That Neuroscience Guy - Lying

Episode Date: October 22, 2021

We tell plenty of lies every day. Sometimes we lie to other people to spare their feelings or make ourselves look better. We even lie to ourselves when we remember things differently than how they happened. But why? In today's episode of That Neuroscience Guy, we discuss the neuroscience of how and why we lie. 

Hi, my name is Olof Kergolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Have you ever told a lie? You know, like, I really like your haircut. Or, oh, you know, I'm sick today. I just can't come into work. I'm sorry. Sadly, we all do it.

You know, we wish we don't, but we all do. Lying just seems to be a part of our human nature. On today's podcast, we're going to talk about the neuroscience of lying. There's some really cool and interesting behavioral research on lying. For instance, Dr. DiPaolo from the University of Virginia found that men and women are both equally likely to lie in 20% of their exchanges that last 10 minutes or more. So check that out. If you talk for 10 minutes or more to someone else, there's a 20% chance that you're telling lies. And Dr. DiPaolo also found out that

over the course of a week, on average, we deceive approximately 30% of the people that we have one-on-one interactions with. 30% of the people over one week. Now, in terms of this proportion of times that we lie, there don't appear to be any gender differences. Men and women are lying the same amount. But there are differences in terms of what we lie about in terms of our gender. Women are more likely to tell lies to avoid hurting other people's feelings. So, for instance, they won't tell their friends that they don't like their haircut. Men, though, are more likely to lie about themselves. In other words, we brag. Indeed, that's what Dr. DiPaolo found. Dr. DiPaolo found that men are more likely to lie to impress others.

Indeed, a typical conversation between two guys contains about eight times as many self-oriented lies as it does lies about others. There's guys bragging about themselves. So I guess that's one key gender difference. guess that's one key gender difference. In another study in 2020, Dr. Zeti, another researcher, found that 96% of a thousand person sample had lied to get out of work in some manner, with the most common reason being sick. I have to be honest, I might have told that lie myself. But anyways, what about the neuroscience of all this? What's going on in the brain? Well, it turns out in the brain, there's three key brain regions that are involved in lying.

First of all, there's the prefrontal cortex. If you remember the prefrontal cortex, that area right at the front of the brain, it's executive function. It's the thing that sort of helps control our lives. You know, classic examples of executive function are our ability to switch between tasks, our ability to set goals and plan. It's the thing that runs the show, if you will. But what is the prefrontal cortex doing in lying? What's its role? Well, the role of the prefrontal cortex, at least in terms of lying, is a really important one. It helps with suppressing the truth. Suppressing the truth requires deliberate effort. It's a decision. I'm not going to tell the truth. At least the brain is saying, I'm not going to tell the truth.

And that requires deliberate effort, and that requires executive function. So you can imagine you're facing someone, and you don't actually like their haircut, and they say, what do you think of my haircut? Well, your system one response, if you think back to decision making, is to say, oh, I really don't like your haircut. And that's where the prefrontal cortex comes in. It clamps down on that. The system two sort of overrides it and says, hey, no, we're not saying that. Let's come up with a better story. And just as a reminder, system one is that gut hunch system that shouts

out what you first think. And system two is that analytical system that's being more deliberative about what you're going to do next. So that's the first brain region involved in lying. The next brain region is the amygdala. And we've talked about the amygdala a lot. Hopefully you know by now, it's emotion. It's one of the key emotional centers of the brain. And the study that we use quite a bit, and it's one I really like because it illustrates the point, is when you look at significant others, there's more amygdala activation than when you look at strangers.

And the same is true for emotional faces. If you look at a face that's got emotional content, say someone laughing or crying, there's more amygdala activation than if there's a neutral face. But what does the amygdala have to do with lying? Well, it's pretty straightforward. Lying involves emotion. It involves it in two ways. You have to add emotion to your lie. If you told your lie with no emotional content, typically tend not to believe it. So the amygdala adds emotion to the lie, if you will. It's contribution. This is the feeling that should go with the statement I'm about to make. And of course, it also is active because you feel emotion about lying.

