Reconstruction of Automobile Destruction Loftus and Palmer (1974) Reconstruction of Automobile Destruction

Aim To investigate how information provided to a witness after an event will influence their memory of that event

Method Two laboratory experiments Independent measures design IV = Verb used DV = The estimate of speed or whether the P saw glass What are variables? There are different types of variables - Independent Variables (IV), Dependent Variables (DV) and Extraneous Variables (EV). # Independent variable (IV): Variable the experimenter manipulates – assumed to have a direct effect on the dependent variable. # Dependent variable (DV): The Variable the experimenter measures, after making changes to the IV. # Extraneous variables (EV’s): These are other variables apart from the IV that might affect the DV. They might be important enough to provide alternative explanations for the effects. E.g. Confounding Variables. Try to identify the IV and DV for each of these examples: # Children who watch too many cartoons have more violent behaviour. # Eating bad food makes your weight increase. # GCSE students have better test scores after attending a revision workshop.

‘About how fast were the cars going when they ________ each other’ Method – Experiment 1 45 student participants were shown short video clips They were split into 5 groups, with 9 participants in each one All of the participants were asked: ‘About how fast were the cars going when they ________ each other’ Each group was given a different verb to fill in the blank. These verbs were ‘smashed, collided, bumped, hit or contacted’. Therefore the independent variable was the verb used. The dependent variable was the estimate of speed given by the participants Experimental Designs There are different types of experimental design. These are: # Independent Measures Design - Each participant in one group only - Larger sample needed - Larger sample is more likely to be truly representative – But costly and time consuming. # Matched Participants Design – Similar to independent measures in that each participant is in one group only, but here the participants in each group are matched on certain relevant characteristics, e.g. sex, age, IQ, etc… # Repeated Measures Design – Here each participant is in both groups or conditions – means that you need a smaller sample, which would be easier to obtain, but a smaller sample is unlikely to be representative of the population.

MEAN ESTIMATE OF SPEED (mph) Results – Experiment 1 How the question was phrased influenced the participants’ speed estimates When the verb ‘smashed’ was used, participants estimated that the cars were travelling much faster than when the verb ‘contacted’ was used. VERB MEAN ESTIMATE OF SPEED (mph) Smashed 40.8 Collided 39.3 Bumped 38.1 Hit 34.0 Contacted 31.8 What do these results show?

Method – Experiment 2 150 student participants were shown a short film that showed a multi-vehicle car accident and then they were asked questions about it. The participants were split into 3 groups (with 50 in each group). One group was asked: ‘How fast were the cars going when they hit each other?’ The second was asked: ‘How fast were the cars going when they smashed into each other?’ The third group was not asked about the speed of the vehicles One week later, all participants returned and were asked: ‘Did you see any broken glass?’ There was no broken glass in the film.

What do these results show? Results – Experiment 2 Did you see any broken glass? Response Smashed Hit Control Yes 16 7 6 No 34 43 44 What do these results show? The results show that the verb used in the original question influenced whether the participants thought they had seen broken glass.

Discussion Loftus and Palmer suggest 2 explanations for the results of Experiment 1: Response Bias: The different speed estimates occurred because the critical word (e.g. ‘smashed’ or ‘hit’) influences or biases a person’s response. 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?

Reconstructive Hypothesis 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. Reconstructive Hypothesis 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)

In your groups, discuss the following points: 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?)

Can you think of any others?? Evaluation - Usefulness This study has many applications: # Police questioning witnesses # Teachers asking/setting questions Can you think of any others??

Evaluation – Other Issues 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?

The correct answer is… c) Knocked Test Yourself… 1. Which of the following was not a cue word in the experiment by Loftus and Palmer? Smashed Contacted Knocked Hit The correct answer is… c) Knocked

The correct answer is… a) Estimate of Speed Test Yourself… 2. The DV in the first experiment was… Estimate of speed The verb ‘smashed’ The question about broken glass The film The correct answer is… a) Estimate of Speed

The correct answer is… c) 5 Test Yourself… 3. In Experiment 1, how many experimental conditions were there? 1 3 5 7 The correct answer is… c) 5

The correct answer is… b) 2 Test Yourself… 4. In Experiment 2, how many experimental groups were there? 1 2 3 4 The correct answer is… b) 2

The correct answer is… c) 1 week Test Yourself… 5. In Experiment 2, participants were tested immediately and then asked to return for some more questions. How long afterwards was this? 1 day 3 days 1 week 2 weeks The correct answer is… c) 1 week

Test Yourself… The ‘smashed’ group The ‘collided’ group 6. In Experiment 2, which group saw the most broken glass? The ‘smashed’ group The ‘collided’ group The ‘hit’ group The control group The correct answer is… a) The ‘smashed’ group

7. Which of the following is true? Test Yourself… 7. Which of the following is true? Experiment 1 and 2 were both repeated measures Experiment 1 and 2 were both independent measures Only Experiment 1 was repeated measures Only experiment 1 was independent measures The correct answer is… b) Experiment 1 and 2 were both independent measures

The correct answer is… b) Students Test Yourself… 8. The participants in this study were: Children Students Teachers Adults The correct answer is… b) Students

Exam Style Questions (2) (2) (4) (2) (2) 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. (2) b) What does the existence of these two kinds of information tell us about memory? (2) 2. From the study on eyewitness testimony by Loftus and Palmer outline two features of the procedure that were standardised. (4) 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. (2) 4. Give one explanation for that difference. (2)