Eyewitness Testimony

• Three main factors affecting Eyewitness Testimony

  • Leading questions
  • Post-event discussion
  • Anxiety
• Leading question


  A question that either by its form or content, suggests to the witness what answer is desired, or leads them to the desired answer

  • Retroactive interference on our memory - incoming information gets integrated and confused with our existing knowledge
• Loftus and Palmer's experiment on leading questions 


  Aim: Test the effect of leading questions upon estimates of speed

  Two experiments were conducted

  Experiment 1:

  • 45 students
  • Watched films of a car accident and were asked questions afterwards
  • Critical question 'How fast were the cars going when they contacted / hit / bumped / collided / smashed each other?'
  • Summary: words associated with more violence affected p's overall judgement of the average speed to be higher

  
• Loftus and Palmer's follow up experiment on leading questions

  Aim: Test whether the participant's memories had actually altered as a result of the leading questions

  Experiment 2:

  • 150 students
  • One week later, p's were asked questions without viewing the film again
  • A question embedded was 'Did you see any broken glass?'
  • Because broken glass is commensurate with accidents occurring at high speed, subjects who were asked the 'smashed' question often said 'yes'
  • Summary: Memory errors (false memory) are created

  A) Smashed

  B) Hit

  C) Control

  
• Post-event discussion


  When co-witnesses to a crime discuss it with one another, their eyewitness testimonies may become contaminated
• Memory contamination 


  Combining misinformation from other witnesses with their own memories
• Memory conformity


  Going along with other witnesses to win social approval and fit in
• Gabbert post-event discussion experiment 


  • p's watched a video of the same crime, but from different perspectives (povs)
  • Both participants discussed events after
  • 71% of p's mistakenly recalled aspects of the event that they did not see in the video (picked up from discussion)
  • Control group 0%
  • Conclusion: Eyewitness testimony is altered / distorted, MEMORY CONFORMITY
• Weaknesses of eye-witness testimony 


  Rachel Foster

  • Film clips in a lab is unlike witnessing a real event (less stressful) as there are less consequences, research lacks ecological validity
  • Artificial findings led Loftus to be pessimistic about our memories, they may be better than what findings suggest
• Evidence against memory conformity 


  Skagerberg & Wright (2008) showed p's film clips and altered certain details (e.g. colour of hair)

  • Participants don't blindly follow the other person, but instead they suggest a blend of the two (e.g. light brown + dark brown ->medium brown hair)
  • Conclusion: The post-event discussion itself alters EWT, not a desire to win social approval or the belief that the other person is right
• Demand characteristics 


  Going along with what you are supposed to do

  • Zaragoza and McCloskey think that participants usually want to be helpful and not the let the researchers down, so they guess when they are asked a question they do not know the answer to
• Anxiety


  An unpleasant emotional state where we fear that something bad is about to happen

  • Stressful situations
  • Accompanied with physiological arousal (increased heart rate, shallow breathing)
• Loftus and Burns (1982) on anxiety


  • P's shown a violent version of a crime where a boy is shot in the face (lab study)
  • Their recall was significantly impaired for events running up to the violent incident
  • Conclusion: Anxiety has NEGATIVE effect on EWT
• Christianson & Hubinette (1993) on anxiety

  • Questioned 58 real victims of a bank robbery
  • Those that were threatened (directly involved) were more accurate in recall compared to onlookers (indirectly involved)
  • Remained true 15 months later
  • Conclusion: Anxiety has POSITIVE effect on EWT

  However, there was a lack of control over confounding variables, which questions the results
• Johnson & Scott (1976) Weapon Focus Effect 


  • Lab study: staged argument, p's in a waiting room waiting for 'experiment' - already in the experiment
  • 1st group: p's hear argument, individual enters holding pen with grease on his hands
  • 2nd group: p's hear argument and breaking glass, individual enters holding a knife covered in blood

  Identification (recognition) of individual - 1st group = 50% accurate, 2nd group = 33% accurate (focused on knife)
• Tunnel theory


  People have enhanced memory for central events

  Weapon focus as a result of anxiety has this effect
• Yuille & Cutshall (1986)

  • Real life shooting in a gun shop where shop owner shot a thief dead
  • Witnesses interviewed 4-5 months after incident, comparing these with original police interviews at the time.
  • Witnesses rated their stress level + emotional problems since event
  • They were very accurate (little change in accuracy after 5 months)
  • Highest level of stress 88% - Lowest level of stress 75%
  • CONCLUSION: Anxiety has no detrimental effect on EWT, it even enhances it
• The Yerkes-Dodson Law

  Performance improves with increases of arousal up to an optimum point and then declines with further increases

  Used to explain anxiety with EWT

  A) Arousal

  B) Performance

  
• Issues with the Weapon Focus Effect theory


  • Surprise factor or actual anxiety?
  • Pickel (1998) tested this with a hairdressing salon video using scissors, a handgun, a wallet or raw chicken as handheld items
  • Results: EWT was poorer in the high unusualness conditions (handgun and raw chicken)
  • Conclusion: Weapon focus effect is due to unusualness rather than anxiety or threat
• Labyrinth of horror - Valentine & Meson (2009)


  • Real world setting
  • p's wore heart monitors during the experience and filled questionnaire after
  • Divided in high anxiety and low anxiety group
  • Result: High anxiety - 17%, low anxiety - 75%
• Confounding variables 


  Factors apart from independent variables that cannot be controlled
• Ethical arguments on testing anxiety on EWT


  • Very risky as psychological harm could be a result of experiment
  • Real life event would be better as they have already experienced the anxiety