Eye Witness Testimony

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

3.Anxiety

4.Age of Witness

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

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

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  

- 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

WEAPON FOCUS

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

Contridictory evidence:

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! 

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

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 

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