Using Body Language To Spot Terrorists

Can airport security personnel be trained to spot the bad guys from behavioral clues?  The science journal, Nature, casts a skeptical eye.   Of particular interest to me is this passage:

Most credibility-assessment researchers agree that humans are demonstrably poor at face-to-face lie detection. SPOT traces its intellectual roots to the small group of researchers who disagree — perhaps the most notable being Paul Ekman, now an emeritus professor of psychology at the University of California Medical School in San Francisco. In the 1970s, Ekman co-developed the ‘facial action coding system’ for analysing human facial expressions, and has since turned it into a methodology for teaching people how to link those expressions to a variety of hidden emotions, including an intent to deceive. He puts particular emphasis on ‘microfacial’ expressions such as a tensing of the lips or the raising of the brow — movements that might last just a fraction of a second, but which might represent attempts to hide a subject’s true feelings. Ekman claims that a properly trained observer using these facial cues alone can detect deception with 70% accuracy — and can raise that figure to almost 100% accuracy by also taking into account gestures and body movements. Ekman says he has taught about one thousand TSA screeners and continues to consult on the programme.

Ekman’s work has brought him cultural acclaim, ranging from a profile in bestselling book Blink — by Malcolm Gladwell, a staff writer for The New Yorker magazine — to a fictionalized TV show based on his work, called Lie to Me. But scientists have generally given him a chillier reception. His critics argue that most of his peer-reviewed studies on microexpressions were published decades ago, and much of his more recent writing on the subject has not been peer reviewed. Ekman maintains that this publishing strategy is deliberate — that he no longer publishes all of the details of his work in the peer-reviewed literature because, he says, those papers are closely followed by scientists in countries such as Syria, Iran and China, which the United States views as a potential threat.

I’m a huge fan of Dr.  Ekman’s work, in fact I recommended one of his books in a recent post.  His early work, which is extensively peer-reviewed, is groundbreaking.  I have to admit, though, that the fact that he is no longer submitting his research to peer review bothers me.    It seems to me that this isn’t the way that science is supposed to work, and it invites just the sort of skepticism he’s apparently receiving.   

I also find it strange that Dr. Ekman is behind the SPOT program.   The article makes it seem as if there’s a hidden army of trained observers watching people in airports and attempting to tell from their behavior whether they have any nefarious goal.    But Ekman himself, in his earlier books, points out that there is no non-verbal indicator of deception.  What the observer is seeing, if he sees anything at all, is signs of stress.   Now  who would expect to find stressed-out people at an airport?

Don’t get me wrong.  Ekman’s techniques can be spectacularly useful in spotting lies.  But you  have to be able to observe a person for a period of time.  It helps tremendously if you can establish a baseline for a person’s behavior ahead of time so that you can see changes.   The ability to question that person is also very important.  

A trained observer certainly could pick out people who seem overly stressed compared to the average passenger, but what you’ll end up with is a huge number of false positives.   You’ll catch a lot of people who are late for their flights, afraid of flying, have oddball nervous tics, and you’ll miss a lot of people who are real bad guys, but just relaxed about it.   Using behavioral analysts in the way the article seems to suggests is like using a drift net to catch a minnow.  You’ll catch mostly fish you don’t want, while the fish you do want swims through.

In my opinion, the place to put trained observers would be at the entry to the security line.  These people would ask everybody questions about where they’re going, why they’re travelling, whom they’re meeting.   This would give them the opportunity to see changes in behavior and to vary the context of their observations.  I’m told that Israel already does something like this.  

Remember, though, that even a system like Israel’s wouldn’t be foolproof, especially if applied on an American scale.   Also, it would be incredibly intrusive.  Would Americans go for it?  I’m not so sure.  

I hope that there’s more to the SPOT program than describes in the Nature article.   For now,  it sounds like yet another multi-million dollar boondoggle.

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