Lie-detectors are unreliable tools for ferreting out spies and have probably tarnished the reputations of thousands of innocent people, a US scientific panel has found.
Although the CIA, FBI and US investigators routinely use them, ”no spy has ever been caught using the polygraph,” George Mason University researcher Kathryn Laskey told the Washington Post.
The National Academy of Sciences study was commissioned by the Energy Department following the scandal around scientist Wen Ho Lee, who was accused, then cleared, of passing nuclear secrets to China.
Lee was wrongly told by investigators he had failed his test, to make him confess to spying, even though the machine had indicated he was telling the truth. He spent months in solitary confinement. In polygraph tests, subjects are asked questions while the
machine measures their heart rate and blood pressure to pick up signs of anxiety and tension associated with lying.
The 17-member panel found lie detectors may have some use in criminal investigations, where subjects can be asked specific questions about a crime, said the Post.
But they warned that the tests have tended to be unreliable in countering espionage, where large numbers of people are asked general questions about whether they have done anything wrong.
”Too many loyal employees may be falsely judged as deceptive, or too many major security threats could go undetected,” they said.
The tests should not be halted, because no good alternative exists, said the panel’s chairman, Carnegie Mellon University statistics and computer science professor Stephen Fienberg.
But the scientists cautioned against a false hope that the tests were truly effective, because this could allow spies who pass the tests to seriously damage national security. – Sapa-DPA