Most of us feel pretty horrible when we lie to others, even if we keep doing it. So that's the role of the amygdala in lying. The last brain region that plays a role in lying is the temporal lobes. What do the temporal lobes do? What is their role in lying? Well, again, we've talked about the temporal lobes quite a bit. If you think back to season one, we talked about the role of the temporal lobes in visual processing, and specifically in terms of perception. So if you remember, when visual information comes into the brain, it passes through the temporal lobes, and that's where we identify shapes and forms and then houses and faces. And like we talked about a couple weeks ago, the temporal lobes also play a key role in language. The language areas of the brain are typically on the left side, but this is the

temporal lobes. So what are the temporal lobes doing in lying? Why are they activated? Well, we have to come up with material for our lies. We need the imagery. So for instance, if I was going to tell you that I went to Hawaii last weekend, even though I didn't, I have to come up with that story. I have to come up with the concept of Hawaii. I have to come up with all sorts. I have to come up with the concept of Hawaii. I have to come up with all sorts of things. You know, what was the plane like and all these things. And the temporal lobe is basically accessing your memory of these things and these constructs and adding all that information in there. So the temporal lobe is adding the material of the lie. So let's put that together quickly. When you tell a lie, first of all, the prefrontal cortex is

activated to suppress the truth, to make sure that you don't say what you're actually thinking. The amygdala is activated, and it's activated because you need to add emotional content to the lie, and you also have some feelings about lying. And finally, the temporal lobes are activated, and that's where the material comes from, the bits and pieces that make up the lie itself. Now, interestingly, sometimes we even lie to ourselves. There's a really cool line of research into false memories. False memories are basically memories that you think you have, but they never actually happened. They're events that didn't occur or things that you didn't do. And interestingly, in recent years, researchers have come to think that a lot of what we remember never actually happened, or at least didn't happen the way that

we think it did. Some estimates go as high as 50% of what we remember is at least distorted, if not completely not true. For example, you might remember very clearly, you know, I drafted and sent that email, I'm sure of it, but you actually did it when you check and look back. Or you might remember that you put lettuce and celery on a grocery list, when in fact, it was tomatoes and cucumbers that you wrote down. And you might forget someone's name. You might think of a person as John and their that you wrote down. And you might forget someone's name. You might think of a person as John and their name is actually Steve. And it can be even more pronounced. You know, there might be events in your life that just didn't happen the way you did. Someone that

was at a night out that wasn't, someone that was wearing a shirt that they weren't, or maybe even potentially an event that didn't happen. I'll give you an example with a really, really cool research study. I've always thought this one was fascinating. I'll walk you through the study and then I'll tell you about the brain regions that are involved. In one of the scenarios, what happens is a participant shows up and they have a picture of themselves as a boy with their dad. Now, what they don't know is that this is all being sort of orchestrated in the background. What they're about to see is they're about to see a bunch of pictures of themselves with their dad in various scenarios. So at the beach or at a park

or on a summer holiday. And in the one that I'm familiar with, in one of the pictures, there's a picture of the boy and the dad and someone's photoshopped it so there's a balloon in the background. And the researcher sits there and says, well, hey, do you remember going on a balloon ride with your dad? And typically the participants answer along the lines of, no, I don't think that that happened that way. So they know that that wasn't what happened. But what the researchers do is they repeat this every once in a while. Imagine every week. Now this is where it gets interesting. When the participant comes back and is shown the picture of the boy and the dad again,

in the back of their brain this has been sort of churning around there and when asked about it again, they begin to start lying. You know, actually, I think I remember that after all. You know, it was a summer day and I remember feeling hot. And they just keep adding to this story. And that's a very staged example, I have to admit. But researchers believe we do this all the time. We keep creating these little fictional stories about what we think happened when it actually didn't. Now, what brain regions are involved in lying when we lie to ourselves? Well, the same ones that we mentioned earlier, the prefrontal cortex, the amygdala, and the temporal lobes,

but we also see additional activity, and that activity is in the medial prefrontal cortex, and that is a region of the brain also associated with executive function, why that region is specifically activated in self-lying isn't exactly clear. But we also see activity in the ventral lateral prefrontal cortex on both sides. These are brain regions associated with working memory. And the best theory about why those regions are involved is that typically when you tell these self-lies, you have to sort of distort what you're bringing back from long-term memory or adapt it. So your working memory system is sitting there going, yeah, let's tweak that a little bit and change the story. But why do we self-lie? No one's 100% sure, but the best working theory has two key components.

