"You can tell a lie but you will give yourself away. Your heart will race. Your skin will sweat ... I will know. I am the lie detector." Thus began each episode of Lie Detector, a strange cross between a relationship counseling session and an episode of the Jerry Springer Show that ran on British daytime television last year. Against a backdrop of flashing computer screens and eerie blue light, participants--usually feuding couples but sometimes warring neighbors or aggrieved business partners--sat on a couch and were quizzed by the program's host. A frequent topic of discussion was one guest's suspicion that his or her partner had been unfaithful. The person suspected of infidelity denied it, of course, and the object of the show was to find out--through cross-examination and computer analysis--whether that person was telling the truth.
However much we may abhor it, deception comes naturally to all living things. Birds do it by feigning injury to lead hungry predators away from nesting young. Spider crabs do it by disguise: adorning themselves with strips of kelp and other debris, they pretend to be something they are not--and so escape their enemies. Nature amply rewards successful deceivers by allowing them to survive long enough to mate and reproduce. So it may come as no surprise to learn that human beings--who, according to psychologist Gerald Jellison of the University of South California, are lied to about 200 times a day, roughly one untruth every five minutes--often deceive for exactly the same reasons: to save their own skins or to get something they can't get by other means.
But knowing how to catch deceit can be just as important a survival skill as knowing how to tell a lie and get away with it. A person able to spot falsehood quickly is unlikely to be swindled by an unscrupulous business associate or hoodwinked by a devious spouse. Luckily, nature provides more than enough clues to trap dissemblers in their own tangled webs--if you know where to look. By closely observing facial expressions, body language and tone of voice, practically anyone can recognize the telltale signs of lying. Researchers are even programming computers--like those used on Lie Detector--to get at the truth by analyzing the same physical cues available to the naked eye and ear. "With the proper training, many people can learn to reliably detect lies," says Paul Ekman, professor of psychology at the University of California, San Francisco, who has spent the past 15 years studying the secret art of deception.
In order to know what kind of lies work best, successful liars need to accurately assess other people's emotional states. Ekman's research shows that this same emotional intelligence is essential for good lie detectors, too. The emotional state to watch out for is stress, the conflict most liars feel between the truth and what they actually say and do.
Even high-tech lie detectors don't detect lies as such; they merely detect the physical cues of emotions, which may or may not correspond to what the person being tested is saying. Polygraphs, for instance, measure respiration, heart rate and skin conductivity, which tend to increase when people are nervous--as they usually are when lying. Nervous people typically perspire, and the salts contained in perspiration conduct electricity. That's why a sudden leap in skin conductivity indicates nervousness--about getting caught, perhaps?--which might, in turn, suggest that someone is being economical with the truth. On the other hand, it might also mean that the lights in the television studio are too hot--which is one reason polygraph tests are inadmissible in court. "Good lie detectors don't rely on a single sign," Ekman says, "but interpret clusters of verbal and nonverbal clues that suggest someone might be lying."
Those clues are written all over the face. Because the musculature of the face is directly connected to the areas of the brain that process emotion, the countenance can be a window to the soul. Neurological studies even suggest that genuine emotions travel different pathways through the brain than insincere ones. If a patient paralyzed by stroke on one side of the face, for example, is asked to smile deliberately, only the mobile side of the mouth is raised. But tell that same person a funny joke, and the patient breaks into a full and spontaneous smile. Very few people--most notably, actors and politicians--are able to consciously control all of their facial expressions. Lies can often be caught when the liar's true feelings briefly leak through the mask of deception. "We don't think before we feel," Ekman says. "Expressions tend to show up on the face before we're even conscious of experiencing an emotion."
One of the most difficult facial expressions to fake--or conceal, if it is genuinely felt--is sadness. When someone is truly sad, the forehead wrinkles with grief and the inner corners of the eyebrows are pulled up. Fewer than 15% of the people Ekman tested were able to produce this eyebrow movement voluntarily. By contrast, the lowering of the eyebrows associated with an angry scowl can be replicated at will by almost everybody. "If someone claims they are sad and the inner corners of their eyebrows don't go up," Ekman says, "the sadness is probably false."
The smile, on the other hand, is one of the easiest facial expressions to counterfeit. It takes just two muscles--the zygomaticus major muscles that extend from the cheekbones to the corners of the lips--to produce a grin. But there's a catch. A genuine smile affects not only the corners of the lips but also the orbicularis oculi, the muscle around the eye that produces the distinctive "crow's-feet" associated with people who laugh a lot. A counterfeit grin can be unmasked if the lip corners go up, the eyes crinkle but the inner corners of the eyebrows are not lowered, a movement controlled by the orbicularis oculi that is difficult to fake. The absence of lowered eyebrows is one reason why false smiles look so strained and stiff.
Ekman and his colleagues have classified all the muscle movements--ranging from the thin, taut lips of fury to the arched eyebrows of surprise--that underlie the complete repertoire of human facial expressions. In addition to the nervous tics and jitters that can give liars away, Ekman discovered that fibbers often allow the truth to slip through in brief, unguarded facial expressions. Lasting no more than a quarter of a second, these fleeting glimpses of a person's true emotional state--or "microexpressions," as Ekman calls them--are reliable guides to veracity.Next Page
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In a series of tests, Ekman interviewed and videotaped a group of male American college students about their opinions regarding capital punishment. Some participants were instructed to tell the truth--whether they were for or against the death penalty--and some were instructed to lie. Liars who successfully fooled the interviewer received $50. Ekman then studied the tapes to map the microexpressions of mendacity.
