"US Congressman Gary Condit has passed a lie detector
test in which he was asked if he had harmed missing
Washington intern Chandra Levy," the BBC reported
on July 13,2001, quoting his lawyer as saying "Mr
Condit had been exonerated by the test." It was
not surprising Congressman Condit would use a "lie
detector" to to try to dispel suspicion. Lie detectors,
or Polygraph machines, as they are also called, are
used throughout the federal government by the FBI, Secret
Service, CIA, Drug Enforcement Administration, National
Security Agency, Department of Energy, Department of
Defense, Bureau of Alcohol, Tobacco and Firearms, Defense
Security Service, and the U.S. Marshall's Service. That
they can detects lies, or exonerate a subject, is however
a fictoid that has persisted in the media decades.
In his secret testimony before the Warren Commission
in 1964, J. Edgar Hoover, said that the "polygraph,
often referred to as a lie detector, is not in fact
such a device." He explained that its value to
law enforcement agents was as a tool of intimidation:
if a subject believed the central deception that the
machine could detect lies, he would have an incentive
not to lie when strapped in the machine. More recently,
in 1983, the Office of Technology Assessment concluded
"the available research evidence does not establish
the scientific validity of the polygraph test for personnel
security screening." There are still no peer-reviewed
tests using randomly distributed true and false answers.
As recently as 2000, the U.S. Supreme Court, in a decision
upholding the absolute ban on the use of polygraph tests
in court-martial proceedings said, "There is simply
no consensus that polygraph evidence is reliable."
In fact, there is no epistemological basis for believing
that the polygraph machine is even designed to detect
lies. It measures emotional responses that can proceed
from many factors including fear, anxiety and nervousness.
Whether or not such emotions are connected to deception
cannot be determined from the data.
Intelligence agencies know that the polygraph machine
is not a lie-detector. If it actually worked, they would
be out of the espionage business. since any mole that
they recruited in enemy intelligence services would
be revealed by a single polygraph test. But, as Aldrich
Ames, and many other KGB moles in the CIA proved by
lying without detection, this is not the case. The government
agencies that use it the FBI, CIA, Secret Service,
NSA, DEA, Department of Energy (to examine thousands
of scientists)-- while, aware that it is not a lie detector,
use it for intimidation purposes.
Polygraphs are thus commonly designed but to deceive
subjects by dazzling them with multiple sensors. The
CIA's polygraph machine, for example, uses rubber hoses
on both the chest and abdomen to measure changes in
respiration, electrodes, which are attached to fingertips,
to measure changes in sweat, skin temperature and vessel
constriction and a blood pressure arm cuff to measure
changes in the heart rate. If any of the three sensors
were actually capable of measuring deception (which
they are not), the other two devices would be redundant.
But three sensors a polygraph instead of a monograph
helps the deception by dazzling subjects. If only one
sensor was used say, for, example, a blood pressure
cuff subjects might focus on the issue of what
blood pressure changes actually measure. Triple instruments
make such a focus more difficult, which is why dazzling,
or overloading the brain, is an effective technique
in such deceptions.
The Fictoid persists in the media, as well as movies,
because it appears to present a scientific solution
to a vexing problem: telling truths from lies.
An entire organization, AntiPolygaph,
is devoted to exposing this fiction.