What is the Science behind Narco and Polygraph tests?

What is the Science behind Narco and Polygraph tests? | Know for UPSC

Science behind Narco and Polygraph tests: In short, polygraph tests record a number of different bodily responses which can then be used to determine whether someone is telling the truth.

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Relevance of Science behind Narco and Polygraph tests for UPSC

What is the Science behind Narco and Polygraph tests?: For UPSC CSE, it covers issues relating to development and management of Social Sector/Services relating to Health, Education, Human Resources.

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What is a narco test?

In a ‘narco’ or narcoanalysis test, a drug called sodium pentothal is injected into the body of the accused, which transports them to a hypnotic or sedated state, in which their imagination is neutralised.
Doing this lowers a person’s self-consciousness, thereby allowing them to speak without inhibition.
In this hypnotic state, the accused is understood as being incapable of lying, and is expected to divulge information that is true.
Because the drug is believed to weaken the subject’s resolve to lie, it is sometimes referred to as a “truth serum”, and is said to have been used by intelligence operatives during World War II.
This test is performed under the guidance and supervision of a psychologist, an investigating officer, or a forensic expert.

Know about Sodium thiopental drug

Sodium thiopental is part of a group of drugs called barbiturates, drugs widely used in the 1950s and 60s to help people sleep better.
They are no longer used for that purpose because they are extremely addictive and potentially lethal.
Sodium pentothal or sodium thiopental is a fast-acting, short duration anaesthetic, which is used in larger doses to sedate patients during surgery.
They act on the central nervous system as depressants.

How Narco Test is performed?

Before the injection, the subject of the test undergoes a general medical examination to check their condition. They are then injected with sodium pentothal.
The dosage depends on the subject’s age, sex and other possible medical conditions they may have. Getting this wrong can lead to dire medical emergencies. Hence, precautions are taken while performing the test.
Subjects are nearly sedated by this drug and reach a semi-conscious state and can answer specific questions.

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Are narco tests accurate?

The accuracy of these tests is not 100 per cent. Many subjects have made false statements in their drugged state. So, this has been deemed an unscientific method of investigation.

What is polygraph test?

In short, polygraph tests record a number of different bodily responses which can then be used to determine whether someone is telling the truth.
They usually measure things like blood pressure, changes in a person’s breathing, and sweating on the palms.
A polygraph test is based on the assumption that physiological responses that are triggered when a person is lying are different from what they would be otherwise.
The polygraph, like any other lie detection technique, measures an indirect effect of lying.
A polygraph test does not involved injecting drugs into the body; rather instruments like cardio-cuffs or sensitive electrodes are attached to the suspect, and variables such as blood pressure, pulse rate, respiration, change in sweat gland activity, blood flow, etc., are measured as questions are put to them.
A numerical value is assigned to each response to conclude whether the person is telling the truth, is deceiving, or is uncertain.
A test such as this is said to have been first done in the 19th century by the Italian criminologist Cesare Lombroso, who used a machine to measure changes in the blood pressure of criminal suspects during interrogation.
Similar devices were subsequently created by the American psychologist William Marstron in 1914, and by the California police officer John Larson in 1921.

How are Polygraphy tests carried out?

Polygraphs have been used around the world, in countries such as Japan, Russia, India and China, but the technology remains largely the same.
There’s a fairly long pre-test interview that lasts for about an hour. This focuses the individual on the questions they’re going to be asked and tries to remove any outside distractions.
This is followed by a practice test, which usually involves a number of straightforward questions. The aim is to relax the individual so they are comfortable and able to understand how the process works.
The equipment is then attached, and it usually includes a blood pressure monitor, electrodes which are placed on the fingers or palm, and two tubes which are wrapped around the chest and stomach.
There may be something that’s put on the tip of the finger that records blood flow and we also use something called a movement detector which is on the seat and picks up if you’re trying to beat the test.
Interviewers ask a number of control questions during the test and then compare the responses to the key questions. It finishes with a post-test interview, where the person will be able to explain any responses they showed.

How accurate Polygraphy tests are?

If the examiner is well-trained, if the test is properly carried out, and if there’s proper quality controls, the accuracy is estimated between 80%-90%.
However, interviewing victims presents a separate problem. Testing victims is a whole different ball game because of the nature of what they’re being asked about, you would expect a lot of arousal anyway.
This means a victim, especially one recounting a traumatic experience, may appear as if they are lying because they are in an emotional state.
Ultimately, experts say there are many caveats to polygraphs and a number of different factors which can lead to an inaccurate result.

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FAQs

Q. Which drug is used during Narco Test?

Ans. A drug called sodium pentothal is injected into the body of the accused during Narco Test.

Q. Which drug is used during Polygraph Test?

Ans. A polygraph test does not involved injecting drugs into the body; rather instruments like cardio-cuffs or sensitive electrodes are attached to the suspect, and variables such as blood pressure, pulse rate, respiration, change in sweat gland activity, blood flow, etc., are measured as questions are put to them.