Interesting article in the New York Times magazine.
By ROBIN MARANTZ HENIG
Published: February 5, 2006

Looking for the Lie

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.