loftus & palmer

• G.M Whipple, 1909 - evidence that eyewitness testimonies are significantly less accurate than what we would hope. -> especially true when trying to recall specific numerical values e.g. time, distance and speed
• studies in the 1970s concluded that people tend to overestimate things e.g. speed and time of complex events
• Marshall (1969) Air Force personnel asked to estimate the speed of a car, their estimates were between 10-50mph (correct answer was 12mph) - they all knew they were going to be questioned beforehand
• Filmore (1971) the language used to describe the motion can impact the accuracy e.g. using words such as "smashed" rather than the neutral word "hit", which can lead to people judging the speed as greater
• Loftus & Palmer (1974) give the inaccuracies in estimates of speed, it seems likely that there are variables which potentially powerful in terms of influencing these estimates
• Bartlett (1932) demonstrated how memories are not accurate records of our experiences. It seems that we try to fit past events into our existing representations of the world, making the memory more coherent or make more sense for us
• overall aim of the study

  test whether the phrasing of questions about a car accident could alter participants memory of an event
• experiment 1 aim

  whether using different verbs to describe a collision between two cars would affect estimates of the speed at which they were travelling when the crash took place
• experiment 1 participants

  45 students, no details of age or gender
• experiment 1 design

  laboratory experiment

  independent measures design

  IV - the verb used in the critical question e.g. 'hit', 'contacted', 'bumped', 'collided' or 'smashed'

  DV - the mean estimate of the speed of the car
• experiment 1 procedure

  shown 7 films of car crashes from training films used by the Seattle police department and the Evergreen safety council

  4/7 films the speeds were known: 20mph, 30mph and 2 were 40mph

  participants asked to write an account of the accident and answer a series of questions after each film

  all but one question were fillers to make it harder for ppts to work out the aim of the experiment and the other was a critical question linked to the aim of the study - 'how fast were the cars going when they hit each other'
• experiment 1 results

  film no. 1 (20mph) - estimated speed 37.7mph

  film no. 2 (30mph) - estimated speed 36.2mph

  film no. 3 (40mph) - estimated speed 39.7mph

  film no. 4 (40mph) - estimated speed 36.1mph
• experiment 1 conclusion

  estimates of the cars speed in the accidents shown varied according to the verb that was used to describe the crash in the critical question

  1. response bias - when ppts were unsure on what speed to estimate, they use the verb in the critical question to give them an idea if it is a high or low figure
  2. memory distortion - verb used in the critical question actually altered the ppt's memory of the crash
• experiment 2 aim

  whether the different speed estimates found in experiment 1 were the results of a distortion in memory - done by seeing whether ppts who heard words associated with high speed estimates would be more likely to incorrectly remember broken glass at the crash site
• experiment 2 participants

  150 students, no details of age or gender
• experiment 2 design

  laboratory experiment

  independent measures design
• experiment 2 procedure

  ppts watched a film of a car crash that was one minute long, the accident was 4 seconds long

  questionnaire was given and were asked to describe what happened in their own words and answer a series of questions - one critical question

  first 50 - about how fast were the cars going when they smashed into each other?

  next 50 about how fast were the cars going when they hit each other?

  final 50 - no question about speeds of cars

  returned a week later - asked 10 questions, critical question was "did you see any broken glass?"
• experiment 2 results

  ppts who had smashed in the critical question estimated a higher speed (10.46mph compared to 8mph in hit)

  smashed: yes - 16, no - 34

  hit: yes - 7, no - 43

  control group - yes - 6, no - 44
• conclusion from both experiments

  way in which questions about events are worded can affect the way in which the events are remembered

  experiment 2 - strongly suggest it is simply not due to response bias but that post-event questions become part of the memory of the event

  therefore wording of questions can distort event memory
• research method - strengths

  • laboratory experiment - highly controlled such as precise timing of films, presentations of the question order, inclusion of filler questions -> possible to eliminate extraneous variables
  • able to determine the IV of the verb affected the DV of speed and recall of broken glass
• research method - weaknesses

  • low ecological validity - watching a film is not the same as witnessing a real event as actual car crash witnesses would be likely to experience more intense feelings like shock or fear -> known emotion that affect memory
• sample - weaknesses

  • all ppts were students - not likely to be truly representative of the population, likely to have been predominately white, middle-class and within a narrow age range and same occupation
  • used to taking in information and being tested on it therefore likely to recall more accurately than most people
  • less likely to be drivers - speed estimates less accurate
• quantitative data - strengths

  • easy comparison of conditions, clearly showing that memory is affected by the wording of questions
• quantitative data - weaknesses

  • no opportunity for ppts to comment either on what they remembered or their experience of being questioned in this way - qualitative data would have added to this
• ethics - weaknesses

  • ppts may have felt obliged to participate even if their experience meant they didn't want to - those who have experienced real car crashes, therefore informed consent is questionable if it is genuine
• reliability - strengths

  • laboratory procedures highly standardised - length of films were specified making them reliable and allows the procedure to be replicable
  • similar results for speed estimates with 'smashed' and 'hit' in experiment 1 and 2, findings are reliable
• validity - strengths

  • high levels of control ensure few extraneous variables influence the outcomes - filler questions reduced likelihood that ppts worked out the aim and some were real accidents -> realistic, raises validity
• validity - weaknesses

  • low ecological validity - artificiality of the remaining films and content, possible that some ppts worked out the aim of the experiment, especially experiment 2
  • ppts had a better view of the crash than in real life situations - more relaxed and less motivated to remember details as they were familiar and safe, also upsetting to witness in real life and emotional response can make the event more or less memorable -> unrepresentative
• practical applications

  • important in helping authorities to understand how to question witnesses to important events such as accidents and crimes -> use of leading questions by the police and courtroom is now tightly controlled, improves rate of successful criminal convictions