We're not calling you a liar, but – Okay, we are.

In January 2013, in an interview with TV host Oprah Winfrey, cycling legend Lance Armstrong shocked the sports world by admitting that he had used illicit performance-enhancing drugs to help him win his seven Tour de France titles. That information itself wasn’t so surprising, since anti-doping investigators already had built an extensively-documented case against him. What disturbed and dismayed the popular athlete’s legions of fans was that for years, Armstrong had steadfastly maintained his innocence, with a passionate seeming sincerity that made people want to believe him. How did he manage to pull the wool over our eyes so convincingly, for so long?

But Armstrong's mendacity wasn't really that amazing, if you dare to think honestly about it. Lying, after all, is something that most humans seem to do habitually throughout our lives. "People do it because it works," University of Massachusetts-Amherst psychologist Robert Feldman, a leading researcher on deception, explained to the Los Angeles Times. "We get away with lies all the time. Usually they're minor: 'I love your tie.' 'You did a great job.' But in some cases they're bigger, and in Armstrong's case, he was pretty confident he could get away with it."

That obviously conflicts with what we were taught as kids, that honesty is the best policy. But to be truthful, that adage is more honored in the breach than in the observance. Certainly, most of us like to think of ourselves as habitually truthful; in a survey of 1,000 Americans published in 2010 in the journal Communication Research, for example, 60 percent

of subjects claimed that they had told no lies at all in the past 24 hours, and a small group of hardcore, apparently shameless prevaricators—about 5 percent of the population—claimed to tell about half of all falsehoods.

But when psychologist Feldman studied what people actually did, as opposed to what they reported, he found a

very different pattern. In a study of 121 college graduate students published in Journal of Basic and Applied Social Psychology in 2002, he found that 60 percent of people lied at least once during a 10 minute conversation, and that on average they told two or three lies in that stretch. The falsehoods ranged from pretending that they were fond of someone they didn’t actually liked, to claiming phony achievements, such as being the star of a famous rock band. Women tended to like to make others feel good, while men more often told lies intended to make themselves look better. But either way, the telling of falsehoods was such a deeply ingrained practice that experimental subjects didn’t even realize they were doing it. When shown surreptitious video of their mendacity, "people found themselves lying much more than they thought they had," Feldman said.

Similarly, a 1996 study by University of Virginia psychologist

Bella DePaulo, in which 147 people between the ages of 18 and 71 kept diaries in which they recorded their falsehoods each day, found that most people lied at least once or twice daily—almost as often as they went to the refrigerator for a snack, or brushed their teeth. DePaulo found that people lied in approximately 20 percent of their social interactions lasting 10 or more minutes, and over the course of a week deceived about 30 percent of those with whom they interacted on a one-to-one basis.

The really shocking truth is that whether you're Lance Armstrong or some ordinary Joe, your ability to tell lies may well be an essential part of what makes you human. Some scientists theorize that evolution may have hard-wired our brains to have the ability to deceive others, because it enables us to trick other humans into cooperating with us to get the things we need.

The Duplicitous Brain

Of course, people aren't the only liars out there. Nature is filled with species that rely upon deception to survive, from the harmless snake that resembles a poisonous species to the orchid that's shaped like a female wasp, which attracts pollinating males. Such illusions are an important tool in many species' survival.

But primates, the evolutionary branch that includes humans, are even more, deliberate sophisticated prevaricators. In the same way that you might stash the last remaining box of Girl Scout cookies behind the cookbooks and pretend that they're all eaten, your distant relative the Rhesus monkey sometimes hides food to avoid having to share with other monkeys. Researchers Andrew Byrne and Nadia Corp from the University of St. Andrews in Scotland, who've studied deception in primates, have found that the ability to lie is linked to brain development. In particular, the size of the cortex, the outermost layer of the brain that&'s responsible for advanced cognitive functions, is a good predictor of how gifted of a liar a particular species may be. That suggests that the ability to lie may be an evolutionary adaptation, rather than, say, an aberrant personality flaw.

Humans demonstrate the ability to lie before they're old enough even to speak. A study published in 2007 by

Vasudevi Reddy, a psychologist at the University of Portsmouth in Great Britain, found that babies as young as six months old engage in fake crying to simulate distress, when what they really want is attention. "You can tell, as they will then pause while they wait to hear if their mother is responding, before crying again," she explains. By age two, children have already developed even more devious techniques, such as bluffing when threatened with punishment. "Later it becomes more sophisticated by saying, 'I don't care' when threatened with a punishment - when they clearly do."

University of Toronto psychologist researcher Kang Lee, in a study published in 2010, found that by age four, nearly 90 percent of children are telling fibs, and that by age 12, lying is nearly universal, though it recedes to about 70 percent by age 16. In an interview with the Telegraph, a British newspaper, Kang said that lying seemed to be linked to

brain development. "Those who have better cognitive development lie better, because they can cover up their tracks," he said.

And as we grow up, we learn to weave increasingly tangled webs.

Interestingly, though, we don't have a specific part of our brain that's devoted to telling lies. Instead, neuroscientists who've done scans of subjects' brains when they're stretching the truth have found that the portion that lights up most consistently is the prefrontal cortex, situated just behind the forehead. That's the area that we use in a lot of different everyday activities involving executive control, which utilizes processes such as planning, problem solving, and attention.

As turns out, we use the same processes in lying, except perhaps that we use them even more intensely, because deception invariably involves a sort of multitasking. "When you lie, you have to do two things that are cognitive," polygraph expert Dan Ribacoff explains. "You have to suppress the automatic response to tell the truth, and then you have to fabricate the lie. So your brain works much harder to lie than it does to tell the truth."

