Eye witness : Misleading information

• Aim of Loftus and Palmer-

  -To investigate how information supplied after an event (post event information) influences a witness's memory for that event.

  -They wanted to investigate effects of leading questions
• Loftus and Palmer Experiment-

  -Consists of 2 laboratory experiments.

  -Both examples of independent measures design

  -Independent variable in both is verb used

  -Dependent variable in 1st experiment is ppts speed estimate

  -Dependent variable in 2nd experiment is whether ppts believed they saw glass or not
• Loftus and palmer - Experiment 1 procedure

  -Ppts were 45 students from University of Washington

  -Shown 7 film clips of traffic accidents

  -The clips were short excerpts from safety films made for driver education

  -Clips ranged from 5 to 30 seconds long

  -After each clip, they were asked to write down an account of the accident they had just seen.

  -Also asked to answer specific questions but critical question was to do with speed of vehicle
• Loftus and Palmer experiment 1 procedure conditions-

  -5 conditions in the experiment (each with 9 ppts)

  -Independent variable was manipulated by wording of questions
• Loftus and Palmer experiment 1 5 conditions:

  1.About how fast cars were going when they SMASHED into each other?

  2.About how fast cars were going when they COLLIDED into each other?

  3.About how fast cars were going when they BUMPED into each other?

  4.About how fast cars were going when they HIT each other?

  5.About how fast cars were going when they CONTACTED each other>
• Loftus and Palmer Experiment 1 findings-

  Verb Mean estimate of speed(mph)

  Smashed 40.8

  Collided 39.3

  Bumped 38.2

  Hit 34.0

  Contacted 31.8
• Loftus and Palmer Experiment 1 conclusion first explanation-

  -They argue that the results could be due to a distortion in the memory of the participant.

  -The memory of how fast the cars were travelling could have been distorted by the verbal label which had been used to characterise the intensity of the crash.

  -The critical verb provides misleading information
• Loftus and Palmer Experiment 1 conclusion 2nd explanation-

  -They argue that the results could be due to response-bias factors, in which case the participant is not sure of the exact speed and therefore adjusts his or her estimate to fit in with the expectations of the questioner.

  -(This is also an example of a demand characteristic)
• Loftus and Palmer Experiment 2 procedure-

  -The second experiment they wanted to find out if the ppts memories really had been distorted by the verbal label.​

  -A similar procedure was used whereby 150 student participants viewed a short (one minute) film which contained a 4 second scene of a multiple car accident and were then questioned about it. ​

  -There were three conditions, and the independent variable was manipulated by the wording of the question.
• Loftus and Palmer Experiment 2 questions-

  -50 of ppts were asked: "How fast were the cars going when they HIT each other?"

  -50 ppts were asked "How fast were the cars going when they SMASHED into each other?"

  -50 ppts were not interrogated about the speed of the vehicles
• Loftus and Palmer Experiment 2 procedure week later -

  -One week later, ppts returned and, without viewing the film again, they answered a series of questions about the accident.

  -The critical question was 'Did you see any broken glass?'

  -The critical question was part of a longer series of questions and was placed in a random position on each participants question paper.

  -There was in fact no broken glass in the film.
• Loftus and Palmer Experiment 2 findings-

  Response Smashed Hit Control

  Yes 16 7 6

  No 34 43 44
• Loftus and Palmer Experiment 2 conclusion-

  -2 sources of information available to us about an event:

  1.The event- what we saw at time

  2.Post event info - supplied by question

  -Overtime these two sources of information integrate into another.

  -Ppts in the “smashed” condition believe the crash to have been more severe than it was and therefore assume that broken glass must have been present. -This is referred to the reconstructive hypothesis.
• Post event discussions-

  -One source of misleading information comes from leading questions.

  -However, misleading information in the real world can come from other sources, for example other witnesses (co-witnesses), when they discuss the details of a crime of accident, following an incident.

  -This is known as post-event discussion
• Post event discussions - Conformity effect 


  -Co witnesses may discuss an event and reach a consensus of opinion
• Post event discussions - Conformity effect Gabbert

  -Gabbert et al asked ppts to individually watch a unique video of an event. The videos were different perspectives of the same event.

  -In the experimental condition ppts were encouraged to discuss what they had seen before individually recalling the event.

  -71% of witnesses who had discussed the event went on to mistakenly recall items acquired during the discussion.
• Repeat interviewing-

  -Each time an eyewitness is interviewed, there is the possibility that comments from the interviewer will become incorporated into their recollection.

  -It is also possible the interviewer could use leading questions, which could alter the individual’s memory.

  -This is especially the case when children are being interviewed about a crime (LaRooy et al, 2005)