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The pulse of a suspicious person -

It was English journalist Daniel Defoe (c. 1660–1731) who in a 1730 essay, 'An Effectual Scheme for the Immediate Preventing of Street Robberies and Suppressing All Other Disorders of the Night,' advanced a theory that the pulse of a suspicious individual could reveal that the person was lying. And the author of 'Robinson Crusoe' was on to something!

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Origins of the polygraph -

The invention in 1878 of the sphygmomanometer by Italian physiologist Angelo Mosso (1846–1910) was able to detect the change in blood pressure in response to certain stimuli.

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The ergograph -

In 1890, Mosso unveiled an early version of the the ergograph, an apparatus for recording the force and frequency of flexion of the fingers.

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An emotional response to deception -

Similarly in the mid-1890s, Italian psychiatrist and criminologist Cesare Lombroso (1835–1909) speculated that measuring a person's heart rate and blood pressure could reveal an emotional response connected with deception.

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Relation between emotions and skin -

Earlier, in 1879, French therapist Marie Gabriel Romain Vigouroux had theorized that when faced with lying, the electrical resistance of the skin would change in such a way that it was measurable. This reaction would later be termed "electrodermal response." Later, Ukrainian-American psychologist Boris Sidis (1867–1923) managed to prove the relation between emotions and galvanic changes in the human skin. Sidis (pictured) published his study at Harvard University in 1901.

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Early polygraph devices -

As medical technology advanced in the early 20th century, Scottish cardiologist James Mackenzie was able to devise one of the very first polygraphs. Unveiled in 1906 and based on the workings of the electrocardiograph (pictured), the device was able to measure arterial and venous pulses and plot them as continuous lines on paper.

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Breathing a lie -

In 1914, Austrian-Italian psychologist Vittorio Benussi (1878–1927) was the first to try to use the assessment of the recording of the breath for lie detection.

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Possible interrogation tool -

While still regarded by many as a medical device for recording a patient's vital signs (pulse, blood pressure, temperature, breathing rate, etc.), the polygraph was seen by others as a possible interrogation tool. In this 1915 photograph, a prisoner undergoes psychological testing with a primitive lie detector as a guard stands behind him with a pistol.

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Criminal application -

In fact, Harvard psychologist Hugo Münsterberg (1863–1916) argued for the machine's application to criminal law, seeing both scientific impartiality and conclusiveness.

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Advanced prototype -

It was one of Münsterberg's colleagues, the American psychologist William Moulton Marston (1893–1947), who together with his wife, Elizabeth, invented an advanced prototype of the polygraph. In tests on fellow students, he reported a 96% success rate in detecting liars.

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Law enforcement tool -

Law enforcement agencies began to take note of this potential new crime-fighting device. Pictured here in 1922 is William Pinkerton, head of the private police and detective force, "questioning" the San Francisco chief of police, who's wearing a lie detector apparatus.

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The "cardio-pneumo-psychogram" -

The invention of the modern polygraph is credited to American police officer and forensic psychiatrist John Larson (1892–1965). Larson, seen here on the right, devised what he called the "cardio-pneumo-psychogram."

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Use of the lie detector -

By the early 1920s, Larson had fully developed his polygraph for forensic use. Pictured here is murder suspect Henry Wilkens taking a lie detector test. It was through the medium of Larson's device that he was cleared of suspicion of the murder of his wife.

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"Father of the Polygraph" -

Berkeley University graduate Leonarde Keeler (1903–1949) developed John Larson's invention to create a far more technically advanced version of the polygraph. He's pictured here testing his lie detector on Arthur Koehler, a witness for the prosecution at the trial of Bruno Hauptmann, who was convicted of the abduction and murder of Charles Augustus Lindbergh, Jr.—the "Lindbergh baby."

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"Truth machine" -

Use of a polygraph by police became widespread throughout the 1930s. Failure to pass a lie detector test helped to condemn Virgil Kirkland (pictured), convicted in 1931 of murdering 19-year-old Arlene Draves. The press described the "truth machine" as having been applied to Kirkland.

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Publicized uses of the polygraph -

One of the most publicized uses of a polygraph was that applied to Robert M. "Red" Manly (pictured). Manly was a suspect in the notorious "Black Dahlia" case of 1947, when Elizabeth Short was found murdered in California, her corpse horribly mutilated. Manly underwent several voluntary lie detector tests to prove his plea of innocence, but he fell asleep repeatedly during the questioning from fatigue and shock. The tests were declared "inconclusive." The case remains unsolved.

