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Lecture 3 deception post


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Lecture 3 deception post

  1. 1. Deception 1
  2. 2. The Polygraph Can a polygraph itself detect lies? Theory  Lying takes more effort than telling the truth  The fear of getting caught increases effort and apprehensiveness  Lying triggers more physiological arousal than telling the truth To maximize reliability several indices (respiration, heart rate and electrodermal activity) are used and several questions are asked 2
  3. 3. Uses of Polygraph Helps in criminal investigations (suspect is asked to take a polygraph test) Verify a crime has occurred (victim is asked to take a polygraph test) Monitoring sexual offenders on probation (United States) Pre-employment screening for security agencies and police 3
  4. 4. Types of Polygraph Tests There are three main types of polygraph tests:  Relevant/Irrelevant Test  Control Question Test (CQT)  Concealed Information Test (CIT) 4
  5. 5. Relevant/Irrelevant Test Asks questions relevant to the crime and irrelevant to the crime No longer used in law enforcement, but used for employee screening (e.g., drug use) Larger physiological responses to relevant questions indicates deception Problem(s)? 5
  6. 6. Control Question Test:3 Types of QuestionsControl Deal with prior Before age 25, did behaviour. you ever verbally Designed to threaten to hurt provoke anxiety. anyone?Irrelevant Used to obtain a Are you left handed? baseline.Relevant Deal with the crime. Did you assault Sam Smith the evening of November 11th? 6
  7. 7. Control Question Test Deception is assessed by comparing arousal levels of relevant and control questions The CQT begins with a pre-test interview:  Control questions are developed  Examiner attempts to convince the suspect of the accuracy of the polygraph If a suspect is believed deceptive they are pressured to confess 7
  8. 8. Control Question Test:Assumptions Assumes guilty people react more to relevant questions and innocent people react more to control questions Problem(s)? 8
  9. 9. Concealed Information Test Assesses if suspect has information that only the criminal would know Asks suspects multiple choice questions, one option is correct Assumes if the suspect is guilty they will react strongly to correct information Not used in Canada or United States 9
  10. 10. Types of Polygraph Studies Laboratory studies  Ground truth is known  Limited application to real-life situations Field studies  Real-life situations and actual suspects  Ground truth is not known Field-Analogue studies  Ground truth is known  Ethical concerns 10
  11. 11. Accuracy of the CQT Majority of guilty suspects correctly identified  84% to 92% guilty correctly identified Relatively large number of innocent suspects falsely identified as guilty  9% to 24% false positive errors Accuracy of original examiners higher than blind scorers 11
  12. 12. Accuracy of CIT Laboratory Studies  Very accurate at identifying innocent participants (≤ 95% )  Less accurate at identifying guilty participants (76% to 85%) Field Studies  94% to 98% accuracy for innocent  42% to 76% accuracy for guilty 12
  13. 13. Countermeasures Both physical and mental countermeasures dramatically reduce the effectiveness of the CQT (Honts et al., 1994) The CIT does not appear to be effected by anti-anxiety drugs (Iacono et al., 1992) Psychopaths are not able to beat the polygraph in lab studies (Miller & Rosenfeld, 2004; Patrick & Iacono, 1989; Raskin & Hare, 1978) 13
  14. 14. Admissibility of Polygraph Did not pass general acceptance test when first admitted as evidence in court (Frye v. United States, 1923) Currently allowed in some States if agreed by both prosecution and defence Not admissible into evidence in Canadian courts 14
  15. 15. Using Behaviour to EvaluateDeception Based on the principle that lying takes more cognitive and emotional effort than telling the truth Looking for “leakage,” change from baseline, or “hot spots” Observable channels: Face, body language, voice, verbal style, (verbal content) 15
  16. 16. Face Face clearest channel for detecting hot spots Must know the universal emotions expressed through the face 16
  17. 17. Universal Emotions 17
  18. 18. Face Macro expressions – inconsistent between facial expression and narrative – “Hot Spot” Micro or subtle expressions – concealed emotional reactions 18
  19. 19. Body Language Receives less attention than the face in those trying to conceal deception Need to be aware of cultural norms Differs from individual to individual – need to know individuals baseline 19
  20. 20. Detecting Deception:Verbal Cues Verbal cues that are suggestive of honesty:  Make corrections in account  Admit to lack of memory 20
