Eye Witness Testimony Flashcards
Eye Witness Testimony
The ability of people to remember details of events which they observed, such as crimes, accidents etc.
Why is accuracy important for eye-witness testimony?
EWT is used in court trials and police interviews, so accuracy is important as it can affect the outcomes of trials, and may lead innocent people to be convicted.
Reconstructive Memory
How our memories can become distorted due to factors such as misleading information.
Misleading Information
In terms of EWT, this is when a witness receives incorrect information about the event.
Schemas
Organised pockets of information in the mind, affected by assimilation and accomodation.
Bartlett (1932) - Summary
Participants essentially played Chinese Whispers. They passed on a story to eachother and as it went on, they began to rationalise the story, removing any confusing ideas, making it shorter and more conventional. This supports reconstructive memory, as participants’ schemas containing information of the real world distorted their recall of the story.
Bartlett (1932) - Strengths
- Good support for reconstructive memory.
- Results have been validated with studies such as Loftus and Palmer (1974), finding similar results.
- Used a story from a different culture to ensure no participants would be familiar with it. This could have been an extraneous variable otherwise, making the study more valid.
Bartlett (1932) - Limitations
- The study is very outdated, may lack temporal validity.
- Details of the procedure are missing, meaning it would be very difficult to replicate, lowering validity.
- There is no statistical information concerning the findings of the study, making the results difficult to use.
- Lacks population validity, the sample only consisted of 20 UK students.
Leading Questions
Phrasing a question in a way that suggests a certain answer.
How could leading questions affect EWT?
Police may direct witnesses with their questions to receive a particular answer that will help their case.
Loftus and Palmer Experiment One (1974) - Aim
To investigate how information supplied after an event (leading questions) can affect a witness’ memory.
Loftus and Palmer Experiment One (1974) - Procedure
Participants watched a video of a car crash and were asked questions about it. The critical question was leading, with the verb changed for different participants. They were asked: ‘about how fast were the cars going when they ____ eachother ?’ The verb was either: hit, bumped, smashed, collided, or contacted.
Loftus and Palmer Experiment One (1974) - Results
Smashed - 40.8 mph
Collided - 39.3 mph
Bumped - 38.1 mph
Hit - 34 mph
Contacted - 31.8 mph
Loftus and Palmer Experiment One (1974) - Conclusion
The verb used unconsciously shifts our memory of the speed. Overall, people are not good at judging the speed of the vehicle.
Which two explanations are there for Loftus and Palmer’s results?
Response-bias factors, and memory representation changes.
Response-Bias Factors
Misleading information may have influenced the answer, but didn’t lead to false memory of the event. Speed estimates only occur due to the critical word.
Memory Representation Changes
The critical verb changes a person’s perception of the accident - this is then stored in a person’s memory of the event.
Loftus and Palmer Experiment Two (1974) - Aim
To investigate whether the change in estimates in experiment one were due to response bias or memory representation changes.
Loftus and Palmer Experiment Two (1974) - Procedure
In a lab, 150 students were divided into three groups and watched a car crash video. They then described the video and answered a questionnaire with the same critical question. One week later, without watching the clip again, they were given another questionnaire, asking ‘did you see any broken glass?’ There was no broken glass in the film.
Loftus and Palmer Experiment Two (1974) - Findings
Smashed - 10.46 mph, 16 saw glass, 34 didn’t.
Hit - 8 mph, 7 saw glass, 43 didn’t.
Control - 6 saw glass, 44 didn’t.
Loftus and Palmer Experiment Two (1974) - Conclusion
Participants are not very good at judging speed. The smashed condition reported seeing significantly higher levels of glass than hit and control conditions, suggesting the verb used can distort the participants’ memory.
Which explanation does Loftus and Palmer’s second experiment support?
This supports the memory representation changes explanation, as the memory of the clip was distorted, even causing some to see broken glass that wasn’t there.
Loftus and Palmer (1974) - Strengths
- Lab experiment - good control of extraneous variables, good validity.
