Brendan I. Koerner writes for The Village Voice. Excerpt:
Q: I’ve been asked by a potential employer to take a lie-detector test. There was a fair amount of pot smoking in my distant past, and I’m worried it’ll disqualify me from the job, which I desperately need. Aren’t there ways to beat the machine?
Before we start discussing techniques for fooling Mother Tech, let Mr. Roboto play lawyer for a sec. You don’t mention who this potential employer is, but unless it’s Uncle Sam, there’s no way in Hades you can be coerced into taking the test. A 1988 federal law, the Employee Polygraph Protection Act, forbids private-sector firms from using lie detectors to screen applicants, though some unscrupulous bosses will try and bully you. (Word to the wise: Don’t cave—worse comes to worst, you’ll have a sure-thing discrimination suit to file.)
No such legal protections exist when it comes to government jobs, however, despite mounting evidence that polygraphs are about as reliable as 17th-century dunking stools. Good thing the Web teems with tips on how to ace any lie-detector test, regardless of the numerous blunt-puffing skeletons in your closet.
As fans of cheesy detective fare already know, polygraphs work by measuring the physiological reactions of testees. The theory goes that a heightened pulse and sweaty palms invariably mean a person’s not on the up-and-up. Problem is, that assumption is rooted mainly in medical folklore. Not a single study exists to support a universal correlation between lying and excessive perspiration, or a speedier heart rate. Some people are just more anxious, and will exhibit the physiological signs of deception when telling the absolute truth—especially when they’re strapped into a machine and brusquely ordered, “Tell us how many times you smoked dope. Tell us!” (For federal jobs, 15 times or more over a lifetime is usually an automatic disqualifier.)
The other great polygraph flaw is its reliance on the “control question.” This is the question a polygrapher asks in order to establish what your lie looks like on the machine. A popular one is “Have you ever driven a car after drinking?”—the assumption being that no adult imbiber’s ever been a perfect angel. But if you’re really the conscientious type, and your answer of “no” is truthful, then you’re royally screwed for the remainder of the test.