Lie detector test,also known as falsehood detection or polygraph test uses questioning method along with technology that sums up physiological functions to find out the truth and falsehood in answers. It is used by law enforcement agencies around the world to find out the culprit.
History– Going back into the 20th century, Depaulo, and Dr. Morris found a “connection between lying and enlarged pupil size, a sign of stress and deliberate concentration.” Additionally, those lying are found to be appearing more stressed than those telling the truth while they also do not seems to be more Fidel, blink more times, or have a less-relaxed composure but “are more likely than truth-tellers to press their lips simultaneously.” However, highly habitual liars “seem unusually calm and make considerably more eye contact with audience.
Accuracy and limitations – Results over the years has shown that test detects deception better than the guess. Few countries such as India and Japan accept this test as viable evidence. Examiner of the test can cause biased opinion within the test with their communications with the subject and in interpreting the test data.
Pursuing the test- There are typically three types of questions used in testing or voice stress analysis testing:
- Irrelevant questions establish a base to compare other responses by asking simple questions with either true or false answers.
- Comparison questions have an indirect connection to the circumstances, and they are fabricated to encourage the person to lie.
Directly connected questions are compared against comparison responses (which should represent wrong responses) and irrelevant answers (which should represent truthful replies).
- Equipments and drugs used – Machine generally used for lie detector test is “polygraph, though it is not completely reliable machine, it only records reactions of body, which changes with the consciousness of mind. Conscious human minds respond according to the emotion that trails like embarrassment, anger, fear, surprise etc.
- Sodium thiopental, cannabis, and ethanol are used as detecting drugs to know the truth from an unwilling object. These drugs are highly unreliable, and they depend upon the subject mixing truth and fantasies in state of unconsciousness of mind.
Extraneous noise also comes from embarrassment or sometimes in state of anxiety and not be specific to hiding the truth. When culprits are aware of the test, their emotional response, especially anxiety, can affect the record badly. Additionally, psychological disorders can create issues with data as certain disorders can lead subject to make a statement they think to be truth but is actually a fabrication of facts.
The professional conducting the test will assess the results in a bid to study and test the differences in spikes and the results of their behavior. The subject will be hooked with tubes and wires which are connected to the Lie Detector Test machine.