Looking for the Lie

February 5, 2006
Looking for the Lie
By ROBIN MARANTZ HENIG
Liars always look to the left, several friends say; liars always cover their mouths, says a man sitting next to me on a plane. Beliefs about how lying looks are plentiful and often contradictory: depending on whom you choose to believe, liars can be detected because they fidget a lot, hold very still, cross their legs, cross their arms, look up, look down, make eye contact or fail to make eye contact. Freud thought anyone could spot deception by paying close enough attention, since the liar, he wrote, "chatters with his finger-tips; betrayal oozes out of him at every pore." Nietzsche wrote that "the mouth may lie, but the face it makes nonetheless tells the truth."
This idea is still with us, the notion that liars are easy to spot. Just last month, Charles Bond, a psychologist at Texas Christian University, reported that among 2,520 adults surveyed in 63 countries, more than 70 percent believe that liars tend to avert their gazes. The majority also believe that liars squirm, stutter, touch or scratch themselves or tell longer stories than usual. The liar stereotype exists in just about every culture, Bond wrote, and its persistence "would be less puzzling if we had more reason to imagine that it was true." What is true, instead, is that there are as many ways to lie as there are liars; there's no such thing as a dead giveaway.
Most people think they're good at spotting liars, but studies show otherwise. A very small minority of people, probably fewer than 5 percent, seem to have some innate ability to sniff out deception with accuracy. But in general, even professional lie-catchers, like judges and customs officials, perform, when tested, at a level not much better than chance. In other words, even the experts would have been right almost as often if they had just flipped a coin.
In the middle of the war on terrorism, the federal government is not willing to settle for 50-50 odds. "Credibility assessment" is the new catch phrase, which emerged at about the same time as "red-level alert" and "homeland security." Unfortunately, most of the devices now available, like the polygraph, detect not the lie but anxiety about the lie. The polygraph measures physiological responses to stress, like increases in blood pressure, respiration rate and electrodermal skin response. So it can miss the most dangerous liars: the ones who don't care that they're lying, don't know that they're lying or have been trained to lie. It can also miss liars with nothing to lose if they're detected, the true believers willing to die for the cause.
Responding to federal research incentives, a handful of scientists are building a cognitive theory of deception to show what lying looks like — on a liar's face, in a liar's demeanor and, most important, in a liar's brain. The ultimate goal is a foolproof technology for deception detection: a brain signature of lying, something as visible and unambiguous as Pinocchio's nose.
Deception is a complex thing, evanescent and difficult to pin down; it's no accident that the poets describe it with diaphanous imagery like "tangled web" and "tissue of lies." But the federal push for a new device for credibility assessment leaves little room for complexity; the government is looking for a blunt instrument, a way to pick out black and white from among the duplicitous grays.
Nearly a century ago the modern polygraph started out as a machine in search of an application; it hung around for lack of anything better. But the polygraph has been mired in controversy for years, with no strong scientific theory to adequately explain why, or even whether, it works. If the premature introduction of a new machine is to be avoided this time around, the first step is to do something that was never done with the polygraph, to develop a theory of the neurobiology of deception. Two strands of scientific work are currently involved in this effort: brain mapping, which uses the 21st century's most sophisticated techniques for visualizing patterns of brain metabolism and electrical activity; and face reading, which uses tools that are positively prehistoric, the same two eyes used by our primate ancestors to spot a liar.
As these two strands, the ancient and the futuristic, contribute to a new generation of lie detectors, the challenge will be twofold: to resist pressure to introduce new technologies before they are adequately tested and to fight the overzealous use of these technologies in places where they do not belong — to keep inviolable that most private preserve of our ordinary lives, the place inside everyone's head where secrets reside.
The Five-of-Clubs Lie
The English language has 112 words for deception, according to one count, each with a different shade of meaning: collusion, fakery, malingering, self-deception, confabulation, prevarication, exaggeration, denial. Lies can be verbal or nonverbal, kindhearted or self-serving, devious or baldfaced; they can be lies of omission or lies of commission; they can be lies that undermine national security or lies that make a child feel better. And each type might involve a unique neural pathway.
