1. Deception
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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. 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
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4. Types of Polygraph Tests
 There are three main types of polygraph
tests:
 Relevant/Irrelevant Test
 Control Question Test (CQT)
 Concealed Information Test (CIT)
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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)?
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6. Control Question Test:
3 Types of Questions
Control 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?
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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
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8. Control Question Test:
Assumptions
 Assumes guilty people react more to
relevant questions and innocent people react
more to control questions
 Problem(s)?
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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
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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
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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
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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
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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)
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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
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15. Using Behaviour to Evaluate
Deception
 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)
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16. Face
 Face clearest channel for detecting hot spots
 Must know the universal emotions expressed
through the face
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17. Universal Emotions
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18. Face
 Macro expressions – inconsistent between facial
expression and narrative – “Hot Spot”
 Micro or subtle expressions – concealed
emotional reactions
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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
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20. Detecting Deception:
Verbal Cues
 Verbal cues that are suggestive of honesty:
 Make corrections in account
 Admit to lack of memory
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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
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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
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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
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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)
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25. Other inherent problems according
to 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
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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
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27. Summary of research on viewing
time (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
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28. Summary of research on viewing
time (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
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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
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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
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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
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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
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33. Detecting Malingered Psychosis
 Clues regarding the symptoms:
 Report rare, atypical symptoms, or absurd
symptoms
 Absence of subtle symptoms
 Continuous hallucinations rather than
intermittent
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34. Detecting Malingered Psychosis
 Other clues:
 Accuse clinician of not believing them
 Presence of accomplice
 Crime fits pattern of criminal history
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35. Assessments: Malingered
Psychosis
 The Structured Interview of Reported
Symptoms (SIRS; Rogers et al., 1992)
 The M test (Baeber et al., 1985)
 MMPI/MMPI-2
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36. Rorschach
 10 inkblots
 “What might this be?”
 Very difficult to fake
 Very useful for assessing psychosis
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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
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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
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39. 15 Item SVT
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