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False positives -

Edward Gein, one of America's most infamous serial killers, was subject to a lie detector test after being arrested in 1957 on suspicion of murdering Bernice Worden and Mary Hogan. The decision to do so was taken after preliminary tests proved Gein to be a suitable subject, cooperative and able to answer simple questions coherently. But the polygraph seemingly exonerated Gein of any other murders, and his psychiatrists concluded that his violence was only directed to women who physically resembled his mother. However, Gein was later suspected of killing numerous other women after authorities searching his house found various body parts scattered within the premises.

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Tests not infallible -

The fact that Gein had passed a lie detector test despite having committed other murders beyond those he'd been accused of highlighted the fact that the polygraph was not infallible. Test quality depends on the skill of the examiner, as the structure and content of the questions are the most important parts of the examination. But not everyone was on the same page.

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Can plants feel pain? -

In the 1960s, Cleve Backster (1924–2013), an interrogation specialist for the CIA, began experimenting with plants using a polygraph instrument, which led to his theory of primary perception. Backster claimed that plants felt pain and had extrasensory perception. Although Backster's work became popular and drew public attention, the reaction by the scientific community was predictable: his claims were rejected outright.

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The big lie -

It was a Keeler model 6317 polygraph machine that was used on Jack Ruby, the man who shot and killed President John F. Kennedy's assassin, Lee Harvey Oswald. Pictured is the very graph detailing the result of his interrogation.

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The polygraph points the finger -

The results of Ruby's polygraph proved that he was lying about two key points, according to the House Select Committee. First, when he stated that he had never met Lee Harvey Oswald before shooting him; second, when he had stated that he had not assisted Oswald in the assassination. The test placed Ruby with Oswald prior to the assassination and showed that Ruby had been part of the conspiracy.

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Popular device -

The manufacture and sale of polygraph equipment in the United States throughout the 1960s soared. A leading distributor of the devices was Lafayette Instrument Company. Founded in 1947 by Max Wastl, the company produced the popular Ambassador (pictured), among other models. The Lafayette Instrument Company remains the world's leading manufacturer of polygraph instrumentation. But doubts about the polygraph's integrity persisted.

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Notable failures -

Notable lie detector failures include the occasion when former CIA counterintelligence officer Aldrich Ames was questioned while under suspicion of being a Soviet and Russian spy. He twice passed a polygraph test while passing secrets to Moscow. Ames was eventually caught and sentenced to life imprisonment without parole.

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Gary Ridgway -

Gary Ridgway, the so-called "Green River Killer," was a suspect in the killing of four women and was given a polygraph, which he passed. Ridgway was subsequently dropped as a suspect and went on to kill another 44 women until he was caught and convicted.

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Charles Cullen -

And in another example of a lie detector test gone wrong, serial killer Charles Cullen, a nurse dubbed the "Angel of Death" for murdering as many as 40 people by giving them lethal injections, fooled the polygraph as an initial suspect and went on to kill another 39 patients before being caught and convicted.

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Passing the lie detector test -

But taking a lie detector test can also pay dividends. Richard Jewell, the man accused of the Centennial Olympic Park bombing at the 1996 Summer Olympics in Atlanta, was hounded by the FBI as well as the press for a confession. The stressful scrutiny began to ease only after Jewell's attorneys hired an ex-FBI agent to administer a polygraph, which Jewell passed.

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Computer age -

The polygraph made its entry into the computer age in the early 1990s when software called PolyScore was developed by statisticians at Johns Hopkins University that greatly increased the probability level of lying or sincerity in a subject.

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Near-100% accuracy -

Today's computerized polygraphs are capable of reaching an accuracy level of 98%. And while the results of a lie detector test are inadmissible in court, the device remains a popular method of verifying statements with many agencies and associations.

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Are you taking a polygraph test? -

So, are you about to take a polygraph examination? The US-based Defense Counterintelligence and Security Agency has prepared a brochure in readiness for anyone under scrutiny. It outlines test requirements and health considerations, among other topics.

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Questions and answers -

It also highlights question areas and questions likely to be frequently asked by subjects beforehand.

Sources: (Library of Congress) (IEEE Spectrum) (ScienceDirect) (Countway Library) (Scientific American) (Invention & Technology) (American Polygraph Association) 

See also: The world's most notorious spies

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