If I had a dime for every time I’ve heard some prosecutor or detective or lawyer tell us that someone is a suspect for a particular crime because he failed a lie detector test, I’d be rich.
But the truth is, according to a panel appointed by National Research Council, a branch of the National Academy of Sciences, lie detector tests are worthless. Actually, it’s worse than that. They are worse than worthless.
Just how useless are they? If you took a sample company or organization of 10,000 employees, of which 10 were spies or saboteurs, and you required every one of the them to take a lie-detector test, you would have 1,606 suspects.
That narrows it down considerably.
Two of the 10 spies will have escaped detection completely. There is no way to distinguish the 8 remaining genuine spies from the 1,598 innocent employees. Among the 2 would be the infamous mole Aldrich Ames who passed twice.
This study did not take into account the fact that when evil corporations or governments realize that all employees are being screened with a polygraph, they can actually do their own screening and train their spies to pass the polygraph.
The “lie detector”, of course, doesn’t actually detect lies. It records various bodily functions like respiration, blood pressure, and sweating. The “expert” polygraph administrator (like an “expert” witch doctor) calibrates the responses by comparing the results to those obtained from known factual truths.
As any amateur would guess, it is quite possible for a nervous, upset, or annoyed employee to “fail” the test simply because he is nervous, upset, or annoyed, as I would be if my employer demanded that I participate in this exercise of quackery.
There is no such thing as a lie detector. Polygraph examinations don’t work. Forget about it.
In Fort Jackson, N.C., your Department of Defense has a “Polygraph Institute”, where expensive and useless research is conducted into this joke.
I’ll bet you’d be really upset if those dollars ended up going to welfare mothers instead. The army would probably argue that some day the lie detector might work. As might the welfare mother, but I think her odds are better.
I believe the police understand that lie-detectors don’t work. They certainly know that you can’t use the results of a lie-detector test in court. So why do it? It seems obvious: to intimidate suspects. It is not all that unusual in cases of wrongful convictions to find that the police actually told the suspect that he might as well come clean because the lie-detector showed that he was lying.
It also seems likely that some suspects will be spooked enough by the process to simply confess.
And we also know that some suspects will actually believe the lie-detector over their own memory. They will actually make a false confession.
2011-06-06