Who Invented Lie Detector? The lie detector or polygraph was invented by John Augustus Larson, a Canadian medical student who unveiled his prototype machine in 1921. Based on William Moulton Marston’s studies on the correlation between blood pressure and emotion. Larson’s Polygraph registered not only cardiovascular fluctuation but also a change in breathing. The talented John Augustus Larson established a protocol of yes or no questions, delivered by the interrogator in a monotone, to create a baseline sample.
Therefore, the result looked convincing, but the diligent Larson never felt that the tests were sufficiently conclusive to market his machine as a bonafide scientific instrument. Moreover, Larson’s assistant Leonard Keeler was less scrupulous. In 1926, he built his own version adding a monitor to detect levels of perspiration and touted it around to various American political parties and law enforcement agencies.
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By the late 1930s, the FBI and around a dozen police departments were using his lie detector. Most courts have since ruled polygraph evidence inadmissible, but almost a million tests are still conducted annually by American companies and other institutions.

How to Fool a Lie Detector?

The American Aldrich Ames, who was exposed as having spied for the KGB between 1985 and 1994, successfully passed a CIA lie-detector test on two occasions. On the advice of his Russian handlers, he prepared beforehand with a good night’s rest, then during the test remained calm and friendly towards the operator. Both times, the polygraph drew a blank.
The lie detectors the history of an American obsession Faking it? Leonard Keeler advertised his polygraph by claiming that it could identify a genuine kiss. In 1935 he used it in earnest for the first time to question two criminals from Wisconsin. After establishing their guilt, they were duly sentenced.
Who Invented Lie Detector
Who Invented Lie Detector Photo Credit – BBC
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