WHAT IS A POLYGRAPH?
The actual name for a polygraph test is a Psychophysiological Deception of Detection Examination. Now that you know that bit of trivia it is not difficult to understand why names such as polygraph or lie detector have become the more commonly recognizable terms. The word polygraph literally means “many writings” and refers to the individual tracings of the various polygraph components on the older analog polygraph instruments. Modern polygraph examiners use computerized polygraph instruments, which utilize electronic tracings on electronic charts visible on a computer screen.
A modern polygraph instrument uses various components to will collect physiological data from three physiological systems in the human body. The first are convoluted rubber pneumograph tubes which are placed over the abdomen and chest which will be used to record the expansion and contraction of the thoracic and abdominal cavities during respiration. Second, there are two stainless steel metal plates attached to the fingers, or adhesive pads which are placed on the palm, which will record sweat gland activity. And third a cardiovascular cuff, identical in appearance and placement on the body to a blood pressure cuff, will be used to record cardiovascular activity. Well trained and experienced polygraph examiners will also use a variety of motion sensor pads to ensure that persons being tested are not attempting to artificially effect the outcome of the test.
A polygraph examination given at Veracity Polygraph will include a pre-test phase, a data collection phase, and test data analysis phase. During the pre-test necessary paperwork will be completed, and the polygraph examiner will discuss all the questions to be asked and familiarize the person being tested with all phases involved in a polygraph. In a polygraph there is no such thing as either a trick question or a surprise question. During the data collection phase, the questions previously discussed with the examinee will be asked three to four times, with the order of the questions changing during each presentation, while physiological data is collected.
After the data on the various charts has been collected, the polygraph examiner will complete an analysis of the test data, and will then render an opinion as to the truthfulness of the person taking the test. As needed, the examiner will discuss with the person taking the test any questions during which physiological responses were noted.
It is worth noting that a polygraph examination does not include the collection and analysis of stress of the human voice while answering questions. Such systems are not polygraphs and do no enjoy the support of the scientific community.