Loftus And Palmer.
RECONSTRUCTION OF AUTOMOBILE DESTRUCTION.
Theories on which study is based:
- Schema theory proposes that memory is influenced by what an individual already knows, and that their use of past experience to deal with a new experience is a fundamental feature of the way the human mind words.
- Knowledge is stored in memory as a set of schemas - simplified, generalised mental representations of everything an individual understands by a given type of object or event, based on their past experiences.
- The schema forms part of Bartlett's theory of reconstructive memory, which forms the basis for Loftus and Palmers study into EWT.
- memory involves interpreting what is seen or heard, recording bits of it and then reconstructing these bits into memories when required.
- This implies that recall can be distorted or biased by certain features of the situation.
- This study focuses on the effects of leading questions on memory.
Relation to the cognitive approach.
- Cognitive processes include how we attain, retain and regain information, through the process of perception, attention, memory, problem solving, decission making, language and thought.
- This study is concerned with Eye Witness Testimony (EWT) and shows that memory is reconstructive.
- Bartlett's (1932) theory of reconstructive memory proposes that individuals reconstruct the past by fitting new information into their existing understanding of the world - a schema.
- Loftus and Palmer showed that EWT is influenced by peoples tendency to reconstruct their memories of events to fit their schemas.
- Both were a lab experiment using an independent measures design.
- The IV was the wording of a critical question hidden in a questionnaire.
- The question asked was: "About how fast were the cars going when they hit/smashed/collided/contacted/bumped eachother?"
- The DV was the estimated speed given by the participant.
- The IV was the wording of a question in a questionnaire:
- One group was asked "About how fast were the cars going when they hit each other?"
- A second group was asked "About how fast were the cars going when they smashed into eachother?"
- A third group was not asked about the speed.
- A week later all the participants were asked "Did you see any broken glass?"
- DV was yes or no.
- 45 students were divided into 5 groups, with 9 in each group.
- All participants were shown the same clip of different traffic accidents which were originally made as part of a driver safety film.
- After each clip, participants were given a questionnaire, which asked them first to describe the accident and then to answer a series of questions about the accident.
- There was one critical question in the questionnaire: "About how fast were the cars going when they smashed/ colided/ hit/ contacted/ bumped eachother?"
- 150 students were divided into 3 groups.
- All participants shown a 1-minute film which contained a 4- second multiple car crash.
- They were given a questionnaire, which asked them to describe the accident and answer a set of questions about the incident.
- There was a critical question about speed:
- One group asked: "About how fast were the cars going when they smashed into eachother?"
- Another group asked: "About how fast were the cars going when they hit eachother?"
- The third group didn't have a speed quesiton.
- One week later all participants, without seeing the film again, completed another questionnaire about the accident, this has another critical quesiton: "Did you see any broken glass- Yes/ No?"
- There hadn't been any broken glass in the film.
Key Findings Experiment 1.
Verb Mean Speed Estimate(mph)
- "Smashed" produced highest speeds and "contacted" produced the slowest.
- The film of a crash at 20mph was estimated to be 37.7mph.
- The film of a crash at 30mph was estimated to be 36,2mph.
- The films of crashes at 40mph were estimated to be 39.7mph and 36.1mph.
Key Findings Experiment 2.
Verb Mean Speed Estimate(mph)
- "Smashed" produced the highest speed estimates.
Response Smashed Hit Control
Yes 16 7 6
No 34 43 44
- More participants in the "smashed" conditon than either the "hit" or control groups reported seeing broken glass.
- The majority of participants in each group correctly recalled that they had not seen any broken glass.
- The verb used in the question influences a persons response- that is, the way a question is phrased influences the answer given.
- People are not very good at judging vehicular speed.
- Based on findings such as these, the Devlin report (1976) recommended that trial judges be required to instruct the jury that it is not safe to convict on a single eyewitness testimony, except in excpetional circumstances or when there is substantial corroborative evidence.
- The recommendation was rejected by the judiciary and the Home Office, but juries are now warned of the dangers of honest mistakes by eyewitnesses.