Loftus and Palmer 1974

Loftus and Palmer 1974

1. Experiment 1

   • Method
     • Lab experiment
       • 1hr 30
     • 45 participants (University of Washington)
       • 5 conditions (5 groups of 9)
         • 'About how fast were the cars going when they ***** each other?'
         • SMASHED, HIT, COLLIDED, BUMPED, CONTACTED
     • Hypothesis: "The participants estimate of speed will increase with the degree of violence suggested by the question concerning the car crash."
       • Aim: Whether the wording of a question can influence the memory recalled.
         • DV: the estimated speed
         • IV: verb in critical question
     • 7 film-clips of traffic accidents
       • After each clip, students were asked to write an account of the accident they had just seen
       • short excerpts from safety films made for driver education
   • Results
     • Conclusions/ Findings
       • The form of a question can affect a witness' answer.
       • Humans are inaccurate at judging the speed of vehicles.
       • 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.
     • 'smashed' elicited the highest speed estimate, and 'contacted' the lowest.

2. Experiment 2

   • Method
     • Aim: they wanted to find out if the participants memories really had been distorted by the verbal label.
       • IV: Wording of question (hit/smashed)
       • DV: answer to critical Q (Y/N)
     • Lab Experiment
       • 150 student participants
       • Independent Measures
     • Participants returned one week later and answered questions about the accident.
       • 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.
     • all viewed a short (1 minute) film which contained a 4 second scene of a multiple car accident
       • 3 condition groups of 50 (SMASHED, HIT, CONTROL)
       • How fast were the cars going when they ****** each other??
   • Results
     • 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.
     • Practical Applications
       • highlights the danger of 'leading questions' and shows how eye witness testimonies are unreliable for legal authorities such as the Police.

3. Evaluation

   • Strengths
     • Lab experiment- high and precise controls
       • Cause and effect relationship could be established
       • Precise controls of variables e.g. being asked the same question etc
   • Weaknesses
     • Low ecological validity- set in a lab.
     • Demand Characteristics
       • response-bias- participants may be unsure of the speed and adjust estimate to fit expectations of the questioner.
     • Sample: Students are not representative of the general population
       • they may be less experienced drivers and therefore less confident in their ability to estimate speeds

4. Background

   • demonstrate that memory is not a factual recording of an event and can become distorted by other information which occurs after the event.
     • demonstrated through leading questions how it is possible to distort a person’s memory of an event.

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