From the Roots to the Branches: Evolution of Polygraph Tests and Future Outlook

Do you remember the last time you lied? Perhaps it was a little white lie, told to spare someone’s feelings, or maybe it was a more significant deception. Whatever the case, lying is a part of human nature. However, when it comes to matters of law enforcement, deception can have significant consequences. This is where lie detection technology comes into play.

A lie detector test, also known as a polygraph test, is a process in which physiological changes in the body are monitored to determine if the person being tested is telling the truth or lying.

A polygraph test examinee dressed in white is being tested.

Polygraph tests are used in a variety of contexts, including criminal investigations, employment screenings, and national security assessments. The purpose of the test is to measure changes in bodily responses, such as heart rate, blood pressure, and respiration, which may indicate deception.

The use of lie detectors dates back to ancient times, but modern polygraph technology was developed in the early 20th century. Since then, the technology has advanced and become more sophisticated, leading to debates about its reliability and validity.

Despite some controversies and limitations, polygraph testing remains a common tool in the arsenal of law enforcement agencies and other organizations that need to determine the truthfulness of individuals. In this article, we will explore the history and evolution of polygraph testing, including the development of early lie detection methods, the introduction of polygraph technology, and recent advancements in the field. We will also discuss the legal and ethical issues surrounding polygraph testing, as well as potential alternatives to this technique.


Ancient methods of detecting lies

Long before the development of modern lie detector technology, ancient cultures had their own methods of detecting deception. In fact, several historical texts describe techniques used to determine the truthfulness of individuals accused of crimes or other misdeeds.

One of the earliest methods of detecting lies was the use of ordeals, which were physical tests designed to determine guilt or innocence. For example, in ancient India, a person accused of theft might be required to retrieve a small object from a pot of boiling water. If the person’s hand was unscathed after removing the object, it was believed they were innocent. Similarly, in medieval Europe, accused individuals might be required to pick up a red-hot iron or walk across hot coals to prove their innocence.

Another ancient method of detecting lies was the use of divination, which involved interpreting signs or omens to determine guilt or innocence. For example, in ancient Rome, the haruspex, or diviner, would examine the entrails of a sacrificed animal to determine the guilt or innocence of the accused.

Other cultures relied on more psychological methods of detecting deception. For example, the Chinese philosopher Confucius wrote about the use of facial expressions to determine if someone was lying. He believed that a person’s eyes would reveal the truth, as they were unable to disguise their emotions.

Although these ancient methods may seem primitive by modern standards, they reveal a longstanding human interest in detecting deception and determining the truth. As we will see, this interest has led to the development of more sophisticated methods of lie detection over the centuries, culminating in the modern polygraph test.


Development of modern lie detection methods in the late 19th and early 20th centuries


In the late 19th and early 20th centuries, there was a significant development in the field of lie detection. During this time, scientists and researchers were seeking new ways to accurately identify when a person was lying or telling the truth. This was driven by the desire to improve the criminal justice system and make it more effective.

One of the earliest methods developed during this time was the analysis of handwriting. Experts believed that a person’s handwriting could reveal their true character and intentions. By analyzing the shape, size, and spacing of letters, experts could determine if a person was lying or telling the truth.

Another method that gained popularity was the study of facial expressions. Researchers believed that a person’s facial expressions could reveal their true emotions, which could then be used to determine if they were telling the truth. This led to the development of the science of physiognomy, which focused on analyzing a person’s facial features to determine their character.

In addition to these methods, researchers also looked at changes in a person’s voice. They believed that a person’s voice could reveal their true emotions, and that changes in tone or pitch could indicate if they were lying or telling the truth.

One of the most significant developments during this time was the use of the Galvanic Skin Response (GSR) test. This involved measuring changes in a person’s skin conductivity, which were thought to be linked to emotional responses. By measuring these changes, researchers believed they could determine if a person was telling the truth or lying.

Another important development during this time was the use of the blood pressure test. Researchers believed that a person’s blood pressure would change when they were lying, which could be used to detect deception. This method was used in several criminal investigations, including the famous case of Bruno Hauptmann, who was convicted of the Lindbergh baby kidnapping in 1935.

