In public opinion, the glory of the device, which always allows a person on lies, was fixed after the polygraph. We decided to check how much this opinion is true.

In recent decades, law enforcement agencies, personnel services and even jealous spouses have been using a lie detector (the everyday name of the polygraph) to calculate the fraud. The polygraph appeared more than once in a variety of films: spy drama "Resident Error", comedies "Acquaintance with parents", animated series "Simpsons" and others in talk shows (for example, "In fact" or "Detector") Heroes undergo a polygraph check, and experts evaluate their reaction, a person says to the truth or lies. Studies with the help of a polygraph is legally voluntary, but it has to be tested on it Every tenth employee In Russia. It is not surprising that on the Internet you can find advice, How to deceive the polygraph.

Lies requires great intellectual efforts. In the study 2001 Scientists analyzed the images of the brain obtained by MRI (magnetic resonance imaging) while the participants had to tell the truth or lie in response to questions about the daily routine. It turned out that the work of deception required a lot of time from the participants than the truth, moreover, there was an activation of certain zones of the prefrontal cortex of the brain. Later, scientists discoveredthat during deception, three main areas of the brain are stimulated, which jointly control the behavior, read external signals and monitor errors, which allows you to create a plausible lie and look natural.

Professor of Psychology University Duke Dan Arieli In 2016 I found out: dishonesty can change the brain, which facilitates lies in the future. During the deception, the subjects recorded a surge in activity in the almond -shaped body - the part of the brain responsible for fear, anxiety and emotional reactions. But the more often people had to deceive others, the fewer signals came from the almond -shaped body. It is logical to assume that the level of anxiety and physiological reactions during lies with regular practice also decreases.

They try to determine the lie with technical means for almost 100 years. In the United States, a lie detector is used from the first half of the XX century: for the selection of hired employees, personnel inspections, exposure of spies, disclosure of crimes. In the USSR, the polygraph began to use only only in 1975.

The polygraph is considered the main physiological method of lies detection. The device records multiple signals from sensors that fix the person’s respiratory rate, heart rhythm, blood pressure, skin system (sweat isolated), movements of the arms and legs. Polygraph possibilities limited The fact that it relies on data on the activity of the peripheral nervous system, while deception is a cognitive act controlled by the central nervous system.

The passage of the polygraph takes from one to three hours. During the study, the device keeps continuous accounting of physiological activity, and an expert polygraphist interprets it. For example, the pulse quickens during excitement, the pressure rises, sweat is released. But such reactions can occur in a person suffering from any diseases or having physiological characteristics.

To determine the physiological norm of a particular subject, two approaches are used. In the so -called Test of control issues A person is asked about events regarding a specific crime and not having a relationship with him, but still forcing to say a lie. For example, most people to the question "Have you ever had to deceive others?" They will answer no. And this will most likely be not true. Studies show that people are still not as honest as they want to think about themselves: about 60% of the subjects can lie at least once during a ten -minute conversation, according to more new data, About 75% of people Lying on trifles up to two times a day.

The main assumption is that the deception due to stress caused by a lie will lead to a measurable reaction in the form of increased sweating, heart rate, etc. However, it should be emphasized that the device does not fix a lie, but an emotional excitement, which can be caused by a lot of causes, not only a sense of guilt. According to the professor David Likken, there is no specific physiological reaction, characteristic only for deception.

The second approach is known as Test of guilt: He tests any knowledge related to the crime committed. The examiner measures the subject's reaction to specific questions, trying to determine whether a person really knows about the event. It can be anything: from the knowledge of how many stab wounds the victim received to the color of the car on which the criminal left. It is assumed that a person who lacks knowledge of the event will react approximately equally to the correct and wrong information, because he does not know the truth. Meanwhile, a person who was at the crime scene will demonstrate a physiological reaction.

It was done some reviews polygraph effectiveness. They allowed us to judge that polygraphs are accurate in 80–90% of cases. However, on the basis of data collected in the verification of students (namely, they most often acted as subjects), it is extremely difficult to conclude about the effectiveness of the polygraph in the investigation of crimes. In addition, the participants in the experiment did not know about how to outwit the device. In a review published in 2003 in the USA National Research Council, it is said that "when checking people who are not trained in countermeasures, tests on a polygraph allow you to distinguish lies from the truth at a level exceeding accident, although much lower than perfection."

Polygraphs can give false works: to argue that a person is lying when he actually tells the truth, and vice versa. David Likken estimated the accuracy of polygraph at 85% for guilty people and 60% for innocent. The fact that 40% of honest subjects are defined as dishonest, can lead to serious consequences - from non -renewal of work to recognition by a serial killer.

The conviction of the accuracy of the polygraph is largely based on a misunderstanding of the essence of his work. The device is extremely accurate in the measurement of physiological reactions, but not in the definition of real lies.

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