The idea behind this principle is that when a person starts being nervous their hands would sweat In ancient China a suspect would hold a handful of rice in his or her mouth during the prosecutor’s address, if the rice was dry at the end of the address the person was considered guilty. The reasoning behind this was that salivation ceases when emotional anxiety sets in 2 The self proclaimed father of the polygraph test William Marston first measured breathing and galvanic skin response of German prisoners of war in an attempt to detect deception or if they were lying, his attempt proved unsuccessful. Later on William Marston developed the systolic blood pressure test. According to Marston’s son the idea for this test originated from his mother saying that when she got mad or excited, her blood pressure seemed to climb. Marston never acknowledged her as a collaborator in his work, but this was in fact the first polygraph test or testing method used for truthfulness. The basis was that if a person was being deceitful that their blood pressure would rise because of the fear of being caught.