Spotting a Liar by Reading Body LanguageInterpreting body language is difficult. So, straight off the bat, it is worth saying that spotting a liar is not going to be easy. Even trained professionals such as policemen and customs officers who regularly encounter people being deceptive can only spot about 50% of the lies told to them.
"Behaviour in the human being is sometimes a defence, a way of concealing motives and thoughts, as language can be a way of hiding your thoughts and preventing communication."
(American psychologist Abraham Maslow, 1908–1970)
When reading someone's hands and arms, legs and feet, or face, you must try to accumulate a congruence of body cues before making a judgement. Well, when trying to sniff out a liar, you're looking for a lack of congruence of body cues. This is because liars tend to fake some of their non-verbal communications but are not skilled enough to fake all of them. They also tend to exaggerate the ones they can fake. Lies work because the clues that give them away are extremely subtle. In fact, they are almost invisible to the untrained eye. This is because the "training course" for liars is pretty comprehensive. We are all taught to lie from an early age, predominantly for social convention. At six, we put on that fake smile for the auntie who smells of cats. Just a few years later, we're all experts at showing surprise and delight at presents as the buyer watches us unwrap. Then, we're pretending to like food we'd rather not eat to appease the cook. And, a few years after that, we're telling our boss that his suit doesn't make him look like a pimp. They're just the white lies. We'll have woven dozens of "black" ones into our lives too by then. However, the cards aren't stacked wholly in favour of the liars. There's one key point in the detectors' favour. The severity of the lie is directly proportional to the strength of the signals given off. This means that if a person is delivering, or being quizzed about, a serious lie (i.e., one leading to severe consequences if detected), he is far more likely to exhibit observable signs, particularly of the fight or flight response.
When a person is involved in serious deception, he will feel as though his mouth has suddenly become dry. As a result, his voice may waver or crack, and he will swallow more. It is a common misconception that people who do not hold eye contact are being deceptive or those who look you in the eye are telling the truth. This is not the case. Liars, con-artists and sociopaths learn very quickly to look you in the eye while being deceptive. Also, people might look away for a number of other reasons, including cultural sensitivities, social inferiority and stress. So, it's far too simplistic to say a liar won't look you in the eye.
"Experience teaches you that the man who looks you straight in the eye, particularly if he adds a firm handshake, is hiding something."
(American author Clifton Fadiman, 1904–1999)
Eye and Mouth BlockingA person who is being deceptive or who is stressed (and that "or" is important) might also engage in eye-blocking (deliberately preventing himself from seeing, usually with his hands) as he subconsciously wills himself out of the situation. In other words, he will try to escape the awkward questioning or the stressful situation by metaphorically sticking his head in the sand. This is clearly the Ostrich Effect at play. It's more common than you might think. Imagine being in a pub during an England versus Argentina match when the referee awards Argentina a penalty. From the instant the referee makes his decision, a high proportion of those around you will put their hands over their eyes. But an even higher proportion will probably put their hands over their mouths.
Mouth-blocking (covering or even just rubbing the mouth) is another activity a liar might do. Young children exhibit this behaviour most clearly. They will often cover their mouths completely with their hands after lying. It's like they're trying to keep the whopper inside. As you get older, you get more proficient at lying, but even an adult liar will give himself away by shortened versions of the mouth-block. A person who rests his chin on his hands, touching the corner of his mouth might also be performing a mouth-block. Interestingly, these traits also occur in someone who is withholding information as opposed to lying. He might think withholding information is not as serious as telling an outright porky (that would be Omissions Bias), but his subconscious won't feel the same way, and it will throw in some cues (which is quite fortunate for those trying to determine whether a person knows something or not). A liar might also touch his nose more. That's another common tell to be thrown in the mix.