One student, for example, appeared calm and reasonable as he listed the reasons why the death penalty was wrong. But every time he expressed these opinions, he swiftly, almost imperceptibly, shook his head. But the movement is so subtle and quick many people don't even see it until it's pointed out to them. While his words explained the arguments against capital punishment, the quick, involuntary shudder of his head was saying loud and clear, "No, I don't believe this!" He was, in fact, lying, having been for many years a firm supporter of the death penalty.
Another student also said that he was against the death penalty. But during the interview, he spoke very slowly, paused often, and rarely looked the interrogator in the eye, instead fixing his gaze on some vague point on the floor. Speech that is too slow (or too fast), frequent hesitations, lack of direct eye contact: these are all classic symptoms of lying. But this man was telling the truth. He paused and hesitated because he was shy. After all, even honest and normally composed individuals can become flustered if they believe others suspect them of lying. His lack of eye contact could be explained by the fact that he came from Asia, where an averted gaze is often a sign of deference and respect, not deception. This scenario highlights Ekman's admonition that before branding someone a liar, you must first know that person's normal behavior patterns and discount other explanations, such as cultural differences.
Ekman has used this tape to test hundreds of subjects. His conclusion: most people are lousy lie detectors, with few individuals able to spot duplicity more than 50% of the time. But Ekman's most recent study, published last year in Psychological Science, found that four groups of people did significantly better than chance: members of the U.S. Central Intelligence Agency, other U.S. federal law enforcement officers, a handful of Los Angeles County sheriffs and a group of clinical psychologists. Reassuringly, perhaps, the federal officials performed best, accurately detecting liars 73% of the time. What makes these groups so good at lie catching? According to Ekman, it's training, experience and motivation. The jobs--and in some cases, the lives--of everyone in these groups depend on their ability to pick up deceit.
Ekman has used his findings to assist law enforcement agents--including members of the U.S. Secret Service and Federal Bureau of Investigation, Britain's Scotland Yard and the Israeli police force--in criminal investigations and antiterrorist activities. He refuses to work with politicians. "It is unlikely that judging deception from demeanor alone will ever be admissible in court," Ekman says. "But the research shows that it's possible for some people to make highly accurate judgements about lying without any special aids, such as computers."
But for those who still prefer a bit of technological assistance, there's the Verdicator--a device that, according to its 27-year-old inventor Amir Liberman, enables anyone equipped with a personal computer and a phone or microphone to catch a liar. A person's tone of voice can be just as revealing as the expression on his face. A low tone, for example, can suggest a person is lying or is stressed, while a higher pitch can mean excitement. Liberman claims the Verdicator, a $2,500 piece of software produced by Integritek Technologies in Petah Tikvah near Tel Aviv, is between 85% and 95% accurate in determining whether the person on the other end of the line is lying, an accuracy rate better than that for traditional polygraphs. "Our software knows how to size you up," Liberman boasts.
The Verdicator delivers its results by analyzing voice fluctuations that are usually inaudible to the human ear. When a person is under stress, anxiety may cause muscle tension and reduce blood flow to the vocal cords, producing a distinctive pattern of sound waves. Liberman has catalogued these patterns and programmed the Verdicator to distinguish among tones that indicate excitement, cognitive stress--the difference between what you think and what you say--and outright deceit. Once linked to a communications device and computer, the Verdicator monitors the subtle vocal tremors of your conversational partner and displays an assessment of that person's veracity on the screen. "The system can tell how nervous you are," Liberman explains. "It builds a psychological profile of what you feel and compares it to patterns associated with deception." And the Verdicator has one great advantage over the polygraph: the suspect doesn't need to know he's being tested. To be accurate, though, the Verdicator must pick up changes--which might indicate deceit--in a person's normal voice.
During the Monica Lewinsky scandal, Liberman demonstrated the system on President Clinton's famous disclaimer, "I did not have sexual relations with that woman." After analyzing an audio tape of the statement 100 times, the Verdicator showed that Clinton "was telling the truth," Liberman says, "but he had very high levels of cognitive stress, or 'guilt knowledge.' He didn't have sexual relations, but he did have something else."
Integritek will not name the law enforcement agencies, banks or financial institutions that are using the Verdicator. But company president Naaman Boury says that last year more than 500 Verdicators were sold in North and South America, Australia, Asia and Europe. The Japanese firm Atlus is marketing a consumer version of the Verdicator in Asia. "We get the best results--close to 95% accuracy--in Japan," Liberman reports. "The Japanese feel very uncomfortable when lying. We get the poorest results--nearer 85% accuracy--in Russia, where people seldom seem to say what they really feel."
In moderation, lying is a normal--even necessary--part of life. "It would be an impossible world if no one lied," Ekman says. But by the same token, it would be an intolerable world if we could never tell when someone was lying. For those lies that are morally wrong and potentially harmful, would-be lie detectors can learn a lot from looking and listening very carefully. Cheating partners, snake oil salesmen and scheming politicians, beware! The truth is out there.
With reporting by Eric Silver/Jerusalem