EWT Flashcards
What is an EWT? (Macleod, 2007)
An account given by people of an event they have witnessed
What are the key areas of an EWT?
Police investigation
Criminal trials
Police investigation
- how police elicit info from witnesses, victims and suspects
- through interviewing and identification processes
Criminal trials
- questioning of witnesses by p and d
- guidance from judge
- jury verdicts
Adams Randall Dale
- EW who was in fact the killer framed Mr.Adams
- film: the thin blue line
History of EWT
Binet
Psychological factors that affect EWT
- anxiety/stress
- memory retrieval
- reconstructive memory
- weapon focus
- leading question
Schema theory
A mental representation of knowledge
- can distort or enhance memory
- what we already know will influence the outcome of information processing
Encoding
Paying attention and transforming information into a meaningful memory
Storage
How info is stored
Retrieval
Recover the experience from memory
Bartlett (1932) war of the ghosts
- carried out a large number of studies: showed the way in which ppts make sense of something affects the way they recall it later
- memory is an active constructive process influenced by both internal and external factors
Loftus (1979)
- witnesses are creating reconstructions of the crime based on their own schematic understanding of the world
Loftus and Palmer (1974)
- gave higher estimates when the word smashed was used instead of hit
Loftus and Zanni (1975)
“The” broken headlight rather than “a” broken headlight, more responses for “the”
Loftus, Miller and Burns (1978)
- was able to get some ppts to recall that they had seen a sign at the end of the road, even though there wasn’t
The Devlin Report
- witnesses accounts of what they have seen are little better than guesses (loftus)
- unless the circumstances were highly unusual , EWT should not result in a conviction in the absence of other evidence
Stress in EWT
Small increases in anxiety and arousal tend to increase the accuracy of Memory but huge increase can have a negative effect
Loftus (1979) weapon focus effect
- ppts recognised the man who came out with pen rather than the knife
Yerkes-Dodson Law
- an increase in arousal improves performance but only up to a certain point
- once arousal has passed a critical point called the optimum, performance tends to decline
Why?
- witnessing violence raises witnesses arousal level past optimum, leading to poorer memory performance
Estimator variable
- variables not controllable in CJS
Examples
- exposure time
- seriousness of crime
- weapon focus
- age
- intoxication
- physical attractiveness
System variables
- retention interval
- types of questioning
- identification procedures
- interview procedures
- line up ID parade
Is EW identification reliable?
No one of the least reliable forms
Busey and loftus (2007)
Problems with line ups
4 problems with line ups?
- physical bias
- no double line procedures
- inadequately matched fillers
- unconscious transference
Devlin Committee (1976)
- 45% led to identification of the suspect
- 82% of those identified were convicted
- in 350 cases only EW was the evidence
Well (1998)
- examined 40 cases in USA in which DNA was found to exonerate a previously convicted person
- 90% cases involved EW evidence in which they falsely identified a person
4 factors that influence EW response during identification parade
- Instructions given to the witness
- Content - ‘selection of fillers’
- Presentation method - simultaneous or sequential
- Behavioural influence - administrator role,
What did the Devlin Committee report say?
Juries should not convict on the basis of EWT alone
What do system variables focus on?
Memory retrieval
