A lie detector test is usually used to measure the degree of truthfulness of the subject’s responses as demonstrated by their physiological reactions to a list of relevant questions. A private investigator tasked with the administration of the lie detector test uses the output generated by a polygraph machine to translate the body’s reactions to the questions asked with regard to the responses given. Of course some people think that the lie detector machine can be cheated and therefore made to produce false results. It is fair to ask the question how to cheat a lie detector test? Below we will look at whether this is possible and if so, how to go about it.


First we will begin by looking at what a lie detector is and how it is administered by a private investigator. This will help us establish the main areas that should be considered when looking to cheat the lie detector test.


A lie detector test is usually conducted over a period of about two hours and involves different stages. These include the preparation of the lie detector test and test questions; collection of chart data output by the polygraph machine and finally the interpretation of the chart data.


In the first stage the private investigator carrying out the test usually introduces the subject to the test and explains what it is all about. During this stage, the investigator also takes the time to create a list of relevant question to be asked during the interview. This is by far the longest stage of the entire test.


The second stage is where the polygraph issues its output in the form of graphs. The investigator usually asks the questions developed earlier a number of times so as to obtain a consistent result.


Lastly, the private investigator then moves to collect all the charts produced and then translates them into an understandable format/report of whether the subject made truthful responses or not.


For the lie detector machine to produce the above results, the subject must be hooked up to the machine through a number of ways. Each way is used to measure some identified physiological response during the body.


The Cardiophygmograph is used by the private investigator to track the subject’s blood pressure variations during the lie detector test. This component is the same as the device used by doctors to check a patient’s blood pressure levels.


The Galvanic Skin Response (GSR) is used to monitor the reaction in the subject’s level of skin resistance. It works by placing a couple of finger plates on fingers in one hand.


Finally there is the Pnuemograph, which is used by the private investigator to track the subject’s breathing rate and any changes thereof during the interview.


Where the test is administered by following the correct order and abiding by established rules by a trained and seasoned private investigator, then it is impossible to cheat a polygraph.