Lie detector — lying? How to cheat a lie detector?

A lie detector is a device that is a complex of involuntary physiological reactions of the body, which are emotional responses to issues that are significant to a person. In a standard detector, these are respiratory and heart rates, galvanic skin response, muscle tone, and indicators of brain electrical activity.

Voice lie detectors from Software SENSE determine the veracity of answers by voice.

The person being tested is first asked neutral questions, the answers to which are known in advance. This is how the natural background of the reaction comes to light. Then questions are introduced, the answers to which are of a fundamentally important nature. If it is possible to fix a change in the reaction, this serves as a basis for doubting the sincerity of the answers. That is, if a person, answering “yes”, tensed up, this should be regarded as “no”, and vice versa.

Concept and history of the invention

From time immemorial, different nations have used ingenious methods to help identify a person with a bad conscience. The story of how the thief grabbed his hat when the wise judge shouted: “The hat is on fire on the thief!” — with different variations is found in the epic of different nationalities. The Chinese once had a custom: accused of stealing during the trial had to keep a handful of dry rice in his mouth. If, after hearing the accusation, he spit out dry rice, he was found guilty. They proceeded from the fact that fear causes a number of changes in the human body, in particular, salivation decreases — «dries up in the mouth.» Therefore, the thief who is afraid of exposure, the rice remains dry.

The lie detector was invented in the 20s by our compatriot A. R. Luria. The method he proposed was quite simple. In response to the presented word, the subject was required to respond with the first word that came to mind and at the same time squeeze a rubber bulb with his hand. Words were presented in a variety of ways, both neutral and those that could have a special emotional connotation for the subject. In the case when the stimulus provoked some hidden experiences, it was possible to fix a certain delay in the verbal and motor response. Luria’s experiment was used in forensic practice. With its help, in a number of cases, among several suspects, it was possible to identify the one who was really exposed as a criminal by subsequent investigative procedures. Luria generalized this experience in the book The Nature of Human Conflicts, which was published in English in New York in 1932 and has not been published in our country since then. And in the United States, the development of this problem was actively continued and eventually led to the creation of a lie detector in its modern modification.

Do lie detectors lie?

In some countries, lie detectors are banned because they violate the freedom of the individual, but the main claims against them are about the reliability of the data. In the US, where lie detector interrogations have been practiced for a long time, a whole association of lie detector victims has already emerged. Many of its members were unfairly discriminated against, or even served all or part of their prison sentences, before an accusation brought against them on the basis of «scientifically sound» polygraph interrogation was accidentally refuted.

There is no exact data on the reliability of these lie detectors, they range from 95 to 50 percent, that is, from very high reliability to complete unreliability.

The manufacturer of VOICE lie detectors claims that in 90 percent of cases, the voice detector produces an accurate result. However, research by Mitchell Summers of the University of Washington, published in the German weekly Zeit, says it’s wrong 63 percent of the time—you might as well flip a coin.

Fixing the presence of an emotional reaction, the standard detector can not say anything about its nature. Rapid breathing and heart rate can be a manifestation of excitement (both pleasant and unpleasant), fear, anger, enthusiasm, and many other emotions.

There is a famous example of this. In the United States, applicants for the position of a cashier in a supermarket were subjected to interrogation on the detector. One woman was not hired due to alleged dishonesty. For example, she was asked the question: “Your mother came to the cash register. Will you give her a smaller amount than the one for which she collected purchases? The subject, as it should, answered — no, but the device fixed — it is lying. The truth was that this woman had recently buried her mother, and the mention of her caused a painful experience.

It is easy for a trained person to confuse a lie detector. Both «external» techniques are used — «ragged» breathing, barely noticeable delays in responses, and internal techniques — memories of disturbing or exciting situations. If you excite yourself on extraneous questions, no one can prove your excitement on control questions …

Total

The lie detector is only a tool, and the success or failure of the case depends on the qualifications of those who participate in this «duel». A trained and skillful specialist will expose an inexperienced liar with the help of a lie detector. An experienced liar will confidently mislead and beat a lie detector if it is managed by a specialist without psychological training. If this is a duel between two professionals, the result, as in any duel, is unpredictable…