October 08, 2002 11:06 AM ET
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By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Lie detectors may sometimes work in specific cases with specific questions, but they are of little use in general screening, for government employment for example, an independent panel said on Tuesday.
After interviewing polygraph experts at the CIA, FBI and other agencies, the panel of the National Academy of Sciences determined that it is possible to fool a lie detector, especially if the subject is being screened for general criminal or spy activity and not for some specific act.
The academy committee, appointed at the request of the Department of Energy, decided that polygraphs cannot be relied on for mass screening of federal employees because they can falsely suggest an honest employee is lying and can be fooled by someone who is trained to do so.
"The U.S. federal government, through a variety of agencies, carries out thousands of polygraph tests each year on job applicants and current employees, and there are inevitable disputes that are sometimes highly publicized when someone 'fails' a polygraph test," the panel, made up of professionals who have never worked with lie detectors, wrote in its report.
"Over 19 months, the committee held a series of meetings, visited polygraph facilities at several government agencies, and examined large numbers of reports and published papers," it added. "We attempted to listen carefully to people representing both sides in the debate on polygraph accuracy, and we then stepped back and reviewed the evidence ourselves."
Sometimes polygraphs can work, they decided -- although something better is clearly needed.
"We conclude that in populations of examinees such as those represented in the polygraph research literature, untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection."
But the lie detector can be fooled by someone who has training -- which, in the case of government agencies, would be precisely the people they are trying to screen out.
"Certain countermeasures apparently can, under some laboratory conditions, enable a deceptive individual to appear nondeceptive and avoid detection by an examiner," the report reads.
"Overconfidence in polygraph screening can create a false sense of security among policy makers, employees in sensitive positions, and the general public that may in turn lead to inappropriate relaxation of other methods of ensuring security," it adds.
"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 report noted that sometimes a person appears to be lying on a polygraph when in fact he or she is anxious -- especially if that person is from a "socially stigmatized" group.