Overall, the development of modern lie detection methods during the late 19th and early 20th centuries was driven by a desire to improve the criminal justice system. While some of these methods, such as handwriting analysis and physiognomy, are no longer widely used, others, such as the GSR test and blood pressure test, are still used for detecting deception.


The introduction of polygraph technology in the 1920s

an old lie detector machine.

In the 1920s, the introduction of new technology began to revolutionize the field of lie detection. This technology was called the “cardio-pneumo psychogram,” and it would later become known as the polygraph.

The early versions of the polygraph consisted of a series of instruments that measured changes in respiration, blood pressure, and heart rate. The theory behind the polygraph was that these physiological changes could indicate when someone was lying.

John Augustus Larson, a police officer in California, was one of the first people to use the polygraph in criminal investigations. Larson believed that the polygraph could help solve crimes by providing more accurate information about suspects. In 1921, he conducted the first polygraph test in the United States.

One of the earliest cases where the polygraph was used in a criminal investigation was the case of William Sheppard. Sheppard was accused of murdering his wife and mother-in-law in 1923. The police used the polygraph to question Sheppard, and he eventually confessed to the murders. Sheppard’s conviction was later overturned on appeal, but the case helped establish the use of the polygraph in criminal investigations.

Despite its early success, the polygraph was not widely accepted by the scientific community. Many scientists were sceptical of the polygraph’s accuracy and reliability. In 1928, a group of psychologists and physiologists formed the Committee on Scientific Detection of Deception to investigate the polygraph and other methods of lie detection. The committee concluded that there was not enough scientific evidence to support the use of the polygraph in criminal investigations.

Despite this criticism, the polygraph continued to be used by law enforcement agencies and government organizations. In 1935, the FBI began using the polygraph in its investigations, and it remains a common tool used by law enforcement agencies today.


The work of early researchers William Moulton Marston and John Larson

In the early 20th century, researchers such as William Moulton Marston and John Larson played a significant role in the development of lie detection technology. Marston, a psychologist, is perhaps best known for his creation of the comic book character Wonder Woman, but he also made significant contributions to the field of deception detection.

Marston believed that changes in blood pressure could be used to identify deception. To test his theory, he invented a device known as the systolic blood pressure test. This test involved inflating a blood pressure cuff around a subject’s arm and then asking them a series of questions. Marston believed that if the subject’s blood pressure increased in response to a particular question, it was a sign that they were lying.

John Larson, a police officer and forensic scientist, was also interested in developing a device that could detect deception. He created the cardio-pneumo psychogram, which measured both breathing and blood pressure. The device was a prototype for the modern polygraph, although Larson himself never referred to it as such.

Larson’s device was first used in a criminal trial in 1921. The defendant was accused of stealing a large sum of money, and Larson’s machine was used to determine whether he was telling the truth about his innocence. While the results were inconclusive, the case helped bring Larson’s invention to wider attention.


Initial use of polygraph tests in law enforcement

A polygraph examination screen and an examinee in the background.

As the use of polygraph technology became more widespread in the 1920s and 1930s, law enforcement agencies began to take notice. The device was initially used in criminal investigations to help determine the guilt or innocence of suspects as well as gather information about ongoing criminal activities.

However, it was not until the 1930s that the use of the polygraph in law enforcement became more widespread. William Marston, a psychologist and inventor who had developed an early version of the polygraph, began working with police departments to use the device in criminal investigations. One of the first major cases in which the polygraph was used in this way was the case of Bruno Richard Hauptmann, who was accused of kidnapping and murdering Charles Lindbergh’s infant son in 1932.

Marston and his associate, Leonarde Keeler, administered polygraph tests to Hauptmann and several other suspects in the case. While the results of the tests were not admissible in court, they did provide investigators with valuable information that helped them identify Hauptmann as the likely perpetrator. Hauptmann was eventually convicted and sentenced to death for the crime.

As the use of polygraph tests became more common in law enforcement, some agencies began to rely heavily on the results of these tests. For example, in the 1950s and 1960s, the Los Angeles Police Department used polygraph tests extensively in their investigations. However, concerns about the reliability of polygraph tests led to their decreased use in criminal investigations in the 1970s.

Despite these concerns, many law enforcement agencies still use polygraph tests as an investigative tool, particularly in cases involving national security or high-profile crimes. Several countries, such as the UK, Japan, Israel, India, and China, incorporated the process into their official investigation processes.

