Newswire:

If The Light Turns Red, You're A Liar

The Pentagon has a shiny new toy it wants to use to fight terrorism in Afghanistan: hand-held lie detectors. [MSNBC]

So far, the military has spent $2.5 million on 94 Preliminary Credibility Assessment Screening Systems (called PCASS, natch).

You attach cables from the machines to the hand of a suspect and ask questions. The sample questions: “Do you intend to answer my questions truthfully?” “Are the lights on in this room?” “Are you a member of the Taliban?”

If they’re telling the truth, the machine glows green. If they are lying, the machine turns red. And there’s even a yellow light if the machine can’t tell.

Soldiers could use the machine to question roadside bombing suspects, for example, or to screen local police officers.

Well, that’s how it’s supposed to work.

The lead scientist who conducted a national study into whether we should use the polygraph for national security says it’s definitely not ready for prime time. Professor Stephen E. Fienberg: “Sending these instruments into the field in Iraq and Afghanistan without serious scientific assessment, and for use by untrained personnel is a mockery of what we advocated in our report.”

Problem: These PCASS devices are even less accurate than regular polygraphs, which aren’t allowed as evidence in court because they’re not accurate enough.

Problem: The PCASS devices have no way to detect if you’re trying to fool the machine.

Problem: People who run lie-detector tests for the government usually undergo 13 weeks of training and a 6-month internship to learn how to correctly read the data. Soldiers would receive a week of training for the PCASS.

Problem: The tests the Pentagon cites about the PCASS say it’s 82-90 percent accurate.

However, they leave out the fact that they just ignored every time it lit up yellow (or “no idea if this person is lying”) If you count the inconclusive readings, the accuracy level falls to between 63 and 79 percent.

Problem: The PCASS tests were all conducted in English in South Carolina. They only tested 266 people, and they were tested in a mock crime scenario, not war. Researchers say those results could differ widely from tests done on a battlefield in Arabic on people with a different culture.

When we first read the article, we thought, “Oh no! All those poor people who are innocent who get a false-positive red light! That’s terrible!” But that’s not the real danger.

The real danger comes from the terrorist who tests “green.” Relying on the detector, the interrogator would then shift his attention elsewhere, allowing the bad guy to escape further scrutiny. Bad.

Coming soon to a police car near you? “Sir, do you know how fast you were going?” “Um… no?” RED LIGHT! RED LIGHT!

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