Since antiquity, civilizations have assumed that there were means to make individuals tell the truth against their own will and interests. Torture was (and still is) one of the most common tools used by interrogators around the world. Along with its inhumane aspects, torture is highly imprecise in revealing the truth, as under torture, a person may confess to exactly what the torturers want to hear in order to end his or her discomfort.
Among ancient Romans, alcoholic intoxication was another way of obtaining information from politicians or foreign diplomats who could not be simply arrested and tortured. This gave rise to the expression, "In vino veritas," meaning the truth is in the wine. The Italian physician Cesare Lombroso was a pioneer in the late 1880s in the search for devices that could measure physiological changes associated with lies during interrogation of criminal suspects, such as the pletymosograph. The device was a modest ancestor of modern polygraphs that recorded blood circulation variations during interrogation. Lombroso asserted that through the observation of how physiological signs changed during interrogation, a reliable and humane means of detecting when individuals were telling the truth or lying could be developed. In 1915, William M. Marston at Harvard University developed an instrument to measure blood pressure that he named the "lie detector." In the early 1920s, American criminologist and psychiatrist John Larson started to develop the first modern polygraph machine that recorded blood pressure levels, pulse rates, breathing rates, and perspiration.
By the 1980s, polygraphing had a one-billion-dollar industry in the United States, with different models and testing methods of application not only for criminal investigation, but also as a tool for testing employees in the workplace. However, its efficacy and accuracy became increasingly disputed by scientists who labeled the polygraph a tool of "junk science" because of the many variables involved physiological changes, the subjective nature of data interpretation by polygraph examiners, the misuse and abuse found in many cases, and the many documented cases of false positive and false negative results. Increased privacy law protection and a string of notable failures in polygraph examinations by those who successfully defeated counterintelligence polygraph examinations brought polygraph practice into increasing disrepute. The failures were well publicized, especially in the wake of the 1985 arrest of Navy spies in the Walker family spy ring and the 1994 arrest of CIA officer Aldrich Ames for selling secret information to the Soviets for years despite being "cleared" by repeated polygraph examinations.
In contrast, many individuals who were convicted for crimes based on polygraph tests in the first half of the twentieth century were later found to be innocent (false positive results), which led courts in general to deny the acceptability of polygraph tests as valid evidence. For that matter, even J. Edgar Hoover, during his many years as director of the Federal Bureau of Investigation (FBI), banned polygraph testing of FBI employees, deeming it a waste of time and money. Nevertheless, polygraphs were again introduced in the FBI and gained increasing prestige in other agencies as well as a tool of interrogation rather than as an accurate scientific test. Today they are largely used in both criminal and security investigations by the police, governmental agencies, and private enterprises.
More controversy on the validity of polygraph tests was sparked in 1999, when Chinese American nuclear physicist Wen Ho Lee was accused of mishandling highly classified data on nuclear weapons. Lee was tested by two different polygraph examiners from the U.S. Department of Energy (DOE). Lee passed one polygraph test, failed a second one, and then passed a third test. Department of Energy (DOE) polygraph examiners still disagree about the tests' contradictory results. Former Energy Secretary Bill Richardson, elected in the wake of the Lee controversy, recommended a wide polygraph-screening program for DOE employees instead of using guards and x-ray scanning at the entrances of DOE laboratories, which had been cancelled by his predecessor. When Congress approved Richardson's petition, another great controversy ensued as scientists and engineers working in some facilities unanimously refused to be tested. The scientists claimed that polygraphs did not increase security, but rather undermined it, since spies are trained to pass the tests; polygraphs create a false sense of security; polygraphs drain valuable resources from other effective and sound security measures; and polygraph tests demoralize the staff, possibly jeopardizing the safety of information in such vital issues as nuclear technology.
