Polygraphs and Phrenology.

[Matthew X]

Lie detectors can be fooled
January 17, 2003 Lie detectors can work in specific cases, but are of little use in general screening, a study has found.
After interviewing polygraph experts at the CIA, FBI and other agencies, a panel at the National Academy of Sciences in America found that it is possible to fool a lie detector, especially if the test is conducted to screen for general criminal or spy activity and not for some specific act.
The committee decided, that based on their study results, polygraphs cannot be relied on for mass screenings of employees because they may produce false results or can be fooled by someone trained to do so.
Better detection system needed
Thousands of polygraph tests are carried out each year on job applicants and employees, and there are inevitable disputes.
The panel conducted the study by visiting polygraph facilities at several government agencies and examining large numbers of reports and published papers, attempting to understand both sides in the debate on polygraph accuracy.
Their conclusion, tabled in a report entitled The Polygraph and Lie Detection (2002), was that although polygraphs can sometimes work, a better system is needed.
They found that in untrained employees, screening for a specific incident, a polygraph test can discriminate lies from truth telling at rates well above chance, although well below 100%.
The report notes that sometimes a person may appear to be lying on a polygraph when in fact he or she is anxious.
The lie detector can also 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.
Other security relaxed
The over-reliance on polygraph tests for screening can create a false sense of security that may lead to less vigilance or the relaxation of other methods of ensuring security, the committee found. – (Health24)
http://www.health24.co.za/news.asp?action=art&SubContentTypeId=0&ContentID=20564