Thursday, April 10, 2008

New Weapon On Terrorism Hand-held Lie Detector

Move over M16 the U.S. Army soldiers in Afghanistan have a new weapon to fight terrorism, the lie detector. Starting this month U.S. Army soldiers in Afghanistan will be issued hand-held lie detectors pushing the debate over accuracy of the polygraph to the battlefront.

According to the soldiers will be issued the new device, known by the acronym PCASS, for Preliminary Credibility Assessment Screening System. Which uses a commercial TDS Ranger hand-held personal digital assistant with three wires connected to sensors attached to the hand.

The Defense Department says the portable device isn't perfect, but is accurate enough to save American lives by screening local police officers, interpreters and allied forces for access to U.S. military bases, and by helping narrow the list of suspects after a roadside bombing.

“We're not promising perfection — we've been very careful in that,” said Donald Krapohl, special assistant to the director at the Defense Academy for Credibility Assessment, the midwife for the new device. “What we are promising is that, if it's properly used, it will improve over what they are currently doing.”

At least one prominent scientist says the lie detector will actually put U.S. soldiers in harm's way, because they will put too much faith in a technology that is unreliable.

"I don't understand how anybody could think that this is ready for deployment," said statistics professor Stephen E. Fienberg, who headed a 2003 study by the National Academy of Sciences that found insufficient scientific evidence to support using polygraphs for national security.

How it all works

An interpreter will ask a series of 20 or so questions in Persian, Arabic or whichever language is needed. Intermingled between the actual questions will be some test questions "Are the lights on in this room?", "Do you intend to answer my questions truthfully?", "is the sun shining?" "Are you a member of the Taliban?" ect. The operator will punch in each answer and, after a delay of a minute or so for processing, the screen will display the results: "Green," if it thinks the person has told the truth, "Red" for deception, and "Yellow" if it can't decide.

The PCASS uses two electrodes to attempt to measure stress through changes in electrical conductivity of the skin. It also gauges cardiovascular activity through with a pulse oximeter clipped to a fingertip. Unlike the polygraph, the PCASS does not measure changes in the rate of breathing, and it has no way to detect countermeasures, or efforts to fool the machine, such as by making unusual movements.


Much debate has been made over the device’s accuracy therefore questioning its usefulness and effectiveness.

The Pentagon says the PCASS is 82 to 90 percent accurate. But Pentagon studies obtained by show a more complicated picture: In calculating its accuracy, the scientists conducting the tests discarded the yellow screens, or inconclusive readings. If you take into account the yellow screens, the PCASS accuracy rate in the three Pentagon-funded tests drops to the level of 63 to 79 percent, a result which is less than effective.

My thoughts

Given the discrepancies in the statistics and the fact that terrorists already know these are being used and are training to combat the effectiveness I don't see much point behind deploying them. You put a lot of lives at risk when you rely on something that is less than effective, or something that is easily circumvented.

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