People often lie to deceive others. The reasons may be known to us or might be unknown. They might even be personal. But the sole fact that humans lie to each other is nothing new. It might be to deceive others, or just used as a defense mechanism. Some are blatant liars as they are easily caught. They either lie poorly or just can’t cover it up. But sometimes, the liars are rather good. It is difficult to just talk along and pinpoint if and when the other person is lying. When it’s upon some security forces to determine if the offender or terrorist they’ve captured is lying if asked about some security-related issues, a Lie detector test or a polygraph is what helps determine if the information given is correct or not.

How lie detectors work

Lie detectors or Polygraphs are instruments made to monitor a person’s physiological actions or reactions associated with lying to determine whether he or she is lying or not. They, of course, cannot detect if what the person said is a lie or not, but are only indicators of deceptive behavior portrayed by a person. It is a combination of several medically used parameters (like heart rate, blood pressure, respiratory rate, and electrodermal activity) as any change in their values is recorded and is open for examination by an examiner. These are most commonly used for investigations regarding criminal activity or national security. However, these can also be used before or during the interview of several governments or security jobs to test if the candidate is clean or not. The exams are specifically designed to look for any uncharacteristic stimuli from the test subject following which the machine shows readings regarding the fluctuations and an examiner reads those readings to determine deceptive behavior. The questions asked are related to a particular event or happening which the subject has to answer with all honesty or else the machine will end up detecting it. The results of the device are not used for any judgment by the court as a machine can still be wrong.