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 History of the Polygraph


Since the dawn of civilization, mankind has sought ways to distinguish truthfulness from deception in those individuals suspected of criminal wrongdoing. Various inventive techniques for the verification of truth and the detection of deception have been tried over the centuries, many of these being ridiculous and barbaric. Despite their primitiveness, each technique was based on the assumption that some form of physiological reaction occurred within a person when confronted with certain stimuli regarding an event under investigation, and that this physiological reaction would, in turn, be manifested in certain recognizable external symptoms that were indicative of honesty or deception.


Ancient judicial methods for the detection of deception were based on religious faith and superstition. These methods consisted of trial by combat, trial by ordeal, or trial by torture.

Lie Detector Tests or Polygraph examinations are used in more than 50 countries by government organizations worldwide, law enforcement agencies, private security firms, the legal community, the corporate sector, and private citizens.


In a trial by combat, physical strength was used to resolve a dispute between two individuals. They would engage in a single battle wherein the outcome was based on divine judgment. It was believed that God would not allow the guilty to prosper and would, therefore, give victory to the person with the truth on his side. In cases where the accused was unfit to fight, for example, when a child, a woman, or a person disabled by age or infirmity was accused, they had the right to nominate a champion to fight on their behalf.


In a trial by ordeal, it was believed once again that God would intervene and protect the innocent by performing a miracle on their behalf. The following are some examples of a trial by ordeal.


Typically, the ordeal of fire required the accused to walk barefoot a certain distance (approximately 10 feet) over red-hot plowshares or to hold a red-hot iron bar, after which the feet or the hands were bandaged and re-examined three days later by a priest. If God had intervened to heal the burns, the innocence of the accused was established. If the injury was festering, the accused was judged to be guilty and was either exiled or executed.


In the ordeal of rice chewing, the suspect was made to chew on a handful of dry rice while being questioned and then told to spit it out after a certain amount of time. The rice was then examined. If the rice came out easy enough and was moist, the suspect was judged innocent. If the Gods made the rice dry and it stuck to the person’s mouth when they tried to spit it out, they were accused of lying and judged guilty. This result was based more on physiological reactions to stress and less on divine intervention. It was believed that stress caused by fear of detection slowed down the flow of saliva, thus causing the suspect to have a dry mouth.


The ordeal of the sacred ass involved a psychological test for detecting deception and not a physiological one. Before trial, priests placed a donkey in a pitch-dark tent and coated its tail with lamp black, a very fine black soot. Crime suspects were brought to the tent and told that the donkey inside was a "sacred ass" and would bray whenever a liar or guilty person pulled on its tail. Suspects did not know that the priests had previously coated the donkey’s tail with lamp black.


One at a time, each suspect was instructed to enter the pitch-dark tent and pull on the tail of the sacred ass to determine their innocence or guilt of the crime in question. Having nothing to fear, the innocent person would go in and pull on the donkey's tail, confident that it would not bray. As a result, their hands would be covered in lamp black when they exited the tent. Upon examination of their hands, it was evident to the priests that the suspect had, indeed, pulled on the donkey’s tail as instructed and was therefore judged to be truthful.


The guilty person would go in the tent and, avoiding any chance of the donkey braying and revealing his or her guilt, they would stand there for a few moments and then exit the tent without ever pulling on the donkey’s tail. When the suspect emerged from the tent with clean hands, free of lamp black, the priests knew that he or she had not pulled on the donkey’s tail as directed and was therefore judged to be guilty of the crime.


Trial by torture can be traced back to the Roman and Greek Empires, the most well-known era being that of the Spanish Inquisition. During this unsophisticated age, physical torture was the primary means of lie detecting. Torture techniques were many and various. By no means reliable, even a truthful person would confess to a crime if tortured for a long enough time.


Polygraphy — the science of truth verification based upon psychophysiological analogues — is barely 100 years old. The following is a timeline of selected events which led up to the birth of the polygraph instrument and Polygraphy as we know it today.


British novelist Daniel Defoe writes an essay entitled "An Effectual Scheme for the Immediate Preventing of Street Robberies and Suppressing all Other Disorders of the Night", wherein he recommends that taking the pulse of a "suspicious fellow" is a practical, effective, and humane method for distinguishing truthfulness from lying. Defoe’s is an early and insightful suggestion to employ medical science in the fight against crime.


Although not for the purpose of detecting deception, German physician and physiologist Carl Friedrich Wilhelm Ludwig invents what he calls a "kymographion", a device with the ability to record changes in arterial blood pressure and respiration simultaneously so that he can draw conclusions about the correlation between external respiration and the circulatory system. Ludwig’s kymographion records these physiological variables in graphical form using a metal stylus that marks a rotating drum wrapped with a sheet of smoked paper.


