Tag Archives: honesty

The Science of Lie Detection

Lying has always been a popular topic for exploration, especially in the entertainment industry. It is very common to see crime shows in which an alleged perpetrator is hooked up to a polygraph machine to determine his truthfulness, or lack thereof. A few years ago, a TV show called Lie to Me hit the airwaves. The show is based on the work of Dr. Paul Ekman, a scientist and author best known for furthering our understanding of nonverbal behavior. Actor Tim Roth plays Dr. Cal Lightman, a scientist and lie detection expert who uses facial expressions and body language to determine whether someone is lying.

Surveys have shown that the average person lies at least once a day, with college students lying as much as twice a day. Since dishonesty is encountered on a daily basis, lying should be easy to identify; however, this is far from the case. Attempts to deceive others in everyday life are as difficult to detect as they are common and, contrary to what’s depicted in Lie to Me, a large body of research reveals surprisingly few valid cues of deception.

Psychologist William Moulton Marston invented the first lie detector in the 1920s. Interestingly, Marston’s invention led to the creation of Wonder Woman, the female superhero who could compel people to tell the truth using her magic lasso. Marston’s invention became the prototype for modern lie detectors, which record on a chart physiological activity such as skin conductance, blood pressure, and respiration. Although physiological activity may offer helpful clues to identify lying, the lie detector is far from infallible.

The polygraph excels at determining increasing anxiety or nervousness, but does a poor job of pinpointing the reason for the anxiety, which may or may not be due to lying. Rather than a “lie detector,” the polygraph may more accurately be described as an arousal detector. On Lie to Me, Dr. Lightman demonstrated how the lie detector test can be manipulated. In the first case, he gave a witness valium and then had her deliberately lie while hooked up to the machine. However, because of her tranquility, the reading indicated that she was telling the truth. In the second case, Dr. Lightman asked a male witness an identical set of questions using two different administrators. The witness answered truthfully each time. When the questions were asked by a man, the machine indicated the witness was telling the truth, but when the questions were asked by an attractive woman, the machine indicated the witness was lying. His attraction to her raised his anxiety levels.

While Lie to Me is accurate about the unreliability of lie detectors, it isn’t as easy as the show makes it appear to read facial expressions and body language to determine honesty. Even people trained in the criminal justice field such as judges and police officers can’t always identify if someone is lying. While there are no conclusive clues that indicate deception, honing skills of observation is still helpful, as people often do provide signs that they are being untruthful.

What do you think? Can lying ever be perfectly identified? PAR wants to hear from you, so leave a comment and join the conversation!


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Lies, Damn Lies, and Statistics*: Dan Ariely’s New Book Tackles the Truth about Dishonesty

Why are lying and cheating so prevalent? Is dishonesty just a part of human nature? What can be done to encourage people to be more truthful?

In a recent interview on National Public Radio’s “All Things Considered,” Dan Ariely, a professor of psychology and behavioral economics at Duke University, talked about his new book, The (Honest) Truth About Dishonesty: How We Lie To Everyone—Especially Ourselves, which was published on June 5. Ariely is interested in the psychology behind lying, and he has conducted a number of experiments over the years that were designed to get at why—and how—people lie. His experiments, which to date have involved more than 30,000 subjects, show that although very few people lie a lot, most of us lie “just a little.” Ariely also discovered some very simple ways to encourage people to be much more honest.

Why do we tell only little lies, or cheat only in small ways? “We want to view ourselves as honest, wonderful people and when we cheat … as long as we cheat just a little bit, we can still view ourselves as good people,” Ariely told NPR’s Robert Siegal, in the June 4 interview. “But once we start cheating too much … we can’t view ourselves as good people and therefore we stop.”

One of Ariely’s favorite experiments involved simple arithmetic problems and a paper shredder. “We give people a sheet of paper with 20 simple math problems and we say, ‘You have 5 minutes to solve as many of those as you can, and we’ll give you $1 per question.’ We say, ‘Go!’ People start, they solve as many as they can, at the end of the five minutes, we say, ‘Stop! Please count how many questions you got correctly, and now that you know how many questions you got correctly, go to the back of the room and shred this piece of paper. And once you’ve finished shredding this piece of paper, come to the front of the room and tell me how many questions you got correctly.’”

Ariely explains that the subjects in this experiment typically claimed that they solved six problems, which they were paid for. What he didn’t tell the subjects, however, is that the shredder was modified so that it only shredded the sides of the paper, leaving the main part of the page intact. On average, people solved four problems, but claimed that they had solved six. “We find that lots of people cheat a little bit,” says Ariely, but “very, very few people cheat a lot.”

