Download Comparison Question Test

Chapter 4
Deception
Copyright © 2012 Pearson Canada Inc.
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Learning Objectives
• Describe the two types of polygraph tests
• Describe the most common errors made
by the Comparison Question Test (CQT)
and Concealed Information Test (CIT)
• Describe physiologically based
alternatives to the polygraph
• Outline the verbal and non-verbal cues of
deception
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Learning Objectives
• Define malingering, and list the three
explanatory models of malingering
• Differentiate between the types of studies
used to examine malingering
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Polygraph Method
• Based on the belief that deception is
related to physiological change
• Measures:
– Respiration
– Heart rate
– Sweating
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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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Types of Polygraph Tests
• There are two main types of polygraph
tests:
– Comparison Question Test (CQT)
– Concealed Information Test (CIT)
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Comparison Question Test
• Includes three types of questions:
– Irrelevant
– Relevant
– Comparison
• Deception is assessed by comparing
physiological responses between
relevant and comparison questions
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Comparison Question Test:
Sample Questions
Question
Irrelevant
Relevant
Purpose
Used to obtain a
baseline.
Deal with the
crime.
Comparison Deal with prior
antisocial
behaviour.
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Example
Are you left
handed?
Did you assault
Sam Smith on
March 11th?
Before age 25,
did you ever
verbally threaten
to hurt anyone?
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Phases of the CQT
• Pre-test interview: Interview with suspect
to develop the comparison questions
• Polygraph exam: Questions are asked
while suspect’s physiological responses
are measured
• Scoring: Polygraph examiner scores the
physiological responses to determine if
the suspect is truthful, deceptive, or
inconclusive
• Post-test interview: If a suspect is judged
deceptive they are pressured to confess
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Control Question Test:
Assumptions
• Assumes guilty people react more to
relevant questions and innocent people
react more to comparison questions
• Suspect falsely accused of a crime might
react more strongly to questions about
the crime than to vague questions
concerning past behaviour
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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
• Rarely used in Canada or United
States
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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
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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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Accuracy of CIT
• No field studies have been conducted in
North America
• Very accurate at identifying innocent
participants
– Around 95% correctly identified
• Less accurate at identifying guilty
participants
– Around 85% correctly identified
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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)
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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 (R. v. Beland, 1987)
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Other Measures
• Thermal imaging:
– Detects facial warming due to blood
flow
• Event-related brain potentials (ERP)
– Electrodes measure brain activity in
response to a significant stimulus
– P300 used to detect guilty knowledge
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Other Measures: fMRI
• Functional magnetic resonance imaging
(fMRI)
– Measures differences in brain activity
when people are being honest versus
deceptive
– Different parts of the brain are
activated when person is deceptive
versus when they are telling the truth
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Detecting Deception:
Verbal Cues
• Verbal cues most consistently related to
deception include:
– Higher voice pitch
– Increased speech disturbance (ah,
umm)
– Slower speech
• Pattern of verbal cues may depend on
how cognitively complex the lie is
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Verbal Characteristics of Deception
(Table 4.3)
• Speech fillers
– Frequency of saying “ah” or “umm”
• Speech errors
– Repetition, change, slips of tongue
• Pitch of voice
• Rate of speech
• Speech pauses
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Non-verbal Characteristics of
Deception (Table 4.3)
•
•
•
•
•
•
Gaze aversion
Smiling
Blinking
Fidgeting
Illustrators
Hand or finger
movements
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• Leg or foot
movements
• Body movements
• Shrugs
• Head movements
• Shifting positions
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Detecting Deception:
Verbal Cues
• Verbal cues that are indicative of honesty:
– Make corrections in account
– Admit to lack of memory
• Verbal cues that are indicative of deception:
– Little detail
– Less compelling accounts
– More nervous and tense
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Detecting Deception:
Professionals
• Vrij (2000) reported accuracy rates:
– Truths = 67%
– Lies = 44%
• Accuracy of professional lie catchers
vary:
– Have a truthfulness bias
– Tend to rely on wrong cues
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Factitious Disorder
• Intentionally produced physical or
psychological symptoms
• Internal motivation to assume the sick
role
• Absence of external incentives
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Somatoform Disorder
• Physical symptoms that cannot be
explained by organic impairment
• Symptoms are not intentionally produced
• Often co-occurs with depression or
anxiety
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Malingering
• Psychological or physical symptoms are
voluntary
• 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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Defensiveness
• Defensiveness refers to the conscious
denial or minimization of physical or
psychological symptoms
– Might wish to appear high functioning to
be seen as a fit parent
– Some patients may not want to admit
they certain symptoms
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Explanations of Malingering
• Three explanatory models of malingering
(Rogers, 1990):
– Pathogenic model
– Criminological model
– Adaptational model
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Pathogenic Model
• Assumes malingering results from an
underlying mental disorder
• The patient attempts to gain control over
his or her pathology by creating fictitious
symptoms
• Little empirical support
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Criminological Model
• Malingering due to:
– Antisocial personality disorder (APD)
– Forensic assessment
– Lack of cooperation
– Discrepancy between findings
• Research does not support an association
between APD or cooperation and
malingering
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Adaptational Model
• Asserts malingering is likely to occur
when:
– A perceived adversarial context is
present
– Personal stakes are very high
– No other viable alternatives are
perceived
• Research findings support this model
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Research Assessing Malingering
• Three basic designs:
– Case study
– Simulation
– Known groups
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Case Studies
• Useful for generating a wide variety of
hypotheses
• Only way to study rare syndromes
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Simulation Design
• Most frequently used
• Participants are told to malinger a specific
disorder and compared to
– Control group
– Clinical comparison group
• High experimental rigour
• Limited generalizability to the real world
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Known-Groups Design
• Involves two stages:
– Establishing the criterion groups (e.g.
genuine patients and malingers)
– Analysis of the similarities and
differences between criterion groups
• Good generalizability to real-world
settings
• Problems classifying criterion groups
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Detecting Malingered Psychosis
• Clues regarding the symptoms:
– Report rare, atypical symptoms, or
absurd symptoms
– Report atypical delusions or
hallucinations
– Absence of subtle symptoms
– Continuous hallucinations rather than
intermittent
(continued)
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Detecting Malingered Psychosis
(continued)
•
Other clues:
– Accuse clinician of not believing them
– Presence of accomplice
– Crime fits pattern of criminal history
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Assessments: SIRS
• The Structured Interview of Reported
Symptoms (SIRS; Rogers et al., 1992)
– Uses a structured interview
– 172 items organized into 8 scales
– Research indicates good validity
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Assessments: M-FAST
• The M-FAST test (Miller, 2000)
– Interview-based method
– 25 items organized into 9 scales
– Useful and reliable screening test for
malingering
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Assessments: MMPI/MMPI-2
• MMPI/MMPI-2 are self-report personality
inventories
– They contain scales such as the
infrequency (F) scale and the Back F
(FB) scale selected to detect unusual or
atypical symptoms
– Research indicates these scales are
the most useful at detecting malingerers
(Rogers et al., 2003)
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