Detection of Deception - complete Flashcards
(32 cards)
What is the nature of deception?
lying and deception is a deliberate act
What is the frequency of lying?
Occurs everyday
DePaulo et al. (1996) College students told 2 lies a day, community members told 1 lie a day
DePaulo et al. (1998) frequency of lying alters between spouses, close friends and strangers
Why do we tell lies?
Vrij (2008)
- Personal advantage
- Avoid punishment
- Make positive impression/protect themselves from embarrassment
- Make others appear better
- Social lies to ease social situations
1-3 = self preserving 4 = other oriented 5 = both
What types of lies are there?
DePaulo et al (1996)
Outright lies - lies in which the information conveyed is completely different or contradictory to that the deceiver believes is the truth
Exaggerations - lies in which the facts are overstated or information is conveyed that exceeds the truth
Subtle lies - involve literal truths designed to mislead
What are non-verbal cues to detect deception?
Vocal characteristics - speech hesitations, rate and pitch
Facial characteristics - smile, gaze and blinking
Body movements - hand movements, head movements and shifting positions
What are the 6 fundamental errors?
- Behaviours wrongly associated with lying
- Actual cues to lying lack understanding or ignored
- Assumed lie behaviours are same across people and situations
- Assumed certain behaviours increase during deception
- People tend to show overt suspicion when doubtful of a persons credibility making person nervous and may elicit behaviours (stereotypical with lying), masking actual cues
- Assumed that a statement is believed simply because its plausible and consistent
What are the three processes liars may experience?
- Emotions
- Cognitive complexity
- Controlling processes - processes are likely to lead to different behaviours
What is the Emotional Approach?
Ekman (1992) - Guilt, fear and excitement. The combination and strength of the emotions depend on the situation and the person.
Guilt - liar, morals, consequences
Fear - liar, person being lied to, high stakes
Excitement - person being lied to, additional onlookers
What is the Cognitive Complexity Approach?
Vrij et al (2008) - Lying is more cognitively demanding that telling the truth
Increased cognitive load leads to neglecting body language
More speech errors and pauses
Looking at the face of our conversation partner is too distracting
What is the Attempted Behavioural Control Approach?
Liars will attempt to control their behaviour in order to look like they are behaving normally (truthfully)
Over-control = leakage of clues such as increased gaze, lack of movement and smooth speech
What are the issues with these underlying processes?
All three processes (emotional approach etc.) may occur together and are not mutually exclusive
One process could be more prevalent than the other according to circumstances e.g. if the lie is complicated the liar will have to think harder than if the lie is easy
Explain the background to ‘micro-expressions’
Porter et al (2005) - deception can be achieved by altering displayed emotions
- simulated, masked, neutral
Ekman suggested that concealed emotions can manifest into micro-expressions that last 1/25 of a second
Its claimed that trained observers can spot these expressions
Explain what a Statement Validity Assessment is? (SVA)
Analyses verbal and written consent
Linguistic analysis of a persons testimony
Undeutsch (1967) hypothesised that descriptions of events that actually happened differ in content and quality from fictitious accounts
Used in Germany and Netherlands to assess credibility of children’s statements of sexual abuse
What does SVA consist of?
Structure interview
Criteria Based Content Analysis
Validity Checklist
What does a structure interview in a SVA consist of?
Ask questions to elicit further critical information
Structure the questions around interviewee’s understanding of events
Avoid susceptibility of children to leading questions
Bull(1998) a child’s description of past events are notably incomplete
What does a criteria based content analysis within a SVA consist of?
Adapted from Steller et al (1989)
General Characteristics - quantity of details
Specific contents - unusual details, details misunderstood
Motivation related contents - pardoning perpetrator, raising doubts
Offence Specific Elements
Evaluate the SVA
It is a truth verifying technique
If criteria are present in a statement they are indicators of truthfulness
Therefore it is not a lie detection technique
Field studies (Lamb et al, 1997) examined statements abuse victims with ground truth being established by medical evidence etc.
More that one rater checked CBCA
Only used 14 criteria but average was 6.74
Experimental studies (Porter et al, 1996) 60 undergrads committed mock theft and then interviewed 3 of 18 CBCA criteria (detail, logical consistency and lack of memory) distinguished truthful and deceptive accounts
What is the accuracy of the SVA in field studies of adult rape allegations?
Parker and Brown (2000) examined SVA as a means of determining truthfulness of rape allegations but was difficult to establish ground truth
What are the overall accuracy rates of SVA?
Vrij (2005)
Accuracy of field studies = Truth 88% and Lie 92%
Accuracy in lad studies = Mean truth 73% and mean lie 72%
Can be manipulated and the CBCA criteria can be included in a false account to make it appear truthful
What are the overall feelings towards using SVA in court?
SVA does not meet Daubert (1993) ruling for admitting this form of evidence in court
Because error rate of 30% and experts are conflicted over the SVA
But SVA is useful for police to give them rough indications of truthfulness of statements
What is a Polygraph test?
Aim is to gain confession, detect deception and encourage public confidence
Used for Investogations, employee screening and pre-clearance screening
Measures blood pressure, respiration and Galvanic skin response
What is the polygraph testing procedure?
Distraction- free environment
Pre-test interview - explain procedure, gather info and review questions
Polygraph examination - instructed not to move, closed questions only, 1/3 test procedures used (RIT, GKT or CQT) (CQT is most used)
What is a Control/comparison question test (CQT) ?
Reid (1974) - consists of three types of questions (neutral, crime relevant and control (encourages deception))
Assumes innocent people will show stronger reaction to control than crime- relevant questions
How is the CQT scored?
Vrij (2008)
Global - polygrapher forms opinion based on examinee’s behaviour
Numerical scoring - No difference = 0, noticeable =+/-1, strong =+/-2 and dramatic =+/-3
High positive = innocence
High negative = guilt
