Eyewitness ID Estimator - complete Flashcards
What are Estimator variables?
Factors which CJS cannot control for There influence on ID can only be estimated post-hoc
Fall into 3 categories : Witness factors (child or elderly, post judgement confidence) Target factors (target distinctiveness, cross racial ID, disguise, presence of weapon) Situational factors (alcohol, cross racial ID, stress and violence)
What is the affect of child witnesses on ID accuracy?
Pozzulo and Lindsay (1998) - Under 4 = less likely to correctly ID suspect
5 and over = no significant difference
All ages poorer on TA line-ups
How can child witness ID be improved?
Havard and Memon (2012) - the mystery man
Reduces false ID rates for children as young as 5 without reducing correct ID rates
Zajac et al (2009) - the wildcard
Viewed live staged event then after 24 hours viewed TP or TA line-up
1/2 children asked to tell experimenter if suspect not present
1/2 asked to point to wildcard if suspect not present
Reduced false IDs from TA line-up
What is the affect of elderly witnesses on ID accuracy?
Searcy et al (2000) - elderly prone to recognition errors for faces seen only once before
- make more false IDs in both TP and TA line-ups
What is the affect of age on ID accuracy?
Fitzgerald and Price (2015)
Meta analysis - children tended to erroneously select person in TA line-up and less likely to select target in TP line-up
Similar for older adults
How can elderly witness ID be improved?
Wilcock et al (2007) - Context Reinstatement (CR), shown mock crime video, used photographic CR (photos of environment crime took place), sig. effect in p’s viewing TA line-up
Wilcock and Bull (2010) - Practice Line-ups, people asked to ID queen from TA line-up, practice led to sig. decrease in false IDs whilst having no effect on correct IDs of suspect
What is the significance of confidence in eyewitness ID?
Confidence is often provided either voluntarily or solicited by police (Brewer, 2010)
A confident witness more likely to be believed by jurors
Only factor affecting jurors verdict
How is confidence measured?
Categorical scale - correlations can be made with line-up performance
1 = positive correlation
0 = no correlation -1 = negative correlation
What is a post-identification feedback?
When feedback is provided after an ID is occurred this can influence a confidence judgement
Co-witnesses can inflate witnesses confidence (Luus and Wells, 1994)
How can the feedback effect be overcome?
Effects can be eliminated (Lampien et al 2007)
But asking witnesses to ignore still results in post ID feedback effect
However PACE code D doesn’t require confidence to be analysed
Request confidence in accuracy taken immediately prior to administrator influence or feedback
Initial confidence can be used as evidence in court
What is the effect of facial distinctiveness on recognition performance?
Light et al (1979) distinctiveness can directly affect recognition performance
Distinct faces recognised more accurately (Light et al, 1979)
more quickly (Valentine et al, 1986)
Less likely to be confused with another person (Bartlett et al, 1984)
Valentine (1991) Face Space Model
How can disguises affect recognition?
Patterson and Baddeley (1977) - changes in appearance resulted in poorer rates of ID accuracy
Changes in hairstyle may be the most efficient (Shepherd and Ellis, 1996)
How can hiding your hair affect recognition?
Cutler et al (1987) - examined the effects of masking a targets hair and hairline cues = without hat - 45% of p’s identified the robber
with hat - 27% identified the robber
Can cross race bias or cross race affect recognition?
Tendency to recognise members of ones own race better than members of another race
Meissner and Brigham (2001) - meta analysis, own race faces led to higher proportion of correct IDs and lower rate of false IDs
Contact Hypothesis (Chance and Goldstein, 1996) - difficulty identifying people from another race due to having limited contact with them
cross race effect decreases the more interactions witnesses have with race in question
Encode more qualitative info about own race
What are “Turnbull Guidelines” (1976)?
A - how long witness viewed suspect for
D - How far away
V - visibility of crime
O - obstructions when viewing crime
K - Did they know suspect
A - If not, what was the reason for remembering suspect
T - time between witness viewing suspect and making ID
E - were there differences in description of suspect compared to suspects appearance
Can stress and anxiety affect ID?
Deffenbacher et al (2004) - High stress = poor performance
Valentine and Mesout (2009) - 20p’s London Dungeon heart rate analysed check if it was scary - it was
56 visitors - completed Anxiety index and encountered an actor
Results - strong negative association between anxiety and ability to report appearance of person encountered
What is weapon focus effect?
People tend to keep their eye on weapons because of their danger and novelty
Distracts their attention from the robbers
What is one explanation for weapon focus effect? (1)
Cue Utilisation Hyp - Easterbrook (1959)
Attention and arousal interact
Physiological arousal decreases number of environmental cues that may be monitored
Weapon is accurately coded - perceived as a threat
This is to the detriment of encoding details about the perpetrator
What is another explanation for weapon focus effect? (2)
Unusual Item Hyp - surprising or unusual objects draw the gaze more readily than objects expected in the scene
Loftus and Mackworth (1978) 3 stage model of early visual scene processing
- general scene analysed to activate appropriate schema
- Once schema activated preliminary scene context processed
- followed by evaluation of the degree to which each object is congruent with activated schema
- attention is drawn to object thus poor recall of events
What is the difference between WFE in lab studies compared to field studies?
Lab - Weapon leads to less info recalled and inaccurate ID (Loftus et al, 1987)
However…
Real Life - no effect of weapon on recall and recognition accuracy
(Tollestrup et al, 1994)
Meta analysis small, but reliable effect suggesting presence impairs actual eyewitness memory (Fawcett et al, 2013)
What is the significance of alcohol in crime?
1/2 of all violent crimes committed in the UK were perpetrated by individuals under the influence (Kershaw et al, 2008)
Victims and witnesses were also intoxicated (Finney, 2004)
What are the problems with estimator variables?
- Interaction between variables
- Their effect may be moderated by certain system variables
- Difficult to assess the extent to which variables are likely to affect the outcome on a line-up
- Likely to vary from person to person
- Ecological validity of the research
