Polygraph Results Often in Question
Monday, May 1, 2006
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.
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. The agency fired a veteran officer, Mary O. McCarthy, on April 20, alleging that she had shared classified information and operational details with The Washington Post and other news organizations, a charge her lawyer disputes.
CIA officials have said that McCarthy failed more than one polygraph examination administered by the CIA, but the details surrounding those interviews remain unclear. Dozens of senior-level CIA officials have been subjected to polygraph tests as part of the inquiry, which is aimed at identifying employees who may have talked to reporters about classified programs, including providing information about the agency's network of secret prisons for terrorism suspects.
"The reason an officer at CIA was terminated was for having unauthorized contact with the media and the improper release of classified information," said Paul Gimigliano, a CIA spokesman. "Don't think in terms of a failure of a polygraph being the reason for termination -- the polygraph is one tool in an investigative process."
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.
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 a federal panel of distinguished scientists. The study found that if polygraphs were administered to a group of 10,000 people that included 10 spies, nearly 1,600 innocent people would fail the test -- and two of the spies would pass.
"Its accuracy in distinguishing actual or potential security violators from innocent test takers is insufficient to justify reliance on its use in employee security screening in federal agencies," the panel concluded.
Polygraph test results are also generally inadmissible in federal courts and in most state courts because of doubts about their reliability. Statements or admissions made by test subjects during a polygraph session, however, can often be used by prosecutors at trial, according to legal experts.
But even critics of the polygraph concede that it can help managers learn things about employees that would otherwise remain hidden. That aspect of polygraph testing lies at the heart of its continuing appeal, said Alan Zelicoff, a former scientist at Sandia National Laboratories who quit because he believed that polygraphs are unethical.