The level of accuracy of a lie detector depends on whom you talk to about it. Both sides of the argument have the same research to look at, but they come to very different conclusions. The lie detector test (or polygraph, to give its official name) is a fascinating topic. Did you know that the term “lie detector” is actually a misnomer?
A polygraph test simply measures a person’s physiological responses when answering questions; most typically, blood pressure, heart rate, sweating (galvanic skin response) and respiration (breathing rate). This is done in order to look for signs of autonomic arousal, from which deception can be inferred.
Investigating the link between physiology and deception has a long history within psychology.
In 1915, William Moulton Marston began to study the physiological symptoms of deception during his time as a graduate student at Harvard University; as a result, Marston would go on to develop the first systolic blood pressure deception (”lie detector”) test.
The fact that it was a psychologist who created, wrote and produced the Wonder Woman comic strip is really interesting. Marston’s work on lie detection is the reason why Wonder Woman has a Lasso of Truth!
Another source says that the polygraph had a different history. The earliest version was developed in 1921 when John Larson cobbled together previously developed measures of respiration, heart rate, and blood pressure that had individually shown promise as a measure of lying.
The American Psychological Association notes that: …most psychologists and other scientists agree that there is little basis for the validity of polygraph tests and that the most practical advice is to remain skeptical about any conclusion wrung from a polygraph. In 2002, a committee commissioned by the National Academy of Sciences to review and report on the scientific evidence on the polygraph, stated that: “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. Although psychological states often associated with deception (e.g., fear of being judged deceptive) do tend to affect the physiological responses that the polygraph measures, these same states can arise in the absence of deception.”
In February of 1994, the FBI arrested Aldrich Ames, who had been a CIA employee for 31 years. Ames was arrested and charged with espionage. He was a Russian spy. For nine years, he had been passing secrets to the Russians in exchange for over $1.3 million. His spying activities had compromised dozens of CIA and FBI operations. Worse yet, his treacherous crimes had led to the deaths of several CIA spies and the imprisonment of many more. During the time that Aldrich Ames was operating as a Russian spy, the CIA had twice given him a lie detector test. Despite having no special training in how to defeat a lie detector test, Aldrich passed both times. Spies are probably the world’s best liars, because they have to be, but most of us practice deception on some level in our daily lives, even if it’s just telling a friend that his horrible haircut “doesn’t look that bad.”
In 1986, Bill Wegerle was suspected of murdering his wife Vicki Wegerle after failing two polygraph tests. One test was given by the local police, the other was given by an expert that he hired. He was not arrested or convicted for the murder of his wife, but he lived under a cloud of suspicion for the murder. In 2005, DNA evidence proved that the BTK serial killer, Dennis Rader, did in fact murder Vicki Wegerle. Fluctuations may indicate that person is being deceptive, but exam results are open to interpretation by the examiner.
According to a polygrapher Dr. Bob Lee, former executive director of operations at Axciton Systems, a manufacturer of polygraph instruments, polygraph examinations are designed to look for significant involuntary responses going on in a person’s body when that person is subjected to stress, such as the stress associated with deception. The exams are not able to specifically detect if a person is lying. But there are certain physiological responses that most of us undergo when attempting to deceive another person. By asking questions about a particular issue under investigation and examining a subject’s physiological reactions to those questions, a polygraph examiner can determine if deceptive behavior is being demonstrated.
“Despite claims of ‘lie detector’ examiners, there is no machine that can detect lies,” a statement from the American Civil Liberties Union (ACLU). “The ‘lie detector’ does not measure truth-telling; it measures changes, but those physiological changes can be triggered by a wide range of emotions.” Undergoing a lie detector test can be an intimidating experience that can challenge the nerves of even the most stoic person. You are sitting there with wires and tubes attached to and wrapped around your body. Even if you have nothing to hide, you could be afraid that the metal-box instrument sitting next to you will say otherwise. Fittingly, undergoing the uncomfortable experience of a polygraph test is often referred to as “going on the box.”
There are times when a polygraph examiner misinterprets a person’s reaction to a particular question. The human factor of a polygraph exam and the subjective nature of the test are two reasons why polygraph exam results are seldom admissible in court. Whether you pass or fail a polygraph exam will often have very little legal ramification. The main argument over the admissibility of polygraph tests is based on their accuracy, or inaccuracy, depending on how you want to view it. The others say that typically, when someone is lying, a well-trained polygraph examiner can tell. It is not 100% accurate though.
The American Polygraph Association is the world’s leading Association, it is an organization whose members are largely polygraph examiners. They estimate the accuracy of the polygraph to be 87%. That is, in 87 out of 100 cases, the polygraph can accurately determine if someone is lying or telling the truth. That sounds pretty impressive, but it is important to keep in mind that the polygraph is failing 13% of the time. Some scientists have claimed that the accuracy may be closer to 75%.
No matter if you agree or disagree with the use of polygraphs, thousands of people undergo these tests every year, and many people’s lives are changed forever by their results.