Overheard in the Lunchroom: While in the office lunchroom the other day, I overheard a conversation about the hot new Fox Network show "Lie to Me". Two people were marveling over the ability of the show's main character, Dr. Cal Lightman, to know when witnesses are telling a lie. In "Lie to Me", Lightman is a world renowned expert in body language and facial expression, who helps police investigate crimes - and spots the liar every time. My lunchroom interlocutors seemed convinced that the fictional Dr. Lightman practiced the latest in real-world science and that his impressive methods are a sample of the tools available to those of us who see and assess witnesses and their credibility.
Hearing the enthusiasm of these TV viewers makes one wonder whether "Lie to Me" signals bad news for trial lawyers, in the same way that "Law & Order" changed the game. Will "Lie to Me" raise unrealistic expectations in jurors, making them imagine that they, too, can catch any witness in a lie, simply by studying their physical cues?
Two thousand years ago, a suspected liar might be tested by placing grains of rice in his mouth. After questioning, if the speaker spat out the rice and it was dry, then a dry mouth betrayed his fear - and a lie. During the Middle Ages, torture was used to extract the truth by obliging "the lying mind to croak out its secret." i Happily, modern methods are more refined - and less painful.
The polygraph machine was first developed in the early 20th Century by Harvard psychologist William Mouton Marston. ii Polygraphs typically measure heart rate, breathing and blood pressure, activity in the peripheral nervous system. These tests are not universally accepted as reliable; their accuracy is sometimes estimated as only better than a 50 – 50 chance. Typically, lie detector test results are inadmissible in court.
Beyond the familiar polygraph, police and security experts (and, occasionally, parents of teenagers) employ certain other techniques to assess whether someone might be lying. Dr. Aldert Vrij, a scientist at the University of Portsmouth, theorized that it takes more effort to create a false story than to tell the truth. Dr. Vrij wondered if suspects familiar with police interviews might be capable of masking visual behaviors associated with lying.
When he asked subjects to recall a series of events in reverse order, describing the most recent event first and working backward to the beginning of the story, the liars were more easily discovered. Asking a witness to tell his story backward imposes an additional mental stress on someone who must fabricate backwards. Dr. Vrij concluded that interviewers "paying attention to visual cues proved significantly worse at distinguishing liars from those telling the truth than those looking for speech-related cues." iii
But investigators trying to assess truthfulness also often look to visual cues like body language, including a stiff physical expression, with limited arm movement, avoidance of eye contact; and touching the face or mouth with hands, or scratching the nose or ear.
The fictional Dr. Lightman was inspired by the model of Dr. Paul Ekman, a psychologist, author and Professor at the University of California at San Francisco. Dr. Ekman's research in nonverbal communication and emotions helped earn him recognition as one of the most eminent psychologists of the 20th Century. He has identified a set of physical indicators which, for certain highly trained specialists, can help identify behavior associated with lying.
According to Paul Ekman, signals to watch for include:
- Higher voice pitch;
- Slight delay in offering false answers;
- Stiffness in body and face;
- Hand-to-face touching, especially rubbing the nose or covering the mouth;
- Flared nostrils;
- Lips thinning and tightening;
- Body takes up less space (shoulders up and elbows pulled in to the sides);
- Forehead tightened;
- Reduced eye contact;
- Heart rate increased;
- Down-turned or hidden palms.
Along with these indicators, Dr. Ekman points in particular to wrinkling of the nose and curling of the mouth as key "micro gestures" which suggest a speaker might be lying.iv One of the common "micro-expressions" used to hide emotion is a smile. If you observe someone very quickly tighten their lips (a sign of anger), but then smile, they may be, in effect, "baring their teeth". According to Dr. Ekman, a speaker may reveal:
- "Emblems": signs of emotion which, when interrupted mid-gesture, hint that the speaker is trying to suppress information;
- "Illustrations": gestures like waving the arms or pointing with a finger, which decrease because liars unconsciously limit their movements; and
- "Manipulations": personal tics like nail-biting, which mean nothing, but are often incorrectly misinterpreted as signs of a lie. v
Judging from the reaction of the two people in my lunchroom to Dr. Lightman's approach, the notion that a sharp eye can detect outward physical markers of lying feels believable and somehow fits common experience. People imagine that they (or their local sheriff) might be capable of spotting these physical gestures themselves and discovering an untruth. They "buy it".
