Polygraph testing: a history of lie detection



Polygraph testing is, in all likelihood, the most well-known and contested forensic tool. Although its history is steeped in lie detection in the context of criminal interrogations, today it has various other applications. From the first traces of early lie detection, to the first model of the polygraph up until the modern polygraph instrument we use today, polygraph testing has a long and compelling history. There is much research and technological advances that we have to thank for bringing us the polygraph testing we depend upon today. In just a few minutes of reading, find out all you need to know about the history of polygraph testing.




What is lie detection?


Before we launch into the fascinating history of lie detection and how the polygraph instrument we know today came to be, it is important to understand the specifics of lie detection itself. Lie detection is quite a significant part of many legal, medical and criminal professions. The latter, in particular, involves police officers who are continuously being challenged by subterfuge after a crime has been committed. Lawyers and judges alike also require the truth in order to judge or work on cases respectively.


Some other reasons for the employment of lie detection are:


  • National security screening
  • Employment screening
  • Suspicions of infidelity
  • Labour case disputes


The history of lie detection


Even before the creation of polygraph testing, there were several early methods of lie detection. One of the first systems to prove truthfulness of a statement uttered by an accused person was employed in China in around 1000 BC. The accused was ordered to fill their mouth with a handful of dry rice and after some time, they were required to spit out the rice. If the rice was found to be dry, the accused was named as guilty of deception.


Although it may sound strange, this method was created around the physiological principle and assumption that decreased saliva and a dry mouth was associated with anxiety and fear. Naturally, this method left much room for error since most of the accused, whether guilty or not, would have felt a degree of fear and anxiety – and most put on trial in this manner ended up being executed.




In European countries, historians have found that their early lie detection methods were enacted during the “trial by ordeal.” It was used by authorities in attempt to uncover the truth and pick out deception. The truth of a claim was decided based on the favourable or unfavourable outcome of an act that the accused was forced to go through.


The idea behind this method was that God would never let a righteous individual suffer or let injustice prevail. For example, within the area of present-day Slovakia, the courts of the 11th century carried out trials by ordeal. Two tests, each involving hot or cold water respectively, were frequently employed.


The test involving hot water consisted of the accused placing their hand in a boiling hot cauldron and holding it there for a decided amount of time. If the hand, upon removal, showed few traces of scalding, it represented a signal that the person’s claim was truthful. In 1593 there was a lot of contestation to this method and doubts as to its appropriateness as a lie detection technique, which resulted in it being disapproved.


Alternatively, the accused was tasked with finding a stone or rink out of a boiling cauldron. The cold water test, on the other hand, involved the accused being thrown into water in a roped sack. Should the person emerge after a short while, it was believed that “not even the water accepts them” and essentially the person was deemed guilty. This method remained popular up until the 18th century.




Similar to the method used in early China but perhaps less informed, some early European courts turned to the use of consecrated meal. The person accused was given a piece of dry bread as well as a piece of hard sheep’s cheese. The individual undergoing testing was exonerated in the event that they managed to swallow the contents in one bite without too much difficulty. If the individual suffocated or choked, however, this resulted in a guilty verdict.


Around the 15th century, people began to realise that the innocence or guilt of a person could not be accurately established using the above methods. This change was also brought about by the development of the various scientific fields. Despite this realisation, the cold water method, mentioned above, was still used for the substantiation of witchcraft.


The development of phrenology and graphology


In 1870, a man by the name of Franz Joseph Gall found that deception could be detection through recognitions of the accused’s emotions. This theory was further developed by his dedicated pupil, Spurzheim. They examined the specific areas the brain with the assumption that relations existed between different abilities and the shape of a skull. Interestingly, their theory indicated the brain as the central organ of the mind, which perceived distinct emotions such as ambition, destructiveness and most importantly in this case – the tendency to lie as well as take part in criminal behaviour.


In mapping the human skull, a new scientific discipline was created – phrenology. Gall proceeded to publicly demonstrate various criminals and the anomaly of their skulls after shaving their heads. Through this discipline, he attempted to discover liars randomly from the audience based on the shapes of their skulls. Although the former may sound rather strange today, in the field of criminology, phrenology significantly aided the spreading of the belief that behaviour such as lying should be studied carefully. Despite this contribution, phrenology, unsurprisingly, fell away and was discredited.




