CREDIBILITY ASSESSMENT:
PITFALLS AND OPPORTUNITIES
Dr Lucy Akehurst
University of Portsmouth
Psychology Department
Email: [email protected]
CUES TO DECEIT
What are nonverbal cues?
Based on the research literature nonverbal cues include:
1. Behavioural cues e.g.
hand and foot movements
eye contact
blinking
as well as
2. Speech characteristics e.g.
pitch of voice
speech errors
pauses
What are verbal cues?
The content of what the interviewee is saying
See:
Statement Validity Assessment
Reality Monitoring
Believed cues (subjective)
Vs
Actual cues (objective)
•
Research methodologies:
Questionnaires, Observation
• Laboratory vs Field
PEOPLE’S BELIEFS ABOUT CUES TO DECEPTION
See Vrij (2008) for review
When psychologists have pooled together the data from
over 50 experiments there are some believed cues to
deception that stand out.
NB: Remember, these are not necessarily actual cues to
deception – just what others believe are useful.
BELIEVED CUES TO DECEPTION
Pitch of voice
Pauses
Speech errors
Gaze aversion
Blinking
Gesticulation
Other hand movemts.
Foot movements
Position shift
Increase Increase Increase Increase Increase Increase Increase Increase Increase when lying compared
to truthtelling
GLOBAL RESEARCH PROJECT
BOND & RAO (2005)
45 countries (3 Africa, 11 Asia, 21 Europe, 3 N America, 5 S
America and 2 Australasia)
1,800 participants, 35 different languages
“How can you tell when people are lying?”
Resulted in 8,543 beliefs...
Liars show a lack of eye contact = most common belief worldwide
(referred to more than 5% of the time in all countries)
Other pancultural beliefs included liars making more speech errors,
showing signs of nervousness and showing forms of inconsistency
ACTUAL CUES TO DECEPTION
Pitch of voice
Pauses
Speech errors
Increase Frequency, no change (but duration )
Increase Gaze aversion
Blinking
Gesticulation
Other hand movemts.
Foot movements
No change -Decrease Decrease Decrease Decrease Position shift
No change --
SUMMARY SO FAR
Behaviour
Belief
Actual
Correct?
Pitch
Pauses
Errors
Gaze aversion
--
Blinking
Gesticulation
Other hand
moves
Foot moves
Posture shifts
--
IN SHORT:
PROBLEM:
We form global impressions based on many cues
(which are often unhelpful) and translate these into
truth/lie decisions.
SOLUTION:
Concentrate on individual cues that have been shown to
be valid indicators of deception – IGNORE THE REST!
THEORETICAL UNDERPINNING
Three processes may underpin the actual cues to deception
– as cited in the psychological literature.
1. EMOTION
2. ATTEMPTED CONTROL
3. COGNITIVE COMPLEXITY
EMOTION
Fear
Guilt
Duping Delight
= AROUSAL
PROBLEM
Strength of emotion/arousal depends on:
Personality of liar
Context of lie
As these are so variable this model does not offer the
most predictive cues.
ATTEMPTED CONTROL
In an attempt to look truthful liars try to control their
behaviours.
Research has found that we are well practiced at
controlling our face but less adept at controlling body
movements and speech.
There is a tendency for liars to appear too rigid and for
their speech to sound rehearsed and ‘unnatural’.
Signs of attempted control=
eye contact regulated
fewer hand movements fewer foot movements fewer gesticulations
COGNITIVE COMPLEXITY
It is difficult to lie.
Must remain consistent, remember what saying, make sure
fits with other evidence.
Brain working ‘overtime’, body ‘shuts down’.
Signs of cognitive complexity =
more pauses more speech errors less blinking fewer movements ACCURACY RATES/HIT RATES - NVCS
Over 30 years of psychological research has shown that
most people (with a few exceptions – but not many!)
achieve hit rates when judging others credibility (using
NVCs) of 45% - 60%.
50% hit rates could be achieved by tossing a coin!
TRUE FOR: STUDENTS, GENERAL POPULATION, POLICE OFFICERS,
CUSTOMS OFFICIALS, SOCIAL WORKERS, PRISON WARDENS…
PEOPLE’S ABILITY TO DETECT DECEIT
Laypersons
Professionals
truth
67%
55%
lie
44%
55%
Professionals accuracy range: 40% (Porter et al.,
2000) – 72% (Mann et al., 2004)
REASONS FOR POOR LIE DETECTION
Detecting lies is a difficult task
No Pinocchio’s nose!
Subtle differences between truthtellers and liars
Liars deliberately attempt to fool lie detectors
Lie detectors make errors
Use of the wrong cues/overemphasis on NVCs
Individual differences not accounted for
Cultural differences not accounted for
Poor interview styles are used
REASONS FOR POOR LIE DETECTION
Detecting lies is a difficult task
No Pinocchio’s nose!
