What is an Eyewitness Testimony?
A legal term referring to the use of eyewitnesses to give evidence in court!
The 3 Memory Stages
Eyewitnesses go through 3 memory stages:-
They encode the memory into their Long Term Memory (LTM) - this can only happen partailly due to different factors during the event, such as the speed, time or actions of the event.
They retain the information for a period of time - some memories may be lost or modified during retention, an dother activities may effect the accuracy of the memory.
They retrieve the memory from storage - there may be a precense or absense of information that may affect the accuracy of the memory.
((Just a lilttle extra if your intrested))
These are the main factors affecting the accuarcy of memory:-
- age, race, gender, individual response to anxiety or stress
- level of violence witnesses and duration of event
One reason why the accuracy of Eyewitness Testimony (EWT) is often very poor because police will use leading questions after an event has happened. Information received after an event can be effected by retroactive interferance, meaning our memories can be easily altered by other information.
A leading question suggests to the witness what answer is desired or leads them to the desired answer!
Gabbert (2003) intorduced The Conformity Effect, where she found that post event discussions can effect the recall of a witness. She found this through an experiment he conducted, where she put particpants in pairs and gave them a different video each of the same event. Pairs in one condition were encouraged to discuss the event before recalling the event individually.
Loftus and Palmer's Experiment(s)
Loftus and Palmer (1974) conducted 2 experiments, where they aimed to investigate how accurate or inaccurate memory was. They did this by studying the effct of verbs upon estimates of speed!
SUMMARY (more detail in next 2 slides):
- Participants were put into groups and told to watch a video of a car crash, and then to answer a questionnaire based on the video. The critical question was the one that asked about the speed of the vehicles involved in the collision. However, each group had a variation of the critical question, where different verbs such as 'bumped', 'crahsed' and 'smashed' were used.
- The same precedure was applied by asking participants (in a questionnaire) about the speed of the vehicles after watching a video. However, the participants were asked to return a week later, to answer more questions without viewing the video again. This time, the critical question was the one asking about wether any broken glass was seen or not (there was no broken glass in the collision).
The laboratory experiment used an independent measures design, and consisted of 45 students, who were split into different varied groups. Each participant watched 7 films depicting a traffic accident- each film lasted 5 to 30 seconds, and were presented in a different order to each group. After each film, each participant was given a questionnaire. The first item of the questionnaire was asking the students to simply give an account of what they had seen. The second part of the questionnaire was a series of specific questions about the film. The critical question was about the speed of the cars. All participants were asked the question:
"How fast were the cars going when they ________ each other?"
The blank was filled with one of the following verbs: 'hit', 'smashed', 'collided', 'bumped' or 'contacted'!
The more violent or aggressive the verb sounds, the higher the speed estimated, for example, the verb 'smashed' will give a higher speed estimate than 'contacted'. Therefore, this shows that the difference in verbs in critical questions affected the estimated speed- leading questions will influence the witness!
The laboratory experiment used an independent measures design, and consisted of 150 students, who were split into different varied groups. A film was shown to each participant, which lasted less than a minute, bu the accident in the vidoe only lasted 4 seconds. After the film, each participant was given a questionnaire. The first item of the questionnaire was asking the students to simply give an account of what they had seen in their own words. The second part of the questionnaire was a series of specific questions about the film. The critical question was about the speed of the cars.
50 participants were asked: "How fast were the cars going when they SMASHED each other?"
50 participants were asked: "How fast were the cars going when they HIT each other?"
50 partcipants were NOT aksed about the speed.
Experiment 2 (Continued)
A week later, the partcipants were asked to return and answer another series of questions (without viewing the video again). This time, the critical question was:
"Did you see any broken glass?"
There was NO broken glass in the accident! The participants could only answer this question with 'yes' or 'no'. Out of 10 questions, this critical question was placed randomly within the list. Loftus and Palmer predicted that as broken glass is expected to be seen in an accident, th eparticipants who were asked the 'smashed' question would say 'yes' to the critical question.
The difference in verb influences the partcipants memory, which is why Loftus and Palmer created their prediction. This shows that leading questions in critical questions can alter what a witness remembers!
Loftus and Zanni (1975)
---> They asked participants: "Did you see A broken headlight?" or "Did you seen THE broken headlight?". &% of those who had the question including 'A head light' said yes, whereas 17% of those who had the question 'THE head light' said yes. This shows that leading questions can alster responses!
Loftus and Pickrell (1995)
---> They planted false memories into participants heads (that never happened) and then asked participants about the memory. It was found that 20% of partcipants claimed the memory was real! This shows that verbal information can alter memory.
Braun et al (2002)
---> He had an experiment which included 4 groups of participants who were vsisiting Disneyland, where the Independant Variable (IV) was a visual representation of Bugs Bunny. When he asked the participants about having met Bugs Bunny in Dsineyland as a child, 30% (of group 2) and 40% (of group 4) recalled the meet. This shows that false memories can be established by the use of visual information!
---> She conducted an experiment where participants were shown images of a man stealing a red wallet. It was found that colour was less subjective than estimating speed (her previous experiment with Palmer), as 98% of participants could identify the colour of the wallet correctly, even after being asked leading questions!
---> Conducted an experiment were a video of a robbery was shown on TV, and agter an identity parade, participants were told to identify who they thought had done it. Only 14% identified the person correctly- this shows that when partiipants dont know what they need to remember, there will be a poorer recall!
Yuville and Cutshall (1985)
---> They interviewed witnesses of a robbery, 4 months after it had happened. Although this experiments lacks ecological validity as it the witnesses werent personally involved (like Loftus and Palmer's experiment), any leading questions asked didnt affect the witnesses!
- EWT has an important practical use but isn't reliable
- All tasks used in experiments are artificial, meaning witnesses acnt experience any real emotions as you would in the given circumstamce
- There are many individual differences to take into account. For example, age: Anastasi and Rhodes (2006) found that we identify better for those who are a similar age to us!