ANGELO MOSSO – 1895 Studied fear and its influence on the hearth and his observations subsequently formed the basis for the technique.
Developed the SPHYGMAMOMANOMETER and the SCIENTIFIC CRADLE, which he used in studying fear on the heart.
CESAR LOMBROSO – 1895 Employed the first scientific instrument to detect deception. This instrument known as HYDORSPHYGMOGRAPH, measured changes in pulse and blood pressure when suspects were questioned about their involvement in or knowledge of a specific response.
Procedure on the use of the “HYDROSPHYGMOGRAPH” in detecting deception: Subject’s hand placed in a water filed tank sealed with membranes of rubber; Subject will be shown pictures connected with the crime or mention will be made to relevant facts of the crime; Pulsation of blood in fist was recorded on smoked drum.
WILLIAM MARSTON – 1915 He dealt with the sphygmomanometer which was used to obtain periodic discontinuous blood pressure readings during the course of an examination;
He also experienced with and helped to develop the pneumograph, which records breathing patterns, and the galvanometer, which registers changes in skin resistance.
JOHN LARSON – 1921 Developed the polygraph, an instrument capable of continuously records blood pressure, pulse, and respiration.
The polygraph instrument which he developed was polygraphic apparatus in a portable form. Had published more than anyone in this field.
THE LARSON POLYGRAPH -This is the first assemblage of apparatus and some of his co-workers in the Berkeley Police Department. A strip of paper on which the tracings are recorded is mounted on two drums, which are turned by a spring mechanism known as a kymograph. The paper is smoked to reduce the friction of the styluses or recording levers which are actuated by Marey Tambours. A manometer is placed on the right shoulder of the subject, the function of whish is to indicate the pressure in the bag, the pressure bag, encased in a leather cuff, is strapped pneumograph is strapped around the chest to record respiration. This type of pneumograph or respiration applicator is sill being used in some of the modern instruments. In a later model developed by Larson, a Jaquet polygraph replaced the kymograph and smoked paper, and the pens moved horizontally instead of vertically as in the original apparatus. In a further modification, metal tambour stacks were substituted for the Erlanger capsule and rubber covered tambours.