Around the same time, graphology began its spread in 1875. It was considered to be a rather useful scientific method of detecting lies. Graphology’s interesting origins began with the effort to detect forged signatures, based on the assumption of its founder, J. H. Michon, that there are peculiarities of handwriting that may relate to specific personality traits. Following this, graphology attempted to identify personal writing movement as a way to establish the nature of the writer. During World War I, graphology was used as a means of lie detection to verify the authenticity of signatures and documents – although it was not widely accepted or deemed scientifically appropriate. Despite this, graphology is still used today in the context of personality assessments and employment profiling.


Contemporary lie detection methods


Around 1881, Lombrosso’s Glove, considered to be the first modern lie detection instrument, was created by Cesare Lombrosso, a famed Italian physician, criminologist and anthropologist. Through this instrument, Lombrosso attempted to measure the changes in an accused individuals’ blood pressure – recorded on a chart or graph. During World War I, this technology was vastly improved by a William M. Marston, and took its final form after the end of the war. It was capable of recording not only the changes in blood pressure, but also the changes in breathing of a subject giving testimony.


Only a few years later, two men, Leonard Keele and John Larso, designed and created a device known as the “Cardio-Pneumo Psychograph,” also known as a lie detector or polygraph. Like our polygraph testing today, the instrument was able to measure respiratory rates, changes in galvanic skin response as well as changes in blood pressure. The assumption which took the forefront in this creation was that there is a relationship between deception and physiological changes.


In this type of polygraph testing, two types of questions were used, the Guilty Knowledge Test (GKT) and the Control Questions Test (CQT). The standard polygraph testing is more often the CQT since it is most frequently used in investigations of a criminal nature. Today, it is a standard part of the polygraph testing process.


During the late 1990’s, polygraph testing was being used in most parts of the world, not only by the police, but also by those wishing to verify the reliability of managers and public safety employees – particularly in the United States of America. Due to its rising acclaim, the polygraph instrument was subjected to a reliability test, whose results suggested that provisions ought to be made for the varying physiological results of individuals when undergoing polygraph testing.




For example, signs of fear, nervousness and emotional disturbances do not only occur in subjects who report false information – but also in those who are telling the truth. It was then discovered that the polygraph instrument must be operated and overseen by a well-trained professional who uses other techniques to look out for deception. This is because while a polygraph instrument measures the physiological responses that are associated with deception, there is no guarantee that these responses will be observed in all subjects who may be deceitful.


Well-trained polygraph examiners, such as us at Polygraph Truths, are able to observe nonverbal expressions as well as practice other supplementary methods to ensure more accurate results from a polygraph test. Studies from 1862 first supposed the possibility that truth, or deception, can be observed through the observation of facial expressions. For example, a genuine smile as a result of feeling happy is exhibited due to the constriction of the zygomatic major muscle which causes the lifting of the corners of one’s mouth. In the case of electrical stimulation, or in other words, a false smile, the smile may appear unnatural.


Similarly, the same observation applies to the circular muscles in the eye, which pull the face higher and depress the eyebrows slightly when constricted. Because the eye muscles and zygomatic major muscle are difficult to control purposely, they can often reveal a person’s true emotional state. There are numerous facial and bodily reactions that are indicative of deception with which polygraph examiners have become familiar and know to look out for.


The truth about lies


Now that you know a bit more about the history of lie detection and polygraph testing, you may be interested to know more about deception – the reason behind the need for lie detection in the first place. Social psychologists define deception to be a communicator’s deliberate attempt to cultivate an understanding or belief in others which the recipient believes to be untrue. The Oxford Dictionary of English defines deception as “a statement that deviates from our perverts the truth.” Whether we like it or not, deception is a ubiquitous phenomenon in human communication. Despite this, its presence almost always summons anger.




Because of the omnipresent nature of lies, there have always been methods of lie detection, as discussed above. Deception and the ability to deceive were the catalysts to much technological, physiological and psychological research which have moved the methods of lie detection from dry rice and hot water to the polygraph exam and lie detection observations we know and depend upon today.