Subtle differences between truthtellers and liars
Liars deliberately attempt to fool lie detectors
Lie detectors make errors
Use of the wrong cues/overemphasis on NVCs
Individual differences not accounted for
Cultural differences not accounted for
Poor interview styles are used
CULTURAL DIMENSIONS THAT BEAR ON NVCS
Immediacy
High contact cultures (e.g. most in Arabic world)
make more eye contact, stand closer, more touching
than low contact cultures (e.g. most in Asian)
Power
Vertical cultures (e.g. India) – status based norms constrain
non-verbal interactions with ‘superiors’ inc downcast eyes
more so than horizontal cultures (e.g. Sweden)
Context
High context cultures (e.g. Japan) means inferred from
surroundings and relationships more so than for low
context culture (e.g. Germany) where meaning conveyed
more so by content of verbal utterances
DETECTING DECEPTION
IN SECOND LANGUAGE
SPEAKERS
Da Silva & Leach (2011)
10 truthtellers and 5 liars – native English speakers (NE)
10 truthtellers and 5 liars – English second language (ESL)
All 30 interviews shown to observers who were asked to make a truth/lie
judgement and indicate their confidence
Results:
ESL ppts who were lying were more likely to indicate that they intentionally
misunderstood questions than NE who were lying
Observers better able to discriminate between NE liars and truthtellers
compared to ESL ppts.
Observers more likely to call NE ppts truthtellers than liars but opposite
bias for ESL ppts.
Significant positive correlation between accuracy and confidence for NE
interviewees but no correlation for ESL interviewees.
DETECTING DECEPTION
IN SECOND LANGUAGE
SPEAKERS
Da Silva & Leach (2012)
10 truthtellers and 5 liars – native English speakers (NE)
10 truthtellers and 5 liars – English second language (ESL)
15 interviews (EITHER the NE OR ESL ppts) shown to observers (N = 60 students
and 61 police officers) who were asked to make a truth/lie judgement and indicate
their confidence
Results:
No difference in performance between students and police officers
Ppts who viewed NE speakers more accurate overall than those who viewed ESL
speakers
As before:
Observers better able to discriminate between NE liars and truthtellers compared to
ESL ppts and truth bias for NE speakers/lie bias for ESL speakers
When categorised observers into fluent and non-fluent English speakers (by self
report) found no differences in performance
SUMMARY
People are not generally very good at detecting lies using
NVCs, even when to do so is important for their job.
Reasons:
Looking for the wrong cues
Even for the ‘actual’ cues differences are very small
Every personality/culture is different
The same person may behave in a different manner dependent on the
situation, type of lie etc..
HOW CAN WE IMPROVE OUR ASSESSMENT OF CREDIBILITY?
What makes lying difficult
(regardless of culture/context/personality)?
Story telling (Vrij, 2008)
Self presentation (DePaulo et al., 2003)
Monitoring (Buller & Burgoon, 1996)
Inhibition of the truth (Spence et al., 2001)
HOW CAN WE IMPROVE OUR ASSESSMENT OF CREDIBILITY?
Gathering evidence:
Do not make up your mind too quickly or be misled by signs
of nervousness (Othello error)
Be suspicious but do not show it
Use an information-gathering style
Let the witness repeat himself
Use comparable truths (baselines)
Ask the witness to elaborate
– use unanticipated questions
Ask the witness temporal questions
ALSO TURN FOCUS TO VERBAL
CUES...
Statement Validity Assessment
Reproduction of conversation
Unstructured production
Unexpected details
Reality Monitoring
Sensory details
Temporal details
Spatial details
CURRENT DIRECTIONS IN DECEPTION RESEARCH AT
PORTSMOUTH (PROFESSOR ALDERT VRIJ ET AL.)
Increasing cognitive load during interviews
Using unanticipated questions to detect deception
Detecting deception regarding intentions
Effects of having an interpreter present
Detecting malingering (insurance claims)
STRATEGIC QUESTIONS APPROACH
Liars prepare themselves for possible interviews
(Granhag et al., 2005). This benefits them as
prepared lies are more difficult to detect than
spontaneous lies (DePaulo et al., 2003)
Ask questions that liars (i) have not anticipated
and (ii) cannot answer with “I don’t know”
IMPOSING COGNITIVE LOAD APPROACH
When lying is more difficult than truth telling:
Increase cognitive load on interviewees. This
increased demand should have a larger effect on
liars than on truth tellers because liars already
find the story telling task more mentally taxing
than truth tellers
......Ask interviewees to recall in reverse order
THANK YOU FOR LISTENING!
[email protected]