All you must know about Polygraphy Test


Polygraphy is the process which is used in medical practice for comprehensive study of  functioning of different body systems with particular reference to circulation, respiration and  peripheral nervous response. This technology has been attempted in forensic investigation  process. The basis of its application is the fact that mental excitation or stimulation there is  alteration of these body functions due to autonomic, particularly sympathetic excitation. 

The Polygraph testing or instrumental measures several psychological method (ex. Heart rate)  changes in these process. From the chart of those measures in the response to the question on  a Polygraph test and sometimes aided by observations during the Polygraph test examiners  infer a psychological state, namely, whether a person is telling the truth or is he lying. This  psychological phenomenon results in the mental excitation. Psychologically, the attempt  made by the individual to conceal the excitation, is known as the “defense mechanism”,  which stimulates the adrenal glands, which in response secrete the adrenaline hormone. 

History Of Polygraphy

Earlier societies utilized elaborate methods of lie detection which mainly involved torture; for  instance, the middle Ages used boiling water to detect liars as it was believed honest men  would withstand it better than liars. Early devices for lie detection include an 1895 invention  of Cesare Lombroso used to measure changes in blood pressure for police cases, a 1904  device by Vittorio Benussi used to measure breathing, and an abandoned project by American  William Marston which used blood pressure to examine German prisoners of war (POWs).  Marston’s machine indicated a strong positive correlation between systolic blood pressure  and lying. 

A device recording both blood pressure and galvanic skin response was invented in 1921 by  Dr. John Augustus Larson of the University of California and first applied in law  enforcement work by the Berkeley Police Department under its nationally renowned police  chief August Vollmer. Further work on this device was done by Leonarde Keeler. 

A device which recorded muscular activity accompanying changes in blood pressure was  developed in 1945 by John E. Reid, who claimed that greater accuracy could be obtained by  making these recordings simultaneously with standard blood pressure-pulse-respiration  recordings. 

The Materials and Methods

The person is made to sit on a chair and the accessories of the instrument are properly  attached on different parts of the body. An arm cuff is placed around the arm for recording  blood pressure and pulse rate and pulse features.

An elastic belt is placed around the chest to  measure the rate and amplitude of respiration with deviations and an electrode connection is  placed, one on the tip of one side index finger for recording galvanic skin reaction (Galvanic  current is used for the purpose).  

The response is recorded graphically on a single paper from where different adverse  responses, the intensity of responses, and the time and extent of exciting reaction, can be  studied. All these measurements are recorded simultaneously in the form of traces on a graph 

paper individually. These recordings on a graph paper, collectively, are known as PolyGram.  It is evaluated to find out whether during the lie detection test the subject experienced  emotional stress from any of the questions asked, or showed no reaction. 

Procedure of interrogation and questioning to the subject 

Step 1- Preparation of the subject: 

The person is subjected to pre-examination interview during which its purpose, aim, the  process of polygraph examination to be followed, should be explained to him to his optimum  understanding. For satisfactory result of the test, the tester should have the knowledge of the  incident.  

The subject should be informed that, he would be asked certain questions, and he is to answer  the questions as yes or no. For this questions will be of suggestive in nature. The subject has  nothing to be apprehensive about any wrong study and interpretation of the Polygraphic test.  But if he deceives then, that will be reflected in the test.  

In the second stage he should be made acquainted with the questions and he has to understand  the questions well so as to give yes or no answers. Ideally, not more than 10 questions should  be asked to him in the same sitting. Initially three categories of questions are asked. 

Irrelevant questions: These are the questions which have no bearing with the incidence of  offence in any way. For example – Is your name Mr. X? Are you 28 years in age? Are you a  usual inhabitant of Y area? Do you work in Z firm?  

Relevant questions: These are the mostly directly implicating him with commission of the  offence or suggestive of having knowledge about some aspects of the offence. For example,  on 11-10-2018 at 5:00 p.m, you stabbed Mr. A at his home or saw Mr. B stabbing Mr. A, on  11-10- 2018 at 5:00 p.m. You have robed SBI bank of Rs.5 lac?. The answers for the relevant  questions should be “yes” or “no”. 

Control questions: For proper understanding and interpretation of the graphic curves  imprinted with answers and mental reaction of the subject to different relevant questions,  control question are asked, which are mostly generalized in nature, related to some minor bad  acts which the person might have committed some time in his early life and should have not  forgotten.

E.g., Have you at any time during your childhood, stolen some money from your  mother’s purse for purchasing some playing materials? Did you ever think to make money by  way of bank robbery or some such way? 

Step 2: Proper examination 

The person to be examined is made to sit on a polygraph chair in such a way that he faces the  instrument and the operator faces him so that during questions and answers he can observe  the facial reactions of the subject. The different settings of test constitutes: 

• first test 

• card test  

• 3rd test 

• mixed question test 

• yes test

• guilt complex test  

• repeat test (re-examination test) 

• peak of tension test. 

