Eyewitness Testimony

• Eyewitness testimony


  Testimony provided by a witness who observed an event
• Factors affecting the accuracy of eyewitness testimony

  • Misleading information
  • Leading questions
  • Past event discussion
• Factors affecting recall of eyewitness testimony

  • Anxiety
  • Weapon focus
• Anxiety


  Can have both positive and negative effects on the accuracy of eyewitness testimony
• Anxiety


  A state of emotional (e.g. worried thoughts and tension) and physical (e.g. increased heart rate) arousal
• Anxiety


  • It can affect the accuracy and detail of eyewitness testimony in both positive and negative ways
• Weapon focus


  The presence of a weapon leads to anxiety and we focus our attention on the weapon, reducing the witness's recall for other details of the event
• Johnson and Scott study

  • Participants were in either a low anxiety 'no-weapon' condition or a high anxiety 'weapon' condition
  • Participants were then shown 50 photographs and asked to identify the person who had left the laboratory
• Those who had witnessed the man holding a pen correctly identified the man 40% of the time
• Those who had witnessed the man holding a knife, correctly identified the man 33% of the time
• Weapon focus effect


  Participants who were exposed to the knife had higher levels of anxiety and were more likely to focus their attention on the weapon and not the face of the target
• Cognitive interview


  A method of interviewing eyewitnesses to help them retrieve more accurate memories
• Techniques used in the cognitive interview

  • Report everything
  • Reinstate the context
  • Reverse the order
  • Change perspective
• Report everything


  Witnesses are encouraged to recall every detail of the event, even if it seems trivial, as this may trigger other memories
• Reinstate the context


  The witness imagines they are back at the original crime scene and gives details about the environment and their emotions
• Reverse the order


  Events are recalled in a different order to prevent people reporting their expectations of how the event must have happened rather than the actual events
• Change perspective


  Witnesses need to recall the event from another person's point of view to disrupt the effect of expectation and schemas on recall
• Yuille and Cutshall study

  • Investigated the effect of anxiety in a real life shooting in a gun shop in Canada
  • 21 witnesses were originally interviewed by investigating police and 13 witnesses, aged between 15 and 32, agreed to take part in Yuille and Cutshall's follow-up research interview, 4-5 months later
• Accuracy was measured by the number of details reported in each account
• Those participants who reported the highest level of stress were most accurate, at approximately 88%, compared to 75% of the low stress group
• Yerkes-Dodson law


  Performance increases with physiological or mental arousal, but only up to a certain point
• Low anxiety levels will lead to less accurate eyewitness testimony
• As anxiety increases, the accuracy of eyewitness testimony also increases, up to an optimal level of maximum accuracy
• However, too much anxiety then starts to lead to less accurate eyewitness testimony
• Leading question


  A question which, because of the way it is phrased, suggests a certain answer
• Loftus and Palmer (1974) study


  • 45 students watched film clips of car accidents and were then asked questions about the accident
  • The critical question (which was a leading question) they were asked was "About how fast were the cars going when they smashed/hit/bumped/collided/contacted each other?"
  • There were 5 groups, each asked the critical question with a different verb
• The verb "smashed" resulted in a mean estimated speed of 40.5 mph (which was the highest for all of the verbs)
• The verb "contacted" resulted in a mean estimated speed of 31.8mph (which was the lowest for all of the verbs)
• Leading question


  Biases the eyewitness's recall of the event
• Response bias


  The wording doesn't have any real effect on their memories, it just encourages them to choose a higher speed for the word "smashed"
• Substitution explanation


  The wording actually changes the memory, supported by a follow up study where participants in the "smashed" condition were more likely to say they had seen glass (even though there wasn't any)
• Post-event discussion


  When there is more than one witness to an event, they may discuss what they have seen with co-witnesses or other people, which may affect the accuracy of each witness's recall of the event
• Gabbert et al (2003) study


  • Participants watched a video of a crime (a girl stealing) from different points of view, then discussed what they had seen before individually completing a recall test
  • A control group had no post-event discussion
• In the post-event discussion group, 71% of the participants mistakenly recalled aspects of the event that they did not see, as they picked it up in the discussion
• In the control group with no discussion, it was 0%
• Memory contamination


  The discussion causes the eyewitness testimonies to become altered or distorted because they combine (mis)information from other witnesses with their own memories
• Memory conformity


  Witnesses may go along with other witnesses to win social approval or because they believe the other witnesses are right and they are wrong, unlike memory contamination the actual memory is unchanged