Link To Us*Contact Beat Polygraph Webmaster
Learn How To Beat The Polygraph

The examiner then scrutinizes the test results in light of the pre-test interview and the first phase control questioning and establishes a "credibility imprint" for the procedure. And what data are physically available as results? Primarily a series of marked lines, complimented by observation and interpretation. The polygraph produces a series of lines of various degrees of smoothness, calibrated by time intervals that relate to apparent autonomic reactions to questions. But the problem of interpretation is immense. Justice Morand expressed considerable frustration at understanding how the graphical results can be interpreted:

At no time was Mr. Reid [a polygraph expert] able to explain to my satisfaction the difference between his perception of the lines on the graph and mine (pp 252, Morand Report).

After a series of examples of testing and results, the Justice came to the conclusion that the graphs are by themselves a small part of the examination process: The choice of which response was decisive appeared to be based largely on the impression of the subject that the examiner had formed after the pre-test interview... the very facts that the charts are a mere approximation of response and that the analysis is made by eye and estimation alone negate the possibility that the polygraph test is a physiological procedure (pp 253, Morand Report).

As Justice Morand indicates, and as the polygraph experts generally will agree, the polygraph test attempts to physically monitor autonomic responses to questions with the purpose of detecting lying, but in fact the testers rely very heavily on subjective evaluation both at the pre-test stage, the first and second stage, and even at the post-test analysis stage, to reach their conclusions. However defensible or not, the physiological results from the graphs are far from the sole basis of the evidence for establishing a case for lying. In fact, the whole procedure is very subjective, based as it is on physical data open to uncertain interpretation, and on particular interpretive skills of each examiner at all stages. Clearly the subjective evaluation and the physiological readings of the polygraph both have a number of practical and conceptual weaknesses that cast a pall over the polygraph's own capability to detect truth or falsehood. Some of these weaknesses are described below.

Major problems

It should be understood that the criticisms of the polygraph testing procedure that are made in this section refer to models for polygraph use that have been design specifically for detecting deception in criminal investigations. Although these criticism may apply to uses of the polygraph in other circumstances, no model that we are aware of has ever been specifically designed or scientifically tested for use in employment. After an exhaustive study of all available scientific literature on polygraph use, a recent Congressional study "The Scientific Validity of Polygraph Testing: A research Review and Evaluation" (November, 1983), confirmed this by concluding that there was no evidence whatsoever concerning the use of polygraphs for employment purposes. The study also found that the uses to which the polygraph was put in both employment and criminal matters were sufficiently different, so that the available evidence on the use of polygraphs in criminal investigations-most of which is of highly questionable scientific value, as we shall see-could not be used to support the use of polygraphs for employment purposes. For example, in using polygraphs for job screening or other employment situations, a polygraph operator may attempt to determine whether a job applicant or employee is honest, trustworthy, reliable or a suitable employee. This is a more complex judgment, or at least require different assessment techniques, than those involved in assessing whether a person is guilty or innocent of a crime.

Since no evidence has been forthcoming regarding the validity of polygraph use in employment, polygraph operators who make their services available to employees have supported their work by using evidence gathered during polygraph use in criminal investigations. When informed by a British House of Commons Committee on Employment that his research was being used by polygraph companies to support the use of the polygraph in employment testing, the response of a major proponent of use of polygraphs in criminal situations, Professor David Raskin, was: For them to use my research in support of any commercial application of the polygraph is quite outrageous. In fact, I regard these tests as dangerous. I calculated in one program nine out of ten people found to be deceptive would actually be telling the truth... 18 states now prohibit the use of employee vetting, because there is no scientific evidence to support using them in the commercial sector, and also because the way in which polygraphs are used can be both abusive and counterproductive (Sunday Times, May 27, 1984).

Dr. Douglas Carrol from the psychology department of England's Birmingham University also told the British Commons Committee that employee screening via polygraph testing was not good procedure and likely to be unjust.

Polygraph screening is likely to identify remarkably few security or employment risks. What it will do, though, is to implicate as risks an exceptionally large number of honest individuals (Sunday Times, May 27, 1984).

Dr. Carroll cited evidence showing accuracy rates of only 63 to 76 percent for the polygraph; Carrol's evidence also indicated that as many as 55 percent of innocent people could be found guilty by the polygraph procedure. Carroll went further: On the scale of idiocies, I think its application in industry and commerce is one of the biggest, most dangerous idiocies of our time. It shatters people's confidence and can ruin their career opportunities (Sunday Times, May 27, 1984).

The Commons Committee heard a good deal of evidence from both opponents and proponents of polygraph testing, both sides agreed that claims about the accuracy of polygraph testing, even with the most highly trained technicians, and in commonly agreed-upon conditions, were typically exaggerated by commercial firms in their advertising. A Martin Seligson of Polygraph Security Services, for example, admitted his firm's accuracy claims were distortions, and conceded that from published reports on polygraphs, "I admit to having pulled out some favourable stuff". Hardly reputable. Or credible.


Polygraph- Cheating Wife / Husband - Polygraph - Police Jobs