Essentials of Polygraph and Polygraph Testing

Nathan J. Gordon

• Editore: CRC Press
• Anno: 2016
• ISBN:
  9781315438627
• Edizione: 1
• Argomento: Derecho
• Categoria: Ciencias forenses

Throughout history, there has been an intrinsic need for humans to detect deception in other humans. Developed in 1923, the polygraph machine was a tool designed to do just this. To date, there have been many improvements made to the basic polygraph instrument. This book outlines the instrumentation as well as the latest in questioning techniques and methods available to the professional interviewer to determine truth from deception. The book covers psychology and physiology, a history of polygraph with the advances of leading figures, question formulation, data analysis, legal implications and legal cases, and the author's developed technique Integrated Zone Comparison Technique (IZCT).

Polygraph History

1

All truths are easy to understand once they are discovered; the point is to discover them.

Galileo Galilei

In 2007, the American Polygraph Association (APA) under the direction of President Donald Krapohl introduced a standard of practice that stipulated that within 5 years (by January 1, 2012), all polygraph techniques being taught at accredited schools and used by field examiners must meet certain levels of criterion accuracy. A meta-analysis study was performed to identify those formats that qualified.¹ All techniques had to have at least two independent research studies showing its accuracy. Approved polygraph techniques had to have less than a 20% inconclusive rate. These techniques would then be classified into the following groups:

Evidentiary techniques	Any polygraph examination that was being conducted to be submitted to a judicial proceeding, which required a mean accuracy of 90% or above.
Paired testing techniques	Paired testing (also known as the “Marin Protocol”) is a method of utilizing polygraph testing in situations in which two or more subjects assert contradictory accounts of a particular incident in such a way that at least one of the subjects must certainly be lying. The method utilizes two independent examiners with established accuracy and error rates to assess the veracity of at least two subjects in such circumstances. Paired testing requires a mean accuracy of 86% or above.
Investigative techniques	Defined as a polygraph examination, which is intended to supplement and/or assist an investigation and for which the examiner has not been informed and does not reasonably believe that the results of the examination will be tendered for admission as evidence in a court proceeding. Types of investigative examinations can include applicant testing, counterintelligence screening, community safety examinations (e.g., postconviction sex offender testing, domestic violence testing, intoxicated drivers on probation), as well as multiple-facet diagnostic testing.^2 The mean accuracy required for investigative examinations is 80% or above.^3

The need to detect deception is hardly a twentieth-century phenomenon. Ever since small familial groups of humans banded together for mutual social benefit, or for protection of person and property, individuals whose practices deviated from the societal covenant have plagued humankind. The activities of these individuals, if not checked, could sometimes destroy the societal group as a whole.⁴

Given that, the search for a reliable means to identify the untrustworthy is as ancient as man. Some techniques were founded in superstition and/or the religious belief that a moral God would in some way reveal the truth and disallow immorality. Many of these attempts, in fact, had some psychological or physiological basis; other methods relied solely on fear of continued pain and torture.⁴

The earliest form of lie detection was the resolving of an issue through battle, which is called “trial by combat.” Consider the problem of two primitive men who approach a fallen prey. Each believes he killed it and that it belongs to him; they refuse to compromise. As simplistic as it seems, each sees himself as making a truthful claim and the other as not. To decide the “truth,” which actually means possession, they engage in combat. The ideal assumption is that the individual with truth on his side will prevail. However, the most cunning and skilled of the combatants usually was victorious and got to eat that night, while the other did not. Not a very fair way of determining truth!

The scenario changed very little by medieval times. It was the custom that knights engage in mortal combat to decide whose Lord had the right in any given controversy (Figure 1.1). While the practice was functionally the same as trial by combat, the ethical premise was different. It was held that while the fighting skill of an individual was not related to his truth or lying, the knight representing the truth would be victorious due to “divine intervention,” that is, that God would ensure the correct outcome.

Figure 1.1 It was thought that the knight representing the truth would be victorious due to “divine intervention.”

The interesting thing about tests for truth is they rarely become extinct. So even today, in any major city around the world on any given weekend night, police are summoned to a local club or bar where two men are about to enter into “trial by combat” to determine who the young lady seated between them is really with.

The next development in the search for truth was “trial by ordeal.⁵” It was assumed once again that God would intervene on behalf of the innocent and would not allow any innocent individual to be harmed. While these attempts to detect truth appeared to be laden with religious beliefs, they were in fact based on practical observations of both psychological and physiological phenomena, which play an important role in the truth-finding processes.

