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Polygraph. History and application

 

Polygraph - a technical tool that is used for psychophysiological research. During the study, the lie detector simultaneously records the parameters of cardiovascular activity, respiration and electrical skin resistance. In addition, when using the new polygraph can register other physiological factors. All research results are fed in real time in digital form. Simply put, a lie detector is designed to assess the reliability of the information.

History
The need to determine what was said there was truth in the moment when people began to join in society. Task to identify a liar is always pinned to the elders, shamans, chiefs, - the wisest men. It is also known that different people have developed special rituals and reception for the determination of fraud.
Even in those days, people have noticed that the perpetrator of the fear of exposure is changing physiological functions.
In ancient China the suspect in the crime was given a handful of dry rice, which he gained in his mouth, and read out the charge. It was found that if the rice remained dry (from fear of being unmasked saliva is suspended), the wine has been proven a liar.

In ancient India, the suspect led up to the sheep, and called him a critical (related to the crime) and neutral (everyday) words. His task was to respond without hesitation, and at the same time quietly beating the drum. If, in response to words related to crime is strongly suspected of beating a drum, it was considered guilty.
In Africa, the shamans of the suspect offered to hold the hands of a small ostrich egg with a very thin layer of the shell. During read out the sentence passed on the suspects around the egg, and it was believed that the offender will yourself that will crush the egg.

It can be concluded that the ancient people also identified a variety of changes in certain physiological processes in fear of being unmasked, and used their knowledge as efficiently as possible. However, to use for this purpose rice, drum, egg, or anything else is very unreliable.
The first instrumental lie detectors have their origins in the work of the Italian physiologist Angelo Mosso. In 1877 he identified with the help of plethysmograph that if the study felt fear, then it affects the heart rate.

But the first experience with the use of tools for detecting deception had only 4 years. The first who had this experience, was an Italian criminologist Cesare Lombroso. He used gidrosfigmograf during interrogations of suspects in the crime and on the basis of the readings elicited guilty.
As early as 1895 C. Lombroso wrote the book "Criminal Man", which described the positive experience of gidrosfigmografa in practice. Tells about an interesting case in which the polygraph helped him to investigate the crime. One offender was arrested on charges of bank robbery, and checked his testimony at the gidrosfigmografe. The device did not record any dynamic changes in blood pressure during the read out the charges in the case of bank robberies. But when I turned criminologist, he believed, to a neutral topic of theft of passports, gilrosfigmograf found a drop in pressure. Later it was proved that the offender had no relation to the bank, but the theft of passports was involved.
Another case: In 1902 Lombroso attracted to the investigation of rape and murder of a girl. During the interrogation of a suspect criminologist again resorted to the help system and found that while the story of the crime the suspect was not the dynamic changes, then brought the images of people cut up and killed the girl. At this time the machine just did not betray any signs of anxiety. Later it was proved that this man was not guilty of the crime.
A. Mosso all this time working with C. Lombroso and found that in addition to blood pressure in response to the stimuli presented and the model menyaetsya breathing. In 1914 an Italian professor of psychophysics Vittorio Benussi published data of the study, which examined the dynamics of the process of respiration. These studies have argued that if the examinee is lying, then the frequency and depth of breathing cycles are changing.

The first polygraph was built in 1921. His fellow Californian police erected by John Larson. This unit can simultaneously record the dynamics of heart rate, blood pressure and respiration. A police officer is systematically used his device on the suspects.

For the first time a portable polygraph was constructed in 1933, a disciple of John Larson Leonard Keeler, who was a member of the laboratory for scientific methods of crime detection in the North-western University. Besides, he added, as a function of the channel polygraph for the measurement of skin resistance. A little later the polygraph put on serial production.

General characteristics of

By way of fixing these polygraphs are divided into two types: analog and digital. The first written data on the chart paper, produce a second record on electronic media with the help of computers.
The modern polygraph consists of a portable personal computer with a touch sensor unit and the output of information.
The purpose of sensory block is removed, enhancing and filtering of signals from the sensors, which detect changes in physiological processes. After that, it converts the received signals into digital code and transmit images to a computer.
In order to register changes in physiological processes such sensors are used:
• Lower (abdominal) and upper (thoracic) breathing.
• blood supply vessels, blood pressure and pulse rate.
• Resistance of the skin electricity.
Be sure to simultaneously control these physiological processes in the course of research. Established international standards can be seen that the exclusion from the study at least one process is considered invalid. Other sensors that use a complete different polygraphs are considered to be purely auxiliary. For example, sensors and voice tremors are used to secure the traffic and noise. In addition, a voice sensor is used to fix the moment the question-answer and write the sound track.

Appointment

As can be seen from the definition, the polygraph is used to record physiological parameters, which are recorded at the facility during a psychophysiological study. The result of the analog and digital polygraphs called polygrammes.


Polygrams structure consists of several components: background, reaction and artifact.
Background - a state of physiological processes of a man who dwells in peace. Background indicates the relative stability of the vital processes of the subject in the absence of destabilizing factors.
Reaction - a sudden change in the dynamics of the recorded physiological process under the influence of matter, the image or object. Everyone is special, it can be seen on a polygraph. Depending on their individual characteristics, the person reacts differently to the destabilizing factors. Someone worsens, someone is weakened, but someone has stabilized. Some people have a reaction of relief. This is when, after a fast-flowing changes of physiological processes are continuous changes in their dynamics.
Artifact - a significant change in the dynamics of controlled physiological processes that are not linked to stringent stimuli. Most often, these changes are due to the influence of exogenous and endogenous destabilizing effects. To exogenous factors include ambient noise, and to endogenous - the movement, coughing, pain, and more.

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