 "Ex-RG Kar hospital principal may undergo polygraph test: How does it work?")
The Central Bureau of Investigation (CBI) may conduct a polygraph test on Sandip Ghosh, the former principal of RG Kar Medical College and Hospital, which is at the centre of a nationwide storm over the rape-murder of a trainee doctor.
Ghosh had resigned two days after the body of the victim was discovered in the seminar hall of the hospital, where the crime took place on August 9.
The agency has already taken custody of the prime accused, Sanjoy Roy and has gotten permission from a local court to conduct a polygraph test on him.
Ghosh has been quizzed by the agency several times over the incident but now they may mull a ‘scientific’ method to seek an accurate picture of the chain of events.
More From This Section
“We want to further verify Ghosh’s answers, as there have been discrepancies in some of the replies to our questions. Therefore, we are mulling over the option to conduct a polygraph test on him," an official told PTI.
What is a polygraph test?
A polygraph test is also colloquially labelled as a ‘lie-detector test’ used by crime agencies to investigate a case.
According to Princeton University, there are various techniques to perform a polygraph test and can be likened to a psychological diagnostic test.
A polygraph examiner obtains a subject’s responses to a carefully structured set of questions and based on their responses, the assessment of truthfulness or deception is done, the university says. The subjects’ physiological responses are measured by a three- or four-channel polygraph machine that records responses on a moving chart.
What types of physiological response are measured?
Princeton University publication explains that three types of physiological responses are measured during a polygraph test: The rate and depth of respiration; cardiovascular activity and electrodermal response.
To measure respiration, a medical device called pneumographs is strapped around the chest and the abdomen.
To measure a subject’s cardiovascular, a blood pressure cuff (sphygmomanometer) is placed around the bicep.
Electrodermal Response (EDR) also known as galvanic skin response (GSR) measures perspiration levels using electrodes attached to the fingertips.
The examination duration may vary between one to three hours. Usually, a pretest interview is also conducted before a polygraph examination to induce “anxiety in subjects who intend to be deceptive” and inform them of their legal rights, etc.
While polygraph, narco-analysis and brain-mapping could play an important clinical, scientific role in investigations, they are still contentious within the medical fraternity.
According to Indian laws, these tests have to be consented to and cannot be submitted as evidence in the court. However, any subsequent revelation in the case, which is a result of such a confession, is admissible, as laid down in a 2010 Supreme Court judgement.