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Polygraph Testing

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Overview of the Polygraph

A polygraph machine records the body's involuntary responses to an examiner's questions in order to ascertain deceptive behavior.  The test measures physiological data from three or more systems of the human body—generally the respiratory, cardiovascular, and sweat gland systems—but not the voice.  There are other tests that test the voice for deception.

"Polygraph"means literally "many writings," referring to the method of recording several physiological activities at the same time. William M. Marston invented the first lie detector in 1917.   Marston claimed he could reveal verbal deception by observing levels of systolic blood pressure.  However, in 1923, the D.C. Court of Appeals stated that there was not enough scientific evidence to support Matston's lie detector machine.  Roughly a century later, Leonarde Keeler invented a machine and school for examiners that paved the way for the modern use of polygraph testing, especially in the legal realm.

Polygraph testing is mainly done for law enforcement, judicial and the private business sector purposes.  Private business sector use of the polygraph is restricted under the Employee Polygraph Protection Act of 1988 ("EPPA").

The EPPA's Privacy Protections

The EPPA was enacted to establish guidelines for examination conducted by private commercial employers, with a few exceptions for positions related to state security and positions under government contract.  Generally, an employer cannot require a pre-employment polygraph test of an applicant.  Even when an employer can request that an employee take a polygraph test, certain criteria must be met.  An employer cannot fire an employee for refusing to take a polygraph test.

As an additional safeguard, the majority of states insist that polygraph examiners qualify for a license to conduct examinations.

Reliability of Polygraph Testing

Because the polygraph test measures bodily responses, a data subject can attempt to alter her bodily responses in order to interfere with the test.  Several common ways to undermine the test include:  taking sedatives to reduce anxiety; using antiperspirant to prevent sweating; and positioning pins or biting parts of the mouth after each question to demonstrate a constant physiological response.

In 2002, a panel from the National Academy of Sciences were charged with "conduct[ing] a scientific review of the research on polygraph examinations that pertains to their validity and reliability, in particular for peronnel secutiry screening." The panel's findings were compiled into the report, "The Polygraph and Lie Detection," and presented to Congress and the Department of Energy.  The panel found polygraph testing to be unscientific because it lacked fixed standards.  After reiviewing the available data and studies on polygraph testing, the panel concluded: "Almost a century of research in scientific psychology and physiology provides little basis for the expectation that a polygraph test could have extremely high accuracy."  Further, there was little hope for advancing polygraph testing.  According to the panel's findings: "The inherent ambiguity of the physiological measures used in the polygraph suggest that further investments in improving polygraph technique and interpretation will bring only modest improvements in accuracy."

Based on the National Academy of Science's report, Congress required the Department of Energy to reconsider their polygraph use in light of the study's findings.  However, the Department of Energy retained and resubmitted their existing poligraph policy to Congress, stating that, regardless of the panel's conclusions, the rules constituted "a balanced approach for the carefully circumscribed use of polygraph examinations as a tool that appears in current circumstances well-suited to accomplish the Congressionally-specified purpose 'to minimize the potential for release or disclosure of classified data, materials, or information.'"

Notwithstanding the controversy surrounding the use of polygraph examinations, the Department of Defense has expressed interest in increasing the use of them for secutiry and counterintelligence.

Protect your Privacy

Even advocates of polygraph test admit to the existence of erroneous results.  Errors can be attributed to a number of factors, which include the preparation of the subject for examination, the examiner's approach to questions, the examiner's interpretation of the results, and the subject's nervousness and anxiety.  

If an examination results in a false positive, i.e. the test indicates that a subject is deceptive when he is not, the subject should request a second examination and have a different examiner conduct the test.  In addition, the subject should also complain to any of the following: the state licensing board; the Department of Labor under the EPPA; or the American Polygraph Association.  The Department of Labor maintains a compliance page with regard to the EPPA.

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Last Updated: October 1, 2003
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