Human Lie Detector: The #1 Sign They’re Lying To You, Catch Liars Instantly! | Dr Leanne Ten Brinke | The Diary Of A CEO Transcript

Steven Bartlett interviews psychologist Dr Leanne Ten Brinke on deception, dark personality traits, and how to deal with them

Steven Bartlett speaks with Dr Leanne Ten Brinke, a psychology professor whose research covers deception detection, psychopathy, and the so-called dark tetrad of personality traits.

Summary

Steven Bartlett interviews Dr Leanne Ten Brinke, a psychology researcher whose work spans deception detection, dark personality traits, and the psychology of influence. Dr Ten Brinke explains that the most reliable cues to deception are sparse detail and visible cognitive effort — not eye contact or body language, which research consistently fails to support. She describes the dark tetrad of psychopathy, Machiavellianism, narcissism, and sadism, noting that roughly 10% of the population scores meaningfully high on these traits, yet clinical-level psychopaths — just 1% of the population — account for approximately 50% of all serious crime. She also presents findings from her own lab showing that people feel measurably less connected to someone who is lying to them, even when they have no conscious suspicion of deception, and that people are more willing to donate money and express sympathy toward genuine pleaders than deceptive ones in simulated missing-person scenarios — suggesting a degree of unconscious deception detection in naturalistic contexts. The conversation also covers how group discussion improves accuracy in personality judgments and how gossip and whisper networks can serve as informal early-warning systems about Machiavellian individuals. The episode closes with seven practical strategies for managing people with dark personality traits, and Dr Ten Brinke's argument that the widespread belief that ruthlessness leads to success is, in her research, simply false.

Key Takeaways

FULL TRANSCRIPT

Introduction and motivation

Dr Leanne Ten Brinke: I want to make people less cynical about human nature, which might seem paradoxical given what I study — deception, dominance, and so-called dark personality traits. But when you understand those topics, and also that there's something you can do about them to make interactions better, it's incredibly powerful and can give us a more accurate view of the world.

Steven Bartlett: Why are the population at large so interested in these subjects? They're fascinated by them. What is underneath all of the fascination and curiosity? What are people trying to figure out when they're interested in psychopathy?

Dr Ten Brinke: I think one of the reasons we're so interested in psychopathy is because it's quite foreign to us. Most of us move through life caring about other people, having compassion, telling a few lies here and there, but by and large being very truthful and honest and playing by the rules. That's the opposite of psychopathy. When you're faced with a personality that is quite the opposite of your whole experience of being alive, you're like, what's going on? I want to understand that. There's also some research on true crime specifically and why people are interested in it. It tends to attract a largely female audience, and some of the motivations people report are wanting to understand and wanting to avoid becoming a victim of these people.

Spotting a psychopath in seconds

Steven Bartlett: Is it possible to spot someone who is a psychopath?

Dr Ten Brinke: Yes.

Steven Bartlett: How long, according to the research, does it take someone to spot a psychopath?

Dr Ten Brinke: You can get a kernel of truth about someone's personality — the extent to which they're psychopathic — in about five seconds.

Steven Bartlett: Explain the research to me.

Dr Ten Brinke: This is research by Scott Lilienfeld and his colleagues. Basically, what they did is they showed people five-second, ten-second, and twenty-second clips of interviews where criminal offenders were being interviewed by a psychologist and rated on their psychopathic personality traits. Then you had random psychology students watching five seconds of that interaction and making a rating — how callous do they seem, how manipulative do they seem? They found there is actually a pretty reasonable correlation between the ratings of these naive observers who watched five seconds and the trained clinical psychologists who did hours-long interviews and gathered collateral information.

We partnered with Scott, got those videos, and coded the verbal and non-verbal behaviour. What we found is that people with higher levels of these traits engaged in what we call Duchenne smiles. They're a genuine-looking smile, but what distinguishes the two kinds of smiles is the activation around the eyes — the creation of crow's feet, lines in the corner of the eyes.

Steven Bartlett: So a genuine person will have crow's feet when they smile?

Dr Ten Brinke: Theoretically — again, Botox and all kinds of things can get in the way of this. But yes, it's totally in the eyes. Whereas a non-Duchenne smile, you have the same kind of upturned lips, maybe you're showing your teeth, you get a big grin, but no activation around the eyes. People who were high in psychopathic personality traits were showing these very happy-looking smiles as they were saying really hostile things. So they were using happy expressions and hostile language at the same time — a weird emotional presentation. They also used a lot of hand gestures, which we called illustrators. Those seem to be things that random observers paid attention to and used to guide their judgments. It's such little information to go on, but it does suggest you can get a sense of someone relatively quickly. Personality is something that exists across time and context, so you'll get better data the more data you have across different times and places.

Facial expressions and high-stakes deception

Steven Bartlett: I've got two more facial expressions here.

Dr Ten Brinke: So this is sadness. Some of the research I've done has looked at people who've gone on TV and asked for help trying to find their missing loved one. In some proportion of those cases, they were actually guilty of killing that person. So they are falsely pleading for help for someone they know is never coming back.

Steven Bartlett: Wasn't this your PhD?

Dr Ten Brinke: This is my PhD. Yes.

Steven Bartlett: What was your PhD in?

Dr Ten Brinke: In psychology, but in a more forensic context. I was studying behavioural cues to emotional, high-stakes deception — trying to spot someone who was, say, in the media saying, "I can't find my wife, please help me."

Steven Bartlett: But they had killed their own wife.

Dr Ten Brinke: Yes. I was comparing a bunch of those cases to cases where people genuinely had no idea where their missing loved one had gone and were desperately pleading to have them home. This is one of the differences we saw in that set of videos. In genuine sadness, you get the downturned lip corners. What tends to be more difficult is this combination in the eyebrows — the inner eyebrows come upward and together. What we saw in the people who were lying was more like surprise. They were able to pull the lip corners down, but instead of the inner eyebrows going upward and together, the whole inner and outer eyebrows would go up, but not together.

Steven Bartlett: And you could predictably tell from footage if someone had done it or not? Was there a correlation?

Dr Ten Brinke: We were able to use four different cues — two verbal and two non-verbal — to predict with about 90% accuracy who was lying and who was telling the truth. Caveat: we tried to replicate that more recently and found much more modest effects. But we did find consistencies, especially with the verbal cues. It was the number of words people used as well as tentative language. Liars would tend to say things like, "If you see this, come home," or call — kind of vague about what the person should do. Saying things like, "It wasn't like an argument per se that we were having." They left a lot of grey area. Whereas truthful people were like, "When you see this, call me."

Steven Bartlett: They were more high-conviction and precise.

Dr Ten Brinke: Exactly.

The three signs someone is lying

Steven Bartlett: I think down there we have some cards that say three signs someone is lying.

Dr Ten Brinke: So one cue to deception is sparse or ambiguous information. The most consistent effect we have that differentiates people who are telling the truth from people who are lying is the amount of detail they give. People who are lying tend to give fewer details.

Steven Bartlett: Interesting. I thought it was the opposite.

Dr Ten Brinke: I hear this a lot — people say liars will natter on and on. That's not what we find in the research whatsoever. Especially when people don't have time to prepare. Whenever people have time to prepare, they can start to look pretty much like a truth teller in terms of the amount of information they give. But if you get someone on the spot, the truth teller just has to remember what happened and tell you. You can even ask for more information — "tell me more about that" — and they can come up with more because they were there. The person who is lying has a much harder task. We call this increased cognitive load — they need to come up with details on the spot, not contradict themselves, remember it for the next time they need to tell this lie, and also try to imagine what you already know.

Steven Bartlett: And how do I not contradict or step in it when I'm trying to explain what actually didn't happen. They must have higher blood pressure just from knowing they're not telling the truth. The cortisol must spike.