The kymographion not only changes the everyday work of physiologists, but other sciences benefit from it as well. Carl Friedrich Wilhelm Ludwig is credited for the invention of one of the most acclaimed apparatuses for quantitative measurement.


Science first comes to the aid of the truthseeker through the research of Italian physiologist Angelo Mosso. Mosso uses an instrument called a "plethysmograph" in his research on emotion and fear in subjects during questioning, and he studies the effects of these variables on their cardiovascular and respiratory activity. Mosso studies blood circulation and breathing patterns and how these change under certain stimuli. The use of the plethysmograph reveals periodic undulations or waves in a subject’s blood pressure caused by the respiratory cycle in response to certain stimuli. Angelo Mosso is the first scientist to report on experiments in which he observes that a person’s breathing pattern changes under certain stimuli and that this change, in turn, causes variations in their blood pressure and pulse rate.


The polygraph instrument was in existence, in its most basic design, as early as 1892. It was then that Sir James Mackenzie, a heart surgeon of London, England, constructed the clinical polygraph. Not intended for detecting deception in individuals, he used this instrument when giving medical examinations as it had the capability to record simultaneously undulated line tracings of the vascular pulses (radial, venous and arterial), by way of a metal stylus on to a rotating drum of smoked paper.


Until the end of the 19th century, no measuring device for the detection of deception is ever used. The first use of a scientific instrument designed to measure physiological responses for this purpose occurs in 1895 when Italian physician, psychiatrist and pioneer criminologist Cesare Lombroso modifies an existing instrument called a "hydrosphygmograph" and uses this modified device in his experiments to measure the physiological changes that occurs in a crime suspect’s blood pressure and pulse rate during the course of a police interrogation.


Notably, Lombroso’s early device for measuring pulse rate and blood pressure is similar to the cardiosphygmograph component of the contemporary polygraph. Although Lombroso did not invent the hydrosphygmograph, he is accorded the distinction of being the first person to use the instrument successfully as a means for determining truthfulness from deception in crime suspects. On several occasions, he uses the hydrosphygmograph in actual cases to assist the police in the identification of criminals.


Sir James Mackenzie, M.D., refines his clinical polygraph of 1892 when he devises the clinical ink polygraph with the help of Lancashire watchmaker, Mr. Sebastian Shaw. This improved instrument uses a clockwork mechanism for the paper-rolling and time-marker movements, and it produces ink recordings of physiological functions that are easier to acquire and to interpret.


Although not for the purpose of detecting deception in suspects, Dr. Mackenzie’s ink polygraph is the first-known instrument that contains the essential features of the present-day instruments, and its construction is based on precisely the same principles. It is written that the modern polygraph is fundamentally a modification of Dr. Mackenzie’s clinical ink polygraph.


Italian psychologist Vittorio Benussi discovers a method for calculating the quotient of the inhalation to exhalation time as a means of verifying the truth and detecting deception in a subject. Using a "pneumograph", a device that records a subject’s breathing patterns, Benussi conducts comprehensive experiments on the respiratory symptoms of lying. He concludes that lying causes an emotional change within a person that results in detectable respiratory changes that are indicative of deception.


Dr. William Moulton Marston, a lawyer and psychologist, discovers a correspondence between telling a lie and a rise in a person's blood pressure. He develops the Discontinuous Systolic Blood Pressure Test and invents an early form of the polygraph when he builds a device with the capacity to measure changes in a person’s blood pressure. Dr. Marston’s technique uses a standard blood pressure cuff and a stethoscope to take intermittent systolic blood pressure readings of a suspect during questioning for the purpose of detecting deception.


Dr. Marston’s discontinuous systolic blood pressure test later becomes one component of the modern polygraph.


John A. Larson, a police officer with the Berkeley Police Department with a Ph.D. in physiology, builds on the work of Dr William Moulton Marston and develops what many consider to be the original "lie detector" when he adds the item of respiration rate to that of blood pressure. Larson's instrument provides continuous readings of these physiological responses rather than discontinuous readings of the sort found in Dr Marston’s device. Larson calls his instrument a "cardio-pneumo psychograph", which later becomes known as a "polygraph", a word derived from the Greek language meaning "many writings" since it could read several physiological responses at the same time and record these responses on a rolling drum of smoked paper for future analysis and evaluation.


