The lie detector or the polygraph test is a scientific terms which is not used mostly in the criminal trials. The principal behind the lie detector test is that lying can be stressful and this stress may be recorded or measured on the polygraph machine.
Lie detector is also called polygraph and this is because the test will be consisting of different records for galvanic skin response, pulse and breathing and they are then printed out on a graph paper. The printout will show when during the questioning period this biological reaction took place and the questions itself. The stress will be presumed and with the presumption, the stress will indicate the lie.
These who use the lie detector in Cardiff, they believe that this test is reliable since people may control all the three physiological functions at once. The polygraph examiners will run the pre examination test on a person and it will measure the reaction of a person when he tells a lie.
However, there are critics of the testing and they argue that there are different subjects which conceal the stress even if they known that they are trying to lie. No reliable way that can be used to know the stress of an individual which is caused by the testing itself or that it is generated because of the lie.
With the lie detection, it is possible to know that a person is lying or not without his confession. Even if many people may be stressed out if they are asked the questions which may lead them into the trouble, a polygraph operator had learnt about the techniques he can use in order to overcome such problem.
Before using the report, the person to be tested will have to be asked some questions that are neutral and others that can cause the emotional discomfort. This will be based on the personal circumstances of someone.
The physiological response of the subjected are calibrated meticulously before the operator can start with core questions. The response to such questions will be measured and then compared to responses which are produced by control and neutral questions.
However, even if these tests are too accurate, they cannot be used with each situation even if the truth is going to be an issue. Some people are guilty of conscience and they have no moral so they will test the honest or they may be good liars who do not become stressed out because of lying or they may have convinced that they are saying the truth even if it is not.
The results may change by using other methods like biofeedback or yogic training. Some people may use illegal or legal drug in order to calibrate the emotions of someone. The law enforcement agencies with the intelligence agencies are the biggest users of this technology. The Edinburgh agency may choose to use their own system or they may use the examiners from other agencies. By now, there are two ways to do the counter measures to the test by changing psychological and physiological state of an examiner. It can also work by increasing the examination by decreasing or increasing the response to the critical examination period.