Dr Ten Brinke: We've actually done some research in my lab to show that people who are lying tend to have increased cortisol reactivity relative to people who are telling the truth. The reason I was surprised to hear it is because I'm a big true crime fan and I often watch interrogation videos. I thought I'd heard before that when they're interviewing someone who is guilty, they will give lots of irrelevant detail on other parts of the story.

Steven Bartlett: I was watching the Jussie Smollett interview he did on TV. Again, he had time to prepare, so maybe that's the caveat. He really described a bunch of pointless stuff. He was talking to the journalist and said something like, "I landed and I called my manager who was in Australia because my manager is on tour with someone else." And then even when he talked about going to Subway and getting the Subway wrap, he mentioned it was a tuna wrap. So the details he was sure on, and that were probably true, he seemed to really expand on. And then when it got into the other stuff — where the bulk of the lies allegedly took place — it was quite vague.

Dr Ten Brinke: We call that embedded lies. He's giving lots of detail where it's truthful, and then almost no detail where it's a lie, and then lots of detail again where it's truthful. You can compare someone's baseline — do they tend to give lots of detail or tend to be sparse? You can look for deviations. If someone tells you a really long story with tons of detail about everything, and then in this one part of the story there's very little information, very sparse or ambiguous information, that can be a red flag. And there is no Pinocchio's nose — there's no one cue. What you're looking for is subtle cues that are red flags and encourage you to follow up, ask more questions, dig into that topic a little bit further.

Steven Bartlett: In the same way they did the research to figure out if members of the public could tell if someone was a psychopath in five, ten, or twenty seconds — have they ever done that with lying, to figure out if people can spot liars?

Dr Ten Brinke: Literally thousands of times. In my lab, we've actually had people steal a $100 bill from a room and then had someone come in and essentially interrogate them — everyone had to deny it. The people who took it were lying, the people who did not take it were telling the truth, and we put $100 on the line. If you're able to convince this person that you didn't take it when you actually did, you can keep that Benjamin. Then we showed these videos to other people. People are not very good at detecting these lies, or really any kind of lies. On average, people perform at about 54% accuracy. If I gave you twelve videos — six liars, six truth tellers — you'd get six or seven right.

Steven Bartlett: What if someone is trained? Do the stats increase?

Dr Ten Brinke: They can increase a little, yes. What is better, actually, is learning how to ask better questions. Instead of just being given a video of someone lying or telling the truth and told to judge it, good lie detectors ask for more information, or they ask unanticipated questions that people haven't prepared for. Then those cues of deception — that sparse information, that sense that they're thinking really hard — really go off the charts. Learning how to ask good questions is actually an essential tool for detecting lies.

Role-playing deception detection

Steven Bartlett: I've got to be careful here because people are going to take this out of context. Say I suspect my partner is cheating on me. I sit them down and say, "Babe, are you cheating on me?" And they say, "No, absolutely not." What would be a good question to ask to ascertain if they actually are?

Dr Ten Brinke: I think where you first made a mistake is you asked a closed-ended question. You didn't even give them an opportunity to have to come up with something more difficult. If you were like, "I think last Friday night you said you had to work late, but I don't really believe that. Tell me about work on Friday night." You're asking an open-ended question.

Steven Bartlett: Let's role play. You're the one that suspects I'm cheating. Last Friday night, I was up to something. Let's do this.

Dr Ten Brinke: Okay. I know you had to work late on Friday night. What were you working on?

Steven Bartlett: Yeah, big investment deal we're working on with a couple of colleagues. We had to get a deck together. I stayed till what, 3:00 a.m. or something crazy like that, and I ended up falling asleep on my desk. Anyway, what are we doing today? What's for dinner?

Dr Ten Brinke: Okay, red flags flying up. I would ask more questions. Like, what client were you working on this for? What's the deck about?

Steven Bartlett: Yeah, we're doing an investment deal with Google. Yeah, it's Google.

Dr Ten Brinke: I could ask you, okay, tell me about what was in the deck. And you give me a little bit of sketchy information. A great question to have in your back pocket is just, "Tell me more about that." You don't even have to try very hard to figure out where you're going to stump them. At some point, the liar is going to have a lot more trouble coming up with additional details than the truth teller. The truth teller was there and knows all those annoying little things — maybe they couldn't get the font on the slide deck to stay right. As a truth teller, if someone asks you for more detail, you can go into more detail. Whereas the person who's lying, who's making this up, that's much more difficult because it didn't actually happen.

The details are also going to be really difficult to verify. If they do give you some details, it might be things you can't check — co-workers you don't know. In general, liars tend to give fewer verifiable details. There's actually a really fascinating study where we're trying to dissect someone's behaviour — paying attention to their words, whether they're fidgeting, which is actually not a good cue to deception, looking at their eye contact, also not a good cue. We're trying to create this crazy algorithm in our head, adding up all of these different behaviours to determine whether someone is lying. Research suggests that if you just ask yourself, "How verifiable was that statement?" — that's a better strategy for accurately detecting lies than trying to use all of these other cues that actually don't work.

Steven Bartlett: If you ask yourself how verifiable is the excuse this person I think is lying gave me.

Dr Ten Brinke: Exactly. The broader finding is that it is better to focus on one cue that works than to try to put together all of these little cues that mostly don't work at all.

Steven Bartlett: And the third one there?

Dr Ten Brinke: The third one is visible cognitive effort. All of this stuff — the details people need to come up with — is really hard to do. They might be speaking really slowly, using lots of ums and ahs, furrowing their brow trying to figure things out. It's important to remember that you could pause for a million different reasons that are not deception-related — you could just be trying to remember something. None of these are Pinocchio's nose, but they are reliably associated with deception.

Body language and eye contact myths

Steven Bartlett: What about body language? People always talk about body language.

Dr Ten Brinke: People put a lot of stock into body language, particularly gaze aversion. If you go around the world and ask people what's the number one cue that someone is lying to you, they will say sketchy eye contact. And there's no research to suggest that that is true. If you think about it for a hot second, it makes so much sense — because I sometimes tell a lie, you sometimes tell a lie, we all know the stereotype that liars can't look you in the eye. So if I want you to believe me, I'm going to make sure I control my eye contact. That's something that's well under our control.

Steven Bartlett: And there's neurodivergence and things like that, which means some people with certain neurodiversities struggle with eye contact but it doesn't necessarily mean they're lying.

Dr Ten Brinke: Exactly. There's some emerging research to suggest that people who are on the autism spectrum are perceived as lying more when they're actually telling the truth — because of this eye contact thing, which people are using as a cue to deception but which is in fact unrelated to deception. There are also cultural differences — in some cultures it's more respectful not to look someone in the eye, which can also lead to errors in judgment.

The dark tetrad: psychopathy, Machiavellianism, narcissism, and sadism

Steven Bartlett: There's this dark personality trait thing I hear a lot — it used to be a triad, now we've got a tetrad?

Dr Ten Brinke: Yes.

Steven Bartlett: Okay. If you want to reveal what each of those is, one at a time.

Dr Ten Brinke: Psychopathy, for example. Psychopathy is a constellation — a set of personality traits. It's not just one thing. There's a superficial charm. They're quite manipulative and tend to be pretty grandiose — they've got a pretty inflated view of themselves. There are also emotional components: they tend to have pretty shallow emotional experiences, a lack of remorse and guilt for harming other people, and they tend not to take responsibility for their own actions. In addition, they tend to be pretty impulsive — living life by the seat of their pants, not really planning far out into the future. They might mooch off a family member or romantic partner. And lastly, they tend to break a lot of rules. This might be just workplace rules or social norms, but psychopathy has largely been studied in criminal populations, so this could also be laws.

The other three of the so-called dark tetrad share some elements but also have unique flavours. The next one is Machiavellianism, named after Niccolò Machiavelli, who wrote The Prince — a kind of how-to manual for gaining and wielding power effectively. As a personality trait, they tend to be pretty cynical about other people. They tell a lot of lies and try to manipulate people, but it's more like three-dimensional chess. They might learn a little tidbit about you and think, "I could use that against him later. I'll put that in my back pocket." When they need to manipulate or blackmail you in the future, they'll have that available. They're very interested in power, which is of course where the name comes from.

