Polygraph

The polygraph, often incorrectly called a lie detector, is a device that measures and records several clinical biomarkers, such as blood pressure, pulse, respiratory rate and skin conductivity, while a person answers a series of questions, and it is used to purportedly detect lies. Its use rests on the discredited assumption that physiological changes can reliably reveal deception, and the scientific community considers polygraphy a pseudoscience, although in some countries it is used as an interrogation tool with criminal suspects or for screening candidates for sensitive public or private sector employment. Earlier devices for lie detection include an 1895 blood pressure apparatus by Cesare Lombroso and the Mackenzie-Lewis Polygraph of 1906. A device recording both blood pressure and breathing was invented in 1921 by the medical student John Augustus Larson and first applied in law enforcement by the Berkeley Police Department, and Leonarde Keeler, as Larson's protege, made it portable, added the galvanic skin response in 1939 and produced the prototype of the modern polygraph that the FBI bought.