externalizing behavior disorders, for example. And so children with these disorders get treated with a lot of other kinds of medications that were developed to treat other things. Some of them do seem to help. So for example, stimulant medications used to treat ADHD do help some children who are at risk for psychopathy. It shouldn't be the first line treatment, you should always start with a parent management training type of approaches, but it's sometimes is a nice adjuvant. It will sort of increase the effectiveness of the behavioral treatment. Sometimes mood stabilizers are used and they can be effective and even antipsychotic medications are sometimes used and can be effective, although I think it's risky to use these drugs for a long time in children.

Do they actually increase the capacity of children to feel emotions like fear, that although we think of them as, quote, negative emotions are incredibly important for adaptive social development and social functioning? Probably not. And to be honest, it's not surprising that pharmaceutical companies don't seem that keen on developing medications that will make children more fearful. Nobody feels comfortable with that, which I get. Again, it's too bad. It's easy for people to forget what a useful emotion fear is to a degree. Obviously, excessive fear is no good. But some low level of fear is incredibly important because, and this is what a lot of my research centers around, not only does it help you respond to negative feedback from other people, but the capacity to feel fear helps you empathize with other people's fear. And that's one of these critical social mechanisms that prevents people from doing things that cause other people fear. And this is a problem in psychopathy, because they don't often feel fear very strongly themselves, they don't understand it in other people, and they literally don't understand why it's wrong to cause it in other people, it's a huge problem.

Now that said, it may be possible to increase other positive social emotions in children with psychopathy through these behavioral sort of parent management techniques I've been talking about, mostly by causing them to view other people as socially rewarding. Because that's a really good thing. If you view interactions with people and having positive interactions with people as intrinsically rewarding, oftentimes that's enough to keep your social behavior on the right side of things all by itself.

The problem is that kids at risk for psychopathy engage in a lot of behaviors that bother other people, from being annoying to being actually harmful. And then you get negative feedback from people and you can end up in these negative reinforcement spirals where you just view other people as not really worth caring about or treating well at all. And that's what you want to avoid. And if the right approach is taken, you can end up with a child who's maybe temperamentally pretty fearless and not the most caring person in the world, but can be totally functional and lead a perfectly good life and have good friendships and relationships.

Mills: Let's talk for a minute about causes, because I know you've done some research, including brain imaging, that found some interesting differences in the brains of children who are manifesting this disorder. And then the other question is, are these things genetic? Do we know?

Marsh: Understanding the causes of psychopathy is obviously really important to coming up with more effective treatments. And again, what the psychopathy research community desperately needs is more resources from mental health organizations. Funding organizations to take psychopathy seriously as a mental illness that needs resources poured into trying to understand it better. That said, we've made some progress. For a while now, brain imaging research in children who have psychopathic traits has been pointing to a relatively consistent finding, which is that if you look at large groups of kids who have serious conduct problems, so aggression, externalizing, delinquency, that sort of thing, only the children who have psychopathic personality traits, so the low empathy, low remorse, uncaring traits, show reduced activity in a structure called the amygdala.

And you see the opposite effect in children who have equally serious aggressive externalizing behavior, but don't have the psychopathic traits. They actually show increased activity in the amygdala. And this is one of those interesting cases where brain imaging has told us something really important to understanding the phenomenon and to identify appropriate treatments. That different kids with conduct disorder, aggression, et cetera, show completely different mechanisms that seem to be underlying their antisocial behaviors, and that's really important to know. And so what we know about the amygdala is it does a lot of things, first of all. It's a densely interconnected structure in the brain. You have two amygdala, one on each side, and they're sort of deep under the cortex and they're evolutionarily ancient. One of the important things they do is regulate the body's fear responding, so they coordinate responses to threats. And people who have lost their amygdalas due to either genetic disorders or in some cases injuries do seem to have kind of muted fear responding as a result.