- Application - provides good support of reconstructive memory, which is useful in police questionning.
- The procedure would be easily replicated - good reliability.
Loftus and Palmer (1974) - Limitations
- Lowered validity due to artificial environment and task. These may affect results, with demand characteristics, lack of ecological validity, and mundane realism.
- Lack of reliability - results differ in Yuille and Cutshall (1986).
- All participants were students at one university - low population validity.
Post-Event Discussion
When there is more than one witness to an event, witnesses discuss what they have seen with others. This can influence the accuracy of the witnesses’ recall.
Gabbert et al. (2003) - Aim
To investigate the effect of post-event discussion on the accuracy of eye witness testimony.
Gabbert et al. (2003) - Procedure
Gabbert et al. (2003) - Findings
71% of the co-witness group recalled information that they had not actually seen and 60% said that the girl was guilty, despite not even witnessing the crime. This was 0% in the control group.
Gabbert et al. (2003) - Conclusion
Findings suggest that post-event discussion negatively affects the accuracy of EWT, as it can distort peoples’ memory.
Gabbert et al. (2003) - Strengths
• High population validity - tested on students and older people, and both found similar results.
• Controlled lab environment, high validity.
Gabbert et al. (2003) - Limitations
• Low ecological validity - artificial environment.
• Demand characteristics - may have been playing close attention as they knew they’d be questioned.
• Low internal validity - incorrect answers here may come from social conformity, or bad memory, not the discussion.
Who’s research demonstrates that anxiety may have a positive effect on EWT accuracy?
Yuille and Cutshall (1986).
Yuille and Cutshall (1986) - Aim
To investigate if anxiety could positively affect recall of a stressful event.
Yuille and Cutshall (1986) - Procedure
13 witnesses of an armed robbery were interviewed 4-5 months after the incident. They were asked to rate their stress level on a 7-point scale. These interviews were then compared to police interviews.
Yuille and Cutshall (1986) - Findings
Those who reported lower levels of anxiety had 75% accurate recall, while those with higher anxiety were 88% accurate.
Yuille and Cutshall (1986) - Conclusion
Anxiety can positively affect recall, meaning it can be useful in EWT.
Yuille and Cutshall (1986) - Strengths
- Interviews had a controlled lab setting, good reliability.
- Good application, helping to establish the reliability of EWT.
- The event that they recalled had high ecological validity - they were actually present at a crime, not just watching a video.
- Consent was received from the participants, eight witnesses decided not to take part.
Yuille and Cutshall (1986) - Limitations
- The use of a case study makes the findings ungeneralisable. The specificity of the situation they were in cannot be generalised to others.
- Only 13 participants used, low population validity.
- Qualitative data was changed to quantative, lowering validity.
- Harm to participants may have been caused. The event was traumatic and to be reminded of it, without full briefing, may have caused harm.
Who’s research demonstrates that anxiety can have a negative affect on EWT accuracy?
Peters (1988).
Peters (1988) - Aim
To investigate whether anxiety levels can affect the accuracy of recall.
Peters (1988) - Procedure
The sample consisted of a group of patients at a health centre, needing injections. A nurse then gave them injections and they went home. One week later, they were asked to select a photo of the researcher, and the nurse from a set of photos.
Peters (1988) - Findings
Recall was better when selecting the photo of the researcher, than the photo of the nurse, possibly due to the nurse being more anxiety inducing.
Peters (1988) - Conclusion
Higher levels of anxiety can negatively impact recall, making EWT of stressful events possibly less accurate.
Peters (1988) - Strengths
- Good ecological validity, the participants were already there to get injections, and the setting was accurate to the task.
- Participants were recruited, and had the choice whether to take part or not.
- Good control of extraneous variables by bringing patients back to the health centre, location may effect recall (context-dependent forgetting).
Peters (1988) - Limitations
- The use of a field experiment makes control of extraneous variables difficult, lowering validity.
- It is likely that participants spent more time with the researcher than the nurse.
- Mental harm may be caused to participants, they may have fears of needles.