  21. 21. Detecting Deception:Verbal Cues Verbal cues that are suggestive of deception:  Little detail/shorter description  Less compelling accounts  More nervous and tense  Pitch  Response latency  Errors in speech  Speech fillers  Rate of speech 21
  22. 22. Detecting Deception:Professionals Vrij (2000) reported accuracy rates:  Truths = 67%  Lies = 44% Aamondt &Custer (2008) professionals no more accurate than others (~56% vs. ~54%) Accuracy of professional lie catchers vary:  Have a truthfulness bias  Tend to rely on wrong cues 22
  23. 23. Penile Plethysmograph (PPG) Direct & objective measure of male sexual arousal patterns to normal vs. sexualized material Assumption: strong relationship between arousal and likelihood of acting on arousal The issue of validity still highly contentious  Does not meet Frye standard 23
  24. 24. Biggest threats to validity Responses can be simulated by manipulating mental images  e.g., child molesters/pedophiles’ use of fantasy and distraction Potential for expert error and lack of competence on the part of the psychologist  Lack of procedural standardization and guidelines for administering, scoring and interpreting data  Would be an excellent procedure to assess sexual interest if standardization occurred (Laws, 2003) 24
  25. 25. Other inherent problems accordingto Laws (2003) Equipment is expensive Labor intensive procedure Attaching an invasive electronic sensor to the body Limited for use among males Need a motivated and physiologically responsive subject High face validity 25
  26. 26. “Viewing Time” Assessment:An alternative to the PPG? Present with a series of pictures of males and females of different ages  Individuals in pictures are fully clothed, partially clothed or nude  They may or may not be erotically posed Subjects controls how long the images are viewed – viewing time is unobtrusively measured Assumption: Subjects will look longer at pictures they find sexually attractive Most useful with child molesters to determine age/gender preferences 26
  27. 27. Summary of research on viewingtime (Laws & Gress, 2004) “Normals”  ↑with sexually explicit content and when alone  Associated with preferred vs. non-preferred sexual objects among hetero & homosexual males  Hetero males & females had increased viewing times for sexual objects of preferred age 27
  28. 28. Summary of research on viewingtime (Laws & Gress, 2004) Men convicted of sexual offending  Laws & Gress (2004) - Viewing time produced consistently accurate age and gender preferences when compared to criminal history  Tong (2007)- PPG and VT seem to speak same language  PPG could be replaced with VT measures combined with self-report measures good at detecting “defensive” men 28
  29. 29. Disorders of Deception Factitious Disorder Intentionally produced physical or psychological symptoms Internal motivation to assume the sick role Absence of external incentives May have insight 29
  30. 30. Disorders of Deception Somatoform Disorder Physical symptoms that cannot be explained by organic impairment Symptoms are not intentionally produced Often co-occurs with depression or anxiety No insight 30
  31. 31. Disorders of Deception Malingering Psychological or physical symptoms are voluntary – have insight There are external motivations for the production of symptoms  Malinger mental illness to avoid criminal punishment, to obtain drugs, or for compensation such as disability  Prevalence quite high in forensic settings 31
  32. 32. Disorders of Deception Defensiveness The conscious denial or minimization of physical or psychological symptoms  Might wish to appear high functioning to be seen as a fit parent  Defensiveness is an important consideration when evaluating sexual offenders 32
  33. 33. Detecting Malingered Psychosis Clues regarding the symptoms:  Report rare, atypical symptoms, or absurd symptoms  Absence of subtle symptoms  Continuous hallucinations rather than intermittent 33
  34. 34. Detecting Malingered Psychosis Other clues:  Accuse clinician of not believing them  Presence of accomplice  Crime fits pattern of criminal history 34
  35. 35. Assessments: MalingeredPsychosis The Structured Interview of Reported Symptoms (SIRS; Rogers et al., 1992) The M test (Baeber et al., 1985) MMPI/MMPI-2 35
  36. 36. Rorschach 10 inkblots “What might this be?” Very difficult to fake Very useful for assessing psychosis 36
  37. 37. Malingered Amnesia Memory deficits:  Inability to recall past events  Impaired ability to establish new memories Offenders may malinger amnesia to reduce punishment for their criminal behaviour Measures assume a malingerer will “overplay” the role and fail on simple tasks 37
  38. 38. Assessments: Malingered Amnesia The Test of Memory Malingering (TOMM; Tombaugh, 1996) The Symptom Validity Test (SVT; Pankratz, 1988)  Forced choice recognition task  Individuals who demonstrate below chance responding are presumed to be feigning amnesia 38
  39. 39. 15 Item SVT 39