Next is narcissism — that's one people know pretty well. These are people who tend to be very entitled and very willing to exploit other people in order to get what they think they deserve. It's a very relentless kind of self-focus.

Steven Bartlett: This word has been used quite a lot in culture. It's thrown around all the time.

Dr Ten Brinke: Constantly. And narcissism, like all of these traits, exists on a continuum. You or anyone else — myself — could take a self-report measure of the extent to which we have these traits, and you can land anywhere from very low to very high. Narcissism has a personality disorder diagnosis at the incredibly high end, which appears in the Diagnostic and Statistical Manual. You could go to a psychologist or psychiatrist, be assessed, and diagnosed if you have extreme levels. But people land everywhere. Part of the problem is that people say, "Oh, she's a narcissist, he's a narcissist," and make this very binary distinction. These exist on a continuum. There's no clear moment where it becomes "you are a narcissist" versus not. It's more accurate to say they have relatively high levels of narcissism or psychopathy or whatever the case is.

Steven Bartlett: And you said there are two main types of narcissist.

Dr Ten Brinke: Increasingly, personality psychologists are identifying a vulnerable type and a grandiose type. Grandiose is the one we all know well — they've got this ego that cannot be popped. They get negative feedback and nothing gets through. They always think they should be the one in charge. For those individuals, they tend to get very angry with a particular kind of threat to their ego — a failure to achieve. They wanted a promotion at work and didn't get it.

Vulnerable individuals actually have a very fragile ego. It can be popped very easily. If they get negative feedback, maybe they get socially rejected — that's when they become quite angry. That's more of a trigger for them.

Steven Bartlett: I asked the question because of a conversation I was having the other day. We were interviewing someone, and during the interview process they were very quick to claim credit for all of the things the company they worked at had done. They were also very quick to say they were good at everything. Even as I walked out of the room with them and said, "Can I message you on this particular app?" they said, "I'm amazing at that app." I walked out of the room, having interviewed thousands and thousands of people over the years, thinking to myself that they were so lovely, but it felt to me like it was more coming from a place of insecurity. When you look at their story, it's a story of someone who has been continually counted out, overlooked for opportunities, and has a bit of a chip on their shoulder to prove themselves. Another person might look at that same pattern of behaviour and say, "That person's a narcissist." So when I heard vulnerable narcissist versus grandiose, I was wondering if it's at all linked to what I'm saying.

Dr Ten Brinke: For vulnerable narcissism, the reason they would respond so poorly to rejection is that they need constant admiration and positive feedback from other people to keep their ego going.

Steven Bartlett: I called this person's former employer to get a reference, and one of the quotes was, "He always needs a gold star." What's the difference between deep insecurity and narcissism in this regard?

Dr Ten Brinke: Deep insecurity would need to be coupled with entitlement — there's still a grandiose sense of self, it's just that it is quite fragile. They think they're really good and they're willing to exploit other people to get what they think they deserve. They may feel like they've been victimised, and that's why they haven't gotten all of the accolades they think they deserve. Regardless of where this person sits on this continuum, they might still have incredible skills, the abilities you're looking for. So is this something you can manage, or is this going to create problems?

Steven Bartlett: I didn't get any sense that they were entitled or that they would use other people to their advantage. I got the impression that people would generally like them and that they weren't entitled at all, but they still had these self-promotional traits. I think in society, the minute someone's overly self-promotional, we run to the narcissist category, whereas it could be other things.

Dr Ten Brinke: In that situation, you need to be quite mindful of the situation as well. Our behaviour is a combination of both our personality and the situation we're in. If you're at a job interview, your whole goal is to show people you can do this job, you've got the skills they need. In a job interview, we might come across as more confident, presenting ourselves in the best possible light. We're very quick to rush to a personality assessment. This is called the fundamental attribution error — when I see someone behave in a particular way, like being self-promoting, I could be like, "Oh, that's narcissistic." We tend to be more likely to do that to others. But if I was in their shoes, I would be like, I was just trying to show Steven what I could do. It's the situation that made me act bigger than my britches. We need to be aware that the situation can impact our behaviour, and we want to not be too quick to make a personality attribution where the situation could explain it.

Personality is a consistent pattern of thinking, feeling, and behaving over time and across context. If you've only got one interaction with this person, you probably get a sense of their personality, but you might see them out with their friends or family and they might not be so boastful. That might suggest this is really the situation talking, not the personality.

Steven Bartlett: What are the gender differences in narcissism in terms of both types, and also our ability to spot these behaviours?

Dr Ten Brinke: When it comes to all of these traits, men tend to score somewhat higher than women. That's a quite consistent finding. That is not to say that women cannot score very high on these traits — there's quite a bit of overlap — but on average, the averages for men tend to be higher than the averages for women.

Steven Bartlett: And there's a fourth one.

Dr Ten Brinke: That's the newest and latest one, which is sadism. When you hear sadism, you might jump to pretty extreme.

Steven Bartlett: I was thinking of like the devil and stuff.

Dr Ten Brinke: I first started studying sadistic behaviour in the context of sexual homicides — reading through descriptions of criminal behaviour and looking for signs of sadistic treatment of the victim. It can get incredibly extreme, and that's probably where our mind goes. But there are also more everyday versions. One good example is online trolling. People who are relatively high in sadism take pleasure in other people's pain. You could do that in incredibly gruesome, horrifying ways, or you could just be pushing people's buttons online trying to get people upset.

All four traits share three things: they are callous — they don't care about other people, their feelings or outcomes. They're manipulative — willing to lie and cheat to get what they want. And they're hostile toward other people. That's the core of all of these traits.

Steven Bartlett: Are they good at hiding it?

Dr Ten Brinke: Yes. Some of the earliest descriptions of psychopathy in particular described it as a mask of sanity. They can seem quite normal on the surface, but if you get a look underneath the hood, you see they're not running the same operating system that you are.

Debunking misconceptions about psychopathy

Steven Bartlett: What is the inverse of all this? There are some misconceptions — people think narcissists or psychopaths can't hold eye contact, for instance. What are some of the ones your research has been able to debunk?

Dr Ten Brinke: I think one of the biggest ones is that all people with high levels of psychopathy are violent, and that's absolutely not the case. Most people think a psychopath looks dangerous. They picture the villain in a movie, but that's not how it works in real life. In that long-winded description of psychopathy I gave you, I did say there was rule-breaking, and sometimes that's criminal rule-breaking, so that could be violent behaviour — but it's not necessarily so. Psychopathy is a risk factor for violent behaviour, but there are plenty of people who would score relatively highly and never engage in violent behaviour. They might break rules in other ways. Whenever we hear the word psychopathy, what comes to mind is a Ted Bundy type character. He reportedly scored, I think, 39 out of 40 on the Psychopathy Checklist Revised. He's a bit of a poster boy for those traits, but certainly people can score highly without being a serial murderer.

Prevalence and origins of dark personality traits

Steven Bartlett: In terms of the amount of the population that have one of these dark personality traits, what are the numbers? How common is it?

Dr Ten Brinke: This is a complicated question because all these traits exist on a continuum. The proportion of people we say are high on these traits depends on where you put the cut point. If we're talking about psychopathy at clinical levels — a score of 30 out of 40 on the Psychopathy Checklist Revised or higher — that's about 1% of the population. Narcissistic personality disorder, at very extreme levels enough to warrant a diagnosis, would be two to five percent. We don't have clinical cut-offs for sadism and Machiavellianism. What we do have is a ton of data from people who have completed self-report questionnaires. If you just look at the people who on average agree with the items we use to assess these traits — things like "I am a born leader" for narcissism, or "I like to see other people get hurt" for sadism — it's about 10% of the population.

Steven Bartlett: Where does this come from? Is it childhood trauma, genetics, something else?

