Chapter 4: Deception Flashcards
polygraph
a device for recording an individual’s autonomic nervous system responses, including sweating, breathing, and changes in heart rate
assumption of the polygraph
deception is associated with physiological change
creation of the polygraph
- 1917: William Marston (creator of Wonder Woman) attempted to use a systolic blood pressure test as evidence of a person’s innocence
- Marston’s testimony was rejected by the court in Frye v. United States (1923) because the test had not gained acceptance by the scientific community
3 outcomes of a polygraph test
truthful, deceptive, inconclusive
applications of the polygraph test
- To help police with criminal investigations
- Polygraph disclosure tests
- Periodic testing of employees
polygraph disclosure tests
polygraph tests that are used to uncover information about an offender’s past behaviour
periodic polygraph testing of employees
- Only allowed in private companies for special investigations of wrongdoing
- Some governmental agencies in the U.S. and Canada still use the polygraph as a general screening tool
2 main types of polygraph tests
The Comparison Question Test (CQT) & The Concealed Information Test (CIT)
The Comparison Question Test (CQT)
a type of polygraph test that includes neutral questions that are unrelated to the crime, relevant questions concerning the crime being investigated, and comparison questions concerning the person’s honesty and history before the event being investigated
what is the most commonly used polygraph test in criminal investigations?
the CQT
assumption of the CQT
Examiners assume they can detect deception by comparing reactions to the relevant and comparison questions
interpreting results of the CQT
- Guilty suspects react more to relevant questions
- Innocent suspects react more to comparison questions
steps involved in doing a polygraph with a suspect of a crime
- gather information
- pre-interview
- attaches sensor and conducts acquaintance test
- testing phase
- scoring phase
- post-test interview
The Concealed Information Test (CIT)
- A type of polygraph test designed to determine if the person knows details about a crime
- Involves a series of questions in multiple-choice format, where each question has one correct answer
original name for the CIT
the guilty knowledge test
development of the CIT
Developed by Lykken in 1960
interpreting results of the CIT
- A guilty suspect is assumed to display a larger physiological response to the correct option
- An innocent suspect is assumed to display an equal physiological response to all options
assumption of the CIT
people will react more strongly to information they recognize as distinctive or important
what response is most commonly measured with the CIT?
palmar sweating
use of the CIT in North America
it is not routinely used in North America
Two reasons for the lack of widespread acceptance of the CIT
- Since polygraph examiners believe in the accuracy of the CQT, they are not motivated to use the more difficult-to-construct CIT
- For law enforcement to use the CIT, salient features of the crime must be known to the perpetrator
how is the accuracy of polygraph tests determined?
accuracy is ideally determined by presenting information known to be true or false to individuals and measuring their corresponding physiological results
two types of polygraph validity studies
laboratory & field studies
ground truth
the knowledge of whether the person is innocent or guilty
laboratory studies
involve simulating criminal behaviour by committing a mock crime
advantages of laboratory studies
the experimenter knows the ground truth and can compare the relative merits of different types of polygraph tests
disadvantage of laboratory studies
limited generalizability
field studies
involve real-life situations and actual criminal suspects with polygraph examinations
advantage of field studies
high external validity
disadvantages of field studies
establishing ground truth and problematic confessions
validity of the CQT
- The CQT has a high false-positive rate: studies show that most guilty suspects (84-92%) are correctly identified as guilty, while accuracy rates for innocent suspects are 55-78%
- The premise that innocent people respond more to relevant than comparison questions doesn’t apply to all suspects
validity of the CIT
The CIT has a high false-negative rate: it is effective at identifying innocent participants and slightly less effective at identifying guilty participants
countermeasures
techniques used to try to control guilt
examples of physical countermeasures
biting your tongue, or pressing your toes on the floor
examples of mental countermeasures
counting backward by 7 from a number greater than 200
impact of instruction on CQT results
30 minutes of instruction on the rationale underlying the CQT was sufficient for volunteers to learn to escape detection in a mock crime study
impact of anti-anxiety drugs on CIT results
Anti-anxiety drugs do not appear to impact the accuracy of the CIT
thermal imaging and polygraphy
Some studies have shown that thermal imaging is a promising polygraphic technique, but other studies have refuted these claims
how do people vs. scientists perceive the polygraph
Both the public and experts view the polygraph negatively, especially scientists
Frye v. United States (1923)
- Polygraph results were first submitted as evidence in the U.S. in Frye v. United States (1923)
- Frye was denied the opportunity to have the results of a polygraph test conducted by Marston admitted as evidence
- This led to the requirement that a technique must obtain “general acceptance” by the relevant scientific community before it can be admitted as evidence
R. v. Beland (1987)
In R. v. Beland (1987), the Supreme Court of Canada ruled that polygraph evidence should not be admitted to determine if someone is telling the truth
Event-Related Brain Potentials (ERPs)
brain activity measured by placing electrodes on the scalp and recording electrical patterns related to the presentation of a stimulus
P300
an ERP that occurs in response to significant stimuli that occur infrequently
advantage of ERPs
they are resistant to manipulation
Farwell & Donchin, 1991 detecting deception study
conducted two experiments where participants role-played one of two espionage scenarios and found that 18/20 participants were correctly identified as guilty and 17/20 were correctly identified as innocent
limitations of Farwell & Donchin’s 1991 detecting deception study
- Guilty participants reviewed the crime-relevant details before taking the CIT