So we think the amygdala is important for fear. It also definitely plays an important role in regulating social behavior although exactly how it's doing that is less clear yet. And we think that because in children who are at risk for psychopathy, the amygdala is not developing correctly, it ends up being too small on average, especially earlier in development. And it's less active in response to the things that it should respond to. For example, the sight of somebody else who's afraid. That seems to be at the heart of the problems that we see in children with psychopathy. Now, it's not the only problem in their brains, but it's the one that has been the most consistently identified and the one that I think is likely to be central to their disorders.

Is the disorder heritable? Well, every psychological phenomena is at least partially heritable. So the same is certainly true for psychopathy as well. A giant meta-analysis that came out in, I think it was Nature Genetics several years ago looked at the heritability of lots and lots of different outcomes, including psychological outcomes. And found that on average, psychological traits like personality traits, things like anxiety, psychological disorders, are on average 50% heritable, which means half of the variance can be accounted for by genetic factors, and the same seems to be true for psychopathy.

So about half of the variance is accounted for by genetic factors. That does mean that if somebody else in the child's family shows signs of psychopathy, that child is at higher risk for developing psychopathic traits. But of course, that is a long way from saying that psychopathy is inborn or innate or hardwired. At every stage of development, genetic potential is interacting with environmental factors to drive outcomes. And so it's pretty clear that features of a child's environment will also shape the degree to which any sort of latent potential for psychopathy gets expressed.

Mills: That raises another question in my mind which is, I think that some people confuse psychopathy and sociopathy. And I'm just wondering if you could explain how they're different and how they're similar.

Marsh: Absolutely. Psychopathy, I will emphasize, is technically the more scientific term. So for example, there are no scientific societies for the study of sociopathy. That's not a thing. There is one for the science of psychopathy, I'm a member of course. As far as I'm aware, there are no sort of scientifically validated measures for assessing sociopathy, there are not journal articles describing sociopathy. Is more of a sort of popular term for describing highly antisocial people. It has been used often in the past to describe people with a diagnosis of antisocial personality disorder. And so I would say that sometimes that's what it's used to mean. Other times, it's used to mean people whose antisocial behavior is mostly result of social forces.

So people who were not born at particularly high risk of becoming antisocial, but due to really terrible things that happen to them often in childhood, experiencing extreme neglect or trauma or abuse, developed antisocial behavior as a result. Now, that's not even the normative consequence of experiencing abuse, trauma or neglect. The typical outcome when you experience those terrible things in childhood is developing anxiety, depression, or post-traumatic stress among other problems. But some children do develop very serious antisocial behavior as a result of those outcomes.

And so again, it's not technically the scientific term, but many people when they talk about sociopathy, that's what they mean. There was no particular sort of innate risk factor, it was purely a social set of risk factors that caused their behavior. Whereas psychopathy is almost always used to refer to people who have this innate set of risk factors that then becomes psychopathy as a result of different patterns that happened during development.

Mills: In my intro, I mentioned some notorious people who are often thought of as psychopaths, and they were all men. And I just want to know, do we know whether psychopathy is more prevalent among men or women? Or does it just manifest differently depending on your sex?

Marsh: This is a wonderful question and it's one that I think reasonable people could disagree on. We know that the scales that are most commonly used for assessing psychopathy now, probably the most famous of which is the PCL-R, the psychopathy checklist, which was developed by Bob Hare. It was developed in an all-male adult population of prisoners in British Columbia. And I think that scale is really good for assessing psychopathy in adult male prisoners in North America. But I think reasonable people could differ as to how effective it is at assessing psychopathy and all its manifestations in other kinds of populations, non-prison populations, children and women. And there are other scales, I'll emphasize.

I really dislike the phrase “gold standard” when it comes to measuring any kind of construct. Any measurement is never the same thing as a construct, it's just one way to measure it. And some of the measures that I often use to assess psychopathy were developed in more general populations, and so may be better at capturing psychopathy in for example, women. So it's possible. So I will say that we do see lower levels of psychopathy in women using a lot of the scales that are used to measure it. This could be because the scales were developed in more male populations and so they don't capture psychopathy as well in women.

