Presentation on theme: "Eye-witness testimony LO: To understand the factors affecting the accuracy of EWT."— Presentation transcript:
Eye-witness testimony LO: To understand the factors affecting the accuracy of EWT
Question time! You will be divided into groups. Using the hand-out given, ask the questions, and then record your interviewee’s responses on the sheet.
Now compare your answers: How accurate are the answers? Do they fit what happened in the crime scene? Compare your answers with the other group and see how the type of questioning can distort the answers based on a person’s memory. What is a leading question?
Loftus and Palmer 1974 Study re-constructing a memory from a car crash scene.
Results – Experiment 2 ResponseSmashedHitControl Yes1676 No Did you see any broken glass? The results show that the verb used in the original question influenced whether the participants thought they had seen broken glass. What do these results show?
Discussion Loftus and Palmer suggest 2 explanations for the results of Experiment 1: 1.Response Bias: The different speed estimates occurred because the critical word (e.g. ‘smashed’ or ‘hit’) influences or biases a person’s response. 2.Memory is altered: The critical word changes a person’s memory so they actually ‘see’ the accident differently, i.e. more or less severe. In order to prove this second point, L&P tested this in their second experiment – would people remember details that aren’t true?
Discussion (cont…) The results again showed that the way a question is asked can influence the answer given: This however was not due to a response bias, as all participants were all asked if they had seen any broken glass. This suggests that the leading question had actually altered the participants memory of the event. Loftus and Palmer suggest that 2 kinds of information go into a person’s memory for an event: Firstly, the person’s own perception, and secondly information supplied after the event (such as leading questions) Reconstructive Hypothesis
Evaluation In your groups, discuss the following points: How realistic were the studies? (Think about the differences between the tasks the participants did, and real life situations where you need to remember what you have seen) Who were the participants? (Could the results be generalised to other people?) How useful was the research? (How can the results of the study be applied to other situations?) Any other issues (Think about the type of tasks, the content of the video, etc)
Evaluation – Ecological Validity Ecological Validity – This was low because it was a laboratory study, and the participants knew they were taking part in an experiment. In real-life situations there would be an element of surprise, so you might not be paying attention. There would be an increase in emotion – such as fear, shock, etc. There may be victims. You might not be asked questions until some time later. You may have the opportunity to discuss what you saw with other people
Evaluation – Participants The participants were all students There are several ways in which students might not be representative of the general population. These may include age, driving experience, educational experience – (i.e. they may be used to paying attention and being tested?)
Evaluation - Usefulness This study has many applications: Police questioning witnesses Teachers asking/setting questions How easy is it to estimate speed? It may be easier for some groups than others, e.g. taxi drivers or police officers. The driver of the car is not mentioned in the article – what if they had been visible as an elderly woman or a young man? What if the car had been a Porsche or a Smart Car?
Test Yourself… 1. Which of the following was not a cue word in the experiment by Loftus and Palmer? a)Smashed b) Contacted c)Knocked d)Hit The correct answer is… c) Knocked
Test Yourself… 2. The DV in the first experiment was… a) Estimate of speed b) The verb ‘smashed’ c) The question about broken glass d) The film The correct answer is… a) Estimate of Speed
Test Yourself… 3. In Experiment 1, how many experimental conditions were there? a) 1 b) 3 c) 5 d) 7 The correct answer is… c) 5
Test Yourself… 4. In Experiment 2, how many experimental groups were there? a) 1 b) 2 c) 3 d) 4 The correct answer is… b) 2
Test Yourself… 5. In Experiment 2, participants were tested immediately and then asked to return for some more questions. How long afterwards was this? a) 1 day b) 3 days c) 1 week d) 2 weeks The correct answer is… c) 1 week
Test Yourself… 6. In Experiment 2, which group saw the most broken glass? a) The ‘smashed’ group b) The ‘collided’ group c)The ‘hit’ group d) The control group The correct answer is… a) The ‘smashed’ group
Test Yourself… 7. Which of the following is true? a) Experiment 1 and 2 were both repeated measures b) Experiment 1 and 2 were both independent measures c) Only Experiment 1 was repeated measures d) Only experiment 1 was independent measures The correct answer is… b) Experiment 1 and 2 were both independent measures
Test Yourself… 8. The participants in this study were: a) Children b) Students c) Teachers d) Adults The correct answer is… b) Students
How to improve the accuracy of EWT The Cognitive Interview Technique
Problems Fisher et al (1987) studied real life interviews by detective officers in Florida over 4 month period. They found that witnesses were frequently bombarded with a series of brief, direct and close-ended questions aimed to elicit facts. However, the sequencing of these questions often seemed to be out of sync with the witnesses’ own mental representation of the event. Witnesses were often interrupted and not allowed to talk freely about their experiences.
The Cognitive Interview Technique EWT plays an important role within the legal system and the serious repercussions when it goes wrong, cognitive psychologists have tried to develop methods for improving the accuracy of EWT. The Cognitive Interview technique is a questioning technique used by the police to enhance retrieval of information from the witnesses memory.
Try it for yourselves Now that you have looked at how leading questions affect EWT, design your own cognitive interview, by designing a set of questions for a car crash scene. Try looking at it from another angle.
Main Techniques Used in the Cognitive Interview Context Reinstatement Mentally reinstate the context of the target event. Recall the scene, the weather, what you were thinking and feeling at the time, the preceding events, etc.
2. Report Everything (RE) Report every detail you can recall even it if seems trivial
3. Recall from changed perspective (CP) Try to describe the episode as it would have been seen from different viewpoints, not just your own.
These techniques all designed to enhance retrieval of the original memory. Although this kind of detail might seem trivial and poorly related to the actual witnessed event, it is designed to provide extra cues that might help to jog witnesses’ memory for more central details.
Exam Style Questions 1. a) In their study on eyewitness testimony, Loftus and Palmer suggest that two kinds of information go into a person’s memory for a complex event. Identify one of these two kinds of information. b) What does the existence of these two kinds of information tell us about memory? 2. From the study on eyewitness testimony by Loftus and Palmer outline two features of the procedure that were standardised. 3. In the study on eyewitness testimony by Loftus and Palmer, the use of the verbs ‘smashed’ and ‘hit’ led to different responses from the participants. Outline one of these differences. 4. Give one explanation for that difference. (2) (4) (2)