Different Phases Of Polygraph Test

The term polygraph means various things. This name refers to a system in which different physiological activities are continuously recorded. Polygraph instrument helps in recording all the changes occurring in heartbeat, respiration and blood pressure.

Currently there are two different types of polygraph systems that are frequently used these days they are analog instrument and the other one is computerized polygraph instruments. Polygraph instrument gathers physiological data from 3 different systems present in human body.  

    

In order to record the respiratory activity, a convoluted rubber tube is placed in subject’s upper chest. Two small metal clips are attached to the fingers this helps in recording the activities of sweat gland. The third device helps in recording the cardiovascular activity. 

Polygraph test is conducted in three phases, they are the pretest interview phase, the second one is in-test phase and the final phase is post-test interview phase. This polygraph test last for minimum 3-4 hours. In the pretest phase, examiner makes some casual conversation with the subject and completes al the paper formalities. In simple terms we can say that in this phase examiner makes himself familiar with the examinee. Just like people are using the common mobile accessories such as, Bluetooth headsets, mobile speaker, Keyboards etc, similarly there are many departments who are making the use of polygraph test for investigation purposes.    
 

In the in-test phase, examiner will conduct the polygraph examination and will gather the polygraph charts. These charts are then analyzed to find out the truthfulness of the examinee. Finally, in the post-test phase, the examiner will offer the examinee an opportunity to explain physiological responses in relation to one or more questions asked during the test.