The test is considered passed if the physiological responses to the diagnostic questions are larger than those during the relevant questions.
New Delhi: On Friday, a special court in Kolkata granted permission for the CBI to perform a polygraph test on Sanjay Roy, the prime suspect in the heinous rape and murder of a junior doctor at R.G. Kar Medical College and Hospital earlier this month. The previous day, this court had sanctioned the Central Bureau of Investigation’s request to administer the test to the former principal of R.G. Kar Medical College and Hospital, Sandip Ghosh, along with five others implicated in the case.
What Is A Polygraph Test?
A polygraph is a device or procedure that measures and records various physiological indicators of a person suspected of a crime. The test, first employed by the Italian criminologist Cesare Lombroso in the 19th century, involves asking the suspect questions while monitoring their blood pressure, pulse, respiration, and skin conductivity, which may fluctuate when a person is being deceptive.
Cardio cuffs and sensitive electrodes are used to monitor the accused’s blood pressure, pulse, and other variables.
Obtaining court approval for a polygraph test involves a complex procedure. The court only consents to such tests after the individuals subject to the test have given their permission. Moreover, while it is a technique used by investigative agencies to uncover the truth, the results of a polygraph cannot be submitted as evidence in a court of law.
How Is It Done?
Prior to the commencement of the polygraph test, the subject undergoes a sequence of preliminary assessments. The process usually starts with a pre-test phase, during which the individual is questioned by the investigative authorities to establish baseline responses. Subsequently, in the second phase, the subject is instructed to intentionally provide false answers to enhance the test’s precision. This phase, referred to as the ‘stim test’, may also induce feelings of nervousness and anxiety in the subject.
A test is deemed successful if the physiological responses to diagnostic questions exceed those to relevant questions.
What Does The Indian Law Say About Polygraphs?
Article 20 (3) of the Indian Constitution protects against self incrimination and gives the accused the freedom to choose for the test or to reject it.
No accused can be compelled to undergo the test. Importantly, forcing an accused to undergo the test is considered a violation of Article 20 (3).
How Accurate Is A Polygraph Test?
Although a polygraph test can detect arousal caused by anxiety, post-traumatic stress disorder (PTSD), nervousness, fear, confusion, hypoglycemia, psychosis, depression, or other factors, it cannot accurately determine lies. These tests are not scientifically validated to be 100 percent accurate.
(With IANS inputs)