There is no such thing as “typical” deceptive behavior—”nothing as obvious as Pinocchio’s growing nose.” When people tell complicated lies, they frequently pause longer and more often, and speak more slowly; but if the lie is simple, or highly polished, they tend to do the opposite. Clumsy deceivers are sometimes visibly agitated, but, over all, liars are less likely to blink, to move their hands and feet, or to make elaborate gestures—perhaps they deliberately inhibit their movements. (…)
A liar’s testimony is often more persuasive than a truthteller’s. Liars are more likely to tell a story in chronological order, whereas honest people often present accounts in an improvised jumble. Similarly, according to DePaulo and Bond, subjects who spontaneously corrected themselves, or said that there were details that they couldn’t recall, were more likely to be truthful than those who did not—though, in the real world, memory lapses arouse suspicion.
People who are afraid of being disbelieved, even when they are telling the truth, may well look more nervous than people who are lying. This is bad news for the falsely accused, especially given that influential manuals of interrogation reinforce the myth of the twitchy liar. “Criminal Interrogation and Confessions” (1986), by Fred Inbau, John Reid, and Joseph Buckley, claims that shifts in posture and nervous “grooming gestures,” such as “straightening hair” and “picking lint from clothing,” often signal lying. (…)
The federal government still performs tens of thousands of polygraph tests a year—even though an exhaustive 2003 National Academy of Sciences report concluded that research on the polygraph’s efficacy was inadequate, and that when it was used to investigate a specific incident after the fact it performed “well above chance, though well below perfection.” Polygraph advocates cite accuracy estimates of ninety per cent—which sounds impressive until you think of the people whose lives might be ruined by a machine that fails one out of ten times. The polygraph was judged thoroughly unreliable as a screening tool; its accuracy in “distinguishing actual or potential security violators from innocent test takers” was deemed “insufficient to justify reliance on its use.” And its success in criminal investigations can be credited, in no small part, to the intimidation factor. People who believe that they are in the presence of an infallible machine sometimes confess, and this is counted as an achievement of the polygraph. (According to law-enforcement lore, the police have used copy machines in much the same way: They tell a suspect to place his hand on a “truth machine”—a copier in which the paper has “LIE ” printed on it. When the photocopy emerges, it shows the suspect’s hand with “LIE ” stamped on it.)
Over the past two decades, inventors have attempted to supplant the polygraph with new technologies: voice-stress analysis; thermal imaging of the face; and, most recently and spectacularly, brain imaging. (…) Thermal imaging, an approach based on the finding that the area around the eyes can heat up when people lie. The developers of this method—Ioannis Pavlidis, James Levine, and Norman Eberhardt—published journal articles that had titles like “Seeing Through the Face of Deception” and were accompanied by dramatic thermal images. But the increased blood flow that raises the temperature around the eyes is just another mark of stress. Any law-enforcement agency that used the technique to spot potential terrorists would also pick up a lot of jangly, harmless travellers. (…)
The word “lie” is so broad that it’s hard to imagine that any test, even one that probes the brain, could detect all forms of deceit: small, polite lies; big, brazen, self-aggrandizing lies; lies to protect or enchant our children; lies that we don’t really acknowledge to ourselves as lies; complicated alibis that we spend days rehearsing. Certainly, it’s hard to imagine that all these lies will bear the identical neural signature. In their degrees of sophistication and detail, their moral weight, their emotional valence, lies are as varied as the people who tell them. As Montaigne wrote, “The reverse side of the truth has a hundred thousand shapes and no defined limits.” (…)
Nancy Kanwisher, a cognitive scientist at M.I.T., points out that the various brain regions that appear to be significantly active during lying are “famous for being activated in a wide range of different conditions—for almost any cognitive task that is more difficult than an easier task.” (…) As he put it, “Saying ‘You have activation in the anterior cingulate’ is like saying ‘You have activation in Massachusetts.’ ”
Kanwisher’s complaint suggests that fMRI technology, when used cavalierly, harks back to two pseudosciences of the eighteenth and nineteenth centuries: physiognomy and phrenology. Physiognomy held that a person’s character was manifest in his facial features; phrenology held that truth lay in the bumps on one’s skull. In 1807, Hegel observed that “the rules that we use in everyday life in interpreting facial expression are highly fallible.”
{ New Yorker | Continue reading }
