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100 Years of the Polygraph

100 Years of the Polygraph

Wednesday 19th October 2022

One hundred and one years ago in 1921 John Larson, a Californian based police officer and physiologist, produced a device which could simultaneously measure pulse, blood pressure and respiration in a person as an aid to detecting lies and deception. However, as with so many inventions—the telephone, television, to name but a couple—others have also been involved in the development. In 1914 Italian psychologist, Vittorio Benussi published a paper concerning the respiratory symptoms of the lie and in 1915, American lawyer William Marston invented a test for the systolic blood pressure as a means of indicating deception. All of these things when taken together formed John Larson's polygraph, which today is often incorrectly referred to as a lie detector test. A polygraph, in fact, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions.

In 1923, the legal system was introduced to the polygraph, with Marston trying to have the results of a polygraph test admitted as evidence in a court case. He was not successful-the court rejected the polygraph results, quite reasonably stating that whilst prepared to consider results from a scientific principle or discovery, it must have been established long enough to have gained acceptance in the field to which it belongs.

Most of the early polygraph research was carried out by Larson, who then was an employee of the Berkley Police Department in California.  Seeing Larson's work as a way of significantly improving the effectiveness of his department, Berkley Police Chief August Vollmer encouraged and allowed Larson to work on real cases with his polygraph. Vollmer, through witnessing the use of the polygraph recognised its practical value-a value soon to be acknowledged and shared by law enforcement agencies throughout the United States and much later, throughout the world.

Larson was assisted in his early work by his then-protégée Leonarde Keeler, often credited with the creation of the first polygraph testing procedures, such as the Relevant/Irrelevant Question Technique. It was Keeler who made the polygraph portable and who invented the galvanic skin response, which was added to the machine as the GSR channel in 1938. However, Keeler had very little interest in the academic life that Larson had, being far more interested in the lure of financial and commercial success, and it was the pursuit of these aims that led him to patent his first polygraph and be the first founder of a polygraph school.

In 1965, the first empirical review of the polygraph was conducted by the US Committee on Government Operations, which in a brutal sum up stated, "People have been deceived by a myth that a metal box in the hands of an investigator can detect truth or falsehood. There is no lie detector, neither man nor machine which can do this". How wrong they were. Those in favour of the polygraph who understood it and were aware of its capabilities remained unmoved by this and argued that the disconnection between the science and practice of the polygraph existed because of the lack of psychological training among polygraphers. Responding to growing criticism regarding the lack of scientific support for the polygraph, polygraphists John Reid and Frank Inbau stated the real lie detector was the individual conducting the polygraph examination. Without doubt, the greater the experience of the polygraphist, the more reliable the result. Well trained and experienced polygraphists produce impressive results constantly, and more importantly, they are produced safely.

In 1983, US President Ronald Reagan issued National Security Decision Directive 84, authorising federal agencies to use polygraphs, which by then had become commonly known as lie detectors, to test if any of their employees had leaked classified information. Following widespread protest among employees, this was rescinded 3 months later. However, with the growing confidence in the efficacy of the polygraph, on February 4th 2015, the US intelligence agencies once again authorised the investigation by polygraphy of members with potential involvement in the leaking of classified information. This resulted in significant increases in the number of polygraph examinations, making it an ideal time to re-evaluate the polygraph.

Polygraph examinations are conducted in adherence to standards set by the National Centre for Credibility Assessment in the United States, which means examinations are based on a Comparative Question Test as opposed to a Concealed Information Test. CQT and CIT represent the two predominant types of polygraph testing procedures, which use the same type of polygraph but differ in the way they are utilised.

Initially, the polygraph was heralded by its proponents as a triumph of science and something which would transform criminal investigations, but after all had been said and done, a lot more had been said than done, and it did not live up to these expectations.  Notwithstanding, over time, both the polygraph and its method of use evolved to become what polygraphy is today. Modern polygraphs no longer use pens scratching away with ink on a roll of paper but instead produce digital outputs sent immediately to a computer on which there is the appropriate polygraph software to be safely stored and peer reviewed as often as necessary.

Today, a variety of modern digitised polygraph models are available to purchase from different companies. Most can be used with a combination of different tools which measure the various outputs of the machine. Some models also have devices that measure movement, voice pitch, and other data that the examiner may require.

Each year, cars, computers, washing machines and virtually everything else undergoes improvement, and the polygraph is no different, constantly undergoing upgrades and improvements, making it more accurate and reliable. Last year saw the introduction of a new addition to the lie detection armour - eye scanning. According to proponents, the effort required to tell a lie is indicated by and within the eyes, and the claim is that it cannot be concealed. Will this method replace the polygraph and polygraphist? At the moment, this is most unlikely. Independent testing has shown grounds for further research, which is continuing, but the day it can be safely relied on is a long way off. At this moment, we have no interest in its use but will be watching the progress it makes carefully.

In the final analysis, when it comes to the detection of lies or deception, there is one thing which is necessary to understand, which is, detection of these has little to do with the polygraph but much more to do with the examiner and his skill in interpreting the information presented before him. A point already made above.

We have assembled what we believe to be the finest team of fully qualified and experienced polygraphists in the country. The depth and breadth of their skills and experience will ensure we continue to lead in this most challenging field of polygraphic lie detection.