Picking porkies with science

Canny interviewers know what body language marks the liar - but it's not an exact science, reports JULIE MIDDLETON.

There are some indisputable facts about lying.

One: we are all accomplished liars, whether they be socially expedient white lies or pathological whoppers. It's part of the human skill set.

Two: No foolproof methods exist for catching those who tell porkies in job interviews. Our shared skill in telling lies doesn't lead to expertise in spotting them.

But we have been trying. Dunking suspected witches in medieval times proved nothing, except that humans drown in four minutes.

Also fruitless was analysis of the bumps on a person's skull (phrenology) in the 1800s or administering "truth serums" - doses of barbiturates intended to rewire the brain so lies were impossible - last century. What tended to result were streams of gibberish.

The latest: American scientists claim to have developed a lie detector which uses a super-sensitive thermal imaging camera to spot minute, stress-related heat rushes around the eyes.

American research reveals that few ordinary people get above a 60 per cent accuracy rate in lie detection when relying on visual and verbal cues - and that's when chance alone should deliver 50 per cent.

But research by American psychologists Paul Ekman and Maureen O'Sullivan found the more accurate lie detectors tended to be secret service agents - people trained to pick up small clues and cues from their environments.

There's hope, then, as long as you know what to spot.

British psychologist and body language expert Adrian Furnham says researchers make certain distinctions when investigating interview lying.

One is between attribution - the tendency to attribute only the more desirable characteristics to oneself - and denial, the suppression of the negative traits.

The other distinction is between self-deception - when people really do believe their own PR - and impression management, when interviewees waffle their way to the "right" impression.

People are better at concealment - often sins of omission - than falsification, Furnham says.

But lying lays involuntary, indelible tracks. Stress signals produced by the nervous system create a dry mouth, sweaty palms, shallow and uneven breathing, a tickly nose and throat, and blushing or blanching.

Says Furnham: "It's when behaviour noticeably alters that it's most meaningful."

But the keys to catching liars aren't necessarily all in the face, he adds.

"The further you are from the face, the nearer you are to the truth."

People are less conscious of their feet or legs, he says. Posture is more sincere than gesture. The frequency of gestures decline as lies mount.

Sudden changes in foot-tapping patterns, feet pointed towards the door in a get-me-out-of-here expression and simultaneous tight arm and foot crossing have all been taken to indicate lying.

Verbal cues of lying include:

* Slow response. Liars take longer than the truthful to answer, and hesitate more.

* Linguistic distance - talking in the abstract even when recalling incidents involving themselves.

* Slow but uneven speech. Trying to think and talk at the same time might lead to a change of pace.

* Over-eagerness to fill silences. Liars seem uncomfortable with what are often short pauses.

* Too many pitch rises. Voice pitch lifts at the end of a reply make it sound like a question. It may sound, says Furnham, like "Do you believe me now?"

Non-verbal cues include:

* Squirming and shifting in the chair.

* Too much, rather than too little, eye contact, which is part of the liar's over-compensation.

* An increase in speech errors such as stuttering, slurring and linguistic slips.

* A loss of voice resonance - it becomes flatter, less deep, and more monotonous.

* An increase in comfort gestures - touching the face and upper body, especially the nose.

This is, says Furnham, "partly because of the need to block the lie or pull it back unconsciously into the mouth, and partly because tension in the nasal cavity can lead to tickling".

* Micro-expressions or facial flickers of surprise, hurt or anger. They're often so fleeting they are missed.

Overall, says Furnham, note any mismatch between what's said and how it's said, as well as differences in apparent anxiety when certain subjects are raised.

"When the eyes, the voice and the words spoken are not in emotional synchrony, it may well be a very good sign of lying."

Watch out for forced laughs punctuating a carefully prepared line. And crocodile smiles: "It is an easy and natural expression to make voluntarily ... but most importantly, it conceals the opposite emotion - dread, fear, anxiety," says Furnham.

The same pointers apply for video interviewing, increasingly common as technology improves and companies search worldwide for talent.

But a study done at the University of Michigan using three different grades of video conferencing technology found that the better the technical quality, the more likely were lies to be spotted.

Says the researcher, Daniel Horn: "These results should give pause to those using such video in sensitive or high-stakes interactions in which detecting lies ... is important."

But all lie detection advice comes with a rider.

Stress signals are obvious in most people under pressure, whether they are lying or not. It would be a rare human who wasn't at least mildly anxious in an interview setting.

High-energy, extrovert types naturally fidget more; uncomfortable surroundings or furniture might influence posture or movement. People with uncomfortable glasses may touch their faces quite innocently.

Some people don't gesture as much as others. In some cultures it is monstrously impolite to look someone right in the eye.

Useful interpretation requires interviewers to understand what Furnham calls "base-rate behaviours" - individuals' normal interpersonal style.

This requires the sort of small-talk and unthreatening questioning that allows the job-hunter relative ease - more than the perfunctory 30 seconds of ice-breaking most interviewers generally allow.

Five to 10 minutes of easy questions at the beginning of an interview - did you get here OK, what do you think of the weather we've been having? - can help to settle people, says Furnham.

"It is too easy to mistake particular signs such as sweating and avoiding eye contact as a betrayal of anxiety, and a function of lying, when it is perfectly normal everyday behaviour for that person."

So what can you do if you suspect a lie? Think on your feet, says Furnham. Formulate a hypothesis on the cause: what's being lied about?

Test the theory by bringing up a topic in the same area and see if the body language pattern recurs.

And keep asking for detail in the way of behavioural interviewers.

Infinity Solutions human resources head Michelle McCormack says this approach seeks from job seekers a "star" - description of a situation, the task or action involved, and the results.

"The interviewer asks a series of questions to drill down on these responses until a 'star' is obtained," she says.

"This minimises the ability of the candidate to provide incorrect or inaccurate information, as they are unable to provide the specific details being requested ... they usually contradict themselves."

Furnham adds that it is hard to lie about emotion, and suggests questions such as "How did you feel about your last boss?" can lead to revealing body language.

"But there are no foolproof methods. Adults tell lies all the time.

"All interviewers can do is predict the probability of a lie, be alert to the fact and catch some of them."