The CIA, the FBI, and other federal agencies use 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 detecting when people are lying, the Washington Post reports. 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 admit to things they might not otherwise acknowledge during an interview or interrogation. Researchers and defense attorneys say the technology is prone to 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, about 25 percent of applicants fail a polygraph exam each year.
The polygraph has emerged as a pivotal tool in the CIA’s aggressive effort to identify suspected leakers after embarrassing disclosures about government anti-terrorism tactics. 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. In settings in which large numbers of employees are screened to determine whether they are spies, the polygraph produces results that are extremely problematic, according to a comprehensive 2002 review by distinguished scientists. The study found that if polygraphs were given to a group of 10,000 people that included 10 spies, nearly 1,600 innocent people would fail the test — and two spies would pass.