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All of our pants are almost constantly on metaphorical fire, is the basic impression I got after watching the new documentary Dishonesty: The Truth About Lies. The film is a fascinating exploration of the current scientific research on the little things that nudge people into lying, cheating, and stealing, and most of the research comes from behavioral economist Dan Ariely, the Duke professor and best-selling author of books like Predictably Irrational: The Hidden Forces That Shape Our Decisions.

The film will be screening for a short time in New York at the IFC Center, starting this Friday. (For bonus social-science nerd fun, Ariely and director Yael Melamde will be at the Friday and Saturday shows to answer audience questions.) But Science of Us got an advance screener of the film, so, herewith, some of the most interesting findings on dishonesty the documentary covers. (All direct quotes in the post are taken from the film. Honest.)

Some of the most interesting insights into human dishonesty have stemmed from a 20-item set of math problems. In much of his research on lying, Ariely has favored something called the matrix experiment, a set of 20 straightforward math problems that anyone could solve, were they given enough time. The trick is, as Ariely explains, they never give their study volunteers enough time. The participants get just five minutes to answer as many questions as they can; then, they take their papers up to the front of the room and shred them. Next to the shredder is one of the experimenters, and the students are instructed to tell this person how many questions they answered correctly, and they’ll be paid the according amount of dollars.

But there’s a second trick: The shredder didn’t actually shred their papers. It only shred the sides, so the researchers can later see who was telling the truth. On average, people solve four problems correctly, but they tend to report getting six right.

When given the opportunity, the majority of people will lie. But the bigger, fatter lies are rare. More than 40,000 people have now participated in some version of the matrix experiment, and more than 70 percent of them cheated. But only a few — Ariely has counted about 20 — could be considered “big” cheaters, those who told the researchers that they solved all the matrix problems correctly, meaning they walked away with $20 they didn’t earn. So these liars stole a total of $400 from the researchers. In contrast, Ariely and his team have documented about 28,000 fibbers, stealing a grand total of about $50,000. “I think this is not a bad reflection of reality,” Ariely said. “Yes, there are some big cheaters out there, but they are very rare. And because of that, their overall economic impact is relatively low. On the other hand, we have a ton of little cheaters, and because there are so many of us, the economic impact of small cheaters is actually incredibly, incredibly high.”

We’re also pretty good at lying to ourselves. Michael Norton, a Harvard Business School professor, has done experiments in which he gives study participants general trivia tests, and some of the papers have the answers at the bottom. So the participants first take that test, and then they’re given another one — this one with no answers at the bottom. They’re also asked to predict how well they think they’ll do on this second test, and most of them predict they’ll get an excellent score on this test, as well. “They just think that they’re amazing test-takers now,” Norton said. Even when he’s tried to get them to think more realistically by promising them more money if their predictions are more accurate, people still overestimate their ability. “This process of deceiving ourselves is so strong, and it happens to us so quickly, where we have a twinge of, Maybe I cheated, and then, No, I didn’t, I’m a genius,” Norton said.

Animals lie, too. It’s a broader take on the idea of lying, but Murali Doraiswamy, of the Duke Institute for Brain Sciences, argues that “all creatures, big or small, have deception as part of their armamentary,” usually as a means of survival. “A plant or a bird might change color and camouflage itself, which is a form of deception,” Doraiswamy said. And the bigger the brain, the better the liar: take chimpanzees, for example. “They may lead their group away from where the food is, so that one particular chimpanzee can come back to the food later on,” he said.

A little dishonesty is good for kids, kind of. Doraiswamy argues that when young kids start to experiment with lying, it’s often more of a way to build their imagination than an attempt to get away with something. “It helps them build their brain, and it helps them build what is called theory of mind,” said Doraiswamy, referencing the psychological theory that says as our brains mature, we get better at figuring out what another person is thinking about (a form of imagination, really). “And unless children lie, and unless children imagine, and dream big, they may not have the full capacity to develop a theory of mind,” he said.

Lying for someone else’s benefit doesn’t really feel like a lie. When people can justify their dishonesty, the lie often doesn’t get picked up by a lie detector, according to Ariely’s research. “Lie detectors basically detect emotional arousal — when we feel uncomfortable,” he explains. When people cheat for their own gain, the lie is detected, no problem. “But sometimes, we ask people to cheat for a charity. And then the lie detector is silent. The lie detector doesn’t catch anything. Why? Because if we could justify it, we’re doing something for a good cause, there’s really no arousal — there’s no conflict, there’s no emotional problem.” The film follows this little factoid with the story of Kelly Williams-Bolar, the Ohio woman who was jailed for lying on her kids’ school records so they could switch to a better district, and it is heart-breaking.

Dishonesty gets easier over time, and neuroscientists think they know why. At first, even a little lie provokes a big response in brain regions associated with emotion, such as the amygdala and insula, said Tali Sharot, a cognitive neuroscientist at University College London. “The tenth time you lie, even if you lie the same amount, the response is not that high. So while lying goes up over time, the response in your brain goes down.” Sharot believes this can be explained by a very basic principle of neuroscience: the brain adapts. “The brain is coding everything relative to what the baseline is,” she explains. So if we don’t usually lie, and then we do, this prompts a big neurological response. But if we lie a lot, the response lessens over time. “After a while, the negative value of lying — the negative feeling — is just not there, so much,” Sharot said. And this, she reasons, makes it easier for people to keep on lying.

But there is an extremely simple way to curb dishonesty dramatically — just remind people to not be dishonest. All you have to do is show people some kind of reminder of a moral code, and the urge to lie dissipates. In one experiment Ariely describes, researchers asked 500 students at UCLA to try to jot down as many of the Ten Commandments that they could remember. After that, they took part in the matrix experiment. None of them recalled all the commandments, and yet none of them cheated, Ariely said. This was true regardless of whether the students were religious or not. Simply reminding them that Thou shall not lie has a weirdly powerful effect.

The study was replicated at MIT, but without the religious context: Students were asked to read MIT’s “moral code” before the matrix task. Again, no one cheated, Ariely said — this, despite the fact that MIT doesn’t even have a moral code. “It is not about heaven and hell and being caught,” Ariely said. “It’s about reminding ourselves about our own moral fiber.”