Detecting Lies

Powerline has a link to an interesting story in today's Washington Post on the alleged effectiveness of polygraphs. The Post essentially states the obvious--lie detector tests aren't always accurate; in fact, their greatest benefit may be as an intimidation tool. A nervous examinee, worried about what the polygraph is indicating, may simply break down and confess misdeeds, even if the machine failed to detect the physiological changes that are often associated with lying.

Polygraphs are back in the news because of the Mary McCarthy case. The veteran CIA officer was recently fired after she supposedly failed several polygraph exams, and admitted unauthorized contacts with reporters. The CIA is one of several federal agencies that use polygraphs for prospective and current employees; the FBI is another. In fact, virtually all of the bureau's agents and other employees--including the director--undergo a polygraph exam every five years. The FBI increased its use of lie detectors in the wake of the Robert Hanssen spy scandal; the CIA is reportedly ramping up polygraphs in an effort to catch leakers.

The Post is quick to note that two spies (Hanssen and CIA turncoat Rick Ames) passed polygraph tests, while hundreds of "innocent" people failed. What the paper fails to mention is that lie detectors are often useful in detecting inconsistencies in the way an examinee responds; while the answer may appear "truthful," the individual may tell the story a different way on the third or fourth time around, or there may be subtle changes in physiology or body language, suggesting that deception efforts may be underway. The paper also fails to report that both Hanssen and Ames were trained in counter-polygraph techniques, so the fact they passed is hardly surprising. The vast majority of examinees have not received that training, so lie detectors should be more reliabile in testing those individuals--an important distinction carefully omitted by the Post.

The Post asks whether it's fair to use a device whose reliability is only fair, at best. A better question might be: what other tool does the government have at its disposal to ferret out spies and leakers? The explosion of media leaks over the past 20 years coincided with a period when polygraph employment was not widespread. As the paper notes, President Reagan scaled back plans to increase the use of polygraphs during the 1980s. Would there have been fewer leaks if Reagan had allowed implementation of the original proposal? We can only speculate, but the "permissive" environment of the past two decades has done little to discourage the public disclosure of classified information. If the increased use of polygraphs produces a decline in leaks, then the program is probably a sound investment, even if the WaPo loses some potential sources.

A personal note: I have undergone a polygraph examination, in connection with a clearance for a special access program. I would not describe it as a pleasant experience, but it was not the stuff of third-rate spy movies, either. The examiner was courteous and completely professional; he did everything possible to put me at ease, realizing that a polygraph is inevitably a stressful experience. And, contrary to the Post account, I did not find the polygraph to be justification for some sort of grand inquisition. The examiner stuck to a basic set of questions, which were administered several times. He seemed satisfied with my responses; prehaps I've led an exceedingly dull life, or I did what you're supposed to do during a polygraph--tell the truth.

Happily, I passed my exam and was read into the program a few weeks later. BTW, a modern polygraph is nothing like its depiction on TV or in the movies. The wildly fluctuating needles have been replaced by a laptop, linked to the examinee through a set of minimally invasive "leads" that measure physiological changes. The examinee can't see the laptop screen, so he or she has no way of knowing what the device is measuring--and what it may reveal about the individual's "truthfulness."