In the ‘90s, psychologist Paul Ekman leapt to fame with his theory of "microexpressions"-the idea that when we lie brief, subconscious flashes of emotion register on our face to reveal our true feelings. People trained to pick up on these cues, Ekman said, can root out the truth with astonishing accuracy. His idea inspired a $1 billion TSA program and the TV show Lie to Me.
There's just one problem. There's no evidence that Ekman's theory has any basis. "It's hokum," says Yale psychologist Charles Morgan III. While something like the microexpressions that Ekman described do exist, truth-tellers exhibit them as well as liars. "There is no clue, no behavior, that always means that someone is lying, and never means something else," says Bella DePaulo, a psychologist at the University of California, Santa Barbara who studies lying (and fellow PT blogger). "All of these behaviors are just hints."
So can science help us unmask deception? Yes. But the key is not just to observe a suspected liar but to ask them the right kind of questions. Making up a story and keeping the details straight require more mental horsepower than just telling the truth. Researchers have found that if interrogators can place an extra "cognitive load" on a liar's intellect they'll likely push it to breaking point and cause the story to fall apart.
Dutch psychologist Aldert Vrij has tested several ways to accomplish this. In one experiment, he asked pairs of subjects to either go eat lunch together in a restaurant or to simply lie and say that they had. Vrij found that when it came to the kinds of questions that they probably expected to face -- "what did you do in the restaurant?" -- the liars were able to come up with such convincing stories that it was impossible to tell the two groups apart. But when he forced them to respond on the fly to unexpected questions, such as queries about spatial layout ("In relation to where you sat, where were the closest diners?''), the liars gave up the game 80 percent of the time.
So if you want to get the truth, sit your suspected liar down for a chat and lay some cognitive load on them. Here are four proven techniques based on experiments that Vrij and others have conducted.