Lie detector or, in more scientific terms, the polygraph is a device that recognizes a person is lying or not.
It seems like a miracle for many to work such a device, but in reality everything is not so difficult there. Let's take a closer look at the principle of the polygraph.
Device Name
Lie detector - what is it and what is the name of the scientific?
A polygraph is a multichannel device that simultaneously synchronously records several indicators of a person: respiration, cardiovascular activity and other physiological characteristics, allowing to determine and assess the reliability of the information that a person provides.
It is also important to note that the device itself is called a lie detector. A polygraph is rather a complex that consists of the device itself and the person (expert or psychologist) who deciphers his data. Without it, it is impossible to make a conclusion.
Therefore, it is also important that this person, a polygraph examiner, should have an appropriate education.
This is necessary in order to be high accuracy and reliability final conclusion.
Who invented?
The lie detector was created almost a hundred years ago - in 1921. American is considered its inventor. John Augustus Larson.
He was the first to be able to record several physiological parameters at once (such as changes in the respiratory rhythm, blood pressure and pulse rate) and realized that they could be evidence of lies.
In the future, his device has been improved and is now pretty serious machineregistering a set of data.
Scope of use
A polygraph study is the fixation using the device of various changes in the reaction of the human nervous system (namely, such parameters as pressure, sweating, rhythm of the heartbeat, respiration, etc.).
Its essence lies in the fact that in the course of the survey a corresponding reaction occurs in a person (heart palpitations, sweating, etc.) to questions that are relevant to him.
And, most importantly, it proceeds unconsciously, often it is not even visible.
Psychophysiological research is used, as a rule, in the following cases:
- Verification of workers directly detection and prevention of thefts (for example, goods, important documents, valuable information or money), the identification of collateral earnings, etc.
- Verification of dismissed employees in order to prevent theft of documents, important information and databases.
- Checks to make a dealif it is of particular importance or seems too doubtful.
- Checks hired to work people for identify various risk factorsthat may threaten other employees or interfere with the normal performance of duties (for example, criminal record, problems at the previous workplace, propensity for fraud).
- Checking domestic workers (cleaners, nannies, etc.) on identifying incompetent behavior (theft, child abuse, etc.).
- Family checkfor example, to identify adultery, addiction to addiction in a teenager, etc.
- Checking with purpose protection of dignity and honor.
A person cannot be forced to undergo a polygraph. But if he refuses, for example, from checking for employment, then this could be the basis for refusing to consider his candidacy for the proposed vacancy.
Who is an expert psychologist, polygraph?
Polygraph profession involves the use of various methods to detect lies using a special device (polygraph, lie detector).
The expert polygraph examiner is necessary for analyzing and evaluating information from the polygraph.
According to the results of the audit, he draws a conclusion, which allows to determine man lied or not.
But it should be noted that his conclusions are not always completely accurate, since the human factor is present here.
It is important that each polygraph examiner is also a psychologist, has a psychological education. This improves the accuracy of its activities.
Principle of operation
How does the polygraph react to what?
The basic principle of the polygraph is based on the belief that the more important the question asked for the object, the stronger will be his physiological reactions.
The test procedure on the detector is as follows. With the object being checked, all issues that will be voiced in the process are discussed in advance. This occurs immediately before the verification procedure.
It is done so that it does not arise. vague reaction, which may appear if the question is unexpected.
Because of this, the object will linger, may get nervous or be surprised - all this will distort the results of the test, since the polygraph will count this answer as “false”.
The test itself is conducted on average 1.5-2 hours. The object is read the questions and offers two answers: "yes" or "no." The polygraph for 15-20 seconds after the voice of the question fixes the reaction of the object to it. The following reactions may indicate a lie:
- slow pulse;
- increased skin response;
- heartbeat is accelerated;
- time of inhalation or exhalation varies;
- breathing rhythm changes;
- muscle tremor increases.
Also to to disorient the object to be tested and destroy its defensive reaction, is some psychological impact.
The expert changes the wording of the question, repeats the same question several times.
He may even ask you to answer all yes questions, including the ones you previously answered no.
Also during the survey asking neutral questions, for example: “Is today Wednesday?”, “Is it morning?”, “Are you sitting on a chair?”, etc. They are necessary so that physiological reactions of a person to a lie are more noticeable.
Also set test questions, for example: "Have you ever taken or appropriated a thing that did not belong to you?"
Such actions at least once in a life each person made, therefore they cause reaction even in innocent. In this case, the innocent, they will cause a great reaction.
Accuracy and Reliability
Can a polygraph be wrong? The accuracy of the polygraph is extremely difficult to measure in controlled experiments.
But experts say that his reliability is approximately 50-70%.
However, it must be remembered that a lie detector is just an apparatus that can fail.
In addition, it is controlled by a person who can also be mistaken and incorrectly decipher the information he received.
Application in judicial practice
Forensic psychophysiological examination using a lie detector is usually carried out in criminal and administrative cases.
Its use is not mandatory, but is not prohibited by the legislation of the Russian Federation (and many other countries).
In this case, the expert polygraph examiner evaluates the response of the checked object during the answers to the questions. If the reaction was strongIt means that these questions are important for the person being checked.
This, in turn, suggests that traces of an event have remained in his memory. That is, it is likely that the object hides some events related to this case.
With this expert can't ask direct questions about crime involvementotherwise it will be incorrect.
He may ask whether he has heard any events, heard something about them, etc.
The use of a polygraph in a criminal process is necessary in order to trace credibility of testimony, testimony and other information.
According to the results of such a check, the expert polygraph examiner makes a conclusion. Its validity and reasoning must be at a high level in order for it to have any force in the criminal process.
therefore of particular importance:
- the quality of the equipment used, its compliance with modern developments;
- the completeness of the materials on the basis of which questions are compiled;
- the qualification of an expert polygraph examiner (the ability to compose questions correctly, use neutral and control questions in the right amount, the ability to correctly analyze the reactions and draw the right conclusions based on them.
Is the polygraph evidence in a criminal case? Polygraph data can be used as evidence in a lawsuit, since its accuracy is high enough and the device is quite difficult to deceive.
But it cannot be used as the main evidence. He can only act as an indirect to help the court render its verdict.
What does the rejection of the polygraph in a criminal process mean? A polygraph test can only be carried out if the person gave written confirmation of consent passing a lie detector. Thus, everyone has the full right to refuse this procedure.
But this does not exempt from testifying.
Thus, a person must necessarily appear at the procedure, but no one will be forced to check - this prohibited by law.
The polygraph is quite actively used in our life, and in different areas. It really allows you to determine with high probability whether a person is lying or not.
How often is the polygraph wrong? Find out about this from the video:
