Polygraph test

Polygraph Test(lie
detection test)
Submitted by:kirti
chugh
Member Of AFRS

Content
 Introduction
 History
 Objective
 Principle
 Indian scenerio
 Legal aspects
 Psychological parameters
 Equipments
 Stages of examination
 Limitations

THE POLYGRAPH TEST
Polygraph test/lie detection test used to prove the
truthfulness of a subject and measures and record
the various physiological changes like :
Blood pressure
Pulse rate
Respiration
Galvanic skin resistance(GSR)
While the subject asked a series of questions
LIE DETECTION TEST ALSO KNOWN AS
‘’DETECTION DECEPTION’’

HISTORY
 The study of physiological methods for
deception test measuring emotional
disturbances began in early 19th
century
 Lombroso in 1895 was the first to use
scientific test to determine guilty and
innocence by studying the change in
pulse rate and blood pressure while
questioning criminals.

HISTORY
 Later Larsen and Kellar independently
designed instruments with new
features to make it more versatile.
 In 1947,Reid introduced a completely
revised polygraph technique.

OBJECTIVES OF POLYGRAPH
TECHNIQUE
 To verify the veracity of the statement of
suspect, witness and complainant in all
type of crime.
 To replace the third-degree method of
interrogation
 To examine white-collar criminals,
economic criminals, and cybercriminals.
 To economize the process of
investigation by screening a large no. of
suspects by differentiating between guilty
and innocent.

PRINCIPLE
POLYGRAPH TEST based on the
principle of psychosomatic interaction
within an individual that is psychological
a change in person’s consciously held
feelings produces a defense reaction in
form of physiological changes in
respiration ,B.P, pulse rate etc..
‘’The psychological and physiological stimulation that
are experienced during interrogation result in
automatic changes which are difficult to control
consciously .A No. Of these changes recorded and
interpreted accurately..’’

INDIAN SCENARIO
In India the polygraph examination is used
in the field of crime investigation.
 The lie detection was introduced in India
for the first time in Delhi at central
forensic science laboratory under the
central bureau of investigation.
 A full fledged lie detection division was
established in the year 1972-1973.
 The lie detection division of
CFSL,CBI,New Delhi has till date
furnished opinions in 3575 cases
involving various cases from
conventional to white collar crimes.

LEGAL ASPECTS OF
POLYGRAPH TEST IN INDIA
 The main provision regarding crime
investigation and trial in Indian
constitution is Article 20(3)
 It deals with the privilege against self-
incrimination.
 Article 20(3)which embody this
privilege reads:
“no person accused of any offence shall be compled
to be witness against himself”
THE RESULT OF POLYGRAPH TEST WILL NOT BE
ACCEPTED IN COURT

PSYCHOLOGICAL
PARAMETERS
There are 3 type of parameters:
suspect, complainant and witness
which is broadly classified as truthful
and untruthful
Polygraph examination situation can be
compared with goal achievement
situation where both truthful and
untruthful person trying to prove their

POLYGRAPH EQUIPMENTS
It us basically a combination of medical
devices that are used to monitor
changes occurring in the body..
PNEUMOGRAPH: To record respiration
,partially inflated rubber tube is fastened
around thoracic or abdominal region of
examinee..
SPHYGMOMANOGRAPH: A blood
pressure cuff is fastened around right
arm in such a way that the rubber portion
of cuff is placed over brachial artery for
satisfactory recording of B.P and pulse
rate

POLYGRAPH EQUIPMENTS
 GALVANOGRAPH: Electrodes are
attached to index and ring finger of left
hand to record the galvanic skin
resistance.
 PLETHYSMOGRAPH: It is a
transducer attached to thumb to
measures blood volume reflecting the
pulse rate…

STAGES OF POLYGRAPH
EXAMINATION
PRE TEST INTERVIEW
It helps to bring the subject in proper
psychological state of mind ,enables
the expert to access the hostile
personality of subject and prepare him
for lie detection….

To be cont…
QUESTIONNAIRE FORMULATION
While questioning the subject, basic
approaches are :
IRRELEVANT QUESTIONS : are
included because the answers to the
questions are admitted truth…
CONTROL QUESTIONS : they are not
related to crime scene but to a similar
situation in which the answers may have
a feeling of concern w.r.t either its
truthfulness or accuracy

To be cont…
RELEVANT QUESTIONS :Questions
pertaining to crime under investigation
based on fact of case…..

TO BE CONT…
EXAMINATION
1. Familiarize the examinee within
examination room ,polygraph equipments
2. Instruct the examinee about the manner he
has to sit during examination .
3. Attach the sensor on examinee and record
normal physiological parameters
4. Instruct the examiner regarding the
administration of questionnaire
5. Review of questionnaire with examinee just
to ensure that he understood the questions
properly .(this step is done before
administration of questionare)

ANALYSIS OF POLYGRAPH
CHART
 Observing the normal reading of
physiological parameters
 Compare the recording of each
physiological parameter on each
relevant question w.r.t normal reading
,recording on control questions
,recording on irrelevant question.
 Marking the reaction on each and
every question on the polygrams.

LIMITATIONS
 Mental abnormalities
 Unresponsiveness of subject
 Some unobserved muscular
movements
 Mental tension of subject due to
offences committed earlier
 Physiological defects like hearing
impairment which interfere in proper
administration of polygraph
examination procedure.

McQs
 Polygraph test violate which article?
A)Article 26
B)Article 20(3)

References…
 https://www.apa.org/research/action/p
olygrap
 Handbook of forensic psychology by
Prof.(Dr.)Vimala Veeraraghavan…

Polygraph test

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Polygraph test