Lie Detectors (still) Don't Work!

Submitted by TroyM; comments by blogger jgl

Everybody knows that polygraphs don't work. With the possible exception of talk show hosts, the public, police, lawyers, and polygraph examiners.

In addition to the original article, John Daly has blogged some good material on the perception of infallibility of the forensic field.

The CIA, the FBI and other federal agencies are using polygraph machines more than ever to screen applicants and hunt for lawbreakers, even as scientists have become more certain that the equipment is ineffective in accurately detecting when people are lying. Instead, many experts say, the real utility of the polygraph machine, or "lie detector," is that many of the tens of thousands of people who are subjected to it each year believe that it works -- and thus will frequently admit to things they might not otherwise acknowledge during an interview or interrogation. Many researchers and defense attorneys say the technology is prone to a high number of false results that have stalled or derailed hundreds of careers and have prevented many qualified applicants from joining the fight against terrorism. At the FBI, for example, about 25 percent of applicants fail a polygraph exam each year, according to the bureau's security director. In the popular mind, fueled by Hollywood representations, polygraphs are lie-detection machines that can peer inside people's heads to determine whether they are telling the truth. The scientific reality is far different: The machines measure various physiological changes, including in blood pressure and heart rate, to determine when subjects are getting anxious, based on the idea that deception involves an element of anxiety. But because an emotion such as anxiety can be triggered by many factors other than lying, experts worry that the tests can overlook smooth-talking liars while pointing a finger at innocent people who just happen to be rattled.

25%! 25%! Somebody warn Maury Povich! I have a chip on my shoulder over this as I've had my career negatively altered because of this crap. I particularly like how they say the real utility is that people "believe" it works. Using this thing on applicants for forensic scientist positions is like placing a 40-year-old cynic on Santa's lap. (or something like that).