The polygraph: does the lie detector really work?

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 are the experts in the field who asked the same questions that, even in today's society, are at the fore. Agenda: Is the polygraph an effective procedure for all the people who undergo or have been subjected to it? Is it easy to circumvent your system of detection? To what extent should it be considered an infallible method of detecting lies?

These are reasonable doubts considering that the machine is capable of putting its victims in question and creating ambiguous situations if it is not known to answer them. We'll see now how the polygraph works and how effective it is.

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The origin of the polygraph

The Italian Cesare Lombroso (prominent anthropologist of the last century), studied the relationship that exists between the changes that develop in the cardiovascular system and the body's reaction to lie. He focused his research on two aspects of the human being:

heart rate and blood pressure. From this study, through new developments and progress in behavioral technique human, contributed to the creation of the polygraph, an invention of John Augustus Larson and Leonarde Keeler.

Since then, from that moment on, the polygraph has been consolidated as an indispensable tool for some sectors, like the justice, the police and the 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 operates it; This "only" will be in charge of 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 using a stimulation analysis, better known as the Stim Test, with the aim of subjecting her to a series of lies and thus assessing whether her body responds to neurolinguistic changes.

Once said interview is concluded, the polygraph test enters the scene, in which the person is connected to a series of sensors that analyze its physiological reaction, and this is developed on a paper printed by the same machine. In this paper appear the records of the physiological activity that the individual has had while each question was asked.

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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 they tell us about the way in which the pores of the skin open or close to let sweat pass through, a substance that makes electricity circulate. Other variables taken into account have to do with the heartbeat.

But the polygraph is designed to detect physiological changes in a person's body and not to detect a lie as such. That is, the apparatus you are not trained to know what a lie is by definitionRather, it shows the body changes that the person undergoes in the course of the polygraph test, without telling us why these changes occur. It is a way of isolating data and, from them, trying to deduce what is the logic by which the physiological activity of the person is governed in order, from that, to try to know if they are 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 difficult to scientifically assess whether a person is lying or notBecause that depends, among other things, on whether she has the ability to lie or whether she simply gets nervous even telling the truth. The context in which the polygraph is applied is not emotionally neutral, and the subject undergoing the machine knows that a slight change in your body can cause you to have many problems in the future.

These are vitally important questions that should not go unnoticed by an expert if a fair test result is to be given with complete certainty. The polygraph tells us if a person is physiologically more or less activated (up to a point), but of course, technically it is far from being a lie detector.

Legal application of this machine

Its use, above all, is given 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. Away from the American continent, its use in European countries is carried out for the assignment of certain jobs in private companies and in organizations of the security sector.

Thus, the effectiveness of the polygraph in the legal establishment It is approved and legitimized, especially in the United States and the countries that are under its influence, since they consider it fundamental evidence in a hypothetical court case. The same does not happen in the rest of the continents, since the doubts that have been raised throughout the years since its implementation back in 38, question the validity of its results.

However, the 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 how the machine works

If you've made it this far, 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

Get to the lie detector test having had enough rest makes us more sure of ourselves. The objective is that the polygraph does not indicate supposed lies for the simple fact that we are insecure.

3. Inform 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 calm after the interview

It is possible that after the test is finished, the technician will tell you that he knows that you have lied about something. This is usually a strategy to see how you react to hearing that.