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The Myth of the Polygraph


Even J. Edgar Hoover knew
that the polygraph wasn’t any good for detecting deception. He dropped the 

polygraph was invented in 1915 by a Harvard man called William Moulton Marston,
 who claimed that his clunky little gizmo could detect lies by measuring blood
pressure. Marston’s main claim to fame derives not from his machine, but
from a doodle he came up with: the cartoon character Wonder Woman.

the past 85 years, the polygraph hasn’t changed much from the Marston prototype.
”The secret of the polygraph is that their machine is no more capable of
telling the truth than were the priests of ancient Rome standing knee-deep in
chicken parts,” says Alan Zelicoff, a physician and senior scientist at the
Center for National Security and Arms Control at the Sandia Labs in Albuquerque,
NM. Zelicoff gave us this view in an article featured in the The Skeptical Inquirer.

writes that the polygraph administrator is a kind of confidence artist or modern
day mesmerist who tries to seduce (or scare) his subjects into believing in the
power of the machine to catch them in the most minute inconsistency.

subject, nervously strapped in a chair, is often convinced by the aura surrounding
this cheap parlor trick, and is then putty in the hands of the polygrapher, who
then launches into an intrusive, illegal and wide-ranging inquisition,” Zelicoff
writes. “The subject is told from time to time that the machine is indicating
‘deception.’ It isn’t, of course. And he is continuously urged
to clarify his answers, by providing more and more personal information.”
At an arbitrary point, the polygrapher calls off the testing, consults the spools
of graph paper and makes an entirely subjective rendering on whether the subject
has given a “deceptive response.”

first-year medical student knows that the four parameters measured during a polygraph–blood
pressure, pulse, sweat production, and breathing rate–are affected by an
uncountable myriad of emotions: joy, hate, elation, sadness, anxiety, depression,
and so forth,” says Zelicoff. “But there is not one chapter–not
one–in any medical text that associates these quantities in any way with
an individual’s intent to deceive. More importantly, dozens of studies over
the past 20 years in psychology departments and medical schools all over the world
have shown that the polygraph cannot distinguish between truth-telling and lying.”

of the Wen Ho Lee affair will remember that at one point the FBI falsely told
the Taiwanese nuclear physicist (accused of spying for the Chinese at Los Alamos)
that polygraph tests showed he was lying. Cops play these sorts of tricks all
the time, faking forensic reports and then shoving them under the nose of their
suspect, shouting that he’s a proven liar and that he’d best sign a
confession right away.

most comprehensive review of the polygraph was conducted in 1983 by the Office
of Technology Assessment, a research branch of congress. The OTA concluded, “There
is no known physiological response that is unique to deception.” The report
did note that the CIA and its companions “believe that the polygraph is a
useful screening tool.” However, OTA concluded that the available research
does not establish the scientific validity of the polygraph for this purpose.
The best that OTA could say about the polygraph was that it might have some limited
validity in “specific criminal incidents.” But the report went on to
observe that in such cases, “the polygraph test detects deception better
than chance, but with error rates that could be significant.” As for the
supposedly revealing physiological responses, the congressional study reported
that they could be masked “by physical movement, drugs or other techniques
to avoid detection as deceptive.”

are numerous ghastly stories of federal employees who were abused by the machine
and its operators. Take the case of 19-year Navy veteran Daniel M. King, who was
suspected of selling classified information. King was locked up in military prison
in solitary confinement for 500 days and subjected to repeated polygraphs. Some
of them lasted for as long as 19 hours. A military judge dismissed all the charges
against him.

few years ago FBI agent Mark Mallah was given a routine polygraph. The polygrapher,
 who had only 80 hours of experience with the machine, concluded that Mallah had
lied. (Zelicoff notes that even barbers must have 1000 hours of training before
getting a license to cut hair.) His life soon transformed into a Kafka story.
 He was stripped of his badge, subjected to midnight searches of his house, his
diary and appointment book seized and scrutinized, his neighbors, friends and
relatives interrogated, his every move outside monitored by helicopters. In the
end, Mallah’s life was pretty much destroyed, but nothing was ever proved
against him. The FBI finally apologized and Congress outlawed the use of the polygraph
for civilian employees in 1988.

worth noting that the Walker brothers and Aldrich Ames both beat the polygraph
with no sweat. Kim Philby settled himself with a dollop of Valium before breezing
through his polygraph exams.

investigator for a defense lawyer in California told us that, while the polygraph
isn’t admissible in most courts, it’s used all the time by prosecutors,
mostly to seal plea bargains. “It’s a perilous option, because the utility
of the polygraph is almost totally up to the operator,” she said. “There are good polygraphers,
but many who work for the district attorneys have only minimal training.”

investigator described a recent case where a defense witness in a homicide case,
 who had passed a polygraph given by a former FBI polygrapher with 20 years of
experience, was sent to the DA for another test given by their examiner, a relative
novice with the device. Defense lawyers can’t be in the room while the test
is given, even when their clients are being examined. The prosecutors videotape
the session, and while the results of the polygraph can’t be used at trial,
the videotape can become evidence. In this case, the defense lawyer waited in
the hall until the witness emerged from the room “with his face red as a
beet.” The lawyer heard the DA’s investigator threaten the witness:
”You little slimebag, I know you’re lying. We’re going to revoke
your parole.” The DA’s examiner had interpreted the readings from one
of his answers as being “deceptive.”

Jeffrey St. Clair is the author of Been Brown So Long It Looked Like Green to Me: the Politics of NatureGrand Theft Pentagon and Born Under a Bad Sky. His latest book is Hopeless: Barack Obama and the Politics of Illusion. He can be reached at:

Alexander Cockburn’s Guillotined! and A Colossal Wreck are available from CounterPunch.

This essay is adapted  from an article in the July 2001 edition of CounterPunch.


Jeffrey St. Clair is editor of CounterPunch. His new book is Killing Trayvons: an Anthology of American Violence (with JoAnn Wypijewski and Kevin Alexander Gray). He can be reached at: Alexander Cockburn’s Guillotined! and A Colossal Wreck are available from CounterPunch.

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