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The science, or lack thereof, of the polygraph test

Although lie detectors have been notoriously wrong in New Mexico and across the country for years, it seems that many people are still not ready to let go of this “science.” The inventor even warned about calling the device a “lie detector” because he knew that the results weren’t there. It seems that people are still clinging to the hope that these devices will one day work 100% of the time. Although innovators are working hard at making that happen, the technology is simply not there yet.

The invention

John Larson, in 1921, was working as a cop for the Berkeley, California, police department. Larson, who held a Ph.D. in physiology and was at the time a criminologist, wanted to make police investigations more scientific and less about emotional reactions from third-party witnesses. Using the work of William Moulton Marston, Larson began to think about how he would be able to make this happen. He understood that people who are lying or are under stress show physical tells. Therefore, being able to measure these physical tells in real time would be a great way to catch people in a lie.

How the machine functions

Currently, the polygraph test will record a person’s heart rate, respiration and perspiration in real time. The machine will typically be hooked up to a person’s chest, fingers and arms. When the person begins to have an increase in heart rate or respiration after being asked a question, the machine will often record that as a lie.

The verdict

After its invention, the polygraph test was used by police departments from all over the country to catch people lying. However, in 1922, a judge prohibited test results of a polygraph from being used in court. The notion was that because the test was so unreliable, it should not be presented as evidence as it could potentially sway a jury.

As you can see, there are serious issues with the modern polygraph test. If you are ever faced with taking this test, you should ensure that you have proper legal counsel from a criminal defense attorney beforehand. An attorney may help you understand and protect your rights.