Liar, liar: Understanding the lie detector

Remember the old nursery rhyme about Johnny's father going through all that trouble just to catch his sugar-stealing son red-handed? Well, he could have just given Johnny a polygraph test instead. Lie detectors, or polygraphs, detects and records the physiological changes which happens to a body while a person answers a list of questions. In this test, sensors are attached to a body (it can be four, it can be six; depends), to record the blood pressure, pulse, breathing rate, skin conductivity etc. But, it is not as simple as it sounds, and you will have to read the rest of the article to understand why.

An examiner does not go guns blazing during the polygraph test. It is done meticulously, and the first stage involves a sort of interview taken prior to the actual test, to gather background information. The information is then used to formulate the questions. The next step is to conduct the "stim test", in which the person will be asked to lie. Yes, you heard that right! But it is not an attempt to establish lying as a fine arts subject, but rather to get inside the head of the subject. You see, after the subject lies, he or she is told that the lie was detected, which actually creates tension. Remember the feeling you get while lying? That guilt and the fear of getting caught which makes us sweat like the criminals on Savdhan India, and causes our hearts to almost come up to our mouths?  Well, this test records those physiological conditions to catch a lying person. Clever, don't you think? But that is not even the actual test. The actual test will comprise of some irrelevant questions, diagnostic questions, and relevant questions. The relevant questions are the ones which the examiner is most interested in. If you are wondering how to pass the test, it is simple (or not)- if your physiological responses to the diagnostic questions manage to be larger than your responses to the relevant questions, then you will have successfully passed the lie detector test.

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Let us assume for a brief moment, that lying indeed is an art, and you are a world-class liar, determined to defeat the lie detector. All you have to do is press a thumbtack to manipulate your physiological responses, or think about something difficult; there are a host of other hacks. Besides these, a polygraph test cannot differentiate between the origin of the responses. It also becomes difficult to separate responses coming from pure guilt, anxiety, and other such causes, which renders it inaccurate. In 1991, most members of the scientific community, all qualified, declared it as apseudoscience. Also, a report published by the National Academy of Sciences in 2003, termed it as "unreliable, unscientific and biased". Despite the controversy surrounding the usage of the polygraph, it is still being used in various countries, and it started after the FBI purchased Leonarde Keeler's portable polygraph with its " galvanic skin response", a feature he added in 1939. The polygraph was the brainchild of his mentor, John Augustus Larson, who invented it back in 1921. Well, while the world continues to debate the use of the lie detector, let us go by our lives, and continue with our sweet little lies, for it is indeed an art, and we ain't fools like little Johnny; just be sure to avoid a polygraph test, though!

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Post Written by - Lopamudra