DAVID LYKKEN AND THE POLYGRAPH MYTH

SECRECY NEWS - David T. Lykken, a psychologist who did pioneering
research and public education on the limits and abuses of polygraph
testing, died last week at age 78. With exceptional clarity he
demonstrated that the polygraph is not a "lie detector" but simply a
recorder of physiological responses to verbal stimuli. And, he
explained, there is no set of physiological responses that corresponds
uniquely to deception.


That does not mean the polygraph is worthless. There is empirical
evidence to support its use in the investigation of specific incidents,
where "guilty knowledge" of particular details may be usefully revealed
by the polygraph.

"The use of the [polygraph] by the police as an investigative tool,
while subject to abuse like any other tool, is not inherently
objectionable," Lykken wrote.

(Not only that, "It seems reasonable to conclude that whether O.J.
Simpson did or did not kill his wife could have been determined with
high confidence using a Guilty Knowledge Test administered within hours
after he was first in police custody.")

On the other hand, he said, the use of the polygraph for security
screening of personnel, as is commonly done by U.S. intelligence
agencies, cannot reliably achieve its purported goal of identifying
spies or traitors and in many cases becomes counterproductive. . .

It is a sign of our times that the scientific critique of polygraph
testing has gained almost no traction on government policy. To the
contrary, the use of the polygraph to perform the sort of screening that
Lykken termed a "menace in American life" is actually on the rise.

"From FY 2002 through 2005, the FBI, DEA, and ATF conducted
approximately 28,000 pre-employment polygraph examinations" as well as
tens of thousands more for other purposes, according to a major new
report from the Justice Department Inspector General.

http://www.fas.org/sgp/othergov/polygraph/dojpoly.pdf

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