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Eye-witness testimony (factors affecting eyewitness testimony (misleading…
Eye-witness testimony
factors affecting eyewitness testimony
misleading information
incorrect information given to the witnesses
PEI & PED
memory contamination
memory conformity
Leading questions
Loftus and Palmer 1974
Procedure
groups of pps watched video of car crash, after when being questioned, different key words used e.g smashed, hit, collided, bumped and contacted
then recorded speeds estimated by pps
pps for smashed and hit words interviewed a week later if they saw broken glass at the seen
Findings
pps smashed more likely to report broken glass
Harsher sounding more aggressive words more likely to have higher speeds
Used artificial materials so not very ecologically valid
Post event discussion
Gabbert et al 2003
Procedure
pps in pairs, watched video of same crime - filmed from different POVs, each pp could see elements of crime the other coudln't
pps discussed what they saw before being individually tested for recall
Findings
71% pps mistakenly recalled aspects of the event they didn't see but picked up in discussion
Control group = 0% of pps
Evaluation
Real life application
May be individual differences in accuracy of EWT
Anatasi and Rhodes (2006)
found older people less accurate than younger people
Lab study and demand characterisitcs
anxiety
positive
Yuille and Cutshall 1986
Procedure
real-life crime, gun shop owner shot thief dead, there were
21
witnesses,
13
agreed to participate in study
pps were interviewed 4-5 months after the incident, accounts were compared to the police interviews at the time of shooting
witnesses also rated how stressed they felt at the time of the incident
Findings
Witnesses were very accurate, there was little change after 5 months h/e some details like colours, age/weight/height were less accurate
Conclusion
Particpants who reported the highest levels of stress were the most accurate
about 88% compared to the less stressed group (75%)
negative
Johnson and Scott 1976
Procedure
pps sat in waiting room thinking they were going to take part in a lab study
Each pp heard an argument in the next room
low-anxiety condition
- man walked through the waiting room carrying a pen with grease on his hands
high-anxiety condition
- heated argument w/ sound of breaking glass, man walked through room holding paper knife covered in blood
Findings
49% pps in low-anxiety condition were able to identify him
high anxiety = 33% pps
Conclusion
tunnel theory of memory
argues that witness's attention is on the weapon (
weapon effect
) because it is a source of danger and anxiety
Evaluation
May test surprise not anxiety
Pickel 1998
found EWT was worse with high unusualness
e.g chicken and handgun
Lack control variables
the extraneous variables may be the reason for the varying recall, not anxiety
ethical issues
Explaining contradictory findings
Inverted 'U' theory
Yerkes and Dodson 1908
argue that the relationship between performance and stress is curvilinear rather than linear
Evaluation
too limited and simplistic
anxiety is difficult to define and measure as it has many elements
cognitive, behavioural, emotional and physical
explanation doesn't account for other factors like the emotional experience of seeing a crime on the accuracy of memory
affects memory
Deffenbacher 1983
found that lower levels of anxiety produced lower levels of recall accuracy, recall accuracy increases with anxiety up to an optimal point
A drastic decline in accuracy is seen when eyewitnesses experience more anxiety than the optimal point
improving the accuracy of eyewitness testimony
cognitive interview
Based on psychological understanding of memory
Fisher and Geiselman 1992
claim that EWT could be improved if the polic use techniques based on psych and memory
they called it the cognitive interview as its foundation is cognitive psychology
Reinstate the context
The witness returns to original crime scene 'in their mind' and imagines the environment and their emotions
based on context-dependant forgetting
Report everything
Witnesses are encouraged to include every detail of an event, even if it seems irrelevant or the witness is not confident about it
seemingly trivial details could be important and may trigger other memories
Change perspective
Witnesses recall the incident from other people's perspectives
prevents the influence of expectations and schema on recall
Reverse the order
Events are recalled in a different chronological order
prevents people from using their expectations of how the event must have happened
prevents dishonesty as it's harder to produce untruthful account
Enhanced cognitive interview
Fisher et al 1987
developed additional elements of the CI
Focus on the social dynamics of the interaction
e.g when to establish and relinquish eye contact
Ideas like reducing the eyewitness's anxiety, minimising distractions, getting the witness to speak slowly and asking open ended questions
evaluation
Some elements of the full CI are useful
Milne and Bull 2002
each individual element of CI was equally valuable
support for effectiveness of enhanced CI
meta-analysis by
Köhnken et al 1999
combined data from 50 studies
the enhanced CI provided more correct information than the standard police interview
time-consuming
Kebbel and Wagstaff 1997
CI requires special training as well as time and many forces have not been able to provide more than a few hours
research may be unreliable due to variations of CI
Studies of the effectivness of the CI use slightly different techniques
thus it's difficult to draw conclusions about CI in general
CI produces inaccurate information
Köhnken et al 1999* found an
81%
increase in correct information but also a
61%** increase in incorrect information when the enhanced CI was compared to a standard interview
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