Medical Detection of False Witness: High-Tech Lie Detectors One Day May Be Impossible to Fool, but So Far the Only Guarantee Is That They Will Stir Up as Much Controversy as the Original Polygraph. (Nation: Techno-Security)

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Try this scenario: Zacarias Moussaoui is led out of a dark cell into a silent room at an undisclosed location. An electrode headset is fitted to his skull while his lawyer watches disapprovingly. After nearly an hour of flicking switches and flashing lights, the procedure concludes. An investigator reviews the results and determines exactly what role Moussaoui played in the Sept. 11 terrorist attacks. You cannot hide your memories from the machine.

Some say this no longer is science fiction. In the months following Sept. 11, articles about techno-security have appeared in the popular press and in professional journals promising just such a result from high-tech lie detectors. One of these machines was featured in the New York Times Magazine's "2001 Encyclopedia of Innovations, Conceptual Leaps and Harebrained Schemes." An INSIGHT review of new polygraph technologies suggests that most of them fit all three categories.

"When one uses any kind of lie detector, one is saying `ask the body, not the person,'" says Mike Gazzaniga, director of the Center for Cognitive Neuroscience based at Dartmouth College. "One assumes with autonomic studies [polygraphs] that the body can't lie," Gazzaniga says. The assumption is that the body's autonomic reactions -- such as blood pressure, breathing and heart rate -- cannot be manipulated to support deception. "They assume that lies are mental constructs," Gazzaniga continues. "Among those things that separate man from animal is his capacity for deception. The question is how to make a science and not folk psychology out of this."

One investigative method established for autonomic research is the "guilty-knowledge test," which consists of confronting a suspect with a series of items, some relevant to a crime and others irrelevant. It is believed that a subject who has "guilty knowledge" will react most strongly to relevant or target items, while an innocent person will not.

Such tests have been disputed since the first polygraph was invented by William Marston in 1917. A polygraph can be an effective tool, but high-profile cases such as those of Aldrich Ames and Robert Hanssen, spies who beat the machine, frequently are cited to show its fallibility. Critics point out that data gathered from these tests are indicative of physiological response rather than veracity, with the latter being distinguished from the former. They say there is no necessary connection between a subject's verbal and physical report.

Polygraph expert Drew Richardson, a former FBI special agent at Quantico Laboratories, says "the test is generally not admissible in court because it is largely not accepted as a valid scientific technique."

But what if a better mousetrap were to become available? What if there were a machine that could not be fooled? What if an autonomic response to lying were to be identified that could not be suppressed? Recently, some have made such claims. Here is a look at those claims and what is being said about them.

Brain fingerprinting: According to Larry Farwell, an independent psychophysiologist at Human Brain Research Laboratory in Fairfield, Iowa, the fundamental difference between a guilty and innocent person is a record of the crime stored in the brain. "The difference between a terrorist who has been through a training camp and an Afghan student is the memory," Farwell says. Brain fingerprinting identifies memories, he claims.

This examination consists of a modified guilty-knowledge test that uses targets and irrelevants, but adds probes that are unique details of a crime that only the culprit could know. All subjects are familiarized with the targets in order actively to identify them during the test. A guilty subject is expected to have the same response to the probes as to the targets.

When one is exposed to something that already is stored in memory, the brain emits an electrical response called a p300 wave. …