Human beings tend to lie in different situations.  When one is arrested in connection to a crime, investigators have various ways to try and extract the truth from a suspect.  In recent times, scientific methods have been devised to detect psychological responses to indicate if the suspect is telling the truth.  One of these methods is the polygraph. This technique is an essential tool for the investigators, law enforcers, and intelligence, especially where there is no direct evidence. This paper explores the various uses of polygraph in an interrogation setting.

Polygraph testing involves interrogating and also physiological measurements such as heart rate, respiration, blood pressure and the reaction of the electro-dermal. There are also a series of questions that one is required to answer with yes or no while sensors transmitting the data are connected on the physiological phenomena by a wire to the polygraph by the use of digital technology for data recording.  More techniques have been added to enhance the responses.  These include brain scans and voice tremors. The polygraph measures physiological responses which are believed to be stronger when one is lying than when telling the truth. According to the theories of the technique, deceptive responses cause a reaction such as increased perspiration, heart rate, electro-dermal reaction and blood pressure relative to how they were before and after the test.  If there is a specific pattern about the same question and a stronger response,  then a suspect may be lying.

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