Dr Ten Brinke: The answer is both. Research suggests that with respect to psychopathy and narcissism, the variation in someone's score on that personality trait is about 50% genetic and about 50% environmental experiences. In some ways, this can make us realise that these people didn't ask to be this way — you don't get to choose your parents, so you don't get to choose your genetics. When it comes to those environmental experiences, they're often early life experiences and not good ones. Research suggests that abuse, a really cold and uncaring parenting style early in life, can increase the likelihood that someone will have higher levels of these traits later in life.

For narcissism, another variable is overvaluation of a child early in life. There was a longitudinal study where they asked parents the extent to which they told their kids things like, "You're special, you're better than other kids." The more the kids got that kind of feedback, the more likely they were to be more narcissistic later down the road. They thought they were exceptional, entitled to things other people were not. And that's different from self-esteem. We want our kids to have high self-esteem — to know they are cared for and worthy. That comes from something different: a warm, responsive parenting style.

Steven Bartlett: In that study, I was thinking about causation and wondering if the parents themselves had a genetic disposition to be narcissistic. Is it conceivable that they then spoke highly to their children, and actually maybe it wasn't the nurturing part, it was their nature — that the child also shared the genetics of the parent who had the proclivity to tell them they were the most amazing thing ever?

Dr Ten Brinke: Totally. I mostly think about this in the context of psychopathy, where sometimes you've got a perfect storm. You might have a parent who has really high levels of these traits, so they're passing on that potential genetic risk factor. But if you've got a parent in your household who is callous, manipulative, and impulsive, it's going to be very difficult to maintain a stable home life for that child. They might end up experiencing some of those abuse and cold parenting styles that are also environmental risk factors for developing psychopathy later in life. So they get a double whammy.

Parenting and early intervention

Steven Bartlett: From all the research you've done on dark personality traits and self-esteem, is there any way to increase one's probability of being a good parent? What is the right approach?

Dr Ten Brinke: Warm and responsive parenting. When you look at treatment for kids who are showing early warning signs of callous and unemotional traits, that's the treatment that seems to work. And that's kind of the silver lining in this whole dark research area — early intervention with kids really can help reduce the likelihood of them developing high levels of psychopathic traits as they grow older. Usually it's training parents. It's not like a kid comes in and talks to a therapist once a week and then we're good. It's more training parents about how to respond in ways that don't escalate or create dominance contests when the kid acts out, but also to reinforce and model warmth and responsiveness.

What's fascinating about psychopathy and callous and unemotional traits in kids is that they tend to be not very responsive to punishment, but very responsive to rewards. If you see kids doing something kind or helpful, the parent-child interaction training teaches parents to repeat what they said — "That was a very kind thing to say" — just repeating, showing, responding to them, paying attention to their behaviour when they do something good or kind, reinforcing it, and giving that attention to increase the likelihood you see it in the future.

Steven Bartlett: And the inverse — a bad way to respond to a child that might lead to some of these dark personality traits in the future?

Dr Ten Brinke: Cold and unresponsive parenting, getting angry, getting frustrated with them. Physically harming them — child abuse is associated with increased likelihood of developing these traits over time.

Steven Bartlett: You mentioned dominating in terms of dominating conversation, trying to outdo them.

Dr Ten Brinke: Sometimes if a kid is having a tantrum, you'll see a parent saying, "No, you can't have that." And then the kid increases the tantrum level. But then once it gets to a certain point, you give in. What that teaches is that you just need to escalate your behaviour — kick it up a notch, kick it up a notch, and at some point you're going to win. That kind of parenting is not going to extinguish the negative behaviour very effectively.

Brain differences in psychopathy

Steven Bartlett: And there's a brain scan in front of you. What is that?

Dr Ten Brinke: This is a functional MRI scan. What they're pointing out there is the prefrontal cortex. Research suggests that people who have high levels of psychopathy tend to have a less active and less connected prefrontal cortex. That's associated with impulse control and also with moral reasoning and moral thinking. If their brains are less active during moral or impulse control tasks in those regions, this might help explain why they're more likely to behave impulsively and not be empathetic to other people.

There's also the amygdala, which is deep within the brain and associated with emotional response, particularly fear. People with high levels of psychopathy tend to experience pretty low fear, and they're not very good at aversive conditioning. If we get punished for something, we learn that when we come up against that stimulus again, we think, "That turned out really badly last time, I'm going to avoid that." Amygdalas in people with high levels of psychopathy tend to be both smaller and less active. So there are brain differences, neurological differences, between people with high and low levels of psychopathy.

Can dark personality traits be changed?

Steven Bartlett: So I guess this begs the question — if someone has those traits, can they be cured?

Dr Ten Brinke: Some change is possible, but "some" being an operative word there. Most of the research we have on psychopathy in particular comes from criminal offenders — individuals who are incarcerated and have to take part in some treatment while they're inside. The research finds that they're not particularly motivated to change. That's a big problem, because they don't particularly care about other people, and it tends to be other people that they are hurting with their behaviour. So it's like, why would I change? This is a you problem, not a me problem. But if they do consistently engage in cognitive behavioural therapies, you can reduce the likelihood of recidivism — the likelihood that they will reoffend upon release.

When it comes to lower levels of these traits, there's really interesting research by Nathan Hudson where people did agreeableness challenges. Agreeableness is kind of the opposite of these traits. They would ping people on their smartphone every day and say things like, "Give a compliment to a friend," "Reach out to a friend and offer them some encouragement," "Buy coffee for the person behind you in line at the café." These little things where people were encouraged to be kind, be helpful to others, to see other people's perspectives. People who actually followed through on those did report having lower levels of these traits after four months than at the start.

Steven Bartlett: And in your book, under the section that says "hard truths," under "dark personalities persist," you write: "Poisonous people aren't likely to change very much. Personality traits are by definition enduring. Although some evolution of our character happens naturally, it takes decades. Data suggests that people become a bit more agreeable over time, and research with incarcerated men finds that even those with clinical levels of psychopathy are less likely to reoffend as they get older. Even so, waiting it out is likely to be a painful strategy. One study asked more than a thousand people who knew individuals who were psychopathic for a long time whether their behaviour had improved past the age of 50. Almost all respondents — 93% — said that, as researchers put it, the behaviour was just as bad or worse after age 50 than it had been previously."

Just as bad or worse.

Dr Ten Brinke: It's their personality. It's kind of like asking a tiger to change their stripes. If you're not motivated to do it — and as we know, people with these traits tend not to be very motivated — that's where that 93% of folks come in. They're not dramatically changing unless they find some reason to do so.

Deception in everyday interactions and its social cost

Steven Bartlett: Is there anything else in this area that you find interesting? Is there anything we haven't covered that you think is pertinent, or any research you uncovered that was fascinating?

Dr Ten Brinke: In my lab right now, I've become increasingly fascinated with how we respond to people who are lying to us when we're not suspicious at all. Most of the research is like, I give you a bunch of videos and tell you some of these people are lying and some are telling the truth, and you make judgments. But that's not how real life works at all. Usually we're having some sort of interaction with people. No one comes in and says you need to judge the veracity of this person. We're just having a conversation. So I've been really interested in how conversations unfold when one person is lying and the other person is none the wiser.

We keep finding these small but consistent effects that people feel less close to their interaction partner when someone is lying to them. We had a study where we got people to just converse — talk to a stranger. One person was told to lie in response to everything. The other person had no idea. At the end of that study, the pairs that had a liar in them said they felt less connected to the other person than pairs where both people were telling the truth. We also found that the more lies people tell — self-reporting on how much they lie in their everyday life — the more lonely they feel.

For the average person, most of the lies we tell are pro-social in nature. I tell you a lie because I don't want to hurt your feelings. But we are finding that actually creates social distance between us as opposed to bringing us closer together. I've been really interested in just the negative impacts of telling lies even when we do it for so-called good reasons.

