Polygraph testing

SIGNIFICANCE: Although polygraph testing has been used since the 1920s, it has failed to gain widespread acceptance as a reliable tool in criminal justice.

Also known as “lie detectors,” polygraphs are instruments that record the physiological responses of persons being asked questions for the purpose of ascertaining the truthfulness of their answers. Questions are assembled in a testing format commonly called a psycho-physiological detection of deception (PDD) examination.

The word “polygraph” has Greek roots that mean “many writings.” In polygraph testing, each “writing,” or pen marking, on a chart paper represents a unique physiological response, such as blood pressure, upper body movement, or galvanic skin response (perspiration). Any increases in these measurements indicate that the subject of the test is being discomforted by the questions being posed. Through careful questioning, monitoring of the tests, and evaluation of the overall results, testers can generally determine the truthfulness of the subjects’ responses to individual questions.

History

The Italian criminologist Cesare Lombroso is credited with developing the principles behind polygraph testing during the 1890s. A pioneer of modern scientific criminology methods, he sought to explain criminal behavior through human biology. He discovered that human blood pressure increases following deceptive responses. Later, William Marston and John Larson separately came to the conclusion that blood pressure and respiration were correlated. Larson constructed the actual recording device in 1921, but Leonarde Keeler and Walter Summers refined the direct predecessor of the modern polygraph testing device around 1924. Following their advances, investigators and employers began to use the polygraph as a matter of practice.

Legal controversies over the use of polygraph testing began around the same time. In 1923, a convicted murderer name Frye took his appeal to the US Supreme Court, arguing that he had been wrongly convicted because the trial court had refused to admit evidence in his favor that was based upon the findings of a crude precursor to the modern polygraph that involved periodic readings from a blood-pressure cuff. Because the scientific community did not accept that method, the Court found it to be unreliable and therefore ordered the evidence to be excluded in Frye v. United States (1923).

Although polygraph technology has advanced greatly since Frye’s time, by the turn of the twenty-first century, only the state of New Mexico admitted polygraph tests into evidence at the trial level. However, in 1998, the US Supreme Court declared that individual courts have the discretion to admit such tests as evidence if they so choose.

Examination Type and Format

Polygraph examinations are most commonly used in two settings: pre-employment screening and criminal investigations. Pre-employment testing involves series of exploratory questions about job candidates’ possible histories of job trouble, substance abuse, and criminal behavior. Until the practice was outlawed in 1988, private employers could require applicants to submit to polygraph examinations for purposes of job suitability and, after they were hired, could require them to take additional examinations at any time. However, passage of the federal Employee Polygraph Protection Act prohibited such testing, exempting only law-enforcement agencies, nuclear power facilities, and pharmaceutical companies.

Polygraph examinations conducted on behalf of law-enforcement agencies or defense attorneys usually focus on specific criminal issues. Depending upon the information available to them, examiners utilize one of many specific-issue question formats. One of the most commonly used is the Control Question Technique (CQT) developed by John Reid. Tests using that format begin by asking subjects “control” questions designed to elicit deceptive, or untruthful, responses from ordinarily truthful subjects. The questions that follow concern the relevant or specific issues at hand. For example, if the polygraph examination concerns the theft of money from a corporation, a control question might be, “Have you ever taken something from someone who trusted you?” The following, specific-issue question would be, “Are you the person who took the money from Company X on the date and time in question?”

Subjects “pass” the tests when their physiological responses to control questions are stronger than those to the specific-issue questions. Conversely, they “fail” the tests when the results are the opposite. However, contrary to the ways in which lie detectors are depicted in the popular media, there is much more to polygraph testing than simply asking questions.

The classic polygraph testing format begins with pre-test interviews that establish rapport between subjects and examiners and allows the examiners to create psychological sets—the focus of attention. Examiners formulate their questions based upon the information they gather during the interviews. After they attach the polygraph to the subjects, “stimulus tests” are conducted that require subjects to lie to certain questions. These trial tests indicate to examiners whether the subjects are testable. Next, the examiners conduct the actual examinations regarding the specific issues at hand. When the subjects are judged to have failed their tests, the examiners begin the post-interview stage and attempt to elicit admissions or confessions.

Technology, Profession, and Industry

For many years, polygraph instruments recorded responses with several ink pens moving across continuously flowing paper charts. Modern polygraph instruments are now computerized. The physiological responses of subjects received by the instruments are digitized and displayed on computer screens. Polygraph software and equipment are now commercially available to both public and private examiners.

Regulation of the polygraph industry varies throughout the United States. Some states have stringent licensing requirements regarding examiner training, test formats, and examinee fitness. Other states simply require examiner registration; many states have no licensing requirements whatsoever. In states requiring licensing, prospective polygraph examiners must attend ten-week polygraph schools, in which they receive training in psychology, physiology, interviewing and interrogation, and chart interpretation. Following their coursework, they must satisfactorily pass several examinations and, in some instances, complete academic research projects.

The American Polygraph Association (APA), the largest professional group of the trade, has attempted to standardize the industry by offering accreditation status to polygraph schools that follow standards approved in its bylaws. In addition to attending regional training sessions, APA members gather once each year to review recent research and practices.

Bibliography

Clifton, Charles. Deception Detection: Winning the Polygraph Game. New York: Paladin, 1991. Print.

Gusterson, Hugh. "Is There Something Fishy About the Polygraph?" Anthropology News, 30 Apr. 2024, www.anthropology-news.org/articles/is-there-something-fishy-about-the-polygraph/. Accessed 9 July 2024.

Hart, Christian. "How Do Polygraphs Work?" Psychology Today, 29 June 2022, www.psychologytoday.com/intl/blog/the-nature-deception/202206/how-do-polygraphs-work. Accessed 9 July 2024.

Kleiner, Murray, ed. Handbook of Polygraph Testing. San Diego: Academic, 2001. Print.

Matte, James A. Forensic Psychophysiology Using the Polygraph: Scientific Truth Verification, Lie Detection. Williamsville: J. A. M., 1996. Print.

Moore, Mark H., Carol V. Petrie, and Anthony A. Braga, eds. The Polygraph and Lie Detection. Washington, DC: Natl. Academies, 2003. Print.

Segrave, Kerry. Lie Detectors: A Social History. Jefferson: McFarland, 2003. Print.

US Congress, Office of Technology Assessment. Scientific Validity of Polygraph Testing: A Research Review and Evaluation. Stockton: UP of the Pacific, 2004. Print.