what is polygraph

What is polygraph

A Brief Introduction to Polygraph: This article will describe the etymology, word formation and definition of the polygraph to the readers. After a brief explanation of the title, the article will explain about the concise history of polygraph. Then, it talks about the creation of polygraph idea and the theory. In the end, you will get familiar with the polygraph usage in different agencies and the benefits of using it.

What is polygraph?

The word polygraph is literally derived from a Greek word “polygraphos” meaning writing much. Therefore, the etymology of the polygraph originated from polys “much, many” and “graphos” writing.

But as a term, the polygraph is a device to record the alternations of distinct pulsations simultaneously. For the first time in 1921, it was used as a lie detector.

Polygraph or lie detector utilizes mostly in law enforcement agencies and police investigations in order to examine deceptive reactions of individuals. Notwithstanding the colloquial term, the polygraph does not recognize lies.

Polygraphs are based on this theory that people who lie or deceive, show physiological evidence of the tension. These tensions included changing in heart rate, feelings of anxiety or nervousness, person’s signals and other more which prove lying.

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The history of polygraph

In the history of civilization, there have been futile or incomplete attempts to discover lies and to confirm the truth. Mankind has found many methods to distinguish truthfulness from deception. They used different inventive materials for confirmation of truth over the centuries. But many of these were foolish, unreasonable and brutal. Despite the initiative, each material was relying on religious faith and superstition. Simply put, they used three general methods. In fact, a trial was held by combat, ordeal, or torture.

For this purpose, during the 18th century people tried to invent methods. For instance, one method was “ordeal of boiling water” test. In this test, the individual would put his hand in bowl of boiling water. If his hand did not burn, he was a truthful person.

Another irrational old and superstitious example is “ordeal of the red hot stones” test. Like the first one, if the individual would walk on red hot stones and his feet did not burn, he was not a liar. As time passed and with the community development, people relied the lie test on pure chance. For example, they used to throw a knife. However, these methods were not reliable and scientific.

The criterion of trial by combat was physical strength. In this case, two people fought each other until one of them was killed. They believed that God will save the innocent.

In trial by torture, the suspect is tortured in different ways. The Roman and Greek Empires usually used this method. In addition to the non-rationality of this method, it should be noted that even the innocent confessed to sin after a long and painful torture.

In general, the oldness of polygraph goes back to more than 300 years.

polygraph detaction

Polygraph invention

Since 1730, research has begun on the invention of a device that can detect lies. These researches led to the initial appearance of the basic design of the polygraph device.

From 1895, many criminologists and people tried to build a perfect and functional lie detector machine. They recorded changes in the person’s blood pressure, blood volume changes. Also, they rated and measured the depth of the person’s respiration.

Sir James Mackenzie was a cardiologist and studied about the cardiac arrhythmias. Eventually, he invented a so-called clinical polygraph in order to graphically record the arterial and venous pulses in 1902. In fact, he did not device this machine to detect deception in individuals. Mackenzie only used this device when performing medical examinations because the device was able to simultaneously record the different types of vascular pulses.

In the 1920s, William Moulton Marston invented the first an early prototype of the polygraph device. He was an American author, lawyer and psychologist. He found that there is a relationship between the lying and a rise in an individual’s blood pressure. Thereupon, he built a kind of blood pressure test device that measured changes in a one’s blood pressure. Today, Marston’s device is one of the main component of the modern polygraph.

John Augustus Larson was a police officer in forensic investigations at the Berkeley Police Department, United States. He also had Ph.D. in physiology. He worked on the Marston’s device and finally he developed the original polygraph machine in 1921. Larson added respiration rate to the previous device. At first time, he called this device as a cardio-pneumo psychograph. Larson’s device could record simultaneously several physiological responses on a smoked paper. It also measured changes in blood pressure, pulse, and respiration of a person while the questions were asked.

After that, Leonard Keeler performed further work on the polygraph device. Leonard Keeler worked with John A. Larson at the Berkeley Police Department. Leonard Keeler added a new feature to polygraph device. In 1939, he updated the machine and made it portable. In this case, the device can evaluate variations in the skin’s insistence to electricity called galvanic skin response. The FBI purchased his polygraph device. Keeler is well-known as the father of the modern-day polygraph. He mixed three essential components including pneumograph, cardiograph and the galvanic skin response. Now they exist in present polygraph machine as the main components. Leonard Keeler opened the world’s first polygraph school in Chicago named the Keeler Polygraph Institute.