Steven Bartlett: You talked about how if we were both sat down and you were asked to lie to me, I would walk away feeling less close — less connected — to you. What is it in your behaviour or in my perception that you think is causing this feeling of disconnection?

Dr Ten Brinke: People who are lying are perceived as less warm, less competent, and less moral. Also, if we think about some of the cues to deception we talked about earlier — when people give relatively few details about themselves, conversations are based on this reciprocal exchange. I tell you something about myself, you tell me something about yourself, and we start to know each other. If you've got someone who's lying to you, they're giving you less information about themselves. So I don't feel like I know you at the end of our conversation. Even though I'm not actively suspicious that you're lying to me about your likes and your interests and what you did on Friday afternoon, it comes across because you gave me less information — and maybe I think he didn't really want to talk to me.

Sympathy, donations, and unconscious deception detection

Steven Bartlett: What are some of the fascinating questions you've gone in search of answers for in your lab?

Dr Ten Brinke: One that I love is how much sympathy people feel for individuals who are lying or telling the truth about how sad they are. Think back to the pleaders we talked about — people who went on TV and asked for help trying to find their missing loved one, half of whom were actually responsible for killing that person. We showed people these videos — they weren't aware that some were lying and some were telling the truth — and we said, "How much sympathy do you feel for this person? How much money would you donate to a theoretical GoFundMe to help support the search for this missing person?"

We find really consistently that people are more willing to donate money to the genuine pleaders relative to the deceptive ones, and they feel more sympathy and compassion for them, even though they don't know that some of these folks are actually deceptive murderers. The effects are not gigantic, but it does suggest that we're not completely clueless moving through the world. But when we reduce it to a simple binary — is this person lying or telling the truth — we lose a lot of the nuance of how we move through our relationships. The sense of, oh, I'm feeling kind of close to this person, closer to that person, I'm willing to help this person more than that person — those are the kinds of things I've been interested in.

Warmth, competence, and trustworthiness

Steven Bartlett: I spoke to Vanessa Van Edwards on this podcast a few times and she does a lot of stuff around body language and how you show up. She talks about warmth and competence, and how some people can overindex on warmth and maybe that brings them down on competence, or they can overindex on competence but be less warm. Through your research and all the studies you've done, can you be warm and competent at the same time, or is there a bit of a trade-off? And what even is it to be a warm person?

Dr Ten Brinke: Warmth is the sense that someone is kind and honest and trustworthy — your benevolent intentions toward another person. We trust people to the extent that they are both warm and competent. I'm going to trust you if I think you have benevolent intentions for me, that you want to be kind to me, but also if I think you can actually execute on that — do you have the competence, the ability to actually do that thing? If you are just warm but you've got no ability to back it up, we tend to trust those individuals less. High warmth and high competence tends to be associated with high trustworthiness.

Steven Bartlett: And does high warmth come with certain behaviours?

Dr Ten Brinke: One is just smiling. Eye contact. It reminds me of the research by Alison Wood Brooks, who I know has been here before as well. Being engaged and interested in your conversation partner — these immediacy cues like leaning in, paying attention, smiling, making eye contact. These things are associated with warmth.

Steven Bartlett: What about resting face? I am occasionally guilty of this when I concentrate.

Dr Ten Brinke: When we have very little information about a person, we're trying to pick up on anything in their body language and non-verbal behaviour to make an assessment. If we've just got a quick look at your face and there's a bit of a scowl on it, that signals anger. And anger is not a warm thing. That tends to decrease our perceived trustworthiness of people.

Psychopathy and leadership outcomes

Steven Bartlett: Any other fascinating questions you've pursued in your lab?

Dr Ten Brinke: I've been really interested in psychopathy as it relates to leadership outcomes. When I finished my PhD, I was trying to figure out what I was going to do next. I was kind of bummed out thinking about murder all the time. I loved these topics, but I had to go somewhere else and think about them in a different context. It was shortly after the Bernie Madoff Ponzi scheme fell apart. I thought, maybe business school — I could go to a different context and study these same personality traits in a different area. I was also interested in this notion of successful psychopathy, because since the earliest descriptions of psychopathy, there's been this suggestion that these traits can actually help you succeed. I often hear that from people — "Yeah, that's terrible behaviour, but sometimes that helps, right?" And I'm like, does it? What does the data say?

So I worked with Dacher Keltner — and Dacher has been here as well.

Steven Bartlett: Has he? Yeah, I love him. He's so wonderful.

Dr Ten Brinke: We studied the extent to which psychopathic personality traits could increase the amount of influence you have in government and also the amount of money you make as a hedge fund manager. Those were the two contexts, because I thought these are hyper-competitive environments where maybe in government you can backstab and do backroom deals. They might be able to get lots of co-sponsors on their bills using backroom tactics. And with respect to money, maybe you're willing to take more risks, willing to cut people or companies down in public, not so worried about hurting other people. I thought these were situations where people with high levels of psychopathy could shine. Dacher was like, no, it won't be. So we were pitting these good versus evil concepts against each other, and consistently we found that high levels of psychopathy were associated with less influence in government and also with making less money as a hedge fund manager — which is very counterintuitive, I think, to people.

Steven Bartlett: What about narcissism and Machiavellianism?

Dr Ten Brinke: It really depends on how you define success. There is some research to suggest that narcissism and Machiavellianism can be associated with rising up in ranks, maybe having a higher salary level, but they're not associated with teams doing great. The work I'm interested in is that people with high levels of psychopathy talk a really good game and make people think they're a great tactical communicator, a very strategic thinker. But if you actually ask how good they are at their job, they say they're a terrible manager. They tend to bully their subordinates, create a huge amount of stress for other people on their team, and their teams have worse outcomes because of it.

Steven Bartlett: When you're talking about team performance, you're saying narcissists typically aren't good at leading teams over the long term?

Dr Ten Brinke: They tend to come across as leadership material early on. There's one study by Del Paulhus which shows this quite nicely. They had student groups working together throughout a term. After the first meeting, they all made judgments about each other — how likable they were, whether they seemed confident and smart and agreeable. The people who were high in narcissism came across really well in that first interaction. They knew what they were doing, came across very confident, seemed like they could lead, wanted to lead. But then as the term went by, people were like, "This person is actually really hostile and doesn't do their work and they're a pain in the butt." The thing that can make narcissism look good at the outset is our confusion of confidence and competence. When someone says they can do something and says it very confidently, we're like, "Oh, they've got this." But that's not the same thing as actually being able to do it.

Analysing a job application voice note

Steven Bartlett: I wanted to play you something. This is a team member of ours — we're going to change the voice and everything. I want to know if you spot anything in this voice note, which is a person supposedly applying for a job, that might be linked to some of these traits we're talking about.

"I love being around people, working with people. I'm an extrovert. I trained as an actor from when I was a child. I was making plays, writing, connecting with people in that way. So being around people is my number one thing — people connected with one mission. A story is a story and I know what makes a story tick from my actor training and writing comedy, writing plays, writing films, and just writing. And now in my role, what I've learned is I can do process. I never thought — I thought, oh, I'm just a creative, I can't do data, I can't do process. And I really can. I absolutely love telling a story with data because when you tell a story, you can use data just like you can use words. And that's something I get lost in. I use AI to do analytics. I've also been a performer, I create. So I think in the future I see melding those two worlds together, building my own thing. I want to be public-facing, be a public speaker. I want to speak on world stages. I'd love to speak at Cannes Lions. I'd love to win awards. I still want to keep being a creator, a creative, and an artist."

That was a script we sent her to read. Was there anything in there that flagged with any of these personality traits?