Building BarriersQuite often, a person being deceptive will try to distance himself from the lie by getting away from those questioning him or by building a physical barrier between him and his accuser. Moving a cup of tea between him and the accuser is one way. But, if you're the accuser and you're sitting opposite him, he's almost certainly going to put the cup of tea between you and him. I mean, where else is he going to put it? For this reason, a smart "interrogator" will move around to test whether the cup of tea is being placed naturally for convenience or subconsciously as a barrier. I once interviewed a soldier who we suspected belonged to a banned radical group. He denied any knowledge of the group. However, when I placed some of the group's propaganda found secreted in his room on the table, he subconsciously placed the glass of water he'd been toying with between me and the leaflets. Placing the glass between him and the leaflets would have been far more natural. It was such a clear example of barricading which, added to the mix of the other traits he was displaying, it gave me added confidence he was lying. And he was.
Lying LegsLegs can be a good indicator of inner emotions, and they can add to the body-language "evidence" that someone is lying. Legs locked at the ankles or legs locked around chair legs (with the person sat as though braced for a crash) can show that an individual is withholding information. However, leg-crossing can mean other things. For example, a woman who crosses her knees and wraps one leg around the other in an ankle lock might just be showing signs of vulnerability or shyness rather than withholding information.
Lying or Stressed?The main tells outlined in this section can indicate that a person is attempting to deceive. However, they might just be indicators that the person is stressed. I have spoken to numerous soldiers over the course of my career either on matters of a disciplinary nature or during security investigations, and most of them exhibit some or all of these behaviours. Some were lying, but the majority were not. They were just experiencing stress. Why? Quite simply, they would rather not be in front of an officer being given a grilling. You might be completely innocent, but the environment makes you feel uncomfortable nonetheless. That discomfort manifests itself as stress, and stress behaviours and lying behaviours are very similar. The trick is to link the behaviours to the questions you've asked and try to isolate the subjects that are causing the observable behaviours. To do this, it might be necessary to put your subject at ease or to wait a while before questioning him. This could reduce the stress signals.
When a military is at war, putting your accused at ease is not the done thing. Experience has taught soldiers that their enemy is far less guarded about withholding information while in a state of confusion or stress. So, soldiers don't want their captors to be stress free. They want them to blurt information while they're still in "shock of capture" (as it's called). Obviously, that's no setting for reducing stress signals, which means that detecting lying signals becomes virtually impossible in someone who's just been taken prisoner of war. (What the captors are attempting is to ensure the prisoner is too flustered to do anything more complex than tell the truth.) An occasion could arise when you might find it useful to question someone while they're still flustered (e.g., questioning a recently caught shoplifter or questioning an employee who's just delivered a pitch that went against your express direction). That's fine. Just don't expect to glean too much information from that person's body language other than him being stressed to the max.
Using Body Language to Sell a LieIs it possible? Yes, but it's very difficult. Remember, you are programmed at a subconscious level to perform the cues that will give you away. A famous example of someone trying to hide their body language and failing is Richard Nixon. When the later-disgraced US president gave a well-rehearsed speech in front of the world about the reasons for the military incursions into Cambodia during the US-Vietnam War, the tone of his voice was smooth, and his body cues were all congruent with telling the truth. Well nearly. Some sharp-eyed cameraman spotted that Nixon had his fist clenched so tight his knuckles were white. Nixon was trying to keep a tight hold of his lie so no one else would detect it.
The biggest thing in your favour is not your ability to suppress the tells or deliver false ones, but the observer's inability to read them accurately. That will give you a lot of "plausible deniability" space to play in. He will never be sure from your body language alone that you're lying. You must keep your confidence in that idea.
The biggest danger you face is when someone knows just one or two body-language signals and takes them as gospel. For example, if you were to look top right just before telling your boss you're late because you ran over a cat, he might say: "That's a lie. You looked top right." As we've repeatedly stated, one tell does not a fact make. But, if your boss thinks it does, you've got quite a job on your hands to undermine his confidence (albeit unfounded confidence) in his own assessment.