History

Dr. James Mackenzie

In the early 1900's physiologists found lying could cause physical changes such as a faster heartbeat or increased sweating. Dr James Mackenzie a British heart surgeon invented the first polygraph, a medical instrument that measured and recorded these changes as continuous lines on paper.

William Marston

In 1915 William Marston used his technique  of discontinuously recording peoples systolic blood pressure in intervals while asking questions. 

John Larson

The polygraph was improved upon in 1921 by John Larson who simultaneously recorded breathing and cardiovascular responses for lie detection purposes. 

Leonarde Keeler

The polygraph instrument was updated again by Leonarde Keeler who filed a patent in 1925 and by 1931 it was granted. Keeler added the Galvanic Skin Response or the measure of the skin's electrical resistance. The modern day polygraph instrument has advanced technologically from a large medical device to a easily portable instrument that attaches to a laptop.