You learn about lie detectors mostly in police investigations. Often when an individual is applying for a job, they will need to undergo a polygraph test as well. The aim of a polygraph test is to find out if the individual is being truthful or lying when answering certain questions.
Whenever a person requires a lie detector test, 4 to 6 sensors are affixed to him. A polygraph is really a machine where the multiple signals in the sensors are recorded on one strip of moving paper. The lie detector test measures the individual’s breathing rate, pulse, blood pressure and perspiration but a polygraph test may also record such things as arm and leg movement. A lie detector test recognise untruthfulness by searching for indications of these physiological changes.
When you are going for a polygraph test, the device first registers the baseline of the vital signs. Examiners then trick you into lying by asking a number of “control” questions which are only distantly related to the point they are investigating. After using the control questions, the candidate is asked relevant questions. Both after and during the exam, a polygraph examiner can consider the graphs and may decide if the vital signs altered considerably on the questions. Within the normal duration of the test, technicians depend on responses they know to be true to supply a baseline by which deceitful answers could be judged as an escalation in nervous reaction.