ABSTRACT
While the first ink polygraph instrument was developed by Sir James Mackenzie (Figure 2.1) for European physicians, which had the ability to continuously record complex physiological changes,1 the first polygraph instrument specifically developed to verify truth was in 1921, by John Augustus Larson, at the Berkley, CA, Police Department. It was able to continuously monitor both respiration and cardiovascular activity. It is classified as an analog pneumatic or mechanical instrument because the only electricity needed was for the chart drive mechanism. The two components measuring physiological activity (pneumo and cardio) did not require any electrical input.
