The central deception involved in the polygraph examination
is the notion that it detects lies.
In his secret testimony before the Warren Commission in
1964, J. Edgar Hoover, made the point that the "polygraph,
often referred to as a lie detector, is not in fact such
a device." So has every serious study conducted by government
agencies has confirmed Hoover's assessment. For example,
the Office of Technology Assessment issued a massive report
in 1983 entitled "Scientific Validity of Polygraph Testing:
A Research Review and Evaluation," concluding that "the
available research evidence does not establish the scientific
validity of the polygraph test for personnel security
screening." There are still no peer-reviewed test 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 measure 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.
Not uncommonly, the emotional response may be to the question
but to the tone and manner of the interrogator. Consider,
for example, one of the most important polygraphs examinations
ever conducted by the CIA, the interrogations of Yuri
Nosenko. Nosenko had been a KGB defector who claimed to
be Lee Harvey Oswald's case officer when de defected to
the US. In 1966, the CIA believed he was a false defector
and wanted to break him. The polygraph operator asked
Nosenko a dozen key questions and assessed that he was
lying in his most important answers. Then, in 1968, there
was a new regime in the CIA that believed Nosenko was
a genuine defector and wanted to rehabilitate him. He
was given a second polygraph and asked substantially the
same questions and gave the same answers. But this time,
it was assessed Nosenko was truthful in all his responses.
What had happened? The variations in Nosenko's emotional
reaction between the 1966 and 1968 polygraph were attributed
to the very different attitudes of his interrogators.
The first had sounded hostile and provoked a "lie" response,
the second sounded friendly and provoked a "truth" response.
The polygraph, though not a lie detector, is an inquisition
tool. As such, it can elicit a confession if the subject
can be deceived into believing that it is a lie detector.
He may then assume that since he cannot conceal the truth,
his best option is to reveal it. Polygraphs are thus designed,
not just to measure responses, but to deceive subjects
that they possess omniscient power to detect lies. To
this end, the polygraph is embellished 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 cup— 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 deception).
The polygraph examiner purports to interpret the data
while asking a series of questions by allegedly comparing
the reactions to each set of questions. A common technique
to deceive subjects into believing the machine is omniscient
is to ask a question early on to which the interrogator
knows the answer and which the subject will answer deceptively.
He can then pretend that the machine caught the lie. In
Nosenko's initial polygraph, for example, Nosenko's case
officer fed the polygraph operator a question about his
rank in the KGB to which Nosenko had previously exaggerated
(according to documentary evidence in the hands of the
CIA) When he repeated this exaggeration on the polygraph,
the operator, following a script, stopped the machine
and told him he was lying.
Such deception techniques does not require a polygraph
machine. Law enforcement agents have gotten similar confessions
by convincing suspects that a office Xerox machine was
a lie detector or, in other cases, that they had ESP.
The polygraph simply combines these techniques in a package
Of course, the CIA, FBIand other Intelligence agencies
know that the polygraph machine is not an effective lie-detector.
If it actually worked, they would be out of the espionage
business. The CIA, for example, would have to assume that
any mole that it recruited in the Russian intelligence
services would be revealed by a polygraph test that the
Russians would admininister.The Russian intelligence services
would conversely assume all their spies would be caught
by the CIA's regular polygraph examination. But, as Aldrich
Ames, Robert Hanssen and many other KGB moles proved is
that they could lie year after year without it being detected
by CIA and FBI polygraphs.
So all the government agencies that regularly use this
device— the FBI, CIA, Secret Service, NSA, DEA, Department
of Energy (to examine thousands of scientists)-- are fully
aware that it is not a lie detector. Nevertheless, the
virtue of this deception is that, so long as deceives
its targets, it provides an incentive to tell the truth.