One, faulty memory reconstruction. Basically, the idea is you're trying to remember something, but there's an absence of detail. So what happens is your brain falls back on, you know, sort of the surrounding information, the gist of the situation, and also familiarity, just adding in things based on what you know about what's going on. So the first part of the situation, and also familiarity, just adding in things based on what you know about what's going on. So the first part of this self-lie is this faulty reconstruction. And the second part is a key part of the brain, and this is the medial prefrontal cortex and possibly why it's activated, is that typically when you bring things back from long-term memory, one part of your brain is like checking it. And we call that retrieval monitoring.

And it's going on and saying, is that an accurate piece of information? You know, is that really what happened? And the medial prefrontal cortex is working with the working memory system and the ventral lateral prefrontal cortex. And it's going, okay, this isn't right. So when we self-lie,

the example is that there's a failure of retrieval monitoring. For whatever reason, these two brain regions aren't doing their jobs. And here's Matt with a cool study about lying. Thanks, Olav. So, so far today, we've talked about how we lie to other people and how we lie to ourselves. But what happens when someone's lying to us? How do we try and figure out if someone's telling us the truth or not?

As it turns out, there's not a whole lot of research on this. It's kind of a new subject. Well, as it turns out, some new researchers found out that there is some parts in the brain that we do use to determine if someone's lying to us. Earlier this year, a team of researchers from the University of Poland tried to figure out what's going on in the brain when we're trying to see if someone's lying to us. In their experiment, they had participants learn signs from the Japanese language. These people didn't know any Japanese before, but they just learned the

signs themselves and what they meant. Once they learned that, the researchers tested them on that to see if they remembered them. They would show them the sign right next to the word that it meant. Imagine seeing the sign for apple next to just the word apple. Once they figured out that the participants had all learned those signs, they decided to test with some lies. They would put the symbol next to an unrelated word, say the sign for apple next to the word house. Again, these participants were able to tell when the computer was lying to them or when the definitions were true. What happened next was a little bit more interesting. The researchers would then include longer and longer sentences to

describe the sign, say the sign for apple, and followed by the statement, a type of fruit grown from trees that is often used in desserts or even eaten by itself. The researchers wanted to see if the length of a lie affected our ability to determine if it was true or not. As it turns out, there's a small subgroup of the participants that was really bad at determining when the longer statements were lies. They were perfectly fine when the statements were short or when it was just a simple definition, but when the statements became long and more descriptive, they became fooled more easily. When researchers looked at the brain activity of these participants,

When researchers looked at the brain activity of these participants, they found that they had quite a few brain areas less active than the other participants. They were using less of their brain. Specifically, they didn't have activity in the hippocampus or small areas of the prefrontal cortex. What this means is that these participants weren't using their memory of what these statements meant, and they weren't using some critical thinking abilities to determine if these were lies. Researchers concluded that this meant that these participants, when they see the longer statements, they automatically assumed that they didn't need to determine if it was a lie or not.

They just figured because there's more information that it'd be true. This is a really interesting finding. Some people may be more susceptible to misinformation if it's presented with more detail and more description, even if that description doesn't match the memories we have or what we know to be true. So, in short, while there's little research on how humans perceive each other lying, there is something saying that the longer the lies are, the more likely some of us are to believe them. That's all I have for you this week. Thanks again and I'll see you next time.

Thanks again, Matt. thanks again matt that's super interesting and a really cool finding all right everyone thanks for listening to the neuroscience of lying remember you can email us if you have episode ideas we want to talk about what you're interested in that neuroscience guy at gmail.com you can follow me on twitter please do please do, and post ideas there, thatneurosagguy. And of course, we have our YouTube channel. I have to apologize because it's really focused on a class I'm teaching on right now, but we're going to keep adding content and every once in a while, I'll drop in some cool stuff in addition to the stuff I'm teaching my students about research methods. That's on YouTube, thatneuroscienceguy. My name is Olive Kregolson and I'm thatneuroscienceguy.

Thanks for listening and see you next week