The validity of polygraph test results and whether or not they are required by law depend on each country’s legal system. Some countries give their results more weight than others.


Development of computerized polygraph tests

In the 1980s and 1990s, computer technology brought about significant advancements in the field of lie detection, with the development of computerized polygraph tests.

These tests use computer algorithms to analyze physiological responses, such as heart rate, blood pressure, and breathing patterns, and compare them to a person’s baseline measurements. The data collected during the test is displayed on a computer monitor, allowing examiners to analyze it more accurately.

One of the major benefits of computerized polygraph tests is that they are more objective than traditional polygraph tests, which rely heavily on the examiner’s interpretation of the data. With computerized tests, the algorithms provide more accurate readings, removing much of the subjectivity from the process.

Computerized tests also have the advantage of being able to store and analyze data over time, making it easier for examiners to detect patterns and trends that might be missed during a single test.

One example of a computerized polygraph test is the Test for Espionage and Sabotage (TES), which was developed by the U.S. government in the 1980s. The TES uses a computer algorithm to analyze physiological responses and detect potential security threats.

Another example is the Computerized Voice Stress Analyzer (CVSA), which analyzes changes in a person’s voice patterns to detect stress or deception. The CVSA has been used by law enforcement agencies in the United States since the 1990s.

Overall, the development of computerized polygraph tests represents a significant advancement in the field of lie detection. While they are not without their limitations, they offer a more objective and accurate method for detecting deception.


Use of physiological measurements in polygraph tests

Lie detector test equipment

The primary focus of lie detection tests is to analyze physiological responses to determine whether someone is being truthful or deceptive. These physiological responses are measured through various means, including monitoring heart rate, blood pressure, and breathing patterns.

During a lie detection test, an examiner will ask a series of questions while monitoring the subject’s physiological responses. Typically, the examiner will start with baseline questions, which are neutral questions that are unlikely to evoke a significant physiological response. The examiner will then move on to relevant questions, which are directly related to the investigation or the reason for the test. If the subject’s physiological responses to the relevant questions are significantly different from their responses to the baseline questions, it may indicate that they are being deceptive.

One of the primary physiological responses that examiners look for during a lie detection test is an increase in heart rate. This is because when someone is lying, their body experiences stress, which can cause their heart rate to increase. However, it’s important to note that other factors can also cause an increase in heart rate, such as anxiety, which can lead to false positives.

Another common physiological response that examiners look for is changes in breathing patterns. When someone is lying, they may breathe more quickly or shallowly, or they may hold their breath for brief periods.

Other physiological responses that may be monitored during a lie detection test include changes in blood pressure, skin conductivity, and pupil dilation.


Criticisms of Polygraph Tests

While lie detection tests using physiological measurements are widely used, they are also subject to a number of criticisms. One of the primary criticisms is that the tests are not always reliable indicators of deception or truthfulness. As mentioned earlier, there are many factors that can influence a person’s physiological responses, and it can be difficult to determine whether a particular response is indicative of deception or not.

Another criticism is that the tests can be influenced by the subjective judgments of the examiner. For example, an examiner may interpret a particular physiological response as indicating deception, while another examiner may interpret the same response as indicating truthfulness. Additionally, an examiner’s preconceived notions or biases about the subject may influence their interpretation of the test results.

Critics also argue that lie detection tests can be easily manipulated by individuals who are trained to control their physiological responses. For example, a person may be able to intentionally raise their heart rate or breathing rate to create a false indication of deception. This is particularly true for individuals who are familiar with the techniques used in lie detection tests.

Moreover, some critics argue that the use of lie detection tests can be an invasion of privacy, particularly in cases where the subject is coerced into taking the test or where the results of the test are used inappropriately, such as in employment screening or as evidence in court.


Recent developments in the field of polygraph testing

An examinee's fingers are attached to lie detector test sensors.

In recent years, there have been various technological advances in the field of deception detection, particularly in the realm of physiological measures. Researchers have developed a range of techniques and technologies that can detect changes in bodily functions that are associated with lying or other forms of deception.

