字幕表 動画を再生する 英語字幕をプリント Hey y'all. Time for two truths and a lie. I'm gonna tell you three things about myself. You have to pick up one that it's not true. Ready? Okay. Number one, I have a machine at home that transforms plain water into carbonated water. Two: I'm really bad at the card game Set Three, Michael Jackson is my aunt. Isn't that obvious? Yeah. God, so bad at games. Lying. We do it a lot. And we're a lot better at it than you'd like to think. Like I'm not a stupid. I could totally make up a better lie than Michael Jackson is my aunt. But check it out; the fact that I appeared to be terrible at lying was in fact a lie. In the ten-minute conversation with a stranger, we humans will tell an average of 3 lies. Researchers who study lying said that the subjects of these lying studies rarely even realize that they're doing it. But why? What purpose does lying actually serve? Well, to put human deception into perspective, it's worth pointing out that humans aren't the only fibbers in nature. My favorite anecdotal examples of non-human lying. Koko the gorilla who was taught sign language back in 1970s. Once actually blamed her pet kitten for ripping a sink out of the wall in her room. Bad bad old ball. So yeah, lying is nothing new with nature. But why did humans specifically do so much of it? Well as I mentioned here before on SciShow, humans are first and foremost social animals. Got really, super-huge brains, and that's mainly because we need them for all the interacting we're always doing. For human successful social interaction is key to success for much of our lives. So it's clear that lying is a great way of keeping elaborate social structures running smoothly while looking out for number one. For instance, if you can keep your social group happy, you're going to reap all kinds of benefits like food, higher social standing, more and better sexual partners and you know you don't make friends and influence people going around and saying things like “Actually, that loincloth does make your butt look big,” or "Hey, uh, I have been having sex with your brother while you're out hunting mastodons, so little Blurgh over there is probably your cave nephew." So the ability to lie and to detect a lie became pretty important to early humans Because lying is actually not very easy for a brain to do And actually caused a bit of an evolutionary arms race. So people start to get better and better at lying. Better liars got better stuff while hopefully remain in good standing with their communities. By the same time token those who were better at detecting lies were cheated on by their mates and screwed over in camel trades a lot or less of it So yes now we've evolved to be good liars and also good at spotting bad liar. So that society became more sophisticated. Folks were like okay okay. Enough with the lying! Because there are a lot of advantages to living in tight-knit communities and structured societies, but you can't really have them when you don't know for sure if the kids you're raising are yours and the camels you just bought has ever been in an accident. Whatever So a society in which bold face lying goes completely unchecked leads to total anarchy. So organized societies started putting the hammer down. Religious systems began to drive home the point that God rewards and cares for the truthful and punishes liars. So if you could survive being thrown into the bog and tied up with a sack of hammers, God was on your side and you were telling the truth. If not, you were obviously lying. Oh. Medieval European judicial system, how I love you. Even now, in modern times, there are laws that prohibit lying and override even our rights to free speech. For instance, you go to jail for lying in the court of law or for lying about having received a Medal of Honor for service in the armed forces. Don't do that. Also, ‘cause you're not an evil... Why would someone do that? So lying it's not okay. But we're all so good at it, and our brains want to do it. And we start lying really early; some researchers say as early as six months old. I mean you've seen a baby fake crying right? It's very obvious. Like they're crying, then they like check to see if anybody's coming over to sympathize, and then they're like “Oh, I'm going to keep crying then.” Scientists think this is the time when babies are actually learning how to be better liars. By the time when kids in college, they're lying to the mom about once in every five interactions And actually, that seems, that seems low to me. I would say five out of five for my college experience. Kids these days, actually, kids every day. By the time, we're adults. We've gotten so very good at lying that we're actually able to do it to ourselves very effectively. The trick of lying to yourself is in the holding of two pieces conflicting information in your head at the same time And paying attention to one while ignoring the other. People who are good liars can hold a bunch of conflicted information in their heads all at once and keep tracking to that Take pathological liars, people who habitually and compulsively lie, cheat, and manipulate other people. The thing about pathological liars is that they're super good at self-deception At the moment they're telling it, they whole-heartedly believe their own lie. Interestingly enough, there is an actual difference between the brain of a normal person and the brain of a pathological liar. That difference is in the very front of the brain, in a place called the prefrontal cortex. Most neuroscience studies focus on the gray matter of the brain, that's the material that actually processes information. However, nearly half of our brains are made up of what's called white matter Which is composed of connective tissues that carry electrical signals from one group of neurons to another. So gray matter is where all the processing happens and white matter connects the different parts of the brain In a study at the University of Southern California, researchers found that pathological liars have about 25 % more white matter in their prefrontal cortex than the rest of us. Suggesting the pathological liars can make a bunch of connections in their brain really fast. And that let them keep all the information in order that they need to sustain the lie. also to read the person that they're lying to, suppress their emotions, and probably believe what they're saying on top of it all. So why haven't pathological liars taken over the world? I mean, they seem to be the next step in human evolution. Well, pathological liars have a surplus of white matter, they also have around 14% less gray matter than other people. And grey matter is where all the critical thinking happens. So the white matter is all like, “I'm gonna tell Jim I used to be a fighter pilot!” And the gray matter is all, “I could tell Jim I used to be a fighter pilot, but I probably shouldn't because that would jeopardize my relationship with Tammi.” So extreme liars have a really hard time maintaining relationships and holding down jobs Because after a while, everybody realizes they are full of crap and they get dumped or fired, Which is not ideal for the person. It's great for everyone. But if there are these super liars out there, how do we know if we're being lied to? I mean, lie detectors might be able to pick up signals like like change the liar's voice, or increased heart rate, or sweating all stuff that we do when we're fibbing out right. But a really good liar might not display any of those symptoms. Well, no matter how good of a liar you are, the fact that you are lying will often leak out, Both through your body language and for your word choices. Let's look at the sample sentences. Believe me, I was not the one who farted and evacuated that movie theater. So do you believe me? Probably not because I did three things in that sentence that made you totally certain that I was, in fact, the person who made them evacuate the movie theater. Do it! One, I said “believe me” liars will always said that or “to be totally honest.” Or Richard Nixon's favorite: “in all candor.” Two, I all of a sudden stopped using contractions. Liars often use more formal language to deny something that they've actually done. And three, I said that movie theater instead of the movie theater. I was trying to distance myself from the whole situation. We think of liars as being fidgety, but we actually tend to freeze our upper bodies when we lie. We make more, not less, eye contact; maybe a little too much to over-compensate for telling a fib. Liars will also do things like shake their heads while saying yes. And smile when they're done telling the story even if it's a terrible one All of this stuff, the reading of what we leak through our words and bodies, is actually the future of lie detection. Training law enforcement officers to read potential criminals to catch them in the act of lying. Of course there are always coming up with new kinds of gadgets all the time, too eye trackers, MRI brain scanners that are going to replace the old lie-detector tests Maybe I'll tell my two truths and a lie to a brain scanner and see how it does. Pretty sure we all know how it's gonna turn out. Yeah, you're right; I'm a terrible liar. Or am I? Thank you for watching this Infusion. All the facts contained within are not lies, we promise! But if you want to check, there are citations in the description. Of course because we're scientists here. If you have ideas for future episodes or infusions, you can leave those in the comments. Or connect with us on Facebook or Twitter also questions. We'll be happy to answer those as well. See you next time.