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You are here    |    Home page    |    Educational Resources    |    How to spot a liar

How to spot a liar



Lying has always been a man’s unchanging companion. Through ages people have lied and learnt to lie often leading to many conflicts and troubles. Together with the development of deceit techniques, grew man’s research on how to detect false statements and as time went on, we learnt to identify wrongdoers.

The beginning of lie detection dates as far back as to Ancient China. It was then, that first methods were discovered. Through thousands of years and generations each civilization searched for ways of finding the best way of identifying false statements when finally man came up with the so-called lie detector. Thanks to research made by our ancestors, we were given the chance of using a device which is actually capable of verifying the truthfulness of given statements.

We have always wanted to achieve the ability to determine what is true and what is not. In the early years, when people were still not aware of the processes happening in our body and when generally mankind had a very basic reception of the World, statements would be accepted or rejected as false, based on given oaths or the reputation of a given person. It was years until the first ideas come up with an actual concept on how to check if someone was lying or not. The first to do so were the Ancient Chinese. Their method was based on a very interesting and clever observation: they realized that any time someone was lying, their mouth would turn dry. This led to conclusions, which would then be the foundation to a first lie detection method. The procedure was simple. The person interrogated was to chew rice while being asked questions.

After the session was over and all the answers were given, the person was to spit out the rice. In the situation, in which the rice appeared to be dry an assumption was made that the given statement was false, because there was no saliva in the mouth to moist the grains which meant that a lie had taken place. In the event of wet rice being spat out, the person was cleared of any accusations because the conclusion was made, that due to the fact that the rice was moist with saliva, the individual who chewed it had nothing to worry about and therefore was not lying. Although today’s polygraphs do not monitor the changes in saliva production during questioning, the Chinese were the first to take the right course in searching for body indications, which could suggest that someone was lying.

As time went by, each civilization would try to find their own unique method but with no proper success. Most of the ideas given were based more on religion (like the The Bocca della Verità -the Mouth of Truth in the Roman Empire) than on actual facts and body reactions. People were so hungry for success in lie detection that as time went on we developed extremely brutal methods which at their end would have nothing to do with any actual statement verification and would lead to a person being killed in absolute agony anyway. These times are known as one of the most darkest in the history of the Roman Catholic Church and although extremely brutal, it proves just how eager mankind was to find ways of identifying lies.

One could say that after this came a short period in which the development of lie detecting methods had radically slowed down. Not many new ideas were given until 1730 when the projects of a new invention were filed. The evolution of technology allowed inventors to build and develop a polygraph which after years of research has now the form which we know today. The key to finding the right solution was the full concentration on the body’s reactions to statements given by people which are being questioned. All of the known polygraph inventors and developers such as Mosso, Lombrosso, Benussi or Larsson concentrated on the one identical factor – stress. What they figured out was pretty remarkable for the time. In some ways, step by step, these men managed to prove that lying also has a lifelong companion and its name was “stress”.

This idea has been kept up till today and is now understood as one of the basic tools in the Lie Detection industry. Further developments of polygraphs have all been aimed at finding new ways on how we could monitor stress levels. Research has been conducted for years and many factors have put under the test. Thanks to this we now have a clear picture showing us what we should concentrate on in order for our tests to be effective. So what do we focus on and how is it monitored?

The first group of body reactions may be classified as the “visible symptoms”. This is behaviour which can be observed by practically anyone. Liars are known to have shorter breath during their lying encounter. As is it known, lying is a stressful event and one of the body’s reaction can actually be shortness of breath. A persons head can also give good clues. Any unnatural movement or tilting can suggest that someone is lying. Also answers with an overload of information, given in a nervous manner can cause suspicions that the person you are talking to is a liar. One of the most effective lie symptoms is also the human eye. It is said that in the event of giving false statements, blinking will be irregular and the eyes can seem to be unsettled. And as much as all of the above methods are good, they have a very serious disadvantage – it is quite easy to learn to control these reactions which is why the polygraph comes in handy. Lie Detectors don’t measure the visible symptoms but concentrate on the second group which we may classify as the “invisible symptoms”.

Monitoring invisible symptoms is much more effective. This is mainly due to the fact that the factors measured cannot in anyway be controlled by us. For this to be monitored properly, professional equipment is needed. And so when we face the challenge of describing the polygraph the most simple analysis would lead to a conclusion that it is basically a medical combination of a couple of devices capable of measuring certain parameters of the body. The performed measurements give a clear view on the body’s reactions during an interview. So how does it react?

The first measured factor is, the already known, respiratory rate. After being seated on the examination chair the examinee is equipped with two rubber tubes filled with air. The first is placed on the chest while the second finds its place on the abdomen. When breathing, the expanding air in the chest forces the air in the tube to escape it. This causes a change of pressure which is monitored and added to the analysis sheet where the changes are extremely easy to find. The next factor is blood pressure and heart rate. A cuff is placed on the arm of the person questions. In the event of lying, blood pressure as well as the pulse raise causing a raise in the sound which blood makes while flowing through veins. This again is detected by the cuff and sent to the polygraph which adds this fact to the examination protocol.

The third of the most known reactions is pretty clever as well. When lying, the body also reacts through the change of skin electrical resistance. In order to monitor this fact special pads are placed on the subject’s fingers. Skin conductivity falls when sweat is produced, sweat is produced when a person is lying. This leads to a conclusion that if someone is lying, the conductivity will be lower and this is what the pads are responsible for. They monitor the changes and give additional information about the body’s reactions.

Years and years of research have finally led us to the point where we are now. We know a lot about the reactions which the body has when lying. We know where to look for further clues because we know that changes in breathing, blood pressure, pulse or skin conductivity are not the end. There is something more for sure and it is our mission to continue the success of our ancestors. With today’s technology we will soon be capable of discovering new reactions and will be able to introduce revolutionary changes to make the polygraph even more accurate. But as of today, we have very good equipment at our disposal monitoring reactions which simply can’t be controlled which entitles us to call our devices a real lie detector.

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Research & Publications

Do you want to find out more about the science of lie detection? You will have seen them in the movies or TV shows, but there’s a lot more to lie detection than meets the eye. You may have questions, how do polygraphs work? Can they be cheated? Find out more by reading our guides and publications on lie detectors and the psychology behind lying.

What is a polygraph lie detector test?

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history of lie detector invention and evolution

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Can a polygraph test be cheated?

Polygraph testing has always been a controversial matter for all kinds of reasons. The most known controversy regards the devices accuracy

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Ancient methods of lie detection

Throughout the ages human beings have always searched for ways of verifying the truthfulness of the information received .

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How a polygraph works.

People are used to lying. One could even say, that lying has become a natural part of each human beings life.

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How to know when somebody is lying to you

For some, this question tends to be a reason for serious research. It is said that our body language can easily display if the things we are saying are true

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Appointment Request
To find out the truth, book a lie detector test now.
0203 129 6800
To talk in confidence to one of our consultants - call now.
Call back request

Choose a time (0800 - 2030, Monday to Sunday) when you would like one of our consultants to contact you