To develop a theory of deception requires parsing the subject into its most basic components so it can be studied one element at a time. That's what Daniel Langleben has been doing at the University of Pennsylvania. Langleben, a psychiatrist, started an experiment on deception in 2000 with a simple design: a spontaneous yes-no lie using a deck of playing cards. His research involved taking brain images with a functional-M.R.I. scanner, a contraption not much bigger than a kayak but weighing 10 tons. Unlike a traditional M.R.I., which provides a picture of the brain's anatomy, the functional M.R.I. shows the brain in action. It takes a reading, every two to three seconds, of how much oxygen is being used throughout the brain, and that information is superimposed on an anatomical brain map to determine which regions are most active while performing a particular task.
There's very little about being in a functional-M.R.I. scanner that is natural: you are flat on your back, absolutely still, with your head immobilized by pillows and straps. The scanner makes a dreadful din, which headphones barely muffle. If you're part of an experiment, you might be given a device with buttons to press for "yes" or "no" and another device with a single panic button. Not only is the physical setup unnatural, but in most deception studies the experimental design is unnatural, too. It is difficult to replicate the real-world conditions of lying — the relationship between liar and target, the urgency not to get caught — in a functional-M.R.I. lab, or in any other kind of lab. But as an early step in mapping the lying brain, such artificiality has to suffice.
In Langleben's first deception study at Penn, the subjects were told at the beginning of the experiment to lie about a particular playing card, the five of clubs. To be sure the card carried no emotional weight, Langleben screened out compulsive gamblers from the group. One at a time, the subjects lay motionless in the scanner, watched pictures of playing cards flash onto a screen and pressed a button indicating whether they had that card or not. When an image of a card they didn't have came up, the subjects, as they had been instructed, told the truth and pressed "no." But when an image of the five of clubs came up, they also pressed "no," even though the card was in their pockets. That is, whenever they saw the five of clubs, they lied.
According to Langleben, certain regions of the brain were more active on average when his 18 subjects were lying than when they were telling the truth. Lying was associated with increased activity in several areas of the cortex, including the anterior cingulate cortex and the superior frontal gyrus. "We didn't have a map of deception in the brain — we still don't — so we didn't know exactly what this meant," Langleben said. "But that wasn't the question we were asking at the time in any case. What we were asking with that first experiment was, 'Can the difference in brain activity between lie and truth be detected by functional M.R.I.?' Our study showed that it can." He said that the prefrontal cortex — the reasoning part of the brain — was generally more aroused during lying than during truth-telling, an indication that it took more cognitive work to lie.
Brain mappers are just beginning to figure out how different parts of the brain function. The function of one region found to be activated in the five-of-clubs experiment, the anterior cingulate cortex, is still the subject of some debate; it is thought, among other things, to help a person choose between two conflicting responses, which makes it a logical place to look for a signature of deception. This region is also activated during the Stroop task, in which a series of words are written in different colors and the subject must respond with what color the ink is, disregarding the word itself. This is harder than it sounds, at least when the written word is a color word that is different from the ink it is written in. If the word "red" is written in blue, for instance, a lot of people say "red" instead of "blue." Telling a spontaneous lie is similar to the Stroop task in that it involves holding two things in mind simultaneously — in this case, the truth and the lie — and making a choice about which one to apply.
Langleben performed his card experiment again in 2003, with a few refinements, including giving his subjects the choice of two cards to lie about and whether to lie at all. This second study found activation in some of the same regions as the first, establishing a pattern of deception-related activity in particular parts of the cortex: one in the front, two on the sides and two in the back. The finding in the back, the parietal cortex, intrigued Langleben.
"At first I thought the parietal finding was a fluke," he said. The parietal cortex is usually activated during arousal of various kinds. It is also involved in the manifestation of thoughts as physical changes, like goose bumps that erupt when you're afraid, or sweating that increases when you lie. The connection to sweating interested Langleben, since sweating is also one of the polygraph's hallmark measurements. He looked at existing studies of this response, and in all of them he found activity that could be traced back to the parietal lobe. Until Langleben's observation of its connection to brain changes, the sweat response (which the polygraph measures with sensors on the palm or fingertips) had been thought to be a purely "downstream" change, a secondary effect caused not by the lie itself but by the consequences of lying: guilt, anxiety, fear or the excess positive emotion one researcher calls "duping delight." But Langleben's findings indicated that it might have a corollary "upstream," in the central nervous system. This meant that at least one polygraph measurement might have a signature right at the source of the lie, the brain itself.
