Lie detector



The polygraph (polygraph, from Greek πολύ – many, γράφω – to write) is an apparatus that is used for objective fixation of physiological parameters (cardiac activity, breathing parameters, electrical resistance of the skin, etc.) in order to analyze the emotional reaction to stimuli presented during the interview, interrogation

For the lie detector at different times, there were different names:

The first device for detecting lies was called the “hydrosfigmometer.” It was invented and used in interrogations by the police in 1890, Italian crime Cesare Lombroso, the device recorded the pulse rate and blood pressure of suspects.The prototype of the present lie detector was developed in the 1920s by John Larson (a California police officer) who simultaneously recorded blood pressure, pulse, and breathing. Larson called the “polygraph” poly “- a lot,” grapho “- to write), borrowing the term from John Hawkins, who came up with the word in 1804. So he called his new device for copying handwritten texts. In 1926, John Larson’s pupil and collaborator, Leonard Keeler, perfected the polygraph. Introduced an additional channel for recording tremors (muscle tremors), thereby initiating a modern stage of “lie detection”. Modern polygraphs – bay-detectors can record up to 50 physiological parameters.


The lie detector can read thoughts, easily detects lies.

No, it’s not. This myth is supported, firstly, for advertising purposes, to create a commercial demand for this kind of services. Testing is expensive, and brings good profits to firms producing detectors. Secondly, in advance to exert psychological pressure on the tested. This approach contributes to victory even before the battle begins. In the modern world, a polygraph is called a lie detector, but this term gives rise to myths. The polygraph does not read people’s thoughts, does not convince of lies, but only fixes physiological activity, changes in physical parameters, information from which comes from the sensors of the device. On such reactions it is impossible to accurately determine the nature of the process itself (lie, positive or negative emotion, fear, pain, fear, etc. ..). While there is no other way to uncover lies, except as an indirect way, because there is no 100% reliable way to identify the physiological activity that accompanies a lie.

Polygraph testing is a scientific standardized procedure.

No, it’s not. There are many doubts and criticisms about the scientific reliability of the results obtained. It is believed that this is more art, and not science, since the results depend on the skill level, experience, intuition of a specialist polygraph examiner. First, the list of questions for testing is not fixed, the polygraph examiner selects and formulates them each time in such a way as to awaken the desired reaction in a particular subject. Secondly, after interrogation, it is necessary to correctly interpret the diversity of physiological manifestations, which differ significantly among different people. At this stage, errors caused by the “human factor” are inevitable.

Suspects themselves can begin to doubt their innocence, because they believe in high efficiency of the device.

Yes it is proved by psychologists. The fact is that before testing, a polygraph specialist convinces the test subject of the absolute accuracy of the polygraph. Before announcing the results, the police inform the suspect that they received reliable information about his involvement in the incident in question. Some people believe this. There are times when innocent suspects deliberately make false confessions after being convicted of the results of a test done on a detector. One of the reasons is that they do not see the opportunity to convince others of their innocence. Therefore, a person decides to take the blame on himself, to admit that he did not commit to get a less severe punishment.

The polygraph is particularly effective in the selection of personnel.

This assertion is not proved. The employer is interested in general information about the applicant at the interview. And to identify the lie, you need to ask specific questions about specific events that happened at a certain time. Common questions are asked when testing only as control. The probability of getting the wrong result increases in proportion to the degree of generalization of the questions. A polygraph test can give information about the behavior of an employee in the past (for example, whether he used drugs in his youth, etc.), but for the employer, it is more important to know what the future employee’s behavior will be, what are the professional qualities. Polygraph can not answer such questions. This limits the possibility of its use for personnel selection.

The lie detector can be tricked.

Yes, it is possible, but not everything is so simple. There are different ways. For example, biting the tongue, tension in the legs, mental counting in the reverse order, reducing the sensitivity of your own sensory analyzers (for this you need to drink some alcohol, sleep a little, get plenty of water before testing, use psychotropic drugs). These actions will lead to certain physiological reactions, which the polygraph registers. By doing this, in response to control questions, the subject thereby increases the probability of the desired result in the test. A mental account in reverse order will allow a person not to think about the questions asked by a polygraph examiner. This will lead to an undefined result of passing the test. However, the test uses control questions that cause the subject to think and comprehend information. In 1994, studies were conducted to deceive the lie detector. Subjects were taught to counteract the device. After they passed the testing. Mental and physical counteractions were equally effective. Approximately 50% of the subjects managed to deceive the polygraph. In addition, only in 12% of cases, an experienced polygraph specialist discovered the use of physical resistance.

Psychopaths can more effectively deceive the lie detector than healthy people.

The level of excitement in people with a sick psyche and pathological liars when reporting a known lie does not increase. Therefore, it is more difficult to identify lies. In addition, there were differences in testing between introverts and extroverts. The professional actors can also deceive the polygraph.

Spies and intelligence officers are trained to trick the polygraph.

Yes, it is. For example, Aldrich Ames, a CIA employee, for years sold the secrets of the USSR, while successfully passed the polygraph tests. Ames therefore thrived in his espionage career, that one of his abilities is the ability to deceive a polygraph. This he dispelled any suspicions of the CIA. Kommersant Ames of KGB Viktor Cherkashin later told in an interview with the British newspaper The Sunday Times how he helped Ames successfully overcome polygraph tests.

The use of a polygraph is not legal.

Not exactly. In law enforcement agencies polygraph is legalized by internal orders, instructions. In commercial structures is regulated by the standard. Created by RAEBUR (Russian Agency for Economic Security and Risk Management of the Chamber of Commerce and Industry of the Russian Federation), which determines the procedure for polling using a polygraph. Polygraph is not prohibited by law. Before testing, the subject signs an application for voluntary consent to this type of control. A person can at any time refuse to conduct a test.

Polygraph is bad for health.

This is not true. For healthy people, it is absolutely harmless. When testing, the subject does not feel any discomfort. A polygraph specialist uses only certified technology.

A polygraph can aggravate a chronic illness.

Yes, it is.Therefore, before research, a specialist is always interested in the state of health of the tested person. If a person has a pre-infarction condition or any other serious problems, it is better not to test.



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