  • One such technology is functional magnetic resonance imaging (fMRI), which has been used to study brain activity associated with deception. fMRI works by measuring changes in blood flow in the brain, which are associated with neural activity. Studies have shown that lying can produce specific patterns of brain activity that can be detected using fMRI. For example, when someone tells a lie, areas of the brain associated with working memory and decision-making are more active than when they tell the truth.
  • Another technology is thermal imaging, which measures changes in skin temperature that can be associated with lying. When someone lies, they may experience a slight increase in body temperature due to increased stress and anxiety. Thermal imaging can detect these changes, making it a potential tool for detecting deception.
  • Researchers have also explored the use of natural language processing (NLP) techniques to analyze speech and text for signs of deception. NLP uses algorithms to analyze language patterns and identify markers of deception, such as an increase in the use of negative emotion words, a decrease in the use of self-reference words, and an increase in the use of tentative language.
  • Voice stress analysis is another technique that has been developed to detect deception. This method measures changes in the frequency and intensity of a person’s voice during speech. The idea is that when a person is lying, they may experience stress, which can cause changes in their voice. However, critics argue that this technique is not reliable as factors such as fatigue and nervousness can also affect a person’s voice.
  • Eye-tracking technology is another recent development in detecting deception. This method uses specialized cameras to monitor eye movements and pupil dilation during questioning. The theory behind this technique is that a person’s eyes can reveal hidden thoughts or emotions, and patterns of eye movement may be associated with deception. However, like voice stress analysis, the reliability of this technique is still being debated.
  • In addition to these new technologies, there has also been a growing interest in the use of artificial intelligence (AI) to detect deception. AI can analyze large amounts of data and identify patterns that may be difficult for human analysts to detect. For example, AI can analyze speech patterns and facial expressions to determine whether someone is lying or telling the truth.


Alternatives to Polygraph Testing

There are several alternatives to traditional polygraph testing. These include:

  • Cognitive interview techniques involve using open-ended questions and active listening to gather information from witnesses or suspects. This approach is based on the idea that people remember events more accurately when they are allowed to tell their story in their own words.
  • Behavioural analysis is another alternative to polygraph testing that focuses on observing and analyzing a person’s behaviour during questioning. This approach is based on the idea that certain behaviours, such as fidgeting or avoiding eye contact, may indicate deception. Behavioural analysts are trained to identify these behaviours and interpret their meaning.
  • Reality monitoring is a third alternative to polygraph testing that involves asking a person to recall details about an event they claim to have experienced. This technique is based on the idea that people remember real events more accurately than fabricated ones. By asking specific questions about the event, reality monitoring can help detect inconsistencies or lapses in memory that may indicate deception.



In conclusion, the evolution of techniques for detecting deception has come a long way since the days of the ancient Greeks. While the polygraph remains a widely used tool, there are promising developments in the field that may lead to more accurate and reliable methods for detecting deception in the future.


Who invented the polygraph?
The modern polygraph machine was invented by John Augustus Larson, a police officer in California. Larson was a medical student and had a background in physiology, which led him to develop the polygraph machine as a tool for detecting deception.
The history of lie detection dates back to ancient times, with various cultures using different methods to determine truthfulness, such as torture, divination, and trial by ordeal. In more recent history, the first scientific approach to lie detection was developed by Cesare Lombroso in the late 19th century. Lombroso studied physiological changes in the body that occur when someone lies, which laid the foundation for modern polygraph tests.
The development of the polygraph was a collaborative effort that involved the contributions of many people over several decades. Some of the key figures who played a role in the development of the polygraph include John Larson, William Marston, August Vollmer, Leonarde Keeler, John Reid, Fred Inbau, Angelo Mosso, Marie Gabriel Romain Vigouroux, Ivan Tarkhanov, Alexander Luria, Boris Sidis, Cesare Lombroso, Vittorio Benussi, Cleve Backster, Max Wastl and others.
The polygraph has had a significant impact on society, particularly in the criminal justice system. Polygraph tests are used by law enforcement agencies to investigate crimes, and they are sometimes used in court as evidence. The use of polygraph tests has been controversial, with some experts arguing that they are not reliable or accurate enough to be used as evidence. The polygraph has also been used in the private sector, such as in pre-employment screenings, and in government agencies to screen employees for security clearances.
The first lie detector, or polygraph, was invented in the early 20th century. John Augustus Larson, a police officer in California, developed the modern polygraph machine in the early 1920s. The polygraph has been continually refined and improved since its invention.
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