So there it was: the first intimation of a Pinocchio response.
The parietal-cortex finding, while speculative, is "interesting to pay attention to because of its relationship to the polygraph," Langleben said. "In this way, we might not have to cancel the polygraph. We may be able to put it on firm neuroscience footing."
One Lie Zone or Many?
Over at Harvard, Stephen Kosslyn, a psychologist, was looking at the map Langleben was starting to build and found himself troubled by the connection between deception and the anterior cingulate cortex. "Yes, it lights up during spontaneous lying," Kosslyn said, but it also lights up during other tasks, like the Stroop task, that have nothing to do with deception. "So it couldn't be the lie zone." Deception "is a huge, multidimensional space," he said, "in which every combination of things matters." Kosslyn began by thinking about the different dimensions, the various ways that lies differ from one another in terms of how they are produced. Is the lie about you, or about someone else? Is it about something you did yesterday or something your friend plans to do tomorrow? Do you feel strongly about the lie? Are there serious consequences to getting caught? Each type of lie might lead to activation of particular parts of the brain, since each type involves its own set of neural processes.
He decided to compare the brain tracings for lies that are spontaneous, like those in Langleben's study, with those that are rehearsed. A spontaneous lie comes when a mother asks her teenage son, "Did you do your math homework?" A rehearsed lie comes when she asks him, "Why are you coming home an hour past your curfew?" The question about the homework probably surprises him, and he has to lie on the fly. The question about the curfew was probably one he had been anticipating, and concocting an answer to, for most of the previous hour.
Kosslyn's working hypothesis was that different brain networks are used during spontaneous lying than are used during truth-telling or the telling of a memorized lie. Spontaneous lying requires the liar not only to generate the lie and keep the lie in mind but also to keep in mind what the truth is, to avoid revealing it by mistake. In contrast, Kosslyn said, a rehearsed lie requires only that an individual retrieve the lie from memory, since the work of establishing a credible lie has already been done.
To help his subjects generate meaningful lies to memorize, Kosslyn asked them to provide details about one notable work experience and one vacation experience. Then he helped them construct what he called an "alternative-reality scenario" about one of them. (The other experience he held in reserve as the basis for his subject's unrehearsed spontaneous lies.) If the experience was a vacation in Miami, for instance, Kosslyn changed it to San Diego; if the person had gone there to visit a sister, he changed it to a visit to Uncle Sol. Kosslyn had the participants practice the false scenario for a few hours, and then he put them into a scanner at Harvard's functional-M.R.I. facility. There were 10 subjects altogether, all in their 20's.
As he predicted, Kosslyn found that as far as the brain was concerned, spontaneous and rehearsed lies were two different things. They both involved memory processing, but of different kinds of memories, which in turn activated different regions of the cortex: one part of the frontal lobe (involved in working memory) for the spontaneous lie; a different part in the right anterior frontal cortex (involved in retrieving episodic memory) for the lie that was rehearsed. That's not much of a map yet, but it is a cumulative movement toward a theory of deception: that lying involves different cognitive work than truth-telling and that it activates several regions in the cerebral cortex that are also activated during certain memory and thinking tasks.
Even as these small bits of data emerge through functional-M.R.I. imagery, however, Kosslyn remains skeptical about the brain-mapping enterprise as a whole. "If I'm right, and deception turns out to be not just one thing, we need to start pulling the bird apart by its joints and looking at the underlying systems involved," he said. A true understanding of deception requires a fuller knowledge of functions like memory, perception and visual imagery, he said, aspects of neuroscience investigations not directly related to deception at all.
