WHAT IS A POLYGRAPH?

It is in effect a medical instrument which measures and records changes in the autonomic nervous system when questions regarding a specific issue or issues are asked by the examiner and answered by examinee.

 When a person experiences a sudden shock or fright, the body floods with epinephrine and nor epinephrine to help one cope with this emergency. This activity is known as the “Fight or Flight response” over which one has no control as it is part of the autonomic nervous system.

 One experiences the same response when telling a meaningful, important or dangerous lie as a defence mechanism against potential personal damage.

 During the Polygraph examination there are 3 phases:

PRE TEST INTERVIEW – during this phase biological data is recorded in order for the examiner to get to know the examinee better; the issue under investigation is clarified and discussed, the physiology of a lie is explained, questions are designed together with the examinee so that there is no surprise questions in the examination, the operation of the Polygraph is explained and instructions for the exam given. Polygraph components are now attached to the examinee.

The Polygraph measures and records the physiological changes in the body with the following components:

o         The PNEUMOGRAPH  COMPONENT- measures movement and respiration in the chest and upper abdomen with the pneumo tube;

o         GALVANIC SKIN RESPONSE COMPONENT – metal finger plates are attached to the ring and index finger of the right hand which measures the changes in the skin resistance;

o         CARDIOSPHYGMOGRAPH – measures the relative blood pressure and pulse rate through a blood pressure cuff attached to the left upper arm;

o         MOVEMENT SENSOR – examinee sits on movement sensor which measures movement and any physical attempt to distort readings

TEST – several charts are collected during which the pre designed questions are asked by the examiner, answered by the examinee and the physiological reactions to the questions recorded.

POST TEST INTERVIEW – with the test complete the examiner will perform an interpretation of the charts, during this phase the result will also be communicated to the examinee, if the result is deceptive the issue at hand is discussed again to give the individual chance to give any further information or to confess. A written report is submitted to employer or party requesting the examination.

Phone: 073 2740768 | e-mail: michael [at] polyinc.co.za