Sunday, 26 November 2017

Loftus + Palmer eyewitness study (1974)


Context/Background

Study is about eyewitness testimony and reconstructed memories

A schema= a cognitive framework/concept where we organise and interpret information about people or things, this tells us what to expect from situations based on memory of information or experiences linked to it

Police and courts often rely on subjective eyewitness testimonies, which can be potentially affected by leading questions


Aim

To see if different verbs affect memory (in 2 experiments)


Method

Experiment 1- Lab experiment, independent measures, IV= wording of critical question, "How fast were the cars going when they hit/smashed/contacted/bumped/collided with each other?" DV= estimated speed

Experiment 2- Lab experiment, independent measures, IV= wording in 2 questions, either "How fast were the cars going when they smashed?" "How fast were the cars going when they hit?" and a separate question unrelated to speed
A week later, they were asked if they saw any broken glass in the clip


Procedure

Ex. 1- 45 students, 5 groups of 9, shown 7 clips of car crashes (staged), then given a questionnaire to describe the accident
Critical question= How fast were the cars going when they _____ each other?
IV's= the verbs used, hit/smashed/collided/bumped/contacted

Ex. 2- 150 students, 3 groups of 50, shown a 1 minute film of a car crash and given a questionnaire to describe it
Critical question= How fast when they smashed? How fast when they hit? and a question unrelated to speed
A week later, they were asked if they saw any broken glass (there wasn't actually any broken glass)


Findings

Ex. 1- 
Verb                             mean speed estimate (mph) 
smashed                       40.5
collided                         39.3
bumped                        38.1
hit                                34
contacted                      31.8

Ex.2-
Verb                             mean speed (mph)
smashed                       10.46
hit                                8

Whether they saw broken glass

Response           smashed       hit        contacted
yes                    16                7           6
no                     34                43         44


Conclusions

Wording in leading questions can affect memory = memory reconstruction 


Evaluation 

Research method- Lab experiment, independent measures

Data type- quant. data so easier to compare, but qual. data may have helped with understanding the research better

Ethics- minimal ethical issues but it may have upset p's affected by crashes

Validity- high control so minimal extraneous variables, low ecological validity

Reliability- highly reliable because it was standardised, so the procedure was replicable

Sample- random sampling method, all white middle class students so ethnocentric and un-generalisable, demand characteristics possible but students are not experienced at driving so speed estimates won't be as accurate
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