In Kosslyn's view, brain mapping and lie detection are two different things. The first is an academic exercise that might reveal some basic information about how the brain works, not only during lying but also during other high-level tasks; it uses whatever technology is available in the sophisticated neurophysiology lab. The second is a real-world enterprise, best accomplished not necessarily by using elaborate instruments but by encouraging people "to use their two eyes and brains." Searching for a "lie zone" of the brain as a counterterrorism strategy, he said, is like trying to get to the moon by climbing a tree. It feels as if you're getting somewhere because you're moving higher and higher. But then you get to the top of the tree, and there's nowhere else to go, and the moon is still hundreds of thousands of miles away. Better to have stayed on the ground and really figured out the problem before setting off on a path that looks like progress but is really nothing more than motion. Better, in this case, to discover what deception looks like in the brain by breaking it down into progressively smaller elements, no matter how artificial the setup and how tedious the process, before introducing a lie-detection device that doesn't really get you where you want to go.
Your Brain Waves Know You're a Liar
Even the most enthusiastic brain mappers probably agree with one aspect of Kosslyn's skeptical analysis: a true brain map of lying is, at best, elusive. Part of the difficulty comes from the technology itself. In the world of brain mapping, a functional-M.R.I. scan paints a picture that is broad and, in its way, lumbering. It can indicate which region of the brain is active, but it can take a reading no more frequently than once every two seconds.
For a more refined picture of cognitive change from one instant to the next, scientists have turned to the electroencephalogram, which detects neural impulses on the scale of milliseconds. But while EEG's might be ideal to answer "when" questions about brain activity, they are not so good at answering questions about "where." Most EEG's use 10 or 12 electrodes attached by a tacky glue at scattered spots on the scalp, which record electrical impulses firing from the brain as a whole. They give little indication of which region is doing the firing.
That's why deception researchers use a refined version of the ordinary EEG, which increases the number of electrodes from 12 to 128. These 128 electrodes, each the size of a typewriter key, are studded around a stretchy mesh cap. Using the cap, investigators can trace where electrical impulses are coming from when a person lies.
The cap is unwieldy and uncomfortable — definitely not ready yet for the world outside the laboratory. Jennifer Vendemia, a psychologist at the University of South Carolina, has been using the cap since 2000, when she began studying deception by looking at a particular class of brain wave known as E.R.P., for event-related potential. The E.R.P. wave represents electrical activity in response to a stimulus, usually 300 or 400 milliseconds after the stimulus is shown. It can be a sign that high-level cognitive processes, like paying attention and retrieving memories, are taking place.
Vendemia has studied deception and E.R.P. waves in 626 undergraduates. She outfits them with the electrode cap and a plastic barbershop cape, which is necessary because, in order to maintain an electrical circuit, each of the 128 electrodes has to be thoroughly soaked. The cap is sopping wet when she puts it on her subjects, and during the experiment Vendemia occasionally comes into the room with a squirter and soaks it down some more.
Vendemia presented her subjects with a series of true-false statements, like "The grass is green" and "A snake has 13 legs," which they were instructed to answer either truthfully or deceptively, depending on which color the statement was written in. The subjects took a longer time — up to 200 milliseconds longer, on average — to lie than to tell the truth. They revealed a change in certain E.R.P. waves while they were lying, especially in the regions of the brain that the functional-M.R.I. scanners also focused on as possible lie zones: the parietal and medial regions of the brain, along the top and middle of the head.
"E.R.P. has the advantage of being a little more portable, and substantially less expensive, than M.R.I.," Vendemia said. "But E.R.P. cannot do some of the things that functional M.R.I. can do. If you're trying to model the brain, you really need both techniques."
One thing E.R.P. might eventually be able to do is predict whether someone intends to lie — even before he or she has made a decision about it. This brings us into sci-fi territory, into the realm of mind reading. When Vendemia has a subject in an E.R.P. cap, she can detect the first brain-wave changes within 240 to 260 milliseconds after a true-false statement appears on a computer screen. But these changes are an indication of intention, not action; it can take 400 to 600 milliseconds for a person to decide whether to respond with "true" or "false." "With E.R.P., I've taken away your right to make a decision about your response," Vendemia said. "It's the ultimate invasion." If someone knows before you do what your brain is indicating as your intention, is there any room left, in that window of a few hundred milliseconds, for the exercise of free will? Or have you already been labeled a liar by your spontaneous brain waves, without your having a chance to override them and choose a different path?
Lies make secrets possible; they let us carve out a private territory that no one, not even those closest to us, can enter without our permission. Without lies, there can be no such sanctuary, no interior life that is completely and inviolably ours. Do we want to allow anyone, whether a government interrogator or a beloved spouse, unfettered access to that interior life?