A leading voice in this issue was Alan P. Zelicoff, the senior scientist at the Center for National Security and Arms Control at Sandia National Laboratories. Zelicoff decided to take the case against polygraphs to the public after both the DOE and the Congress had ignored scientists' concerns. Among his arguments, Zelicoff (who is a physicist and physician) alerted the public that polygraphs are deceptive devices subject to the manipulation and incompetence of polygraph examiners. Such examiners, he noted, routinely induce nervousness and anxiety in the subjects being tested by telling them that the machine is indicating "deception" (which it is actually not) and by continuously pressing the individual to "clarify" his or her answers by providing more personal, intimate information.
Zelicoff also reinforced his case by citing how innocent people had their lives and careers ruined by erroneous interrogation of polygraph tests. Such was the case of David King, a Navy veteran held in prison for 500 days under the suspicion of selling classified information. King was arrested after failing a polygraph test and was subjected to repeated polygraph scrutiny, with some of these sessions lasting up to 19 hours, all with contradictory results. After a military court dismissed all charges against King, he was released, but his further military career prospects were tainted. As a physician, Zelicoff argued that the four parameters measured by polygraphslood pressure, pulse, perspiration, and breathing ratesan be affected by a myriad of emotions. He asserted that there is no medical literature that associates variations in these parameters with the intention of hiding the truth by individuals.
Charles R. Honts, a psychologist at Boise State University in Idaho, is considered one of the most qualified U.S. experts on the use and misuse of polygraphs, and is frequently requested to serve as an expert witness in court. Honts has spoken against the use of polygraphs in the workplace by government and private companies. Since the appearance of polygraphs, the main advocates of polygraphs have been psychologists and law enforcement agents. However, a growing number of studies by psychologists are concluding that polygraphs constitute incomplete science and are more likely a tool for suspect intimidation, where suspects are led by examiners to believe that polygraphs are high-precision devices that detect lies without human inference. The ethical aspects of how tests are conducted by inexperienced or poorly prepared examiners, plus the alleged use of unethical intimidation techniques by some examiners, have been the object of questioning in scientific literature, as well.
FBI forensic scientists, in turn, are testing methods of improving polygraph accuracy by using the test in association with a variety of known psychological methods utilized for detecting deception. One such psychological method is known as the guilty knowledge test/technique (GKT). GKT was adopted in 1959 as a valid psychological test for interrogating suspects in association with polygraphs. GKT is based on the premise that guilty subjects will show higher levels of physiological reactions when exposed to details of a crime that were not publicized when such facts are presented among incorrect information. It also assumes that innocent people will not show the same levels of physiological reactions. GKT is a popular test in association with polygraph tests among the Israeli law enforcement and security agencies. A paper published in Forensic Science Communications in 2003 showed the results of a study with 758 examinations made by polygraph examiners of 25 FBI field offices from November 1, 1993, to August 31, 1994, indicating that GKT should be used as a supplement in order to improve prevention of false positive results in polygraph tests.
Despite the controversies, the use of the polygraph is still advocated by some. Besides the strong power for lobbying that a billion-dollar industry has, polygraphs remain die-hard devices because they were also ingrained in the popular imagination as an infallible tool, partially due to the way they are portrayed in movies, television shows, and in thriller novels. Electroencephalograms (EEGs), however, are much more useful in detecting facts, because the brain stores true experiences and the fabricated facts in different areas. When individuals wired to an EEG machine are shown a sequence of images, including a crime scene and pictures of other persons, the brain areas responsible for true memories are activated by the recognition of images associated with the individual's real experiences.
In 2005, experiments on lie-detector technologies were being assessed by forensic experts at the Human Brain Research Laboratory in Fairfield, Iowa. Scientific methodologies and specific criteria for tests must first be adequately developed and validated, in order to prevent the birth of another popular myth.
SEE ALSO Brain wave scanners; Circumstantial evidence; Ethical issues; Evidence; Expert witnesses; FBI (United States Federal Bureau of Investigation); Federal Rules of Evidence; Interrogation; Malicious data; Psychology; Statistical interpretation of evidence.
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