Loftus and Palmer 1974

Experiment 1
1. Method
  1. Lab experiment
    1. 1hr 30
  2. 45 participants (University of Washington)
    1. 5 conditions (5 groups of 9)
      1. 'About how fast were the cars going when they ***** each other?'
      2. SMASHED, HIT, COLLIDED, BUMPED, CONTACTED
  3. Hypothesis: "The participants estimate of speed will increase with the degree of violence suggested by the question concerning the car crash."
    1. Aim: Whether the wording of a question can influence the memory recalled.
      1. DV: the estimated speed
      2. IV: verb in critical question
  4. 7 film-clips of traffic accidents
    1. After each clip, students were asked to write an account of the accident they had just seen
    2. short excerpts from safety films made for driver education
2. Results
  1. Conclusions/ Findings
    1. The form of a question can affect a witness' answer.
    2. Humans are inaccurate at judging the speed of vehicles.
    3. results may have been distorted the memory of the participant: it may have been distorted by the verbal label which had been used to characterise the intensity of the crash.
  2. 'smashed' elicited the highest speed estimate, and 'contacted' the lowest.
Experiment 2
1. Method
  1. Aim: they wanted to find out if the participants memories really had been distorted by the verbal label.
    1. IV: Wording of question (hit/smashed)
    2. DV: answer to critical Q (Y/N)
  2. Lab Experiment
    1. 150 student participants
    2. Independent Measures
  3. Participants returned one week later and answered questions about the accident.
    1. Critical question: 'Did you see any broken glass?' was part of a series of questions in a random position on each participants question paper. There was no broken glass in the film.
  4. all viewed a short (1 minute) film which contained a 4 second scene of a multiple car accident
    1. 3 condition groups of 50 (SMASHED, HIT, CONTROL)
    2. How fast were the cars going when they ****** each other??
2. Results
  1. the verb 'smashed' had a significant effect on the mis-perception of glass in the film. Participants in the 'smashed' group were more than twice as likely to recall seeing broken glass.
  2. Practical Applications
    1. highlights the danger of 'leading questions' and shows how eye witness testimonies are unreliable for legal authorities such as the Police.
Evaluation
1. Strengths
  1. Lab experiment- high and precise controls
    1. Cause and effect relationship could be established
    2. Precise controls of variables e.g. being asked the same question etc
2. Weaknesses
  1. Low ecological validity- set in a lab.
  2. Demand Characteristics
    1. response-bias- participants may be unsure of the speed and adjust estimate to fit expectations of the questioner.
  3. Sample: Students are not representative of the general population
    1. they may be less experienced drivers and therefore less confident in their ability to estimate speeds
Background
1. demonstrate that memory is not a factual recording of an event and can become distorted by other information which occurs after the event.
  1. demonstrated through leading questions how it is possible to distort a person’s memory of an event.

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Loftus and Palmer 1974

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	Created by katherine.crick almost 11 years ago