Lie Detector invention history – History of the polygraph machine

Jul 21, 2022 | News & Science, Polygraph Examiner

Polygraph history

Since the very beginnings of our civilisation people have been aware of the advantages arising from discovering a lie detection method and have searched for ways to verify given statements.

As time went by, new ideas were developed and implemented until the methodology evolved to the point where the World was presented with a polygraph – an actual machine capable of detecting lies, ready to revolutionize criminal cases or any other field in which they could be used.

The polygraph we know today has also gone through many modifications and is a machine which is much more advanced technologically than its version from the 19th Century. For us to be given the possibility to use it, hundreds of years of research, development and experiments were needed. Just the fact that this all begun with a single handful of rice shows us that the polygraph is truly a workpiece of a whole civilization.

Knowing the truth is sometimes one of the biggest advantages one can have. Having the ability to detect lies would allow us to verify the truthfulness of people surrounding us and help us select the people we want to trust.

Raw beginnings

Lie detection was already considered an important case way back in Ancient China. That is where the first methods were established. The Ancient Chinese made one very clever observation that lying was connected with stress. Stress, on the other hand, was connected with a fall in saliva production which caused a person’s mouth to go dry. A person questioned was asked to chew a handful of rice during questioning. Once the interview was over, the grains would be spat out and examined. If moist – the person examined was considered truthful. On the other hand if the rice appeared to be dry, that meant the person was lying and the statements given were to be dismissed.

Detecting lies was needed for many different reasons, for instance the warriors of Ancient Sparta needed this knowledge to be able to identify those new and young warriors, who were truly fearless. At the day of their challenge they would be placed at an edge of a cliff and asked if they were scared. Obviously the answer was always negative but it was not about the answer itself but about the way it was said. If the older warriors detected any sign of freight in the young boys’ voices, they would push their apprentices down the cliff.

Time went on and so did the evolution of lie detection. Each tribe would have their original ways to determine whether someone was lying or not and the methods used would sometimes be absurd as also brutal. An extremely brutal example of such practices was the Inquisition. Methods used to determine who was lying or not were extremely brutal and in most cases would lead to the death of the person interrogated. Known as one of the darkest times of the Roman Catholic Church, those times also gave mankind an idea on how to verify given statements.

Of course the Inquisition would hardly ever accept an answer which would save an individual’s life but despite the controversy another very interesting observation was made. At that time people had also started to analyse the blood flow during an interrogation. Although they weren’t aware of it yet, the factor they were examining was the pulse. Despite not knowing exactly what was the subject of the measurement, people still managed to make an observation, which would later be confirmed a couple of centuries later. They realized that each time someone was lying, the pulse of a given person would rise. This led to new methodologies which gave the beginning to developing a real polygraph.

Getting closer

Although technology developed, nobody managed to come up with an idea which would be even close to the polygraph which we know today. That is until 1875 when an Italian physiologist, Angelo Mosso began research on the subject of how fear was related to lying.

In his studies, Mosso proved that if lying was connected with fear, there would be ways of measuring changes in the subject’s body which would lead to the detection of a polygraph technology. The Italian researcher realised that not only the pulse could be affected by lying but also other features such as respiratory rate or blood pressure. This gave him the impulse to move on and construct a series of devices called “plethysmographs”. The constructed machines would measure changes in breathing or blood pressure and gave Mosso a first actually scientific way to determine who was lying and who was telling the truth.

The idea was very simple. If during questioning a change of breathing or blood rate would be observed a conclusion would be made that the subject was afraid. This connected with the well-known to human kind theory, that lying was connected with stress and fear, gave the conclusion that the person interviewed was giving false statements. Although still pretty far away from achieving an actual polygraph, human kind had finally come up with a device, which was capable of helping in making the decision if someone was lying or not.

Developing a new theory

After Mosso’s success, research continued to go on. The father of a new discovery was French therapist, Dr. Marie Gabriel Romain Vigouroux. In 1879 he started researching a new factor, which would later be known as the “Electrodermal Response”. The theory said that when faced with lying, the electrical resistance of the skin would change in such a way that it was measurable. In order for this to be possible a stimuli was needed. Dr. Vigoroux summarized all of his studies in an article which got published in 1879, forming a foundation for further research to take place.
Many attempted to find new facts about this discovery and some of them managed to add their small part to the development of the new technique.

Boris Sidis, a psychology professor at Harvard University was next to mark his name in the story of the Polygraph. He performed a series of experiments all happening as a part of a study named “ A Study of Galvanic Deflections Due to Psycho-Physiological Phenomena”. Sidis managed to prove the relation between emotions and galvanic changes in the human skin. All of his discoveries and conclusions were once summarized and presented in front of the American Psychological Association at Harvard University in 1909.

