Introduction to E.W.T
The evidence given in court, or in investigations by someone who has witnessed a crime
5 factors affecting accuracy of E.W.T;
1. Pre-exsisting schemas
2. Misleading information
4.Age of Witness
Introduction to Schemas
What is a schema?: It is knowledge packages, built up by experience of the world that can aid interpretation of new info
5 ways that a schema can led to reconstructed memories;
Ignore aspects of a scene that do not fit a schema
'Fill in' missing info
*Distort memories to fit in with prior expectations
*Use schemas to provide a basic guess
Brewer and Treyens (1991): The effect of schemas on visual memory.
There were 30 participants in a waiting room for 35 seconds with 61 objects in it and they consisted of mundane and non-mundane objects in it
Lindsay et al (2004): read accounts to participants.
Either a) a palace burglary
b) a school trip to a palace
Next day, shown a video of a museum burglary and asked to recall events.
Group a) made more errors than b)
Conclusion: Memory of events can be distorted by knowledge of a similar topic = interference
Introduction to Misleading Information
What is it?: Info given that may distort memories by altering and adding info, given to the witness after the event.
Loftus and Palmer (1974): Memory could be influenced by the type of question people were asked. 2 experiments.
1) They showed a series of car crash videos to 45 students, asked them to fill out a questionairre afterwards
They were asked if the car 'smashed, collided, bumped, hit or contacted'
They found; sentence estimated the speed of the cars
Average Speeds estimated
Smashed - 40.8mph, Collided - 39.3 mph, Bumped - 38.1 mph, Hit - 34.0 mph, Contacted - 31.8mph
Loftus and Palmer (74) continued...
It is clear that speed influenced perception
Conclusion: It could be distortion - memory is changed or response-bias - influenced by a judgement, e.g they were unsure of the speed so the word suggested the speed.
2) 150 students shown videos of cars crashing with a questionnaire afterwards. The words were only 'hit' and 'smash' with two experimental groups. They were asked 'Did you see any broken glass?' with no broken glass in the film
Findings; Smashed - 32%, Hit - 14%, Control - 12%
It is clear here that questions can influence memories
This supports the reconstructive-memory hypothesis where info can be retained at a time of an event and altered by info presented after an event
Evaluation of Loftus and Palmer (74)
- Experiment was well controlled
-Watching the videos do no reflect real life situations, lacking validity
-No way to prove memory is distorted---> demand characteristic participants respond in a different way because they think they should
-University students - lack of validity, cannot generalise to the rest of the population
They may have witnessed an unplesant crime or in a serious and pressured situation
High levels of anxiey --> decrease in ability to encode/retrieve memories
Peters (1998): people who were receiving inoculations (anxiety-causing events) - manipulated
Participants (Ps) met a nurse, giving them an injection + researcher for equal amount of time
1 week later - asked to identify nurse + researcher (photos) - reseacher readily more recognised than nurse. --> Anxiety of injection directly affected the accuracy of memory drawn to syringe
WITNESS OF CRIME COULD BE DRAWN TO SPECIFIC ASPECT
Loftus et al (1987) monitored gaze of P during crime - focused on weapon --> less able to recognise robber
Support for this;
Mitchell (1998); presence of weapon, unusual + it is a novelty --> weapon focus effect
VIOLENCE --> ANXIETY
Loftus + Burns (1982): Ps watch crime film. Group 1) extremely violent Group 2) non-violent
Non-violent - more detailed recalled - shock disrupted storage
Anxiety: Naturalistic Studies
Yuille and Cutshall (1986); interviewed 13 witnesses of a shooting - no recall affected
Yerkes - Dobson's law
Ideal point - anxiety helps memory above/below helps memory!
Age of Witness
Dekle et al (1996): Children are found to be more willing than adults to make a positive identification but they are often incorrect
Lindsay and Poole (2001): Children aged 3-8, science demonstration. Parents read them a story containing some elements of the science demonstration --> questioned on science demonstation
They couldn't remember if original or mislead info, poor source monitor (children)
Flyn et al (1992): Found that children were good at remembering 1 day after but after months, it decreased in accuracy --> important! There are very long delays between crime and court
Conclusion to Children as Witnesses
Gordan et al (2001): Young children can provide detailed and accurate witness statements but susceptible to suggestion and accounts should be viewed with caution
Davies et al (1994) Some of the differences between child and adult witnesses have been overstated and children can provide valuable testimony provided care is taken in the interviews
The Elderly as Witnesses
Yarmey (1984) when asked questions about staged events, 80% of Ps compared to 20% of younger adults failed to mention that the attacker had a knife in his hand
Cohen and Faulkner (1989) showed a film of a kidnapping to groups of middle-aged and elderly Ps. They then read a narrative account with what they had seen. 50% said it was consistent 50% inconsistent - misleading info
ELDERLY MORE SUSCEPTIBLE TO MISLEADING INFORMATION