Dr Ten Brinke: I think one would be just kind of talking about other creatives not nailing it — putting other people down. That would be one thing. She also does talk about herself a lot and being able to do all of the things. Those are the biggest things I noticed. She comes across very — she does not sound timid. But again, we need to recognise that if this is a job interview, you're supposed to be talking about yourself. So you've got some situational effects. You wouldn't want to be too quick to run to a narcissism assessment there. But those are just little red flags. When I interact with someone and I see some of these little red flags — talking about yourself a lot, putting other people down — they're like little ember flags. I'm just going to store that and look for that pattern in the future. If there's a second interview, talk about teamwork. Tell me a time you worked on a team. And if they're constantly putting other team members down or taking credit for everything the team did, you can start to ask more pointed questions that might help you get at the extent to which their ego is quite inflated, or whether they're just trying to make a positive first impression and share their skills in a short amount of time.

Steven Bartlett: Do you find that in that message — the person said they went to theatre school — there's often an assumption that people who are actors or have certain roles where they're on stage performing have higher levels of some of these things. Is there any truth to that?

Dr Ten Brinke: Not to my knowledge. Although I think where it would mostly intersect is if you have any training in the Stanislavski technique — trying to experience an emotion. If I need to portray sadness in a scene, I might recall a time I genuinely felt sad to try to bring that emotion up, as opposed to trying to fake it. That kind of training might help you to mimic some emotions. But I don't know of any research that would suggest actors would be higher in these traits.

Reading dating profiles for dark personality cues

Steven Bartlett: We have some cards here which are people's dating profiles. I'm wondering if you can spot any of these dark personality traits just by looking at them.

Dr Ten Brinke: All right. So this is Ryan. He's a chief of staff in Washington DC. "Professionally trained to argue my point. So yes, I'm probably going to win the debate about what to have for dinner." Okay, this feels like a red flag. "Savvy, strategic, and persuasive by trade." This feels very much like Machiavellianism — controlling the situation, being a smooth talker. Savvy meaning they're controlling you, maybe using information to get you to do what they want. Strategic — we talked about that very strategic social style where they're playing three-dimensional chess to get what they want. "Off the clock, you'll find me exploring the city, enjoying great food, travelling, and keeping life interesting. Looking for someone who makes me laugh." The words that might be euphemisms for some Machiavellian traits would be savvy, strategic, persuasive — like, I can get anybody to do anything because I'm just going to manipulate them into doing it. These could be red flags. He could be a perfectly nice guy, but these are things I would go into that conversation thinking about. Does he seem very cynical of people? Is he quite power-hungry? Is he willing to manipulate other people to his own ends?

Steven Bartlett: What about that last line about "makes me laugh"? I found that to be quite self-serving in a way — you're looking for something yourself there.

Dr Ten Brinke: Potentially. All right, so this is Haley, who is a lawyer. "My friends call me Hurricane, but you can call me Haley. Equal parts chaos and good company." Chaos is immediately bringing up potential psychopathy — that impulsivity, you kind of don't really know where she's at. In women in particular, psychopathy can be associated with pretty volatile emotions. "I'll happily spend the weekend trying a new workout class or plotting a harmless prank on my friends." That's a sadism red flag — someone who might be delighting in someone else getting hurt. "Outspoken, tough enough to handle myself." Toughness is associated with psychopathy. "Do you think you can handle me?" That's up to you.

Okay. David is a brain surgeon. Very impressive. "Surgeon by day, theatre enthusiast and cocktail appreciator by night. I'm confident enough to pick the restaurant, self-assured to admit when I'm wrong occasionally. My friends would describe me as the life of the party." This is giving potential narcissism cues — loves a lot of attention, life of the party, confident enough to pick the restaurant. "Self-assured enough to admit when I'm wrong occasionally" — he put that in brackets, so you might not see a ton of that behaviour. "Don't worry, I'm sure I can find the time for you somewhere." Winky face. So you might not be a priority. I'm seeing narcissism vibes here. What I would pay attention to in our conversation would be: does he ever ask anything about me, or do we just talk about him and how fabulous and amazing his life is the whole time?

Dating profiles are like an advertisement you put out there. This is not an entire person's personality. We can gather more information over time, but some red flags there.

This is Chad. He's in law enforcement in Texas. He's barbecuing in the picture, which feels on brand. "Looking for my wife who will join me for life. No debt and no kids. Don't worry, ladies, I'm housetrained. When I'm off duty, I'm very independent. You'll find me hunting outdoors, grilling, or challenging my buddies. Looking for someone genuine to share life's adventures with."

Steven Bartlett: Nice guy. Seems okay.

Dr Ten Brinke: Yeah.

Steven Bartlett: If I was to go on a date with any of these people — Haley, Ryan, David, Chad — what are the verbal and non-verbal cues I would be looking for to figure out if they had any of these dark personality traits?

Dr Ten Brinke: These are early warning signs you can look for. Do they interrupt you often but refuse to tolerate it when you interrupt? That's an indication of impulsivity as well as potential dominance — they want to dominate you. Sometimes people get excited and just want to interject and share something. What we're really interested in here is the refusal to tolerate it when you interrupt, which makes them quite angry.

Do they consistently ignore personal or professional boundaries? Maybe you're on one of these dates and you say, "I'd really rather not talk about my family right now," and they continue to ask you about your family. Always pushing on boundaries even when they're set explicitly.

Do they seem weirdly calm? This is related to psychopathy and that shallow emotional affect — not experiencing fear, sadness, or concern for other people when you would expect them to in a conversation.

Do they seem to be the authority on every subject? This is a narcissism vibe — they know everything about everything and you don't know anything.

Do they offer impulsive, off-the-cuff responses to your questions? Not really thinking about things, just saying whatever comes to their mind immediately — a sign of potential impulsivity, associated with psychopathy.

Do they seem to come across as tough, combative, or cruel? Psychopathy is associated with aggression, wanting to dominate people, cruelty — and of course sadism.

This one's interesting: do they make intense eye contact with you, seeming to peer into your soul? One of the things clinicians have noted with people with high levels of psychopathy is that they tend to make really intense eye contact.

Do they seem to lack emotions related to self-awareness, such as embarrassment or shame? These are the broader self-conscious emotions — remorse, guilt — that are associated with a deficit in psychopathy.

Do they spend a lot of time talking about themselves and show much less interest in you? That's our old friend narcissism.

And when others are struggling, do they find it enjoyable, annoying, or boring? That would be associated with sadism.

Seven rules for dealing with dark personalities

Steven Bartlett: With two things in mind — first, that these dark personality traits are very common relative to the impact they can have on lives, and second, that according to your book and the research, people don't tend to change — this leads me to the conclusion that we might have to figure out how to deal with these people. If I look at some of those stats around antisocial personality behaviours, it would suggest roughly one in five people are going to be antisocial in some way. We can't just hope to avoid them in our lives.

Dr Ten Brinke: Everyone's got a story, I think. People feel relatively powerless because the approaches we tend to take with other people when they hurt us don't work very well for these individuals. When someone hurts us, we might show them, tell them, "That really hurt me," and then they feel guilt and might apologise. Or we might punish them in some way and that leads them to avoid that behaviour in the future. These are precisely the things that don't really work with people with psychopathy. So we're left being like, how do I deal with this? My tools are not working. But there are things you can do. We've got seven rules for dealing with people with dark personalities.

The first one is to establish clear boundaries. I want to preface this by saying that setting out the rules is not a guarantee they won't be broken. We've talked about how psychopathy involves breaking rules — that's a defining feature of that personality. But research suggests that establishing clear rules and making them explicit decreases the likelihood of selfish behaviour compared to if there are no rules whatsoever.

Sometimes in my workplace we have a respectful workplace policy, and when I read it I was like, why do people need to be reminded of this? But there are really good reasons to have one. It makes very explicit how we expect people to be treated here. That's going to decrease the likelihood that people, even with moderate levels of these traits, will violate those rules. And more than that, if they do violate the rules, you've got something written down. Otherwise it's very hard to do anything about it. In a relationship, you can make this really clear — what's okay, what's not okay — and you've got to tell the other person. It can't just be in your head. It can also help to read in a buddy. If you've got a friend and you've told them these are the things I want out of a relationship partner, these are no-goes, these are behaviours that cross the red line — having a friend who knows what those are and can tell you when your boundaries are slipping can be really useful.