How Lies Leak Into the Open
Even a practiced lie-catcher like Paul Ekman recognizes that lying is a matter of privacy. "I don't use my ability to spot lies in my personal life," said Ekman, emeritus professor of psychology at the University of California, San Francisco. If his wife or two grown children want to lie to him, he said, that's their business: "They haven't given me the right to call them on their lies."
In his book "Telling Lies," Ekman underscored this point. His Facial Action Coding System, a precise categorization of the 10,000 or so expressions that are created by various combinations of 43 independent muscles in the face, allows him to do the same kind of mind reading that Vendemia can do with her E.R.P. cap. Facial expressions are hard-wired into the brain, according to Ekman, and can erupt without an individual's awareness about 200 milliseconds after a stimulus. Much like E.R.P. waves, then, a facial expression can give away your feelings before you are even aware of them, before you have made a conscious decision about whether to lie about those feelings or not. "Detecting clues to deceit is a presumption," Ekman wrote. "It takes without permission, despite the other person's wishes."
But in many situations, it's important to know who's lying to you, whether the liar wants you to or not. And for those times, Ekman said, his system of lie detection can be taught to anyone, with an accuracy rate of more than 95 percent. His holistic perspective is almost the polar opposite of brain mappers like Langleben's and Vendemia's: instead of focusing on the liar's neurons, Ekman takes a long, hard look at the liar's face.
The Facial Action Coding System is the key to Ekman's strategy. Basic emotions lead to characteristic facial expressions, which only a handful of really good liars manage to conceal. Part of lying is putting on a false face that's consistent with the lie. But even practiced liars, according to Ekman, may not always be able to control the "leakage" of their true feelings, which flit across the face in microexpressions that last less than half a second. These microexpressions indicate an incongruity between the liar's words and his emotions. "It doesn't mean he's lying necessarily," Ekman said. "It's what I call a 'hot spot,' a point of discontinuity that deserves investigation."
Ekman teaches police investigators, embassy officials and others how to spot liars, including how to read these microexpressions. He begins by showing photos of faces in apparently neutral poses. In each face, a microexpression appears for 40 milliseconds, and the trainee has to press a button to indicate which emotion was in that microexpression: fear, anger, surprise, happiness, sadness, contempt or disgust. When I took the pretest to measure my innate lie-detecting capabilities, I could see the microexpressions in about 70 percent of the examples. But after about 15 minutes of training, I improved. The training session let me stop the action if I missed a question, since Ekman's idea is that if you know what you're looking for — and the microexpressions, when frozen, are vivid and easy to name — you can spot them even when they flash by in an instant. In the post-training test, I scored an 86 percent.
In addition to microexpressions, Ekman said, certain aspects of a person's demeanor can indicate whether he is lying. Voice, hand movements, posture, speech patterns: when these vary from how the person usually speaks or gesticulates, or when they don't fit the situation, that's another hot spot to explore. Word choices often change with lying, too, with the speaker using "distancing language," like fewer first-person pronouns and more in the third person. Also common are what Ekman calls "verbal hedges," which liars might use to buy time as they figure out what they want to say. To illustrate a verbal hedge, Ekman pointed to one of the many cartoons he uses in his workshops: a shark standing in a courtroom, looking up at the judge and saying, "Define 'frenzy."'
Ekman enjoys using these insights to unmask the lies of public figures (though he has a rule that prohibits him from commenting on any elected official currently in office, no matter how tempting a target). At his home in the Oakland Hills, he has a videotape library of some of the most notable lies of recent history, and he showed me how to watch one when I visited last fall. It was from a presidential news conference in early 1998, during the first days of the Monica Lewinsky scandal. Ekman smiled as he watched it; he knows this clip well. "I want you to listen to me," President Bill Clinton was saying, shaking his forefinger like a schoolmarm. "I did not have sexual relations with that woman."
There it was: the president's "distancing language," calling Lewinsky "that woman," and an almost imperceptible softening of his voice at the end of the sentence. When this news conference was originally broadcast, Ekman said, "everyone I had ever trained from all over the country called me and said: 'Did you see the president? He's lying."'