Eyewitness Testimony & the Cognitive Interview Flashcards
What is Eyewitness Testimony (EWT)?
The evidence provided in court by a person who witnessed a crime, with a view to identify the perpetrator of the crime
Stages of an Eyewitness event transferring to memory
- Eyewitness encodes details of event in LTM
- Eyewitness retains information for a period of time
- Eyewitness retrieves the memory from storage
Misleading information
Supplying information that may lead a witness’ memory for a crime to be altered
Misleading Information: Leading Questions
Questions which suggest to the witness what the desired answer is and leads them to that desired answer
Misleading Information: Post-Event Discussion
A conversation between co-witnesses or an interviewer and an eyewitness after a crime has taken place which may contaminate the witness’ memory for the event
Leading Questions: Loftus & Palmer (1974)
- Lab experiment with 150 students
- Watched film of car crash and asked leading question asking them to estimate speed (had a variety of verbs, eg. smashed, hit), those with more aggressive verbs had faster estimates
- Questioned a week later, and asked if they saw broken glass (there was none)
- 16 in ‘smashed’ group said they did, 7 in ‘hit’ group, 6 in control group
Post-Event Discussion: Conformity Effect
- Co-witnesses may reach a consensus view of what actually happened
- Occurs due to ‘memory conformity’ - more likely to pick up incorrect ideas because we believe we are wrong and the other is right
- Could occur due to ‘memory contamination’, where the mixing of memories leads to misinformation
Post-Event Discussion: Repeat Interviewing
Each time an eyewitness is interviewed there is the possibliity that comments from the interviewer will become incorporated into their recollection of events
Anxiety
A feeling of unease, such as worry or fear
Arousal
A physiological state in which the heart and breathing rate increase
Weapon Focus Effect
Attention spotlight is drawn to dangerous objects, preventing perception of other objects
Anxiety decreases EWT accuracy: Johnson & Scott (1976)
- Man ran through ‘waiting room’ carrying a pen covered in grease (low anx. condition) or a knife covered in blood (high anx. condition)
- Participants asked to identify man from set of photographs
- Mean accuracy in low anx. group was 49%, and in the high anx. group it was 33%
- Loftus et al (1987): this was due to weapon focus effect
Anxiety increases EWT accuracy: Christianson & Hubinette (1993)
- Questioned 58 real witnesses to bank roberies in Sweden
- Witnesses either high anx. victims (bank teller) or low anx. bystanders (customers)
- All witnesses showed good detail recall (75%<), but those in higher anx. could recall more details
Resolving the Conflict: Deffenbacher (1983)
- Reviewed 21 studies on anxiety & EWT, found that 10 had results that linked higher arousal levels with increased EWT accuracy, whilst 11 showed the opposite
- Suggested Yerkes-Dodson Effect (moderate anxiety increases accuracy)
Catastrophe Theory
- Some suggest Y-D effect does not happen in extreme anxiety situations - reduces internal validity
- Many participants show rapid decline in recall after peak anxiety is reached
The Cognitive Interview
A procedure designed for use in police interviews that involve witnesses - designed to improve EWT accuracy
What are the 4 techniques used in cognitive interviews?
- Mental reinstatement of original context
- Report Everything
- Change Order
- Change Perspective
Mental Reinstatement of Original Context
- Witness mentally recreates physical and psychological environment of the incident
- Makes memories accessible as recreating mental state can unlock retrieval cues
Report Everything
- Witness is encouraged to report every detail, even if it seems insignificant
- Memories are interconnected, so recaling one item may cue others
- If many witnesses reveal small details, the bigger picture can be pieced together
Change Order
- Events should be recalled in a different chronological order to the original sequence
- This disrupts effects of expectations and schema on recall
Change Perspective
- Witnesses should recall incident from perspective of someone else
- This disrupts the effect of expectations and schema on recall
Supporting Evidence of Cognitive Interview: Kohnken et al (1999)
- Meta-analysis of 53 studies found 34% increase in correct information provided in cog. in. compared to other techniques
- However, most studies involved volunteers, which are usually college students in a lab
Opposing Evidence for Cognitive Interview: Konhken et al (1999)
- Effectiveness has been in quantity, not quality of information
- Found 61% increase of incorrect info in cog. int. compared with standard interviews
- Police need to treat cog. int. infor with caution as it is not always accurate