Using his polygraph, John A. Larson is the first person to continuously and simultaneously measure changes in a subject’s pulse rate, blood pressure, and respiratory rate during questioning. His polygraph is used extensively, and with much success, in police investigations at the Berkeley Police Department.


Leonarde Keeler, who gains firsthand experience in polygraph interrogations as a result of working with John A. Larson at the Berkeley Police Department, works to devise a polygraph that uses "inked pens" for recording the relative changes in blood pressure, pulse rate, and respiratory activity, thus eliminating the need for smoking the paper and having to preserve it with shellac.


The Keeler Polygraph comes on the market as the "new-and-improved" lie detector, an enhanced version of John A. Larson’s polygraph.


Leonarde Keeler further refines the Keeler Polygraph when he adds a third physiological measuring component for the detection of deception — the psychogalvanometer — a component that measures changes in a subject’s galvanic skin resistance during questioning. In doing so, Keeler marks the birth of the polygraph as we know it today.


Leonarde Keeler patents what is now understood as the prototype of the modern polygraph — the Keeler Polygraph. Today, Leonarde Keeler is known as the "Father of Polygraph".


John E. Reid, a lawyer from Chicago, develops the "Control Question Technique" (CQT), a polygraph technique that incorporates control questions that are designed to be emotionally arousing for truthful subjects and less emotionally arousing for deceptive subjects than the relevant questions. The Reid Control Question Technique is a breakthrough in polygraph methodology and it continues to be the polygraph technique that is used by most examiners today. Reid’s CQT replaces the "Relevant/Irrelevant Question Technique" (RIT), a technique which uses relevant or irrelevant questions during a polygraph examination.


Leonarde Keeler opens the world’s first polygraph school — the Keeler Polygraph Institute, in Chicago.


Richard O. Arther experiments with two pneumographs and finds there is a difference between the thoracic and the abdominal pattern about 33% of the time. By utilizing two pneumograph channels, the best recordings of the respiratory changes would always be recorded.


Arther also experiments with the use of Galvanic Skin Response automatic and manual modes and finds there is not a significant difference between the two.


Cleve Backster, building upon the Reid Control Question Technique, develops the "Backster Zone Comparison Technique" (ZCT), a polygraph technique which primarily involves an alteration of the Reid question sequencing.


Cleve Backster also introduces a quantification system of chart analysis, making it more objective and scientific than before. His system for the numerical evaluation of the physiological data collected from the polygraph charts is standard procedure in the field of Polygraphy today.


The study of the use of computers in the physiological detection of deception progresses through several phases.

Late 1970s

Dr Joseph F. Kubis, of Fordham University in New York City, is the first researcher to use potential computer applications for the purpose of polygraph chart analysis.


Research is conducted on computerized polygraph at the University of Utah Psychology Laboratory by Drs John C. Kircher and David C. Raskin.



Drs John C. Kircher and David C. Raskin develop the "Computer Assisted Polygraph System" (CAPS), which incorporates the first algorithm used for evaluating physiological data collected for diagnostic purposes.




At Johns Hopkins University Applied Physics Laboratory, Dr Dale E. Olsen, assisted by Mr John C. Harris, completes a software program called "POLYSCORE". The program implements an algorithm-based chart-scoring system to analyze the polygraph data collected and to estimate a statistical probability of deception in a subject after questioning.




Polygraph makes its formal entrance into the computer age.




POLYSCORE Version 5.1 analyzes the data from polygraph examinations administered in 1,411 real-life criminal cases provided by the United States Department of Defence Polygraph Institute for study and comparison purposes.


Validated algorithms exceed 98 percent in their accuracy to quantify, analyze, and evaluate the physiological data collected from polygraph examinations administered in real-life criminal cases.




The United States Department of Energy (DOE) commissions a review committee of The National Academy of Sciences (NAS) to study the scientific evidence on the polygraph. In this endeavor, the Committee sifts through existing evidence in the polygraph research literature and does not conduct any new laboratory or field research on polygraph testing for, as they report:


"Real-world conditions are difficult — if not impossible — to replicate in a mock-crime setting or a laboratory environment for the purpose of assessing polygraph effectiveness."


The Review Committee of The National Academy of Sciences concludes that, although there may be alternative techniques to polygraph testing, none can outperform the polygraph, nor do any of these yet show promise of supplanting the polygraph in the near future.


Present Day


Polygraph examinations or psychophysiological credibility assessments are used in more than 50 countries around the world by government organizations, law enforcement agencies, the legal community, the corporate sector, and private citizens.


Withstanding more than a century of research, development, and widespread use, the polygraph examination remains the most effective means of verifying the truth and detecting deception.

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