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The polygraph: does the lie detector really work?

The polygraph: does the lie detector really work?

August 10, 2022

The polygraph, commonly known as a lie detector , has become part of our society since it became known at the end of the 30s and by the hand of John Augustus Anderson and Leonarde Keeler, its inventors.

When this machine began to be used, many experts in the field posed the same questions that, even in today's society, are the order of the day: is the polygraph an effective procedure before all the people who submit or Have they been subjected to it? Is it easy to circumvent their detection system? To what extent should it be considered an infallible method to detect lies?

They are reasonable doubts considering that the machine is capable of putting its victims in question and create situations of ambiguity if you do not know how to answer them. We'll see now how the polygraph works and to what extent it is effective .


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The origin of the polygraph

The Italian Cesare Lombroso (outstanding anthropologist of the last century), studied the relationship that exists between the changes that develop in the cardiovascular system and the corporal reaction with the lie. He focused his research on two aspects of the human being: the heart rate and blood pressure . From this study, through new developments and advances in the technique of human behavior, contributed to the creation of the polygraph, an invention of John Augustus Larson and Leonarde Keeler.

Since then, from that moment, the polygraph was consolidated as an indispensable tool for some sectors, like justice, police and army , mainly, in order to help detect the lies and / or deceits of the people.


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How is it used?

The operation of the apparatus itself does not require great skill on the part of the expert who manages it; This "only" will be responsible for paying attention to the interviewee and the results that come out of the polygraph test.

First, the person with whom you want to use the polygraph participates in a conversation (interview prior to the polygraph test) with an expert interviewer by an analysis of the stimulation, better known as Stim Test , with the aim of subjecting it to a series of lies and assessing if your body responds to neurolinguistic changes.

Once the interview is over, the polygraph test comes on, in which the person is connected to a series of sensors that analyze their physiological reaction , and this is revealed on a paper printed by the same machine. In that paper appear the records of the physiological activity that the individual has had while each question was posed.


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How does the lie detector work?

What the sensors placed on the skin measure is the electrical conductivity of this . These measurements are made in real time, and tell us about the way in which the pores of the skin open or close to let sweat pass, a substance that circulates electricity. Other variables taken into account have to do with the heartbeat.

But the polygraph is designed to detect the physiological changes of the person's body and not to detect a lie as such. That is, the apparatus is not trained to know what a lie is by definition , but rather, it shows the bodily changes that the person suffers during the course of the polygraph test, without telling us why those changes occur. It is a way to isolate data and, from them, try to deduce what is the logic by which the physiological activity of the person is governed, from that, to try to know if he is lying or not.

The dilemma that arises from the reliability of the machine in question is in constant debate, given the infinite variables that the human being presents in any type of situation. So that, It is very complicated to assess scientifically whether a person lies or not , because that depends, among other things, on whether she has the ability to lie or if she simply gets nervous saying, even, the truth. The context in which the polygraph is applied is not emotionally neutral, and the subject who submits to the machine knows that a minor change in his organism can cause him to have many problems in the future.

These are issues of vital relevance that should not go unnoticed by an expert if it is intended to give a complete and fair result of the test.The polygraph tells us if a person is physiologically more or less activated (to some extent), but of course, technically it is far from being a lie detector.

Legal application of this machine

Its use, especially, occurs in some government agencies in the United States of America (CIA or NSA to name a few examples) in order to find out if the person is lying or not. Far from the American continent, its use in European countries is carried out for the assignment of certain jobs of private companies and in organizations of the security sector.

Thus, the effectiveness of the polygraph in the legal bodies is approved and legitimized, especially in the United States and the countries that are under its influence , since they consider it a fundamental test in a hypothetical court case. The same does not happen in the other continents, since the doubts that have been raised over the years since its implementation in there in 38, leave in question the validity of its results.

However, countries that resort to the practice of the lie detector, approve its use and the result provided by it. It is considered as a determining test in a hypothetical case of submission of a person, so it could become an essential factor for the resolution of doubts in a judicial process .

How to pass the polygraph test

Some tips to successfully pass a polygraph test:

1. Understand the operation of the machine

If you have arrived here, you should already meet this requirement. Knowing what one of these tests consists of is a good way to feel less vulnerable.

2. Sleep well the day before

Arrive at the lie detector test having rested enough it makes us more sure of ourselves . The aim is that the polygraph does not point out alleged lies for the simple fact that we are insecure.

3. Inform the technicians about the medications you take

If you are taking any drug, it is important to know, since its effects could interfere with the test .

4. Breathe deeply during the test

When you have passed the stage where you are asked the relevant questions, make sure your blood is well oxygenated . To achieve this it is good that you have practiced before, so you will not believe that you are improvising.

5. Remain in a state of calm after the interview

It is possible that once the test is over, the technician tells you that he knows that you have lied about something. This is usually a strategy to see how you react to hearing that.


Do Lie Detectors Actually Work? | Earth Lab (August 2022).


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