For example, they may emphasize physical aggression, or different forms violent crime that are much more likely to be engaged in by men than women we know. And so they don't quite as accurately capture the ways that psychopathy manifests in women, which is much more likely to relate to social aggression, sort of emotional bullying, manipulation, that sort of thing.

It's also possible that there are true gender differences. And I would believe that, in part because we know from giant personality assessments that have been done in countries all over the world that there are average differences in the personalities of men and women, with men tending to be a little lower in a trait called negative emotionality, a little lower in a trait called conscientiousness, and lower in trait agreeableness. And these are all personality constructs that do relate to psychopathy. People with psychopathy, not surprisingly, are less agreeable, less conscientious, and lower in some forms of negative emotion. And so given that, I think it's reasonable to say that probably psychopathy at the tails will show up more often in men than women. And yes, I think it's also true that we're undermeasuring it in women because the scales aren't picking up on some of the ways that it manifests.

Mills: Now, if in your normal life you encounter people who you think have some of these traits—I mean, I asked in the intro, what can you do? Other than just trying to avoid people who are like this, is there anything that you can do to protect yourself from these kinds of people?

Marsh: Yes, the first thing I'll say is psychopathy does not present the way people think it does. I vividly remember the very first time I went to interview a child with psychopathy when I was a postdoc at the National Institute of Mental Health. And he had pretty severe psychopathy. He was in a locked psychiatric ward at the NIMH, he was there for a long-term study that his parents had enrolled him in. And I had heard these horrible stories about his behavior in the backgrounds. Uncontrollable violence, his parents would often take his brother to stay in a hotel for long periods of time, they were so worried about this boy trying to really seriously hurt or even kill his brother. And when he was being punished, he would do awful things like smear his own poop on the walls. It was bad stuff.

And so the last thing I expected to see when I walked into his room—and I knew how to keep no sharp objects in my pocket and make sure that I never let him get between me and the door, I mean, all the normal things that you do when you work with potentially violent populations. But I walk into his room at the NIMH and from his—he was sitting on his bed and he pops up to shake my hand. It's just the cutest kid and he looked like he was out of a cereal commercial. Like an adorable smile and just sort of an aw-shucks demeanor, freckles on his nose. I mean, he just was so cute and sweet and friendly and charming. He seemed more mentally healthy than the average child, it was just astonishing. And he agreed that he had engaged in all these bad behaviors that had resulted in him being at the NIMH, but there was always sort of an explanation for that. He just was having a really bad day that day and looking back maybe he shouldn't have done that.

And that is what I learned. And the most important lesson about psychopathy is that you can't tell when somebody has it because they have a crazed look in their eye or they seem really gruff or there's weird eye contact. Some people say, “Oh yes, there's a certain thing that people with psychopathy do.” I've never seen it personally and I think part of the reason is that I work with people who have not spent a long time in prisons or institutions, which does things to your demeanor, obviously. People who are out in the community who have very high levels of psychopathy present as genuinely likable, charming, well adjusted, friendly, often very helpful people in reality.

I mean, this is how they managed to do all the terrible things that they do, is because people don't see them coming. I mean, Ted Bundy was infamous for that. And I will say that many serial killers are not psychopathic. Some of them have very odd forms of psychosis or compulsions or other problems. But usually it's some sort of perfect storm of multiple problems. Ted Bundy was highly psychopathic in addition to being a serial killer, but you never would guess it. I've met psychology professors at the University of Washington who had Ted Bundy as their student and introduced them to their wives and wrote letters of recommendation for him and had absolutely no idea that he was simultaneously murdering women on the weekends when he wasn't in classes.

You can't tell. If I lined up all the children with psychopathy that I've ever worked with over the years and all the healthy kids that I've worked with over the years and asked you to pick out who was who, you'd never be able to tell. So this is the first part of making sure that you can protect yourself from psychopathy, it's just not assuming that it'll look like your stereotype of it. The most important thing you can keep track of is how people treat other people. It's very hard to detect in somebody you just met.