- There were no aversive consequences linked to performance
- The same size was very small
Functional Magnetic Resonance Imaging (fMRI)
measures the cerebral blood flow (a marker of neurological activity) in different areas of the brain
brain activiation during lie conditions
Lie conditions produce greater activation in the prefrontal and anterior cingulate regions as compared to truth conditions
accuracy of fMRI lab studies
- fMRI lab studies have found that deceptive and honest responses are around 90% accurate
- But, simple covert movements like moving your left toe significantly decrease deception-detection accuracy in fMRI
limitations of fMRI research
- It is based on averaging data across multiple participants
- It may not generalize to real-life scenarios
- It may have a particularly powerful influence on juror decision-making
jury perception of fMRI lie detection study
found that evidence from fMRI lie detection resulted in more guilty verdicts compared to other types of evidence. However, if expert testimony that questioned the validity of the fMRI was included, the number of guilty verdicts was reduced to a similar level as the other conditions
lies in North America
The average North American tells 2 lies per day
lies we tell friends vs. acquaintances
People tell more altruistic lies to friends but more self-serving lies to acquaintances and strangers
assumption behind nonverbal lying behaviour analysis
it is more difficult for people to control aspects of their nonverbal behaviour than their verbal behaviour
tone of voice and detecting deception study
found that participants who were instructed to focus on the message source’s tone of voice were more successful at detecting deception than those who were given no specific instructions
facial expressions and detecting deception study
found that nurses focused on controlling their facial expressions when attempting to deceive. Observers who watched nurses attempting to deceive were more likely to detect deception when they were shown a videotape of the nurses’ bodies than their faces
efficacy of nonverbal behaviours as indicators of deception
Nonverbal behaviours such as gaze aversion, smiling, and self-manipulation are not accurate indicators of deception
microexpressions
brief facial expressions that reflect the emotion a person is feeling
microexpressions and detecting deception
when people are attempting to conceal emotion, the true emotion may manifest as a microfacial expression
pitch and detecting deception
Liars tend to speak in a higher-pitch voice than those telling the truth
speech disturbances and detecting deception
- Most studies have found an increased use of speech disturbances and a slower rate of speech during deception
- Cognitively more difficult lies may be associated with one pattern of speech disturbances, whereas cognitively simpler lies may be associated with another
verbal cues to lying
- Liars provided fewer details than truth-tellers
- Liars told less compelling accounts compared to truth-tellers
- Liars were rated as less cooperative and more nervous
- Truth-tellers were more likely to spontaneously correct their stories and more likely to admit to a lack of memory
- Deception cues were easier to detect when liars were motivated to lie than when they were attempting to cover up a personal failing or transgression
911 calls of innocent people vs. perpetrators of murder
innocent callers were more likely to make requests for help for the victim, correct misperceptions during the call, be rude and demanding of immediate assistance, and cooperative with the 911 operator. They also displayed considerable emotion and spoke quickly. Callers who had committed or organized the crime were more likely to provide irrelevant details, state that the victim was dead, blame or insult the victim, be polite and patient, and display little emotion
potential verbal charcateristics of decepetion
- Speech fillers (frequency of saying “ah” or “umm”)
- Speech errors (word or sentence repetition, sentence change, sentence incompletion, or slips of the tongue)
- Pitch of voice (changes in pitch)
- Rate of speech (number of words spoken in a specific time period)
- Speech pauses (length of silence between question asked and answer given; number of noticeable pauses in speech)
potential nonverbal characteristics of deception
- Gaze aversion (avoiding looking at the face of conversation partner or interviewer)
- Smiling (frequency of smiles or laughs)
- Blinking (frequency of eyeblinks)
- Fidgeting (scratching head, playing with jewellery)
- Illustrators (gestures to modify or supplement what is being said)
- Hand or finger movements
- Leg or foot movements
- Body movements
- Shrugs (frequency of shoulders raised in an “I don’t know”–type gesture)
- Head movements (nodding or shaking head)
- Shifting positions
deception detector rate for professional lie catchers vs. citizens
- The average rate of detection is similar for professional lie catchers as it is for regular citizens
- The rate for both is just above chance
- The only group of professionals that performed better than chance were U.S. Secret Service agents
3 explanations for poor performance in deception detection
- People share the widespread false beliefs that fidgeting and avoiding eye contact are related to deception
- People have a truth-bias
- There are only small differences between liars and truth-tellers
truth-bias
the tendency of people to judge more messages as truthful than deceptive
when are police officers better at detecting deception?
In high-stakes situations
why do police officers perform better in high-stakes situations?
- Research has shown that high-stakes lies are easier to detect
- Police were more familiar with the setting and the type of individual they were judging (suspects)
Vrij & Mann, 2001 police officers and lie detection study
- Found that police officers were not very accurate at detecting deception and their accuracy was not related to age, years of police work, level of interviewing suspects, or confidence
- Experienced police officers reported being more confident
Brinke & Porter, 2012 deceptive pleaders study
found that deceptive pleaders used fewer words and more tentative works. There was also less activation of the “grief” facial muscles
trait-related differences in detecting deception
There are no specific traits related to detecting deception in others
detecting deception training programs
Training programs may be able to help professionals become more accurate at detecting deception, particularly through teaching them truthfulness cues