Actually, You Can Hide Your Lyin' Eyes

We all want to believe that if we scrutinize a person carefully enough, we can spot some errant physical detail that will reveal we're being conned. Police detectives, for example, traditionally have watched for suspects who avert their gaze or glance around when answering questions, believing that such behavior is a subtle sign of dishonesty. As FBI behavioral scientists noticed in a 2011 article, however, 23 of 24 peer-reviewed studies in the scientific literature found no relationship between those behaviors and deception. Similarly, fidgety feet and hands, vice stress and changes in body posture seem to be, at best, only weak indicators at best that a suspect is not telling the truth. One big problem: Truthful individuals are often nervous in police interrogations, and exhibit some of the behaviors traditionally associated with lying.

"No one indicator of lying exists," the FBI researchers concluded. "If so, research would have identified it by now, and almost everyone could unerringly detect when people lie."

That doesn't mean that it's impossible to detect deception through physical cues, but it requires a much more sophisticated approach. The FBI scientist studied a wide range of characteristics, from blood pressure and respiration to facial expressions and pupil dilation. They found that the key to spotting deceptive subjects was to watch for subtle changes in their facial expressions, gestures, body language, voice and/or choice of words over time—"leakage," as the scientists call it—that was inconsistent with the story that the subjects were telling. (A glaring example of this might be a person who shakes his head from side to side while saying "yes.")

In particular, the researchers learned to watch for "microexpressions"—fleeting changes in facial expression, sometimes occurring in a fraction of a second, that revealed an emotion inconsistent with the demeanor that a liar was trying to project. The researchers found it easiest to spot such signs of lying by studying videotapes of interrogations, but with practice, law enforcement investigators were able to learn to spot microexpressions as much as 80 percent of the time.

Lying Has Its Pluses and Minuses

Some believe that deceptiveness actually is an essential part of our existence. As Leonard Saxe, a polygraph expert and professor of psychology at Brandeis University, told Psychology Today in 1997: "Lying has long been a part of everyday life. We couldn't get through the day without being deceptive."

Which leads to the question: Is lying really all that bad? If you're a con artist trying to fleece elderly people out of their retirement money, of course, it's pretty clear that what you're doing is harmful to others (though it's beneficial financially to you). But other sorts of deception—say, an undercover police detective who poses as a criminal in order to infiltrate and build a case against organized crime—have clear benefits to society. And lying can even lead to positive behavior. One study found that students who claimed to have a higher grade-point average than they actually did were more likely to improve their grades in the future.

On the other hand, being truthful has its benefits as well. University of Notre Dame psychology researchers Anita E. Kelly and statistician Lijuan Wang in a study presented at the American Psychological Association's convention in 2012, asked half of a group of 110 subjects to stop telling lies for 10 weeks. The other half, who acted as a control group, could

stretch the truth as much as they liked. (Both groups came to the lab each week and took a polygraph test on the number of lies told that week, to ensure compliance.) Kelly and Wang found that the non-liars experienced fewer emotional woes, such as feeling tense or melancholy, and were less likely to have physical complaints such as sore throats and headaches as well. Additionally, the non-lying subjects reported that their social interactions and close personal relationships improved.

Five tips on how to lie... and get away with it.

In the “Liar Liar” episode of Brain Games, we learned that lying is a deeply ingrained part of being human. But while most of us tend to shade the truth, we aren’t all necessarily that good at it. And there are few things more embarrassing –or even potentially hazardous—than being caught in a lie, whether you’re trying to convince a teacher that the dog really did eat your homework, or doing your best to wriggle out of difficult questions at a Congressional hearing. The good news is that just as you can learn to hit a curveball or train yourself to control your fear of giving speeches, with a little practice and the right techniques, you can become a much more convincing prevaricator. Here are some suggestions from experts on how to be a masterful liar.

Do your homework. A 1990 study by psychologist Bill Flanagan showed that liars who work out the details of their stories beforehand are more successful at fooling people Be sure that you practice your story and commit it to memory, so that you don’t stumble over portions of it.

Read your listener. We often assume that we can tell whether someone is lying based upon the nonverbal clues, such as whether or not they make eye contact. But it works both ways. Psychologist Charles V. Ford, in his 1996 book Lies! Lies!! Lies!!!: The Psychology of Deceit, notes that a skillful liar will visually scan his or her target, trying to pick up on the person’s nonverbal behavior and responses to statements. That way, you can tell whether or not your lies are going over, and whether you need to make subtle adjustments in your story to make it convincing.

Pick and choose what you lie about. Dutch psychologist Aldert Vrij , who has studied skillful liars and identified 18 different characteristics that make them effective at deception, says that lies that bend the truth are generally more persuasive than wholesale fabrication. In addition, a lie that’s wrapped in truthful details requires less cognitive effort to maintain.

It’s easier to conceal than it is to fabricate. If a listener tries to stump you with a detailed question, simply respond “I honestly don’t know.” As Vrij notes, such a response is preferable to a constructed lie because lack of knowledge can’t easily be refuted.

When you’re in trouble, counterattack. Stan Walters, author of the book The Truth About Lying, explained in a 2010 Psychology Today article that most people are uncomfortable confronting a liar and making an accusation—a weakness that a skilled liar can utilize to his or her advantage. "You'll often see politicians respond to accusations with aggression,” Walters noted. “"What they'll do is drive critics away from the issue, so they're forced to gather up their resources to fight another scrimmage."