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New anti-terror weapon: Hand-held lie detector

U.S. troops in Afghanistan first to get new device; ‘red’ means you're lying

Jimmy Hall for msnbc.com


U.S. troops in Afghanistan this month will receive a new tool that the Pentagon says will help them root out potential terrorists — a hand-held lie detector.

By Bill Dedman

Investigative reporter


updated 5:00 a.m. CT, Wed., April. 9, 2008

FORT JACKSON, S.C. - The Pentagon will issue hand-held lie detectors this month to U.S. Army soldiers in Afghanistan, pushing to the battlefront a century-old debate over the accuracy of the polygraph.

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. The device has already been tried in Iraq and is expected to be deployed there as well. “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.”

But the lead author of a national study of the polygraph says that American military men and women will be put at risk by an untested technology. "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. "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."

The new device, known by the acronym PCASS, for Preliminary Credibility Assessment Screening System, uses a commercial TDS Ranger hand-held personal digital assistant with three wires connected to sensors attached to the hand. An interpreter will ask a series of 20 or so questions in Persian, Arabic or Pashto: "Do you intend to answer my questions truthfully?" "Are the lights on in this room" "Are you a member of the Taliban?" 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 cannot be used on U.S. personnel, according to a memo authorizing its use, signed in October by the undersecretary of defense for intelligence, James R. Clapper Jr.


Defense Department

A model of the PCASS, with sensors on the palm instead of the fingertips.


The Army has bought 94 of the $7,500 PCASS machines, which are sold by Lafayette Instrument Co. of Lafayette, Ind. The algorithm, or computer program that makes the decisions, was written by the Advanced Physics Lab at Johns Hopkins University. Besides the Army, other branches of the U.S. military have seen the device and may order their own. The total cost of the project so far is about $2.5 million.

Congress has not held any hearings on the PCASS device. Myron Young, a spokesman for the Pentagon’s Counterintelligence Field Activity agency, which sponsored development of PCASS, said it informed congressional committees in a memo in November that the device had been approved for use. But five months later, no hearing has been scheduled. Congress has already scaled back its oversight of the polygraph. Five years ago it eliminated a requirement that the Defense Department produce an annual report on polygraph use.

Less accurate than a polygraph

Polygraphs have sparked a fierce debate for at least a century. While supporters claim the devices are reliable, the National Academy of Sciences allows only that they're "well above chance, though well below perfection." Polygraphs are not allowed as evidence in most U.S. courts, but they're routinely used in police investigations, and the Defense Department relies heavily on them for security screening.

Both the proponents and critics agree on one thing: This new device is likely to be less accurate than a polygraph, because it gathers less physiological information.


Jimmy Hall for msnbc.com

A PCASS screen displays "Red," indicating the device has decided the subject is being deceptive. The screen also shows the question that prompted the strongest response, in this case regarding a bomb threat.


Like a polygraph, the PCASS uses two electrodes to attempt to measure stress through changes in electrical conductivity of the skin. It also gauges cardiovascular activity, though with a pulse oximeter clipped to a fingertip, rather than a polygraph's arm cuff, which has the advantage of measuring both pulse rate and blood pressure. 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.

The training is different, too. While polygraph examiners for the Defense Department must have four-year college degrees and experience in law enforcement, the PCASS operators are mostly mid-level enlisted personnel and warrant officers, some as young as 20 years old. While polygraph examiners take a 13-week course and a six-month internship, PCASS operators undergo only one week of training, though most have military training as interrogators. The Defense Department says PCASS is simple to operate, because judgment of truthfulness is left to the computer.

Discarding 'inconclusives'

The debate over the device’s usefulness boils down to a disagreement over its accuracy.

The Pentagon, in a PowerPoint presentation released to msnbc.com through a Freedom of Information Act request, says the PCASS is 82 to 90 percent accurate. Those are the only accuracy numbers that were sent up the chain of command at the Pentagon before the device was approved.

But Pentagon studies obtained by msnbc.com show a more complicated picture: In calculating its accuracy, the scientists conducting the tests discarded the yellow screens, or inconclusive readings.

That practice was criticized in the 2003 National Academy study, which said the "inconclusives" have to be included to measure accuracy. 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.

Even if you accept the lower accuracy rates, the Pentagon officials say, the device is still better than relying on human intuition.

"Let's take a worst-case scenario here, and let's say PCASS really is 60 percent accurate," said Krapohl, who heads the project for the Defense Academy for Credibility Assessment at Fort Jackson, S.C. "So let's get rid of the PCASS because it makes errors, and go back to the approach we're currently using, which has less accuracy? As you can see, that's really quite untenable if we're interested in saving American lives and serving the interests of our commanders overseas.”

Msnbc.com asked Fienberg, a professor of statistics and social sciences at Carnegie Mellon University in Pittsburgh, to review the unclassified Pentagon studies of the PCASS. He said he was not impressed.

"I, like everyone else I know, want the troops in Iraq, in Afghanistan, elsewhere in the world, to be protected," Fienberg said. "I want terrorists to be detected. I do not want to be living in a threatened world, and I want to give my government the best possible advice.

"They need devices that work. And if they rely on things that really don't work, and act as if they do, we will have a greater disaster on our hands than we already do in the field in Iraq. We simply do not know what a device like this hand-held device will produce in that kind of setting, except for the fact that there's scant evidence that it will produce anything of value."


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I think all Americans ought to be concerned.We maybe sending our troops out with something that may not even work.I guess it is better than sending them out with helmets that don't meet requirements,and vehicles that don't protect them from bomb blast.

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Each terrorists should have his day in court before these are used. It's against their constitutional rights....

Oh yeah. I forgot. They are not American citizens. They don't get a day in court. They should have every opportunity to lie, be released, and then finally complete their mission by killing a few of our soldiers on their way to greet their 72 virgins. This device is not 100% correct,so we should just trust the terrorists and free them.


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