Classic Study: Loftus and Palmer (1974)

Question 1

what was the aim of the study ?

Answer 1

• interested in the idea that human memory is fallible
• wanted to see if memory can be influenced by information which occurs after an event (post-event information)
• this included leading questions

Question 2

what type of sampling was used in experiment one ?

Answer 2

opportunity

Question 3

what was the sample of E1 ?

Answer 3

45 students

Question 4

what was the procedure of E1?

Answer 4

1. shown short clip of traffic accident
2. ppts divided into five groups
3. following the film, ppts asked: “about how fast were the cars going when they ______ (into) each other?”

Question 5

what was the range in length of the clips shown in E1 ?

Answer 5

5-30 seconds

Question 6

what were the five verbs used in the question, depending on the group ?

Answer 6

• smashed
• collided
• bumped
• hit
• contacted

Question 7

what was the independent variable for E1?

Answer 7

the verb used in the question

Question 8

what was the dependant variable for E1 ?

Answer 8

the mean estimate of the speed per group (mph)

Question 9

what verb was attributed the highest average speed ?

Answer 9

‘smashed’ - 40.8 mph

Question 10

what verb attributed the lowest average speed ?

Answer 10

‘contacted’ - 31.8 mph

Question 11

what were the conclusions from E1 ?

Answer 11

• the experiment provided powerful evidence of the effect that post-event information can have on the recall of an event
• however, the question remained whether this was because the information in the question biased a person’s response or actually altered the person’s memory of the event

Question 12

why was a second experiment conducted ?

Answer 12

to test whether the post-event information altered the person’s memory or if it just biased their answer

Question 13

what was the sample for E2 ?

Answer 13

150 students

Question 14

what was the procedure of E2 ?

Answer 14

1. ppts shown one minute film that included a short scan of a car accident
2. 50 ppts were asked:”how fast were the cars going when they smashed (into) each other”
3. another 50 asked the same but instead of ‘smashed’, it was ‘hit’
4. the third control group was not asked to estimate the speed of the vehicles
5. after a week, they were asked back in
6. given a questionnaire based on the film (not given second viewing)
7. randomly placed in it was the critical question: “did you see any broken glass?”
8. there was no broken glass in the film

Question 15

how many conditions were there, and what were they ?

Answer 15

3

1. ‘smashed’
2. ‘hit’
3. control

Question 16

what was the independent variable of E2 ?

Answer 16

the wording of the critical question

Question 17

what were the findings of E2 ?

Answer 17

yes, to seeing broken glass:

• ‘smashed’ = 16
• ‘hit’ = 7
• control = 6

Question 18

what were the conclusions from E2 ?

Answer 18

• findings from E2 suggests that post-event information did not simply create response bias
• post-event information actually altered the person’s memory of the event and generated expectations - such as the likelihood that there would be broken glass

Question 19

what is a strength of the study ?

Answer 19

aspects of the study were well-controlled

Question 20

How was the study made internally valid ?

Answer 20

• took place in a lab so there could be strict control variables
• the content of each was standardised for each ppt - as was the stimulus material

Question 21

what is the competing argument to the strong validity of the study ?

Answer 21

• watching a film of a car crash is unlikely to produce the same emotional response as witnessing one in real life
• there wasn’t the same amount of emotional investment- there was no risk of someone going to prison for the answer they gave - makes them more careless with their answer
• the lab study took away from the ecological validity

Question 22

assess the applicability of the study

Answer 22

• led to a review of the American justice system
• research into EWT and the fallibility of human memory was a major consideration in the Delvin Report, published in 1976
• recommended that juries should not convict on the basis of a single eye-witness testimony
• this shows that Loftus’ work has implications that stretched beyond the lab

Question 23

assess the generalisability of the study ?

Answer 23

• they used university students - their level of education may have affected the results as they will most likely be more intelligent than the general average and thus be better witnesses
• students often have less experience with cars - this may have affected their judgement of speed
• either way the sample is not representative of the general population and so is not generalisable

Question 24

assess the reliability

Answer 24

• Yuille and Cutshall (1986) showed that witnesses to a real-life shooting in Canada gave very accurate reports of the crime four months after the event even though they had initially been given two misleading questions.
• this suggests that, in real situations (when the stakes might be higher), witnesses are less influenced by post-event information.