Since 1993, polygraph has officially entered into the computer age. Nowadays, polygraph devices are utilized in more than 40 countries around the world. With more than a century of research, development and extensive use, polygraph is the most efficient tool for detecting lie.

Who is using the polygraph?

Today, the majority of the countries in whole world use polygraph instrument to detect lie. In general, the three main sectors of society use polygraph. They are:

  1. law enforcement agencies
  2. legal community
  3. private sector

All the law enforcement agencies such as Federal Law Enforcement Agencies, State Law Enforcement Agencies, and Local Law Enforcement Agencies, for example, Police and Sheriff’s Departments use polygraph in their organizations. Also, state police organization use polygraph. Even Customs, Federal Government as well as the Army, Navy, Air Force and Marine Corps utilize polygraph. In addition, the polygraph used in many sectors we mentioned bellow:

  • Private Sector – some of the companies and corporations under the EPPA rule
  • Legal Community – Attorney Offices, District Attorney Offices, Public Defenders Offices, Defense Attorney
  • Attorneys in civil litigation
  • companies for the matter of employee theft and employment
  • The judiciary
  • criminal court
  • border control interviews
  • intelligence interviews

Therefore, the polygraph performs a serious role in the security of industry.


Benefits of using polygraph

Definitely, the use of the polygraph device has many benefits that we point out to some of the most important ones.

  • Lie detector tests are very reliable, safe and convenient
  • Analyzing and measuring the person without pain
  • Very accurate and professional
  • very affordable and accessible
  • not investing much money on buying lie detector machine
  • obtaining instant results within a matter of minutes
  • reducing the time of police investigation
  • Right judgment
  • Not revoking the innocent right
  • Having more safe industries and society
  • enhancing the national security
  • aiding to interrogate suspects in terrorist activities

Uses of polygraph

There are several situations where polygraph tests can be used to verify the truth and solve a case. In this part, you will understand different kinds of cases where polygraph can be extremely fruitful.

  • Detecting Qualified Employees

As a business owner, you always want to hire qualified people. In this situation, the business owner can use polygraph test in his hiring process. In the United States, the majority of the government employees must take a polygraph test before being admitted into their posts. Basically, this test is called as a pre-employment test. The aim of the pre-employment test is to get true information about the person’s background. For instance, educational status, previous work history, and any activities related to gambling, criminality, embezzlement, fraud and drug use.

  • Using in Private Investigations

Several polygraph companies corporate with private investigators in order to solve different crimes or issues. Investigators give polygraph test from their case suspects to specify whether they are really a segment of the case or not. In addition, Sincerity and suspect’s participation in the case are also determined through the test.

  • Checking Fraud and Theft

It is effective to use polygraph test in resolving fraud and theft cases. The suspects take the polygraph test to determine if they really committed the theft or fraud. Moreover, the examiners understand the amount of stolen resources and how to steal or fraud commitment.

  • Review the Case of Sexual Offences

Sexual rape and other similar offences are kinds of sensitive and disturbing cases. To determining the guilty person, polygraph technology can be used in sexual offences and crimes.

  • To Verify Media Sources

Some of the media claimed that they verify the News sources via polygraph. Therefore, polygraph helps media personnel to know the truthfulness and validation of the News before they publish them.

  • Military Uses

Some important government organizations hold confidential files which they are the basic of conspiracy theories. These organizations such as the military, CIA, FBI and the other ones intend to determine who is the reliable and loyal. Therefore, they use polygraph in their special programs such as catching spies.

To wrap it all up, polygraph test can be used in many various cases from criminal cases to confirming the potential company employees.


To conclude, it is essential to emphasis on the fact that polygraphs are imperfect. Thus, there is always the possibility of error in the lie detector during the test. On the other hand, it does not mean that the results of the test are always wrong. In contrast, with this imperfection, polygraphs are very useful and advantageous, particularly, when comprehensive and precise information is prerequisite. As a whole, the invention of polygraph is very great assistance to human societies.

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