Steven Bartlett: I was thinking of one particular context I know of — I'll keep it anonymous. There's a family with five kids, and one of the family members was telling me that they are the only one who has maintained a boundary against one of the older parents who has a track record of some of these dark personality traits. Because she has always maintained a boundary against the father, the father has almost left her alone and has gone for the other four siblings more so. The other four siblings are suffering because they don't have an established boundary. It's interesting that someone who has a boundary seems to be preyed on less by the narcissist or person with Machiavellian personality than those who haven't established one. Is that true, or is that just anecdotal?

Dr Ten Brinke: We do know from research — mostly in workplaces — that workplaces with codes of fairness see people with high levels of these traits less likely to, say, keep a bunch of the bonus money for themselves instead of sharing it fairly. So there's evidence that having rules in place increases the likelihood they will follow those rules relative to a no-holds-barred situation. There's also research on how people with high levels of psychopathic traits choose who to prey upon. Individuals who are not very assertive tend to be more likely to be targeted — it's almost like picking the weakest of the herd. So asserting some boundaries can help to not have that target on your back.

Steven Bartlett: I was thinking about a guest I interviewed on this podcast who had gone through domestic violence. She was telling me about the love-bombing process and how this individual had broken down her boundaries and her confidence over time, then isolated her from her friends and family, wouldn't allow her to call her mum, would give her a script when her mum called. One of the remarkable things I observed is how over time they'd broken down her confidence in order to seemingly control her.

Dr Ten Brinke: Yes, in a domestic violence situation, it reminds me of the emerging research on gaslighting — where someone makes their partner doubt their sense of reality, correcting them all the time, like "You're being too sensitive, you don't see the truth around you." What's so insidious about that is that it makes you dependent on that other person. And then the isolation can really decrease your ability to get out of it, because you don't have someone else who can check your sense of reality — that you really are seeing and feeling and remembering things that really did happen, even though they're telling you it didn't.

Steven Bartlett: What is gaslighting? Because we throw around the term all the time. The minute someone lies, we say, "You're gaslighting me."

Dr Ten Brinke: It's a pattern of denying someone's version of reality. You might tell people that they shouldn't be feeling the way they're feeling, that things didn't happen the way they're remembering, that they can't trust their own sense of perception of reality. It can be incredibly destabilising and isolating. What is worrisome about that is that we really need other people to help us see reality. If we're only seeing it through their lens — that we can't be trusted, our own eyes and memory can't be trusted — we start to depend on their perception, which is essentially a control tactic. Research does suggest that people with high levels of these traits endorse these tactics. They don't see anything wrong with doing that to a romantic partner, which would probably mean they're more likely to engage in it.

Steven Bartlett: A lot of romantic arguments would sound like gaslighting within that definition. Let's go back to the cheating example. You suspect I'm lying. So you say to me, "No, you weren't at the office till 3:00 a.m." And I go, "Yeah, yeah, I was. You don't know what you're talking about, Leanne. You weren't there. You're making this up in your head." Who was gaslighting who there? Because you denied my reality and now I'm denying your reality.

Dr Ten Brinke: Wait, but were you actually at the office?

Steven Bartlett: Does it matter? I'm trying to figure out which one of us was displaying gaslighting behaviour.

Dr Ten Brinke: I think it would be like if I say, "I feel insecure, I feel threatened by whatever you were doing on Friday," and you're like, "No, you don't. You shouldn't feel that way. There's no reason for you to feel that way. You're blowing things out of proportion." That's essentially denying someone's actual experience. My experience is that I feel threatened. Even if I might be wrong about that, that is my experience. You could deny the facts — you could say, "No, at 2 a.m. I was falling asleep on my desk." You could maybe argue with the facts. But it's when you start arguing with someone else's perception of reality — of their own subjective experience — that's when you stray into gaslighting.

Steven Bartlett: In the example I gave earlier from my guest, that's exactly what happened to her. What he started to do was hide her stuff in places — he put her car keys in the fridge to make her feel like she'd gone crazy.

Dr Ten Brinke: Which is absolutely bonkers.

Steven Bartlett: Okay, so that was establishing clear boundaries. Really, what I was getting at is: do they try and erode those boundaries, or do they leave you alone?

Dr Ten Brinke: They're likely to try to push on them, but less so than if you have no boundaries at all.

The next one is don't give them power over others. We've talked about how all of these traits relate to power — Machiavellianism is named after the pursuit of power, psychopathy is associated with domineering people, narcissism is "I'm better than you, I'm a born leader." People with these traits tend to be very interested in having power over other people. But we know from research that this does not tend to go well for those individuals working underneath them. People who are working under a boss with more psychopathic traits report being more stressed out. They also tend to bring that stress home, which creates more family conflict — it doesn't stay where it is. They tend to create division within teams, and they increase the likelihood of turnover and tension. So giving them power over others is not a great way to deal with them.

But there are other things you can give them that they do want. This is essentially negotiating 101 — you can look for win-wins when negotiating with them, recognising that what they consider motivation might not be what you consider motivation. Imagine you've got an employee who is bullying his subordinates and you're like, "You really need to treat your team better because they are so stressed out, they're going home from work and crying to their spouses, they're getting sick." You're trying to make them feel compassion for other people to get them to behave better. That's not motivating to them. People with high levels of these traits are callous, not concerned about other people. However, that doesn't mean they can't do something kind or helpful — they might just do it for a different reason. If you know the team is suffering under this person's bullying management style, you could say, "You've got this sales bonus coming up, but your team is so stressed out that you're not going to meet that target and you're not going to get your bonus. You need to treat your team differently." Money, power, status — they like those things. It's not that they can't behave better; it's that they might do it for a different reason.

The next one is use the carrot, not the stick. We've talked about how people with high levels of psychopathy are very reward-sensitive but not very punishment-sensitive. Their brains don't process punishment in the same way — they don't develop that link between "if I do this behaviour, I fear punishment again." So they're more likely to repeat it than people with low levels of these traits. Punishment has a place, I suppose, but it's not going to be as effective with these personalities. And what we're losing a huge opportunity on is not using the carrot instead, when the carrot is so powerful. Sometimes people are like, "They're a bad person, I'm not going to reward anything they do." But if they do something kind or honest or helpful, reward them. Not with power over others, but maybe with a bonus at work, with a job title — because they really care about status. That's a reward they will really like, and you are going to increase the likelihood that you get more of that behaviour in the future.

Steven Bartlett: I think there'll be some people listening right now thinking, shouldn't you just fire these people? Shouldn't you get all of these people out of your life if they've got sadism, narcissism, Machiavellianism, psychopathy?

Dr Ten Brinke: Given that a reasonably sized minority of the population has some elevated level of these traits, you're going to be chucking a lot of people. And they might genuinely have some really useful skills that you want in your company — you just need to learn how to manage this personality trait. Even if you have a low tolerance for these traits, you're not going to be able to completely avoid them at all times. It might not be your decision to remove them from the company. It might be a sibling, a brother-in-law — someone you want to have a relationship with even if that relationship is not perfect. Maybe you see him twice a year and you don't want to cut him out because that means you don't get to see your sister anymore. The stay-or-go question is just so complicated, and there are so many reasons why you might not be able to do that. So we need to learn the skills to manage interactions with these people as well.

The next one is emphasise your common identity. People with high levels of narcissism are not particularly interested in being fair to you or being kind to you, but they are interested in loyalty. There are these fascinating studies where they just tell people, "Oh, you guys have the same birthday," or "You have the same fingerprint type" — which I don't even think is a thing. But people think they have some sort of commonality, and then people with high levels of narcissism get less angry when you give them negative feedback if they think you've got something in common with them. So if you start your conversation with, say, that combative uncle at Thanksgiving who always talks about himself — "Oh, you know, we went to the same university, we root for the same football team" — you start with what you have in common. You're like, "Okay, we are one." And then if you need to say, "You really need to pick up your game and help with the care of grandma," he might be more willing to listen to that, as opposed to just receiving negative feedback out of nowhere.