In his May 26 Wall Street Journal essay, “Why We Lie,” Ariely discusses some of the reasons that people behave in dishonest ways. Conventional wisdom suggests that when faced with a choice to be honest or dishonest, people weigh the costs (such as getting caught) against the benefits (such as gaining something useful or helping another person) and make their choice logically. Ariely’s research shows, however, that this is rarely the case. In fact, he found that level of cheating is generally unaffected by the probability of getting caught.

What factors cause people to cheat more or cheat less? In a variation on the math/paper shredder experiment, Ariely had the administrator of the test take a cell phone call while giving instructions to the participants, engaging in a distracting, unrelated conversation and seeming to ignore the test subject. In this case, subjects cheated, on average, twice as much. “I think this goes back to the law of karma, right?” says Ariely. “If somebody has mistreated you, now you can probably rationalize [your cheating behavior] to a higher degree.” Cheating also seems to be infectious: If another participant was flagrantly cheating, other subjects in the room cheated more.

If “getting caught” is not a disincentive to lie or cheat, then what is? For many of us, a simple reminder about honesty—a reminder of the moral code—can make a big difference. In an experiment at UCLA with 450 subjects, Ariely and his colleagues conducted another variation on the math problem experiment. This time, before the subjects began, they asked half of the participants to recall the Ten Commandments and half to recall ten books they’d read in high school. In his Wall Street Journal essay, Ariely explains the results. “Among the group who recalled the 10 books, we saw the typical widespread but moderate cheating. But in the group that was asked to recall the Ten Commandments, we observed no cheating whatsoever. We reran the experiment, reminding students of their schools’ honor codes instead of the Ten Commandments, and we got the same result.” Even a simple statement such as “I promise that the information I am providing is true” is often enough to encourage most people to be honest, according to Ariely.

If you have read Dr. Ariely’s book, or if you have other ideas about the psychology of dishonesty, PAR wants to hear from you—leave a comment and join the conversation!

*Nineteenth century British Prime Minister Benjamin Disraeli is perhaps better known for his literary career than his political accomplishments. He once quipped, “There are three types of lies: lies, damn lies, and statistics.”

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Polygraph Tests: How Accurate Are They?

Lying, it seems, is a very common part of human interaction. In their book 50 Great Myths of Popular Psychology (2010), Scott Lilienfeld and his colleagues cite studies in which college students and others in the community admit to lying once or twice a day, on average. But how hard is it to tell if someone is lying? Don’t liars give off tell-tale signs of their deceptions? In fact, research reveals surprisingly few valid cues of deception, and Lilienfeld asserts that “most of us are dead wrong about bodily cues that give away liars” (p. 116).

If people are poor judges of truthfulness in others, does technology offer a better solution? Is the polygraph, or lie-detector test, an accurate means of detecting dishonesty? Most Americans (67% in one study) believe that lie-detector tests are “reliable” or “useful,” and films and television programs tend to corroborate this belief with story lines that portray polygraph testing as infallible.

The science, however, tells a different story. Lilienfeld and his colleagues explain that rather than truthfulness, the polygraph machine simply measures physiological activity—and then it is up to the examiner to ask questions and interpret the results. Factors such as blood pressure, respiration, and sweating can offer clues to lying because they are associated with how anxious the examinee is during the test; however, anxiousness is not the exclusive domain of lying, and “an honest examinee who tends to sweat a lot might mistakenly appear deceptive, whereas a deceptive examinee who tends to sweat very little may mistakenly appear truthful” (p. 118).

Another problem is confirmation bias, that is, the tendency for polygraph examiners to see what they expect to see. Examiners may have a preconceived notion of the examinee’s guilt based on outside information. Further, information on countermeasures, or techniques to “beat the test,” is widely available on the internet.

Estimates of the accuracy of one popular form of the polygraph test, the Comparison Question Test, put it at 85% for guilty individuals and 60% for innocent individuals. “That 40% of honest examinees appear deceptive provides exceedingly poor protection for innocent suspects,” suggests Lilienfeld (p. 120).

Because of their limited validity, polygraph tests are rarely admissible in court, and federal law prohibits most employers from administering lie detectors. Yet the public perception is that polygraph tests are accurate measures of truthfulness. Are people simply vulnerable to the images they see in television and movies, or is there something else that makes us want a machine that can detect the truth?

We would like to hear your opinion on this topic, so please post a comment and let’s start the conversation!

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