of top US scientists made a statement as to that a few years ago. All the evidence shows that they are not at all reliable.
Amazing our government agencies: CIA, FBI, courts, still allow them.
http://www4.nationalacademies.org/news.nsf/isbn/0309084369?OpenDocumentDate: Oct. 8, 2002
Contacts: Vanee Vines, Media Relations Officer
Andrea Durham, Media Relations Assistant
(202) 334-2138; e-mail <news@nas.edu>
FOR IMMEDIATE RELEASE
Polygraph Testing Too Flawed for Security Screening
WASHINGTON – The federal government should not rely on polygraph examinations for screening prospective or current employees to identify spies or other national-security risks because the test results are too inaccurate when used this way, says a new report from the National Academies' National Research Council.
Much of the evidence assessing the validity of polygraphs, also called "lie detectors," is based on their use in the investigation of specific, known events such as crimes. In these cases, lie-detector tests can differentiate lying from telling the truth at rates well above chance, but they are far from perfect. The report concludes that the polygraph's accuracy is not good enough for security screening for two reasons. First, accuracy is almost certainly lower when the tests are used this way rather than in the investigation of specific incidents. Second, the large groups of people being checked include only a tiny percentage of individuals who are guilty of the targeted offenses; tests that are sensitive enough to spot most violators will also mistakenly mark large numbers of innocent test takers as guilty. Tests that produce few of these types of errors, such as those currently used by several federal agencies, will not catch most major security violators – and still will incorrectly flag truthful people as deceptive.
"National security is too important to be left to such a blunt instrument," said Stephen E. Fienberg, chair of the committee that wrote the report, and professor of statistics and computer science, Carnegie Mellon University, Pittsburgh. "The polygraph's serious limitations in employee security screening underscore the need to look more broadly for effective, alternative methods."
Concerned about potential security violations at national energy laboratories, the U.S. Department of Energy asked the Research Council to conduct a study of the scientific validity and reliability of using polygraph testing to identify personnel who may jeopardize national security. Employees who work in sensitive positions at DOE labs and similar federal sites are subject to testing by law. When used this way, however, the drawbacks of current polygraph exams are abundantly clear, the report says.
more at
http://www4.nationalacademies.org/news.nsf/isbn/0309084369?OpenDocument