MSNBC: 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. 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.
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. MORE
RELATED: In the mid-1990s, I became interested in the science (or lack thereof) behind polygraphs as one of my closest colleagues at Sandia (and a very senior member of the technical staff) lost his opportunity for a key appointment to a high-level advisory position in the intelligence community as a result of flunking his polygraph. Because of my background in medical decision analysis (indeed, the polygraph is a “diagnostic” tool, although almost completely without diagnostic value), he asked me to look into the actual utility of polygraphs in identifying spies within the national security context
At that time, there were very few published, peer-reviewed scientific summaries of the polygraph, and it rapidly became clear that polygraphers were — as a group — nothing more than interrogators who used the polygraph machine as a ruse to convince the unsuspecting interviewee that their machine could devine deception from truth-telling. This is almost completely false; there is some modest evidence that in specific incident investigations (such as the investigation of a murder, robbery, or other highly unique event) that the polygraph has diagnosticity greater than chance. However, in the setting of national security screening, the polygraph is probably worse than worthless. That is: the polygraph is much more likely to falsely “diagnose” deception than it is to identify true deception. MORE