How do lie detectors work?

Polygraph/Lie Detection:-

          Y­ou would have seen or heard about Lie Detection all the time in police investigations or Live television Shows like Sacch ka Saamna, and sometimes a person applying for a job will have to undergo a Polygraph test (for example, certain government jobs with the FBI or CIA require polygraph tests). The goal of a lie detector is to see if the person is telling the truth or lying when answering certain questions.

How do Lie Detectors work ???

           A Lie Detector works on the principle of nervousness and under pressure condition of a person. Under these conditions his body exhibits some physiological changes.These include increases in the blood pressure, heart beat rate and perspiration on hands and soles. These changes are monitored and detected by a lie-detector. The Person to be examined is made to wear a chest band, a blood pressure cuff and electrodes on his palms.

         He is then subjected to a series of questions in order to see his normal reactions.This is followed by more complicated questions. based on his responses a trained specialist can find out whether the accused person.