First time in court

The year 1895 brought the work of an Italian criminologist Cesare Lombroso. He was the first person to conduct experiments with a device focused on measuring blood pressure and pulse in order to detect deceit. Lombroso would monitor the change of blood pressure straight after certain questions were asked. A dedicated device was responsible for the measurements and was given the name of a Hydrosphygmograph.

In 1895 the Italian published documents which showed the use of a plethysmograph and a sphygmomanometer in order to interrogate criminals. This gave wonderful effects. Seven years after the documentation was presented, in 1902, a mechanical device was used to support the process of proving a man’s innocence in court for the very first time. The debut of the machine was well received which meant that the society was giving a clear green light for further development. As each month passed the first polygraph was slowly becoming a reality.

Focus on breathing

In 1914, Italian Vittorio Benussi focused on the breathing processes of a person interrogated. He made an announcement that a liar could be recognized by his breathing rate. In order to prove his discovery, Benussi constructed a pneumograph, which would be responsible for breathing measurements.
The technique used in the time later proved to be the foundation to the way we monitor this factor today. All is based on the so-called I/E ratio which stands for “Inspiration/Expiration ratio”.

Researched and measurements conducted by Benussi proved that if we divided the length of inspiration by the length of expiration during a lie, we would discover that the I/E ratio has a trend of growing when false statements are given. The last element was finally ready.

Father of the polygraph

After years of research and studies conducted by exceptionally talented scientists, the World was finally given the first ever polygraph, also known as a Lie Detector. A device capable of monitoring more than one factors during questioning. There were three basic factors: blood pressure, pulse rate and breathing rate.

The machine was presented in in 1921 by a medical student named John Augustus Larson. The young doctor decided to build a device which would aid the work of investigators in criminal cases. This led him to being the first person ever to measure more than one body process at a time.

With the polygraph finally announced, work began in order to improve the accuracy of the new invention. The first matter that Larson decided to improve on was to come up with a certain interviewing technique which would strongly improve the performance of the new invention. The young scientist though did not come up with a uniquely new idea but based his method on a procedure which was already once invented. The inventor referred to a technique developed by American psychologist, lawyer and inventor William Moulton Marston who had produced a scientific method of interviewing even used during World War I. But the concept which Larson had presented to the Berkeley Police Department in 1921 was a widely modified version of Marston’s idea.

Thanks to working as a Police Officer, the Larson managed to develop a technique called the R/I (relevant/irrelevant) procedure. The method was simple, as questions were being asked, Larson would make a mixture of questions. Some of them would be relevant to the main subject of the examination while others were totally irrelevant to the given subject. This gave good effects and allowed the proper use of the first polygraph.

The invention itself is considered such a breakthrough, that it was listed on the Encyclopaedia Britannia Almanac 2003 list of 325 Greatest Inventions. Larson continued his life until 1965, when he died of a heart attack at the age of 72. He himself did not add any other relevant features to his device but opened a whole new chapter in the history of criminal investigation.

Further developments

Once the first polygraph had finally been presented and actually used, more and more researchers began to find ways, in which the polygraph could be improved even more. The one to do so could be nobody else but John Larson’s co-worker Leonard Keeler.

The two men had the opportunity to work together at the Berkley Police Department where Keeler would gain experience in polygraph statement verification. He was so fascinated with the invention that he decided to improve the device with some ideas, that he had come up with. And so just 4 years after the first use of a polygraph, in 1925, Leonard Keeler constructed a new version of the device equipped with special ink pens, which were responsible for the presentation of the changes happening in a person’s body during questioning.

From now on, the examiner had a much easier job in observing changes in the subjects breathing rate, pulse as also blood pressure. This of course was to improve the accuracy of the performed tests. But Keeler did not stop with that. 13 years later, in 1938, Keeler came up with a totally new addition to the lie detecting machine.

The knowledge he used had already once been discovered back in the 19th Century by Dr. Vigoroux but this time, the aim was to invent a device or attachment which would precisely measure skin electrical resistance. This marked the birth of the psycho galvanometer. Once everything was connected together and ready to use, the authorities were presented with the Keeler Polygraph, the first to have the form of a polygraph very close to the ones we use today. And as much as we could call Larson “The father of the polygraph”, it goes without doubt that Keeler is definitely “The father of the modern polygraph” and quite frankly this could not be more true, because the form of the polygraphs we use today is extremely similar to it.

Keeler continued with his research in the field of polygraph examining and managed to add some improvements to interviewing techniques. He became a well-recognized polygraph examiner known around the World thanks to the astonishing results he achieved with his device. In 1931 the device received its patent, which would later make it the most popular polygraph for next 30 years. Keeler though did not stop and continued to examine criminal after criminal.

