The document discusses the history and development of the polygraph, or lie detector test. It notes that Cesare Lombroso invented the first device to measure changes in blood pressure in 1895. John Larson invented the modern polygraph in 1921. The document outlines the key principles behind how polygraphs work to detect deception based on physiological responses. It also discusses the development of polygraphs in India, the testing process, types of questions asked, accuracy rates, and legal issues regarding their use.

1. Dr. A.P.J. Abdul Kalam Institute of Forensic Science And Criminology
Bundelkhand University Jhansi (U.P.)
Polygraph
Presented By:
Ahsan Ali
M.Sc. Forensic science
3rd Semester

2. Polygraph ( Lie Detector )
Cesare lombroso- Invented in 1895 device to measure change
in blood pressure
John Augustus Larson- Invented in 1921. also known as
Father of polygraph He is medical student at the university of
California at Berkely.
Leonarde Keeler- He is co inventer of the polygraph. He
develop the cardio pneumo psychogram. Capable of detection
Deception Technices.

3. INTRODUCTION
It lliterally means 'many writing’. It is derived from two
Greek words 'poly’ which means many and ‘graphs’ which
means writing.
“A polygraph, popularly referred to as a lie detector test.it
is a device or procedure that measures and records several
physiological indicators such as blood pressure,pulse ,
respiration and skin conductivity while a person is asked
and answeres a series of questions.

4. Development
In India
In India lie detector or truth verification
technique was introduced first time at Delhi in
central forensics science lab. Under the central
bureau of investigation.
A lie detection division was established in year
1972.

5. Principle
The polygraph is based on
the principle of psychosomatic
interactions.
This results into
psychological changes in body.
Like pulse rate , blood pressure
, breathing rate and sweating.
There is always interaction
between Human mind And
Body which is basis for
development of lie detector.

6. Instrument
Sphygmographs
Galvanometers
Pneumographs

7. Phases of test
PRE TEST- The examiner discusses the test
issues with the subjects and review the test
question that will be asked.
TESTING PHASE – Subjects psychological
responses are recorded as the subject answers
the question.
POST TEST –Examiner reviews the data
obtained and interprets the polygram.

8. TYPES OF QUESTIONS
Is your name ?
• Irrelevant- not relevant to crime under
investigation.
Have you ever
committed any
crime ?
• Relevant – Questioned asked to crime
related under investigation.
Did you know
anything about
murder weapon ?
• Control – Relevant question are mixed in the
Grapher can compare the psychological
reaction in determine if the examine is lying.

9. Accuracy
This test Provides 90 – 95 %
Accuracy , with the competent
examiner and good working
condition of machine.

10. Legal Aspects of
Polygraph test in India
Article 20 ( 3) – Self incrimination ,
no man is bound to witness against
himself.

11. 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 )

12. Objectives of test :
 To verify veracity of statement or complaint
 Replace third degree method of interrogation.
 To examine white collar criminals, cyber
criminal etc.
 To differentiating between guilty and
innocent.

13. REFERENCES
Forensic science in criminal
investigation and trials By B.R. Sharma.
Forensic Psychology sixth edition By
Joanna Pozzulo , Craig Bennel ,
Adelle Forth
Introduction to Forensic And
Criminal Psychology sixth edition
By Dennis howitt.

14. Thank
you