What is polygraph testing

When did human need for lie detection begun
The search for truth is not something that occupies our attention only for the period of the last hundred years that the polygraph has existed as an instrument. From the beginning of the world, and from the beginning of written history until today, human civilization has had the opportunity and time to understand many facts about human nature, and accordingly it has come to the universally known knowledge that any person who is dishonest in his words, actions and intentions, will sooner or later, in some way give away their own lies and deceptions through various indicators such as words, actions, gestures, various small signs and signals that can be interpreted both verbally and non-verbally.

Throughout history, we list the oldest data related to the search for truth and exposing lies. Even in the Holy Bible and Moses’ 10 commandments of God, God tells Moses: “don’t be a false witness against your neighbor.” King Solomon is the oldest person in history known to have tried to define a methodology by which to determine the truth. The Papyrus Vedas, a document dating from around 900 BC, an ancient Hindu record is the oldest written record of lie detection. The document mentions the distinction between verbal and non-verbal symptoms of lying. “Erasistratus”, 304-250 BC, Greek physicist and anatomist was the first to recognize the physiological changes that occur when lying. He noticed that his son’s pulse quickened every time the king’s young wife approached him.

What were the first methods of lie detection
Throughout history, we can distinguish various methods used to determine the truth. We will list some of the methods that were used during the formation of modern society. The “duel method”, created around 1500 – in an era of superstition, inquisitors did not look for evidence or guilt, nor did they believe that the truth could be determined by questioning the accused. It was believed that the truth could only be determined with the help of a “higher force. “Trial by torture” – based on the idea that God would never allow an innocent person to confess to something they are not guilty of. “Trial by hot steel” – originated with the Bengali tribes in India, a hot iron was placed on the suspect’s tongue 9 times, scorched tongue = liar = death. “Trial by scales” (India, 600 BC) – weighing was used to determine the truth, the accused was weighed, assessed, then weighed again. If weight loss is registered on the second measurement, it means goodbye. “Hot water trial” – another primitive way of checking where the defendant put his hands in boiling water and returned for assessment the next day, if his hands were fried it meant he was lying. The saying “stinks a liar” comes from the trials that took place in Africa once upon a time. The “red water trial” originates from the African continent – the defendant ate rice and then drank a gallon of red water, if he vomits it means he is innocent. “Trial with the aid of the holy donkey” – originated in the Middle East and consisted of the defendant being sent into a tent with a donkey and asked to pull the donkey’s tail, it was believed that if the donkey did not make a single sound, the person was innocent . The “Rice Trial”, originated in India – also used a method based on the assumption that the guilty could neither swallow dry rice nor spit it out. Dry rice, which has not been swallowed or not spat out means that the person is guilty.

When was the first polygraph invented
First polygraph instrument was invented by doctor John Larrson from university of California in year of 1921. Dr John Larrson was the first to use blood pressure in polygraph procedure, was the first to use breathing patterns in the polygraph procedure, was to first to invent portable polygraph instrument and was the first person to constantly use polygraph in criminal cases. First usage of polygraph testing was for detecting German spies in USA before and during World War Two. First analog polygraph instrument was invented by Leonard Keeler, the man who was a psychologist from Stanford University and this man is called “father of modern polygraph”. He was the first to introduce four channel instrument, first to standardize question techniques (Releveant/Irelevant technique), the first who publicly defended polygraph and first man to open a polygraph school. In year 1952 he invented polygraph Keeler model 6338 which was developed with the help of reasearchers from Chicago, was the first polygraph model with four channels, which became a standard after that, with inc available in more colors and the price of the instrument was 2350 US dollars. First digital polygraph instrument was invented in year 1992 and after that polygraph is only digital and all analog polygraph instruments are not used any more. Modern digital polygraph instrument has 6 to 9 channels and is connected to laptop and has its own software which is updated on regular basis.

What kind of polygraph tests there are
We can distinct two main types of polygraph tests, and those are single issue tests and multiple issue tests or “screening tests”. Single issue tests are polygraph tests where there is a know allegation or action that some person is suspected of doing, there is just one issue and all the questions are related to this main issue, directly or indirectly. It is the most commercial and most used type of polygraph test in the world. It is simple, clear, precise and to the point. It is most widely used when some incident occurs and post incident we want to determine is this person related to that incident or not. “Screening tests” are tests where there is no know allegation but there are more themes of interest from the persons past which someone want to investigate. So, there is more different types of questions related to more different subjects and themes. The themes of interest are some persons behavior from the past. Per example, when applying for a job screening test can be used to ask questions related to theft from previous employers, drug usage, spying for other companies. It is a more diverse test which is less accurate than single issue tests but is also widely used. Sometimes polygraph examiner can combine the two types of test to gather more information.

Use of polygraph in the world today
Today polygraph is an instrument that is seriously accepted and used on world level and finds its regular use as best available method for credibility assessment in the world. Governments of 67 countries around the world use polygraph on a regular basis and even more countries use it in private security sector, detective agency sector and on individual level. A specialized polygraph test called the CIT test is official evidence in court in Japan, India, the American state of New Mexico, as well as in Hungary, therefore, persons are convicted in court proceedings on the basis of the CIT polygraph test, which has an accuracy of 99.94%. The number of states that accept the polygraph as evidence in court is increasing slowly but surely. Most states today use analog and computerized polygraph instruments. The United States continues to dominate the use, application, standard setting, and conduct of polygraph research. However, many European countries, as well as countries from Latin America and Asia, are slowly catching up with the US in terms of usage in this interesting and intriguing field, which we call the polygraph. The polygraph isn’t perfect, but it’s still by far the best available credibility tool in the world.

The article What is polygraph testing first appeared in TravelDailyNews International.

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