Loftus & Palmer (1974)

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  • Created by: ernily
  • Created on: 19-04-15 16:16

Loftus & Palmer (1974) - Aims & Context

  • Eyewitness Testimony: The use of eyewitnesses to give evidence in court concerning the identity of someone who has committed a crime.
  • It relies on memory, so how can they be sure that they are telling the truth.
  • Leading Questions: A question that, either by its form or content, suggests to the witness what answer is desired. They can explain how questioning by police can affect eyewitness testimony.
  • Bartlett (1972) demonstrated how memories are not accurate records of our experiences.
  • Marshall (1969) found that when Air Force personnel, who knew in advance that they would be asked to estimate speed, saw a car travelling at 12mph, they estimated 10-50mph.
  • Filmore (1971) suggests that the words "smashed" and "hit" may involve differential rates of movement. They also lead the listener to assume different consequences to the impacts to which they are referring; hit is perceived as being more gentle than smashed.
  • The Devlin Committee (1973) recommended that juries should be instructed that it isn't safe to convict on the basis of eye witnes testimony alone, as EWT is unreliable.
  • The aim of Loftus & Palmer's study was:
    • To investigate the accuracy of memory.
    • To investigate the effect of leading questions on the estimate of speed.
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Loftus & Palmer (1974) - Procedures

  • Experiment 1:
    • 45 students, shown 7 film clips of traffic accidents.
    • The lengths of the clips ranged from 5-30 seconds.
    • Each participant received a questionnaire where they were asked to re-count the accident, and asked specific questions.
    • The "critical" questions was the same question given to 5 groups, except each group had a different verb; "About how fast were the cars going when they hit/smashed/collided/bumped/contacted each other?"
  • Experiment 2:
    • 150 students, again had to estimate speed.
    • Part 1:
      • They were shown a film of a car crash which lasted less than 4 seconds.
      • They were then split into 3 groups and given a questionnaire.
      • Group 1 had the verb "smashed", Group 2 had the verb "hit", and Group 3 was a control; they had no critical question.
    • Part 2:
      • The participants returned one week later and were given the critical question "Did you see any broken glass?"
      • The implication of the broken glass could lead to faster speed estimates.
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Loftus & Palmer (1974) - Findings & Conclusions

  • Experiment 1:
    • The mean speed estimate for smashed was 40.8% (highest verb)
    • The mean speed estimate for contacted was 31.8% (lowest verb)
  • Experiment 2:
    • Part 1: "Smashed" still gave the higher speed estimates.
    • Part 2:
      • When "smashed" was used, 16 people reported seeing the broken glass.
      • When "hit" was used, 7 people reported seeing the broken glass.
      • With the control group, 6 people reported seeing the broken glass.
  • Conclusions:
    • Response Bias Factors: Different speed estimates occur because of the critical verb influencing the response.
    • Memory Respresentation Altered: The critical word changes a person's memory, so their perception of the accident is affected.
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Loftus & Palmer (1974) - Evaluating The Methodolog

  • Method - Lab Experiment
    • Controlled environment, so extraneous variables can be controlled.
    • Cause and effect relationships can be established.
    • Low ecological validity due to artifical setting.
  • Reliability:
    • Study has been replicated with standardised procedures (e.g. same questionnaire questions, same verbs used, same clips shown) and similar results have been acquired, which shows that the study is consistent and therefore reliable.
  • Validity:
    • Lacks ecological validity due to the artificial environment.
    • The accidents were only film clips, so the participants would not have experienced the panic or anxiety that they would've done in a real life situation.
    • Participants were aware that they were being observed, so there was the risk of participant effects. Could mean the results aren't generaliseable.
  • Sampling:
    • US Students: Young people act differently to adults.
  • Ethical Issues:
    • Lack Of Informed Consent: Participants were deceived about the aims of the study.
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Loftus & Palmer (1974) - Alternative Evidence

  • Loftus & Zanni (1975) - Develops:
    • They showed participants a film of a car accident.
    • Participants were then asked if they saw "a" broken headlight, or if they saw "the" broken headlight.
    • When "a" was used, 7% of participants reported seeing the headlight.
    • When "the" was used, 17% of participants reported seeing the headlight.
  • Loftus (1979) - Contradicts
    • Participants were shown a video of a man stealing a red wallet from a woman.
    • Participants were asked about the colour of the wallet and 98% of them identified the colour correctly.
  • Loftus et al (1978) - Supports
    • Participants were shown slides of events leading up to a car accident. 
    • One group saw a car at a "STOP" sign first, the other group saw a car at a "YIELD" sign first.
    • Half of the group were asked about the "STOP" sign first, the other half was asked about the "YIELD" sign first.
    • 75% of participants picked the correct slide when the questions related to the sign they saw first.
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