Eye-witness testimony

• Eye-witness testimony can be inaccurate or distorted
• Eye witness testimony is evidence provided by people who witnessed an event. Relies on recall memory
• EWT includes descriptions of criminals and crime scenes
• Witnesses in EWT often inaccurate in recollection of events . (Important factor for police interviews)
• EWT - many cognitive psychs focus on factors affecting accuracy of EWT and how it can be improved
• Loftus and Palmer (1974) investigated how EWT can be distorted
• Loftus and Palmer (1974) EWT - Experiment 1 method

  • Ps shown film of multiple car crash
  • Asked series of questions "How fast do you think the cars were going when they hit"
  • Word hit was replaced with: Smashed, collided, bumped or contacted
• Loftus and Palmer car crash question

  " How fast do you think the cars were going when they hit "
• Loftus and Palmer (1974) EWT - Experiment 1 results

  • Word smashed had highest estimated speed (41mph)
  • Word contacted had lowest estimated speed (32 mph)
• Loftus and Palmer (1974) EWT - Experiment 2 method

  • Ps split in 3 groups
  • Group one verb " smashed "
  • Group two verb " hit"
  • Group three no verb given
  • One week later asked question "Did you see any broken glass"
• Loftus and Palmer (1974) EWT - Experiment 2 results

  • No broken glass in film, Ps in group 1 (smashed) more likely to say there was glass
• Loftus and Palmer (1974) EWT - Conclusions

  Leading questions affect accuracy of memories of events
• Loftus and Palmer (1974) EWT - Evaluation

  • Implications for police interviews
  • Artificial experiment = video is less emotionally arousing
  • Later study found Ps witnessed a real robbery gave accurate description of robber
  • Experimental design could have had demand characteristics due to Ps expectations of the purpose of the experiment
  • Leading questions may have given clues on nature of the study
  • Reduced validity and reliability
• Loftus and Zanni (1975) looked at leading questions
• Loftus and Zanni (1975) - leading questions - Method

  • Shown film of a car crash
  • Asked "Did you see the/a broken headlight"
• Loftus and Zanni (1975) - leading questions - Results

  • 17% those asked the question with " the " claimed they saw a broken headlight
  • 7% asked the question with " a " claimed they saw a broken headlight
• Loftus and Zanni (1975) - leading questions - Conclusion

  • Use of word " the " is enough to affect accuracy of recall
• Loftus and Zanni (1975) - leading questions - Evaluation

  • Good implications for EWT
  • Lab study = control of extraneous variables
  • Possible to establish cause and effect
  • Study artificial = lack ecological validity
• Post event discussion can affect accuracy of recall
• Shaw et al (1997) Accuracy of recall method

  Paired Ps with confederate

  Shown videos of staged robbery and were interviewed together after
• Shaw et al (1997) Accuracy of recall results

  Participant responding first, recall was accurate 58% time

  Confederate responding first and accurately, Ps accurate 67% time

  Confederate answering first inaccurately, Ps accurate 42% time
• Gabbert et al (2004) Accuracy of recall Method

  2 groups of Ps

  Young adults and older adults watched staged crime and then exposed to misleading information
• Gabbert et al (2004) Accuracy of recall.

  How was info mislead

  • Conversation with confederates
  • Reading written of crime
• Gabbert et al (2004) Accuracy of recall, results

  • Both groups of adults more likely to report inaccurate info after conversation rather than report
• Age of witness can affect accuracy of ewt
• Valentine and Coxon (1997) - Age affect on EWT - Method

  • 3 groups of Ps (children, young people, elderly people)
  • Watched video of kidnapping
  • Asked series of leading and non-leading questions
• Valentine and Coxon (1997) - Age affect on EWT - results

  Elderly people and children gave more incorrect answers to non-leading questions

  Children the most mislead by leading questions
• Valentine and Coxon (1997) - Age affect on EWT - Conclusion

  Age has an affect on EWT
• Valentine and Coxon (1997) - Age affect on EWT - Evaluation

  • Implications in law when children questioned
  • Artificial experiment = less emotionally arousing
  • Lack ecological validity
  • Results show how well people remember things from TV but don't generalise to other situations
• Low and high levels of anxiety have a negative affect on accuracy of memory
• In violent crimes, the witness may focus on central details
• Loftus (1979) - weapon focus in EWT - Method

  • Ps heard discussion in nearby room
  • Condition 1, man came out room with pen and grease on hands
  • Condition 2, man came out of room with a knife
  • Ps asked to identify the man in 50 photos
• Loftus (1979) - weapon focus in EWT - Results

  • Ps in condition 1 were 40% accurate
  • Ps in condition 2 were 33% accurate
• Loftus (1979) - weapon focus in EWT - Conclusion

  When anxious and aroused, witnesses focus on a weapon at the expense of other details
• Loftus (1979) - weapon focus in EWT - Evaluation

  High ecological validity as Ps weren't aware it was staged

  Ethical considerations (distress seeing a man with a knife)
• Yuille and Cutshall (1986) showed evidence of real shooting and accurately recalled events
• Cognitive interview was developed to increase accuracy
• Cognitive interview was developed by geiselman et al (1984) to increase accuracy of witness recall
• Stages of cognitive interview. Stage 1

  • Relax the witness and tailor the language to suit the witness
• Stages of cognitive interview, stage 2

  Witness mentally recreates environmental context and internal context