Polygraph 

Prepared by:Niraj Bartaula

Polygraph Devices

Introduction

• Is scientific, diagnostic, instrument known as lie detector.

• Appropriate to be called as truth verifier.• Invented in 1921 AD by John Augustus Larson.• Measures several physiological indices.• Used by FBI and CIAA (US law enforcement

and federal government agencies).

How can a machine detects whether someone is telling truth or not ?

Testing procedure

• At first pre-test than diagnostic question is asked.

• 3 basic type of question:- 1) irrelevant 2) relevant 3) control

• Passed if psychological response to diagnostic question is larger than those during relevant question.

Accuracy

• Very accurate however it is unreliable.• According to APA (American polygraph

Associatiation) in 250 studies over 25 years. Accuracy of polygraph is 90- 95%.

• Lie detector test cost 500 pound in UK and 400$ in USA.

How there recording made?

Two strain gauze is taken. One across chest and another across abdomen.

Ability of skin conductivity is recorded by placing electrodes pads on finger.

Cardio- vascular activity is recorded using standard blood pressure cuff placed on forearm.

Who should not take polygraph test?

Person with serious heart condition. Pregnant women Mentally incompetence Nerve damage or paralysis. Any person who has stroke or is an

epileptic (person who is in pain, headache, toothache)

For polygraph test

o Good night sleep.o Don't consume alcoholic beverage. o Don't use illegal drugs for 24 hrs prior to

examination.o Injury , illness or physical condition that can

impact you.

Issues that a Polygraph test is done

• Criminal Investigation• Abuse • Sex Offenders• Child Custody• Personal Investigation• Arson• Infidelity

How to pass Polygraph Test?

• Remember that polygrapher is not your friend:-• Beware of pre-test tricks:-• Conceal your knowledge of polygraph:-• Don't believe in rumour:-• Answer firmly, seriously and without hesitation:-• Biting tongue is highly affective:-• Change breathing pattern when control question is

asked:-• Handle the post test interview:-

In Context Of

Confession of truth using such method is the severe violation of human right . Confession are obtained using 3rd degree interrogation methods like merciless beating, deprivation of water and food, questioning in dark room etc.So nepal police alternative to 3rd degree treatment is Polygraph test.

Result Of Polygraph In Nepal

• Upto now 12-13 incident has been investigated by polygraph in Nepal.

• Mahendranagar :-Unidentified mask people looted 2 crore 31 lakhs

• Ramananda chowk of Janakpur : Bomb blast incident by Sanjay saha (CA Member) arrested by taking 2 hour polygraph examination.

• Dhangadi: Nepal police used polygraph for carrying out investigation into incident of looting about 4 crore of Nabil bank by its own empolyee.

Conclusion And Discussion Polygraph lacks constitutional and scientific validity.India supreme court has also banned to use polygraph

citing it is a violation of human right to life and privacy. Even in USA , land where polygraph is invented ,

Polygraphy has been banned by supreme court treating it as unreliable.

But in nepal nobody has been raising such question so it is in practice.

Reference

• http://cib.nepalpolice.gov.np/ accessed on 12/03/2014

• http://www.webmd.com/ accessed on 15/03/2014

• http://en.wikipedia.org/wiki/Polygraph accessed on 15/03/2014

Any Query?