But if you get to know somebody for a little while, the things to look out for are first of all different people having extremely different impressions of them. Some people saying that this person is like a really horrible person, other people saying this person is the nicest person in the world. That kind of chameleon-like behavior is not always indicative of psychopathy, but sometimes it is. The other thing we look for is a pattern of behavior that suggests this person does not really care about anybody but themselves, right? Do they ever actually do anything that sacrifices their own welfare to help anybody else, including people that they say are friends or that they love? Do they really seem affected and truly moved when other people are suffering? Do they seem just a little too glib, just a little too able to kind of talk their way out of situations. So they always seem to be kind of skirting just on the edge of acceptable behavior, and not seem to think that maybe the rules apply to them as much as they do to other people.

Those are the kinds of things you want to look for when you're just in daily life and think that somebody may have high levels of psychopathy. I should also mention that there are people who are fairly callous people who have most of the traits of psychopathy who are actually just fine people to know in your life. I wouldn't necessarily let them propose an outing to go whitewater rafting or anything like that. Many people with psychopathy say they often get their friends into a lot of trouble. But the most important predictor of future behavior is past behavior. And so I know people who have psychopathy who have learned that if they treat other people well, it works better for them too. And so oftentimes, they can make good friends. You just have to always be aware of what you can and can't count on them for.

Mills: Let's switch gears and talk about the happier side of your research, which is about empathy, compassion, and those extreme altruists like the people who donate kidneys to strangers. What's the connection between what seems on its face to be the opposite extreme of human behavior?

Marsh: Yes. So I've been incredibly fortunate in my research career to have been able to work not only with people who have psychopathy or at risk for psychopathy, who to be honest, I really enjoy that research. I really feel for the parents of the kids who have psychopathy, but I really enjoy the kids themselves. But I've also worked with people who were on the other end of what I call the caring continuum, who are unusually caring and altruistic to the point that they will even give kidneys to strangers or rescue other people from fires or drowning. And that the genesis of this research was the relatively recent understanding that psychopathy is not like a discrete group or taxon. It's not like we have psychopaths here and then the rest of the population over here. It's a continuum. There are people who have mildest psychopathic traits, some people have moderately or very severely psychopathic traits. So it's like a lot of things.

It's sort of a normal—well, not a normal distribution, but certainly a distribution. And that discovery prompted me to wonder, well if it's a distribution with super uncaring, uncompassionate people on one end, and most of us somewhere in the middle, what's on the other end? And if we can understand what it looks like to be sort of anti-psychopathic, that can help us learn a lot about the origins of compassion and care, which are the things that my research focuses on. And so, after a bit of thinking, the population I landed on to see if they looked anti-psychopathic was people who donate kidneys to strangers. Because if there's any behavior that indicates more care about the welfare of other people, even total strangers, it's that when you're willing to give up an internal organ, a vital internal organ at significant, sometimes expense and inconvenience and serious pain to yourself, I don't know what it is.

It's really sort of a magnificent act of generosity. And so about 10 years ago, I started bringing altruistic kidney donors to my lab at Georgetown to conduct brain scanning research with them. And one of the first things we found about them is that they are indeed sort of anti-psychopaths. They have amygdalas—whereas people who are psychopathic have amygdalas that tend to be too small and not active enough, people who were very altruistic have amygdalas that are larger than average, and tend to be even more responsive to the sight of other people in distress.

So if you show them a picture of somebody who looks very afraid, they have a bigger than average and negative response to it. And that seems to support their being better able at recognizing when other people are in distress. So if you show them fearful faces, they're better than average of recognizing them. And I think that means that they have the personalities that are unusually caring and responsive to other people's need and suffering, and that makes them unusually motivated to help when other people are indeed suffering.

Mills: And you yourself are the benefactor of somebody who was apparently one of these altruistic, right? I mean, can you tell that story because it's kind of amazing. I saw your TED talk about it.

