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- 1. SCIENTIFIC LIE DETECTION AND POLYGRAPH By Aaradhya Soni 07/28/20XX # FORENSIC PSYCHOLOGY
- 2. 07/28/20XX 01 INTRODUCTION 02 HISTORY 03 HOW DOES IT WORK 04 ADMINISTRATION OF THE TEST 05 EXAMPLES OF QUESTIONS 06 ACCURACY 07 LIMITATIONS 08 THE PRACTICAL APPLICATIONS 09 CONCLUSION TABLE OF CONTENTS
- 4. INTRODUCTION - Lie detector, also known as a polygraph - Records physiological phenomena (blood pressure, pulse rate, respiration) of a human subject. - Operated during questioning to assess truthfulness Utilised in police interrogation and investigations since 1924 - Controversial among psychologists - Not always accepted as evidence in court - Physiological indicators chosen are not easily controlled voluntarily - Uses a pneumograph tube around the chest - Utilises a blood pressure-pulse cuff on the arm - Impulses recorded on moving graph paper driven by an electric motor
- 7. In ancient times, people used trial by ordeal, where accused individuals faced physical tests, hoping divine intervention would prove their innocence. Swearing oaths was another method to establish truthfulness. Use of torture: Interrogators employed various forms of physical torture to extract confessions, though the reliability of such confessions was questionable. Ancient Method Renaissance Era 18th Century Franz Joseph Gall: Developed phrenology, which claimed to detect deception based on the bumps and contours of the skull.
- 8. William M. Marston: Created the systolic blood pressure test, an early precursor to the modern polygraph. Polygraph Invention: John Augustus Larson and Leonarde Keeler developed the polygraph machine, which measures physiological responses like heart rate, respiration, and skin conductance. 19th Century Early 20th Century Mid 20th Century Rise of Polygraph Testing: The polygraph became widely used in criminal investigations and employment screenings.
- 9. Cognitive Interviewing: Psychological techniques, such as cognitive interviewing, were developed to enhance the accuracy of eyewitness testimonies. Functional MRI (fMRI) and PET scans: These technologies allowed researchers to study brain activity associated with deception, leading to insights into the neural basis of lying. Late 20th Century Advances in Neuroscience Modern Techniques Computerised Voice Analysis: Utilising speech patterns and voice analysis software to detect deception. - Eye-tracking technology: Monitoring eye movements and gaze patterns to identify signs of deception.
- 11. POLYGRAPH OVERVIEW A. Tool for lie detection. B. Measures physiological responses.
- 12. Physiological Measurements I. Heart rate. II.Blood pressure. III.Respiration. 07/28/20XX
- 13. HOW DOES IT WORK I. Polygraph machine records multiple signals using 4 to 6 sensors attached to the patient's body. II.The person's breathing rate III.The person's pulse IV.The person's blood pressure V. The person's perspiration
- 14. HOW DOES IT WORK The Nervous System reacts to different situations differently. For this, it uses different parts of it, namely: I. Somatic Nervous System II. Autonomic Nervous System a) Sympathetic Nervous Systems •Cardiosphygmograph: collects blood pressure and heart rate data Pneumograph : measures respiratory patterns Galvanograph: measures electrodermal activity or sweat
- 16. STEPS Familiarizing the subject with the test Pre-test Interview Formulating Questions Analysis of the result 01 02 03 04
- 18. EXAMPLE OF QUESTIONING QUESTION TYPE QUESTIONS RESPONSES N1 Do you live in Evanston? “YES” C1 During the first 18 years of your life, did you ever cheat on an academic assignment? “NO” R1 Did you cheat on the Deception midterm? “NO” N2 Are you a psychology major? “YES” C2 Did you look at the answer sheet of the student next to you during the midterm? “NO” R2 Before starting college, did you ever copy someone else's work? “YES”
- 20. ACCURACY R/I: a Extremely poor CQT: ● 83-89% for guilty subjects ● 53-75% for innocent subjects ● 12-47% incorrectly classified (falsely accused of guilt) DLT (Raskin & Honts, 2002): ● Guilty- 73-84% depending on type of directed lie ● Innocent- 84-87%
- 22. LIMITATIONS 1. Lie Detection Challenges: Imperfect accuracy despite advancements. 1. Countermeasures: Vulnerable to manipulation, affecting reliability. 1. False Results: Risk of labeling innocent or missing lies. 1. Ethical Issues: Privacy invasion, potential abuse. 1. Legal Dilemma: Admissibility and bias in court.
- 24. APPLICATIONS I. Enhancing interview and interrogation accuracy. II.Detecting deceptive statements. III.Streamlining evidence gathering and suspect identification. IV.Evaluating witness credibility and mental state. V. Improving ethical interrogation practices. VI.Minimizing false confessions and miscarriages of justice. VII.Strengthening courtroom proceedings with additional evidence. VIII.Ensuring a fair legal process and reducing false accusations.
- 26. CONCLUSION 1. Psychology and Crime: Psychology helps us understand the motives and behaviors behind criminal activities, informing crime prevention and investigations. 2. Advancements in Lie Detection: Recent technological advancements, including AI and brain imaging, have improved the accuracy of lie detection methods. 3. Practical Applications: These advanced lie detection techniques find practical use in criminal investigations, court proceedings, and high-profile cases, enhancing fairness and accuracy in legal processes.
- 27. CREDITS:This presentation template was created by Slidesgo, and includes icons by Flaticon, and infographics & images by Freepik THANK YOU! DO YOU HAVE ANY QUESTIONS? 07/28/20XX