Loftus and Palmer

• What was the background?

  Schemas enable us to predict events and make sense of unfamiliar circumstances. Schema driven errors can cause witnesses to crimes to filter information during acquisition and recall and schematic understanding may influence how information is stored and retrieved. This could cause distortion to occur without the witness realising and can lead to confabulation known as honest lying. Distortion can occur due to the influence of leading questions
• What was the aim?

  To investigate the effect of leading questions on the accuracy of eyewitness testimony 
• What was the method of experiment 1?

  • Lab experiment with independent measures design  
  • IV – wording of a critical question hidden in a questionnaire “About how fast were the cars going when they hit each other?”  
  • DV – estimated speed given by participant asked on the question “About how fast were the cars going...” when the critical verb was changed 
• What was the sample of experiment 1?

  45 students were divided into 5 groups, from the USA 
• What was the procedure of experiment 1?

  • All participants shown same seven clips of different traffic accidents (originally part of driver safety film) 
  • After each clip ppts given a questionnaire which asked them to describe the accident and answer questions about the accident 
  • One critical question “About how fast were the cars going when they hit each other?” 
  • One group given this question while others were given verbs “smashed”, ”collided”, ”contacted” or “bumped” INSTEAD OF HIT 
• What were the findings of experiment 1?

  • Smashed produced the fastest speed estimates and contacted produced the slowest 
  • Crash of 20mph was estimated to be 37.7 mph 
  • Crash at 30mph estimated to be 36.2 mph 
  • Crashes at 40mph estimated to be 39.7mph and 31.6mph 
• What was the method of experiment 2?

  • Lab experiment, independent measures 
  • IV – wording in a questionnaire “About how fast were the cars going when they smashed into each other?” “About how fast were the cars going when they hit each other?” A third group was not asked about speed  A week later all ppts asked to complete another questionnaire containing the critical question “Did you see any broken glass” 
  • DV – number of people who said “yes/no” 
• What was the sample of experiment 2?

  150 students were divided into 3 groups, from the USA 
• What was the procedure of experiment 2?

  • All ppts shown one minute film which contained a four second multiple car crash 
  • Given a questionnaire
  • Critical question about speed: 1 group asked “About how fast were the cars going when they smashed into each other?” Another “About how fast were the cars going when they hit each other Third group did not have a question about speed 
  • One week later all ppts completed another questionnaire about the accident which contained the further critical question “Did you see any broken glass – Yes/No?” There was no broken glass in the original film 
• What were the findings of experiment 2?

  • More participants in the “smashed” condition (n=16) than either “hit” (n=7) or control groups (n=6) reported seeing broken glass  
  • Majority of participants in each group correctly recalled they had not seen any broken glass 
• What were the conclusions?

  • The verb used in a question influences a participant’s response  
  • Misleading post event information can distort an individual’s memory