Loftus and Palmer


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  • Loftus and Palmer
    • Background
      • Research has shown memories can be inaccurate. this is a problem for eye witness testimony
      • James Marshal 1969 found air force personel when asked to estimate the speed of a car going 12mph estimates ranged from 10-50mph
      • Leading question - Certain question or statement that leads a person to give particular answer
    • First experiment
      • Aim
        • If estimates of speed would be influenced by wording of Question asked
      • Method
        • Design- Lab experiment Independent measures Snapshot study
        • IV - The verb given to PP's  DV - The PP's estimate of speed
      • Sample
        • 45 American college students. Divided into 5 groups one for each verb
      • Materials and apparatus
        • Pps shown 7 film clips and asked to fill in a questionaire after each clip
        • Clips were from a driver education program for evergreen safety council and Seattle police department
      • Procedure
        • PP's were asked to describe accidents and to estimate the speed of the car
        • Each group had different verb in the question on questionnaire Hit , Bumped, collided, smashed contacted
          • Different order of film clip were used for each group
            • Two Explanations
              • Response bias, verb smashed makes the accident sound high impact leading to a higher speed estimate
              • Memory representation the verb changes the  perception of the accident this is stored with the memory
      • Results
        • Mean estimate was faster for PP's with Smashed than Contacted
          • PP's were not able to accurately estimate speed, crashes were at 20,30,40 mph yet estimates were between 36-40
      • Discussion
        • Form of a question can have an effect on the answer to a question
    • Second Experiment
      • Aim
        • If a leading question would change recollection of event
      • Method
        • Design - Lab experiment, independent measures         IV - verb in critical Q DV- the estimate of speed of car Longitudinal study
        • Sample - new group of 150 American students
      • Procedure
        • Part one
          • PP's asked to describe the crash with the critical question "How fast were the cars going when they *VERB* into each other?"
          • Group one had verb - Smashed Group two had verb Hit Group three was control and wasn't asked question
        • Part two
          • A week later Pp's were asked if they saw any broken glass ( there was no broken glass)
          • It was presumed those that though the cars were traveling faster, may have thought they saw broken glass
      • Results
        • Part One
          • PP's in smashed condition gave a higher speed estimate smashed - 10.46 mph  Hit - 8 mph
        • Part Two
          • PP's in smashed condition though they saw broken glass more than hit condition or control
            • Did you see broken glass? Smashed - Yes 16  No 34 Hit- Yes 7 No 43 Control - Yes 6 No 44
      • Discussion
        • Memory is determined by two sources 1) - Your own perception learned at the time of original event 2) External information supplies after eg leading question.

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