Critical Analysis of Polygraph test 

(1) The test does no longer inform as to whether the person is truthful or not. Test only  display approximately the physiological adjustments which must be interpreted by using the  expert.  

(2) In asking the question no technology is worried and it utterly relies on to deception and on  the information of the tester.  

(3) An individual who can manipulate his feelings to a super extent can still inform a lie, in  case, if an individual has control on himself by way of practice of yoga or in any other case,  this check is sure to get fail. 

Constitutional validity of polygraph test Judicial Response 

The lie Detection division renders valuable Polygraph aids in a number of important  investigations conducted by CBI, Judiciary, Delhi Police and other law enforcement agencies.  The Lie detection division maintain latest version of the computerized Polygraph equipment.  

The objectives of Lie detection are:  

• To verify the statements of suspects, witnesses and the complaints.  

• To economise and accelerate the process of investigation by screening innocent person  where a large number of suspects are involved.  

• Scientific interrogation of suspects in white collar crimes.  

• To corroborate the findings of investigation by investigating officers. The main legal  provisions which governs the expert evidence (Lie Detector test), are in Indian Constitution,  Code of Criminal Procedure, Indian Evidence Act. In Indian Constitution there are various  provisions which are related with the protection of the accused person. 

In the Constitution of India, the provision of life, liberty and freedom has been given under  Article 20 and 21. According to Article 20(3) ―no person accused of any offence shall be  compelled to be a witness against himself‖. This article applies only to an accused and only  speaks of self-incrimination evidence by way of compulsion. 

Under this Article only an accused person can avail the protection if he is compelled to be a  witness against himself. Every civilized society guarantees the right against self incrimination as a fundamental of fair trial in a criminal offence. According to this principle,  a person accused of a criminal offence cannot be forced to incriminate himself or yield  evidence against himself. 

Landmark Cases in India 

1.State of Bombay v. Kathi kalu Oghad 

The Hon‘ble Supreme Court observed that conducting the Polygraph by the police without  the consent of accused person is clear violation of article 20(3) of the Indian Constitution. 

The right against forced self incrimination is enshrined in Article 20(3) of the Indian  Constitution as well as in the Criminal Procedure Code.  

In this case the Bombay High Court had to decide whether compelling the accused person to  undergo this test would violate his right to silence and compel him to provide evidence  against himself. In this case Palshikar J. held that the right against self-incrimination applies  only to court proceeding and not to police interrogation. 

2. Selvi v. State of Karnataka 

The court held that Indian constitution protect the individuals right against self incrimination  and article 20(3) give right to accuse to not be a compelled witness against himself. The main  idea behind article 20(3) is to protect accuse against self incrimination and to save accuse  from becoming an evidence against himself. 

After hearing the argument from both sides Supreme Court has proposed certain guideline  which is needed to be followed before enabling polygraph analysis test and also said that  consent of accuse need to be taken before enabling polygraph analysis otherwise it will be  clear infringement of right against self incrimination of Indian Constitution. 

Other cases where polygraph test was used 

Polygraph techniques have grown in recent criminal investigations and evidence, there is  increasing concern about the factors that may adversely affect their accuracy and their uses in  administrative and judicial proceeding. 

If Polygraph test conducted in a rape case: In Bangalore, Karnataka, one Pratibha Srikanth, a  woman employee of BPO was raped and murdered. The charge was framed on a driver hired  by the company. The driver was subjected to polygraph test, brain mapping test, and narco  analysis test. 

Polygraph test conducted in Shivani Bhatnagar murder case: The Indian Express  Journalist Shivani Bhatnagar was murdered at her East Delhi apartment on 23rd January,  1999. In this case murder charge was framed on a Haryana Cadre I.G. Police Mr. R.K.  Sharma and. five other accused persons. The polygraph tests were conducted on Shivani‘s  husband, her sister, brothers and brother-in-law.  

Polygraph test conducted on Nithari’s serial killing accused: In Nithari, Noida (U.P.), a  businessman Mohinder Singh Pandher and his domestic help Surinder Koli were accused of  murdering 30 missing children. At the time of writing this book, the CB1 is investigating into  the case.

In scientific tests suspected killer admitted serial killing of missing children  investigating agencies used polygraph, brain mapping and narcoanalysis tests on both of them  and also on a female servant who allegedly lured children who were killed by both duo. 

Polygraph test conducted on Mumbai serial killer: Ravindra Kantrole, a suspect of serial  killing of seven people in South Mumbai in Marine Drive and Azad Maidan Police Station,  was subjected to scientific tests like polygraph, narco analysis and higher version of brain  mapping tests [i.e., Brain Electrical Oscillation Signature (BEOS)]. During these tests he  confessed his involvement in the crimes.



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