Tuesday, February 18th, 2025

What is a polygraph test on which CBI’s hopes rest, know everything about it

New Delhi: In the case of rape-murder of a trainee doctor in Kolkata, six people including Sanjay Roy will undergo polygraph test. These include former principal of R.G. Kar Medical College and Hospital Sandeep Ghosh and four doctors who had dinner with the victim on the night of 8th August. On Friday, CBI presented the main accused Sanjay Roy in the special court of Sealdah, from where he/she was sent to judicial custody for 14 days. Let us know how this polygraph test is conducted?Question: What is a polygraph test
answer:
The lie detector machine is called a polygraph machine. It is used to detect whether a person is speaking the truth or lying. It is just like an ECG machine.

Question: How does the test work?
answer:
The polygraph test is based on the assumption that when someone is lying, there is an increase in heart rate, changes in breathing, sweating etc. During interrogation, devices like cardio-cuff or sensitive electrodes are attached to the person and BP, pulse etc. are measured.

Question: How did this test start?
answer:
Such a test is said to have been first used by Italian criminologist Cesare Lombroso in the 19th century. he/she used a machine to measure changes in the BP of criminal suspects during interrogation. Similar machines were later created by American psychologist William Marston in 1914 and California police officer John Larson in 1921.

Question: Do we get the exact answer?
answer:
Neither the polygraph test nor the narco test have been scientifically proven to be 100% successful. They remain controversial even in the medical field. However, investigating agencies give them priority.

Question: Are the results considered proof?
answer:
The result of the test cannot be considered a ‘confession’. However, any information or material discovered later with the help of such a test can be accepted as evidence. The Supreme Court held in the case ‘Selvi vs State of Karnataka’ (2010) that if an accused reveals the location of the murder weapon during the test and the police later finds the weapon at that place, the statement of the accused will not be evidence but the weapon will be.

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