Basically, the lie detector tests can be done by analog and computerized test. In this article describes about the equipment used for conducting the lie detecting test. Both the detecting test enables to examine the report by the examiner after and while performing the tests. Both the tests performed have their own advantage. A specially designed software is used to analyze the victim’s response with real time graphs. The latest techniques are adopted in the performance of the polygraph tests. For organizing the polygraph test many agencies are available to conduct these tests and the examiner of the report has the complete response of the analysis.
The components of polygraph instrument
The polygraph instruments include the instruments namely cardio-sphygmograph, second instrument pneumograph and finally the Galvano graph. The purpose of the cardio-sphygmograph is to measure the blood pressure and heart beat are measured by this component of polygraph. A cuff is placed to wrap around the hand to the blood pressure instrument. While interrogating the cuff remains boosted, when the equipment started its working it produces sound and one can able to hear. Some times the sound may double or amplified. The frequency wave gives information about sound of the heartbeat and the magnitude wave gives the information about the blood pressure of the concerned victim.
Pneumograph component of the polygraph
Now the second component named pneumograph component of the polygraph consists of instrument observes the movement of respiration of the victim. Simply it measures the rate of respirate of the person. It has two components to connect to the victim’s body one is placed on the chest and the remaining one is placed on the abdomen of the victim. They have tubes filled with air inside.
Coming to the point of Galvano graph it counts the number of respirations took by the victim. The Galvano graph has two electrical sensors are to be attached to the finger tips. By connecting to the tips of the fingers because it has sweat glands present at that point to measure perspiration result. Mostly the pneumograph and cardiosphygmograph components have more important information to produce than the Galvano graph.
Analog lie detector and its components
When the computerised lie detector is not invented the analog lie detector is used in detective case solving. The analog lie detector is one kind of polygraph that uses to measure at least three consecutive physical responses of the victim. In this analog instrument of lie detection rubber tubes are used to fix on the chest and abdomen to count the number of respirations is made by the victim. The graph can be plotted on the roll paper fixed below the pin. The stress has felt by the victim in answering the random question asked can reveal whether it is a lie or truth.