Marsh: Thank you. Yes, he certainly was a true altruist. It happened when I was a teenager. I certainly credit it for the trajectory that my research career has taken. I was driving home on Interstate 5, the large freeway in Washington State, back to my hometown of Tacoma—also the hometown of Ted Bundy, and the hometown of the Green River Killer, and several other similar notorious killers.

Mills: There's something in the water.

Marsh: Yes, I know. There's no way it's an accident that I'm also interested in psychopathy. In any case, so I'm driving on an overpass back into town when a very small dog ran out in front of my car, which how it got there, I'll never know. And I swerved to avoid it, which I now know you shouldn't do, even though the impulse is always there. And the combination of hitting the dog and swerving to avoid it caused my car to spin out of control. It was fishtailing and then literally spinning in giant circles across the freeway until finally it came to a rest in the fast lane of the freeway just over the crest of this overpass so that the oncoming cars couldn't see me until they were almost on top of me. And the engine died. And I was 100% sure that I was also going to die because I had no phone, couldn't get the car to turn back on. There was no shoulder for me to escape to.

I just remember keeping trying to turn the car back on and being unable to do so. And so I don't know how long I sat there. I mean, time does funny things when you think you're about to die. But what ended up happening was as I was sitting there waiting for the end, I hear a rap on the passenger side door which was inside next to the shoulder and turned to see a man standing there who I later figured out must have pulled his car over on the opposite side of the freeway within seconds of having seen my stranded car, and then run across the freeway to reach me again in the middle of the night dark with cars and trucks flying past.

And to make a long story short, he got in my car, got it back up and running again, which required putting it back in park, and then got us back to safety on the other side of the freeway and then disappeared. He was like, “Are you going to be okay? Do you need me to follow you before you get home just to make sure you get home okay?” And I said, “No, no, I'll be okay.” He said, “Okay, well then you take care yourself.” And off he went into the night. I don't know his name. I don't know anything about him. But I know that he was truly heroic.

Mills: Yes. It's quite an amazing story.

Last question. I like to ask this a lot of researchers. What are the big questions that are fascinating you now? What are you working on and in your mind, sort of the most important questions that we could still answer?

Marsh: There's so many. I mean, it's one of the reasons I absolutely love being a psychology researcher and a neuroscience researcher is because these are relatively young fields and there are so many things we still have to know. And plus, what's more interesting than trying to understand human psychology and behavior? I think the most interesting question and certainly the one that I'm in the middle of pursuing is what is it that allows somebody to truly care about somebody else? I mean when you really boil it down, it's love. Which I know is a little bit of a fluffy term and sometimes researchers try to avoid it. But the scientific definition of love is to care about somebody else's welfare for its own sake, not because of how it affects you.

And from having worked with altruists for 10 years now, I genuinely believe that it's possible and that common to genuinely care about the welfare of other people, because they're intrinsically valuable to you. And how does the brain enable that? How did, how do we have this capacity to genuinely care about other people? There must be some pathway in the brain that enables it, probably built on the pathways that originally evolved to support parenting, which is of course, the original form of love, is the love that parents have for their offspring. And we think that in general, most forms of care-based altruism emerge out of the capacities for parental care. And so I would love to try to figure out how it is that the brain enables that capacity to emerge. I mean it's the most beautiful form of alchemy I can imagine. I'd love to figure out the answer.

Mills: Well, thank you so much for joining me today, Dr. Marsh. This has been really interesting. I appreciate you taking the time to explain your work to the world.

Marsh: It's been a pleasure. Thank you so much for inviting me here.

Mills: You can learn more about Dr. Marsh's work and other research on psychopathy in the March issue of APA's magazine Monitor on Psychology. Go to our show notes for the link, at speakingofpsychology.org. You can also find previous episodes of speaking on psychology there or on Apple, Stitcher or wherever you get your podcasts. And if you listen to us on Apple, please leave a review. If you have comments or ideas for future podcasts you can email us at . Speaking of Psychology is produced by Lea Winerman. Our sound editor is Chris Condayan.

Thank you for listening. For the American Psychological Association, I'm Kim Mills.