By the time of 1935 he had already managed to examiner over 2000 wrong-doers. The inventor marked his name in one more astonishing project. In 1947 he established the Chicago-based Keeler Polygraph Institute – the first ever polygraph school. This would be his last major achievement before his death in 1948. Through his whole career, Leonard Keeler is said to have conducted over 30,000 examinations.

A great success

Undoubtedly the polygraph was a great success and thanks to its wide applications, expectations grew regarding its further improvement. The next person to have a significant influence on the development of the revolutionary truth verification methodology was John E. Reid, a lawyer from Chicago. Between 1945 and 1947 he developed a new technique which was named as the “Control Question Technique”. The concept was based on asking control questions for comparison. For those, who were telling the truth, the irrelevant questions would cause a stronger reaction than for those who were actually lying. John E. Reid was known also known for the development of the so-called “Reid technique” which was to be used during interrogations.

The method caused a lot of controversy which has lasted until this day mainly due to the fact, that there are strong opinions that the “Reid technique” can produce false results. Despite that it goes without saying that the “CQT” (Control Question Technique) revolutionised polygraph testing once more and gave new possibilities for the improvement of polygraph accuracy. John E. Reid did not only stop with changing his interviewing methods. The lawyer is also known to be the first person to use motion detectors during polygraph examinations. Those were used to monitor the activity of the body’s muscles during interrogation. Any sign of unnatural movement gave a hint, that the person answering the questions was a liar.

The last big improvement to the lie detector before the computer era was introduced by Cleve Backster. The ex CIA polygraph examiner introduced a totally new technique of a quantified chart analysis. This allowed examiners to deliver much more effective and accurate results. The presented method, with the use of a numerical analysis, has been used till today and is an absolute basic tool in achieving reliable polygraph results.

The 1950’s also marked the beginning of production for Lafayette Instrument Company. Though established already in 1947 by Max Wastl, it took the company a couple of years before it started manufacturing polygraphs on a regular basis. Lafayette has since become the biggest polygraph manufacturer in the world offering devices of the highest quality. The machines are approved by all polygraph associations and are an absolute number one among professional polygraph examiners. The founder, Max Wastl, couldn’t even imagine how big an influence his new company will have on the further development of the polygraph.


The use of the polygraph continued and their popularity grew with each month. The devices had come widely used in the United States with tens of thousands of tests conducted each year. As technology developed, it had soon become time for the polygraph to enter the computer era. Research had already started in the 1980’s when a group of scientists at the University of Utah invented a “Computer Assisted Polygraph System” (CAPS). This meant that from now on a computer would be responsible for the initial interpretation of the measurements thanks to an algorithm placed in it.

Research continued with a great result in 1992 when the polygraph made its official step into the computer era. What did this mean for the device? One very important factor had to be taken into account. Thanks to the fact, that the polygraph could now be connected to a computer, researchers received a whole new field, in which they could search for the further improvement of the polygraph technology. They key to doing so was to improve the computers used to analyse the measurements.

Technology went on, computers became more and more advanced technologically, more capable of presenting precise results. Dedicated software would soon be developed making the use of the polygraph even more reliable. Lafayette Instrument Company also took an active part in the development of their machine. In 2007 the manufacturer presented the first ever wireless polygraph. They later went on to constructing the LX4000-SW, which is now one of the most known models in the world.

Polygraphs today

The polygraph remains to be a very popular method of verifying statements and with many associations and agencies now everyone has the chance of using the polygraph for their own needs. The popularity among corporate cases grows from year to year but what is more interesting is the fact, that the industry has noted a dynamic increase in the demand for private cases as well. It goes without saying that polygraph examinations are a highly wanted service.

Despite all of the popularity, along with the rapid computer development more and more controversy arose around the device. It has been a couple of years now since the polygraph was used as a fully reliable source of evidence in court. This is because of the general debate which has taken place about the accuracy of the polygraph. Those in favour of the device show research which has proven, that the polygraph is capable of reaching an accuracy level of 98%. On the other side, other groups remind us that that is a statistic valid for a couple of extreme cases and that the average accuracy rate lays in the range of 60-70%.

Although official scientific research has been made to confirm the usefulness of the polygraph, the device has still not been approved for full use in court. In many countries and states it is used as a supplement and is often useful when investigators search for new evidence. Undoubtedly the polygraph is a machine with many capabilities and can be truly called an invention of many generations. Beginning from a handful of rice to a highly advanced device it is pretty obvious that it’s further development will at some point deliver us a machine which will be capable of delivering us the information that we need.

The hard work of our predecessors must be continued and it won’t be long until the world is once again introduced to another revolutionary solution in the lie detection industry.

Copyright 2022 © All rights reserved LIE DETECTOR TEST UK

Regional offices and discreet controlled locations across the United Kingdom