For example, in China, in approximately 1000 BC, it was common practice to have an accused person chew a handful of dry crushed rice and then attempt to spit it out. If the rice became wet from saliva and therefore easy to spit out, the person was considered truthful. If the rice remained dry due to a lack of salivation in the mouth and did not stick together making it difficult for the suspect to spit out, then he was thought to be lying. However, the gods were not involved in this test as much as the salivary gland. As you can see, this test was based on the physiological phenomenon of inhibited salivary gland activity caused by fear or stress. The truthful individual had normal salivary gland activity, causing the rice to become wet and easy to spit out. The stressed or deceptive person had a dry mouth, and the rice in his or her mouth remained dry, making it difficult to spit out. It is unclear how the Chinese arrived at their test for truth. They either just observed that liars’ mouths remained dry or had some understanding that the autonomic nervous system inhibits salivation and all digestive processes when an individual is under serious threat.

It is interesting that testing for a dry mouth was and continues to be found in a wide range of diverse and unrelated societies. The most severe version of these tests often consisted of putting some type of hot object on the tongue. If the person was truthful, the normal saliva in the mouth protected the tongue from being burnt. If the person was lying, the mouth became dry and the hot metal burned and blistered the unprotected tongue, as can be seen in Figure 1.2. Even today, in the Middle East, it is common in some geographical areas that the accused in minor cases can choose this traditional method to prove their innocence.

In various societies, truth tests were developed whose premises were psychological, not physiological. Trial by the “sacred ass⁶” is a classic psychological test that was practiced in India, around 500 BC. In this test, a donkey was staked out in the center of a pitch dark hut. The priests informed the suspect that inside the hut was a “sacred ass” that could differentiate between a truthful person and a liar when its tail was pulled. It did this by braying only when the guilty (lying) person pulled its tail. They were also told the animal would remain silent if an innocent (truthful) person pulled its tail.

Figure 1.2 According to many cultures, if the person was lying, the mouth became dry and the hot metal burned and blistered the unprotected tongue.

Each suspect was sent into the hut alone with instructions to pull the tail of the “sacred ass.” Unbeknownst to the suspects, the priests had covered the donkey’s tail with lamp black, or soot. The truthful individuals, having nothing to fear, entered and pulled the tail. The donkey may or may not have brayed, but those who were innocent came out with soot all over their hands. The guilty party, on the other hand, would enter the hut and not risk pulling the donkey’s tail and disclosing their guilt. He might promise it an apple or stroke the donkey’s head, but he would not pull the tail. After all, he believed if he did not touch the tail of the “sacred ass,” it would have no reason to bray and he would fool the priests into incorrectly identifying him as truthful. However, by not pulling the tail, it became a simple matter for the priests to properly identify him by his clean hands.

Society’s next advancement in its search for truth was “trial by torture.” The assumption was that an innocent suspect would withstand any amount of suffering to preserve his reputation and, in religious societies, his immortal soul. In reality, given enough pain, any man might confess, and most torturers knew that. “The trial,” in fact, became indistinguishable from the punishment itself and was justified in that the “truth seekers” found almost everyone guilty. “Trial by torture” was the method of justice during the infamous witch hunts and inquisitions in Europe (Figure 1.3).

Figure 1.3 Three women executed as witches in Derneburg, Germany, in October 1555. Europeans began prosecuting suspected witches in the fourteenth century. Sixteenth-century woodcut with modern watercolor.

These latter methods are of particular interest, since they did not have as their basis the seeking of truth. Rather, the method addressed a perceived threat from forces whose existence could not be proven. Thus, “trials by torture” were not always designed to find truth, but sometimes to justify and validate the prejudices and fears of the society and the claims of its leaders. Such “trials” were commonplace during the Middle Ages and the Renaissance and continue into more recent periods when people believed that witches or some other group (e.g., Jews, communists, reactionaries, homosexuals) threatened the social order.

During the infamous witch hunts in Europe, two of the ways an inquisitor attempted to prove a person was a witch were⁷ (1) finding the “devil’s mark” and (2) getting a confession. The devil’s mark was an alleged spot on a witch’s body that showed she had been attached to the devil (much like we have a navel where we were once attached to our mothers). Although the devil’s mark was invisible, it could be found because it was a spot on the witch’s body that would not bleed. Suspected witches were tied down and continuously pricked as the inquisitors searched for the spot. It is not known how many witches were discovered by finding the elusive mark; however, many “witches” confessed during the process. Unfortunately, “trial by torture” is still used today to solve “crimes” by confession, the solution of the crime being of greater importance than whether the suspect is actually guilty or innocent.

As civilized societies searched for a m...