Steven Bartlett: I sat here with Tali Sharot, who's a neuroscientist who's looked at the subject of disagreement quite extensively. She put people in brain scanners and got them to disagree with each other, and observed that the brain changed when someone disagreed with you. I was on a phone call the other day with about ten different people from a company we're doing a deal with, and I observed that one person would often open their rebuttal when they had a difference of opinion with the phrase "I completely disagree" — and then make their point. I got straight off the call and did a bit of research on whether that's effective or not. What I found is that there is extensive research across social psychology, behavioural economics, and linguistics showing that opening a counterargument with explicit adversarial phrasing like "I disagree" actively hinders your ability to persuade somebody. When you start a rebuttal with "I disagree," several psychological mechanisms trigger in the other person's brain. It seems somewhat linked to what you're saying about keeping the other person receptive.

Dr Ten Brinke: Totally. This reminds me of another study on domineering bosses. If you need to give them negative feedback — say you hate the way a particular process is running, these three forms should be one form — if you say, "This is so stupid, you need to change the way we're doing this," coming in hot, particularly people with high levels of narcissistic traits are like, "We don't like this kind of ego threat. You're criticising me. I'm just shutting it down." Whereas if you phrase it as a question — "What do you think if we turn these three forms into one form?" — phrasing it as a question makes it softer and makes them more willing to just hear it. You might ultimately not get to that one form, but you'll at least get a little bit further in that conversation. That's true for everybody, but especially when it comes to people who are really domineering, which these personalities tend to be.

Steven Bartlett: So you kind of co-create the solution.

Dr Ten Brinke: Exactly.

The next one is become a detective and notice their cues. We know that they tend to lie a lot — being manipulative and telling lies is part of their MO. That's what all of these traits share. Being able to identify what those cues of deception are. Know that we're not looking for gaze aversion. We're not looking for fidgeting. We're looking for a lack of verifiable details, relatively few details, signs of cognitive strain, and maybe following up if we start to see some of those red flags.

And finally, avoid face-to-face negotiations. This is a really simple move that can be really helpful. Some research out of the same university as me, the University of British Columbia, had people with various levels of these dark traits engage in a negotiation — just over the price of concert tickets. What they found is that whenever those negotiations occurred face to face, the person with the high level of psychopathic traits or any of these dark traits got a really good deal. They were able to command a whole bunch of money for these concert tickets. Whereas if they engaged in this negotiation over text, that wasn't the case. These dark traits can be really domineering, really superficially charming in person, and you can let your guard down and they're going to take advantage of you. If you reduce them to words on the page, they lose some of that charisma. But there are also other practical reasons — you've got a written version of what was agreed upon. They can't gaslight you and tell you you're misremembering what was agreed. You've got some time to think about how you want to respond.

And if violence is a concern — say you're in a domestic violence situation and you've got to negotiate some sort of settlement in a divorce — being face to face can be dangerous. It literally puts some physical distance between yourself and that other person if violence is a concern. So there are all kinds of potential upsides to putting it into text, into the chat, as opposed to sitting down face to face.

Steven Bartlett: I was thinking about all the things linked to having a bit more time and also the medium of text. One of the things that came to mind is if someone does have those dark personality traits, they are probably more cautious about what they say if it's permanent and written. And the other one is that in written form, you as the person on the receiving end have time to show other people and get another perspective — even putting it into AI, asking Google, checking if the facts are right, or asking your partner if this is appropriate behaviour.

Dr Ten Brinke: Totally. And involving other people can be so helpful. Research suggests that whenever we discuss with other people before making a truth-lie judgment about someone else's statements, we tend to be more accurate. Whenever we're making judgments about someone's personality, if we're talking as a group, we tend to be more accurate. Another study that Dacher Keltner did — he talked to a bunch of girls in a sorority and asked them who gets talked about the most in gossip, and also had people rate their personality. It was the more Machiavellian girls who were talked about the most.

Steven Bartlett: Talked about positively or negatively?

Dr Ten Brinke: Negatively. And so, you know, people sometimes hear about whisper networks — "stay away from that guy at work." I would caution just believing everything you hear in the rumour mill. But sometimes people spread information about their experience with a person, and we can learn from other people's experience before having to go through it ourselves if we pay attention.

Three common mistakes when dealing with dark personalities

Steven Bartlett: And you've got three final cards down there — three common mistakes people make when dealing with dark personalities.

Dr Ten Brinke: The first one is believing there's nothing you can do. We've talked about how some of our go-to responses when people hurt us — trying to make them feel badly, trying to make them apologise, trying to punish them — don't work so well. But we've also talked about all of the things you can do. So we don't need to feel completely helpless.

Another is assuming they have the same inner experience as you. When we're trying to figure out what motivates people, what motivates you to do a thing might not be the same thing that motivates them. I need to try to get into their head, figure out what their goals are, what would be motivating to change their behaviour in this situation, and try to frame our interaction in that way. Try to convince them to change their behaviour for that reason — not because I think they should, or not because I would feel guilty if I did what they did.

And lastly, thinking you can change them. If your ultimate goal is, "I'm going to stick around and they're going to be kind and honest and super conscientious and helpful all the time, they're never going to break any rules" — we need to be clear-eyed about the likelihood of that happening. Instead, we need to deploy some of these strategies for making our day-to-day interactions a little more positive, as opposed to just hoping that someday they're going to wake up with a different personality.

The most important takeaway

Steven Bartlett: What is the most important thing we haven't talked about that we should have talked about as it relates to your work, zooming in on the people listening who might benefit in their lives?

Dr Ten Brinke: I think it's a matter of numbers. We've talked about the 10% of people who would generally agree with items we use to measure these traits. That means 90% of people would generally not agree. I want people to keep into perspective that 90% of people are good and kind and honest and not breaking the rules. We've got this 10% — and that's not to say that 10% is causing little harm. In fact, they're causing hugely outsized harm. With respect to psychopathy, that's about 1% of the population, and offenders with clinical levels of psychopathy account for about 50% of all serious crime. These people are doing incredibly outsized harm. And we feel that in our lives too — not necessarily in criminal records, but we've got one person who's constantly making things hard because of these traits, causing strife at work, abusing people at home. If we can learn to mitigate the damage from just this small, relatively small group of people, then we can dramatically improve our lives, our workplaces, our day-to-day interactions.

Closing question: the greatest lie we've all been told

Steven Bartlett: We have a closing tradition on this podcast where the last guest leaves a question for the next guest, not knowing who they're leaving it for. The question that's been left for you is: what is one great lie we've all been told?

Dr Ten Brinke: I think one great lie we've all been told is that to be successful, you have to be in it for number one, and you need to exemplify some of these traits in order to get that promotion, to get that raise, to run that company that's worth millions of dollars. Even I went searching for evidence for that — to show that people with high levels of psychopathy could use their callous, cunning, fearlessness to make more money as hedge fund managers. And I found the opposite. So I think even in those areas where we think these traits lead to success, they fall short. And really, taking other people with us and thinking about success as prestige and respect from other people, care and concern about us from other people — that's a much truer version of success.

Steven Bartlett: Leanne, thank you so much. Thank you for writing a book that is incredibly illuminating in a way that is research-based whilst also being just unbelievably engaging. These subjects are so pertinent to everybody listening. Much like you were when you started your career, we're all just trying to figure out the ultimate barrier and opportunity that sits in front of us — and that's just other people. And as you said, we kind of go through the world thinking that everyone else's internal experience is a mirror of ours. It's very easy to get frustrated or to feel like you're the problem or you're inadequate if that's the lens you take to life. Through your research, you do exactly what you said — in a weird way, you do make us more empathetic and maybe more optimistic and less cynical about the nature of human experience.

Dr Ten Brinke: Thank you, Steven. This has been so wonderful.