12 Facts About Polygraph

Polygraph, often incorrectly referred to as a lie detector test, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions.

The NAS found that "overall, the evidence is scanty and scientifically weak, " concluding that 57 of the approximately 80 research studies that the American Polygraph Association relied on to reach their conclusions were significantly flawed.

The Employee Polygraph Protection Act of 1988 generally prevents employers from using lie detector tests, either for pre-employment screening or during the course of employment, with certain exemptions.

The video, ten minutes long, is titled "The Truth About the Polygraph" and was posted to the website of the Defense Security Service.

Polygraph was invented in 1921 by John Augustus Larson, a medical student at the University of California, Berkeley and a police officer of the Berkeley Police Department in Berkeley, California.

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Polygraph results are only admissible in civil trials if the person being tested agrees to it in advance.

Polygraph testing is widely seen in Europe to violate the right to remain silent.

Early devices for lie detection include an 1895 invention of Cesare Lombroso used to measure changes in blood pressure for police cases, a 1904 device by Vittorio Benussi used to measure breathing, the Mackenzie-Lewis Polygraph first developed by James Mackenzie in 1906 and an abandoned project by American William Moulton Marston which used blood pressure to examine German prisoners of war .

Polygraph entered Harvard Law School and graduated in 1918, re-publishing his earlier work in 1917.

Polygraph's appears in a picture taken in his polygraph laboratory in the 1920s .

Polygraph's device was then purchased by the FBI, and served as the prototype of the modern polygraph.

Polygraph failed to catch Gary Ridgway, the "Green River Killer".