Eckman cautions that reliance on visual cues like body language and "micro gestures" like these for lie detection is difficult, because the clues are not easy to see and can be masked by other behaviors. Savvy witnesses can manipulate the process with physical and verbal actions that can mislead the observer. Building trust in the listener by positive body language (leaning forward) and voice (using a lean, good vocal range) can counteract some of the signals of lying and make the speaker seem credible.
Researchers at the University of Pennsylvania are now studying even more exacting tools for lie detection, which track activity in the central nervous system. Dr. Ruben Gur and colleague Daniel Langleben, Ph.D. are evaluating the effectiveness of functional Magnetic Resonance Imaging (fMRI) in lie detection. The brain uses more energy in telling lies and that activity appears in different areas of the brain, and the fMRI can detect that brain activity. Scientists Gur and Langleben have found that lies show distinctive physical signs in fMRI test results, regardless of the respondent's age, race, or cultural background.vi
Estimates of the accuracy of the fMRI test in lie detection span from 76% to 90%, which represents a dramatic improvement over polygraph examination results. This has raised interest in whether fMRI might represent a real advance in objective lie detection science.vii But fMRI poses its own challenges, ranging from the obvious impracticality of having to test a subject while he lies perfectly still inside a large MRI machine, pressing a button in response to hundreds of carefully crafted questions, to concerns about the Civil Rights implications of such a process.
So, until this type of fMRI is perfected, we are left with the imperfect polygraph, human intuition, and Dr. Ekman's work. While Dr. Ekman has taken the study of nonverbal indicators of lying to a more sophisticated level, he acknowledges that there are limits to the technique, and that the detection process is very complex. He says, "We don't want jurors thinking that because they saw 'Lie to Me,' that they can tell when someone on the stand is lying." viii
Dr. Ekman and colleague Dr. Maureen O'Sullivan have spent nearly fifteen years studying people's natural ability to detect lies. "We've tested about 15,000 people in every profession you can think of – CIA, judges, lawyers. Less than one percent are any good at it. Most people are only at about the level of flipping a coin."ix In effect, Dr. Ekman believes that "most liars can fool most of the people most of the time." Professional training in the use of Dr. Ekman's techniques can improve the lie detection abilility of police or psychologists, within their own professions, to better than "flip of the coin" chances. More accurate lie detectors tend to place an emphasis on non-verbal cues, and to watch for a wider array of clues, both visual and verbal. x
While Dr. Ekman concedes that his exacting list of visual cues that reflect lying is not fool proof, his research with Dr. O'Sullivan has revealed a small class of people who possess unique abilities using such cues to identify a liar: the "Wizards".
O'Sullivan and Ekman have found fewer than fifty "Wizards", people with an exceptional, innate ability to identify a liar at a much higher accuracy rate than normal. They are equally divided by gender. They actively practice the technique of evaluating micro expression. Some report childhood trauma which might have led to sensitivity to emotional expressions. Some are attorneys. Many have spent time in the Secret Service. All are acutely aware of environmental signals. xi
The fictional Dr. Lightman certainly demonstrates this Wizard-like ability to interpret the most infinitesimal facial movement to spot a lie. It seems likely that fans of "Lie to Me" will put stock in the idea that Dr. Lightman's skill comes not from an exceptional inate "Wizard" ability, but from simple training in visual observation techniques. Ordinary jurors might indeed imagine that they have some of the instincts to detect the lies of a witness simply based on the visual cues they think they can see. If 'Lie to Me' turns out to have a strong audience and good ratings, we might indeed see more jurors in the courtroom who have unrealistic expectations of themselves, witnesses and the lawyers before them.
