Narcoanalysis VS Polygraph analysis

Subject: Science and technology

Context : Shraddha Murder Case,

Polygraph analysis:

Itis based on the assumption that physiological responses that are triggered when a person is lying are different from what they would be otherwise.
Instruments like cardio-cuffs or sensitive electrodes are attached to the person, and variables such as blood pressure, pulse, 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

Narcoanalysis:

Narcoanalysis involves the injection of a drug, sodium pentothal, which induces a hypnotic or sedated state in which the subject’s imagination is neutralized, and they are expected to divulge information that is true.
The drug, referred to as “truth serum” in this context, was used in larger doses as anaesthesia during surgery, and is said to have been used during World War II for intelligence operations.
Investigating agencies employ these tests in investigation, and are sometimes seen as being a “softer alternative” to torture or “third degree” to extract the truth from suspects.
However, neither method has been proven scientifically to have a 100% success rate, and remain contentious in the medical field as well.