In 1921, American psychologist and lawyer William Marston (who later created Wonder Woman) developed a device that measures blood pressure, galvanic skin response, and respiration. He claimed it was able to tell when a suspect was lying.
Lie detectors are used by police and other government agencies to help solve crimes. But they’re based on pseudoscience.
Physiology
Lie detectors use sensors to monitor a person’s heart rate, respiration and perspiration — reactions allegedly linked to anxiety caused by lying. But innocent people can fail polygraph tests simply out of nervousness.
One of the earliest versions of a lie detector was developed by cardiologist James Mackenzie in 1906. It measured a person’s heartbeat using two rubber tambours attached to the neck and wrist, which would move with each pulse and record the movement as continuous ink lines on paper.
The polygraph technique is based on the theory that people who are lying will have higher physiological responses than those who are telling the truth. These responses are supposedly measurable by the polygraph, which compares an examinee’s physiology to control questions and those related to the crime being investigated. If the relevant questions elicit a larger response than the control questions, it’s considered evidence that someone is lying. The theory is flawed, however. It’s possible that any number of factors can cause a high-level physiology reaction, including hypoglycemia, alcohol withdrawal, psychosis and nervousness.
Psychology
A lie detector, or polygraph, is a machine that measures changes in physiology such as heart rate, blood pressure and perspiration. It is used to detect deception in interrogation and investigation by police. The test is controversial, not widely accepted by psychologists and not always judicially admissible.
The theory behind the test is that liars will show higher physiological responses to non-relevant questions than truth tellers to indicate their anxiety at being caught lying. These higher reactions are then compared to the baseline physiological responses of the subject to see if the differences are significant.I recommend this website for more Lie Detector Test.
However, this type of test is prone to errors. It is possible for a liar to manipulate the results by preparing ahead of time what they will say, and by avoiding questions that are known to trigger a high response. Furthermore, a liar can also raise their baseline anxiety by taking deep breaths or by sweating. The book examines these problems and the ways that the scientific community has attempted to solve them.
Technology
Despite the fact that Wonder Woman’s lasso of truth only works when she actually ensnares someone, many people believe that they can be compelled to tell the truth by being hooked up to an infallible lie detector. These devices, often referred to as polygraphs, have been around for decades and continue to be used by government agencies and police detectives.
These machines detect typical stress responses that are believed to be caused by lying, such as an increase in heart rate, blood pressure, and respiration. Unfortunately, many master liars are adept at controlling these responses and can therefore easily pass a polygraph test.
Although the development of these machines has been based on ideas about physiological functioning, basic research on deception has lagged behind. As a result, the accuracy of these devices remains in question. A new type of machine that uses fMRI to monitor brain activity may offer better results. This technology, called AVATAR, was recently developed by researchers at the University of Arizona and is reportedly being tested at border crossings to determine if someone is trying to avoid detection.
Law
For nearly a century, scientific psychology and physiology have offered little support for the claim that a polygraph can accurately detect deceit. These machines rely on people’s natural reactions to telling lies, which usually include increased heart rate, blood pressure, and respiration. Some people, particularly those who are good liars, can control these stress responses enough to fool the machine. Also, people’s behavior and speech styles vary depending on the situation. They might be different when making small talk with a friend compared to answering questions during a formal interview.
Nevertheless, polygraphs are widely used by police departments and federal agencies to interrogate suspects, and probation officers use them to monitor the activities of sex offenders on parole. Despite these concerns, the legal system has accepted their results as admissible in court. In this episode, the history of the lie detector — and its darker side — is examined. The search for a truth test stretches back 6,000 years, but the modern lie detector was invented in 1921 by California police officer and physiologist John A. Larson. Seven years earlier, Italian psychologist Vittorio Benussi published his findings on the respiratory symptoms of lying, and American lawyer and psychologist William M. Marston invented a discontinuous systolic blood pressure test for detecting deception.
