The search for truth in the matter of lies has occupied mankind for thousands of years. Some theorized that deception could be assessed by monitoring physiological changes.

The modern polygraph records several physical measures simultaneously, including heart rate, blood pressure and sweat gland activity. A spike in these measures during questioning suggests that someone is lying.

John A. Larson

In 1921, Larson, a medical student working for Berkeley Chief of Police August Vollmer, constructed the first polygraph for use in criminal investigations. His cardio-pneumo psychograph simultaneously tracked a subject’s systolic blood pressure and respiration using an Erlanger sphygmomanometer and kymograph and recorded them on smoke-blackened paper.

He had been influenced by the work of William Moulton Marston, who had found that a person’s blood pressure changes when he or she lies. He also took into account the research of Cesare Lombroso, who found that electrodermal reactions to words can indicate deception.For more info I’ll suggest you visit the website UK Polygraph Association.

While Larson hoped his device could put an end to physical abuse in interrogations, it was his protege Leonarde Keeler who made the lie detector a common feature of American life. His documentary, “The Lie Detector,” airs Tuesday at 8 p.m. on New Mexico PBS and streams online.

William Moulton Marston

The modern lie detector, also known as a polygraph, measures several physiological responses including heart rate, blood pressure, and sweat gland activity. A rise in these symptoms is believed to indicate deception and can be read on a graph that records the responses on a rotating drum of smoke paper.

During his early studies, Marston discovered that lying could be detected through a person’s physiological reactions to questioning. These changes included a faster heart rate, increased blood pressure, dry mouth and perspiration.

Marston was a multi-talented man, a psychologist and inventor with an impressive list of achievements. He was the creator of Wonder Woman and her truth-invoking golden lasso, an author, and a pioneer in the field of women’s rights. He also authored the foundational theories behind DISC behavioral analysis.

Cesare Lombrosso

Cesare Lombrosso (1835-1909), born Ezechia Marco Lombroso, was an Italian physician and criminologist. He served in the Austro-Italian War as a military surgeon and later studied at the universities of Padua, Paris, and Vienna. He became a professor of legal medicine and hygiene at the University of Turin, where he also taught criminology and psychiatry.

His work focused on anthropological criminology, which combined ideas from physiognomy, degeneration theory, and phrenology with concepts from social Darwinism and eugenics. He believed that criminality was hereditary and could be identified by physical markers such as the shape of the skull. He conducted detailed studies of living and dead criminals to identify these markers. His most famous book was L’UomoDelinquente (The Criminal Man, 1876). He was a prominent advocate of humane treatment of criminals and limitations on the use of torture.

Vittorio Benussi

While modern polygraph machines have incorporated technological advancements, they still operate on the same principle as the first devices. These instruments monitor changes in a subject’s physiological responses, including heart rate, blood pressure, perspiration and breathing. They are designed to detect deception by comparing the subject’s normal responses with those that occur when they are lying.

Benussi’s research on dreams and sleep was also notable. He published I sogni: studiclinici e psicologici di un alienista (Dreams: Clinical and Psychological Studies by an Alienist) in 1899, which was later cited by Freud in his Interpretation of Dreams.

He was also an important figure in the development of experimental psychology in Italy. He worked with leading researchers of his time in Berlin and Graz, and made theoretical discoveries that were adaptable to experimental tests. He based his research on the concepts of kinesthetic awareness and emotional functional autonomy.

Leonarde Keeler

After learning about Lombrosso’s findings, Keeler began experimenting with an instrument to detect deception. He constructed his first polygraph in 1921, which simultaneously recorded a subject’s heart rate, blood pressure, and respiratory variations on a rotating drum of smoked paper. It worked so well that it reportedly resulted in the confession of a murder suspect.

But the device had many drawbacks. For one, it took a half hour to set up and the tracings of a suspect’s responses had to be smoked to preserve them. To reduce the preparation time, Keeler replaced the smoked paper with ink pens. He also added a galvanometer to measure the subject’s skin resistance. This improved the polygraph significantly. It is now considered the forerunner of modern lie detection technology.