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14410779731257090974

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  • 1. What is Eye Witness testimony? video clip What is Eye Witness testimony? video clip
  • 2. What is EWT?
    • Legal term for witnesses who give evidence in court concerning the identity of a suspect.
  • 3. Three stages of EWT
  • 4. Eyewitness testimony Loftus and Palmer (1974)
  • 5. Do leading questions distort the accuracy of EWT?
    • Aim: to investigate the accuracy of memory after witnessing a car accident,
    • in particular to see if leading questions distort the accuracy of an eyewitnesses’ immediate recall.
  • 6.  
  • 7. Procedures
    • Forty-five students
    • Shown films of traffic accidents.
    • Questions afterwards included a critical one about speed of car containing the word ‘hit’, ‘smashed’, ‘collided’, ‘bumped’ or ‘contacted’.
  • 8. Findings Verb Mean Speed estimate Smashed 40.8 Collided 39.3 Bumped 38.1 Hit 34.0 Contacted 31.8
  • 9. Findings
    • The group with ‘smashed’ estimated the highest speed (about 41 m.p.h.).
    • The group given the word ‘contacted’ estimated the lowest speed (about 30 m.p.h.).
  • 10. Conclusions
    • Leading questions (post-event information) can have a significant effect on memory (could be on original memory or recall).
  • 11. Criticisms
    • (1) Lacks validity because it is not true to real life and lacks realism.
    • Other research has found that recall is more accurate in real life (Yuille and Cutshall, 1986).
    • This may be because people don’t take the experiment seriously or are not as emotionally aroused as in real accident.
    • (2) It has experimental control and therefore some validity.
    • This is because the IV (verb) effects the DV ( estimate. This demonstrates a causal relationship between leading questions and recall of information.
  • 12. RM
    • A Control group does not receive the independent variable. But it’s performance is assessed on the dependent variable.
    • The results can be compared with the experimental group.
    • The control group serves as a baseline measure.
  • 13. Validity
    • Lab experiments may not be taken seriously
    • Participants are not emotionally involved.
    • Foster et al better identification in real life set up.
  • 14. There is research support.
    • Loftus and Palmer (1974)
    • Procedures: 3 groups of participants: They were asked a series of questions including did you see any broken glass.
    • group 1: smashed , group 2: hit ; group 3: no questions about speed of vehicle .
    Verb condition smashed hit control Yes 16 7 6 No 34 43 44
  • 15. Loftus and Palmer (1974)
    • Findings: those given ‘smashed’ were more likely to recollect broken glass (there was none).
    • Conclusions: Shows a significant effect of post-event information on later recall of events.
  • 16. However…
    • Loftus (1979b)
    • Finding : when shown a series of pictures of a man stealing a red wallet from a women’s hand bag, 98% correctly identified the colour. Furthermore despite later being given an erroneous description of the wallet as brown, participants persisted in describing the wallet as red.
  • 17. Conclusions:
    • This shows that we may have good recall for important information, and the recall of such information may not be distorted even by misleading information.
  • 18. ARMED ROBBERY
  • 19. EWT in real life
    • Yuille and Cutshall 1986 interviewed 13 people who had witnessed an armed robbery in Canada.
    • The interviews took place more than 4 months after the crime and included two misleading questions.
  • 20. Yuille and Cutshall 1986
    • Findings: Despite these questions, the witnesses provided accurate recall that matched their initial detailed reports.
    • Conclusions:
    • This suggests that post event information may not affect memory in real life.
    • This study also shows that EWT can be very reliable .
  • 21. Individual Differences
    • Linsday 1990 identified two sources of misinformation.
      • Observation of event itself
      • Subsequent suggestions
    • Schacter et al 1991 found that elderly people have difficulty remembering the source of their information, but not the content.
    • This group is more prone to the effect of misleading information.
  • 22. Individual differences
    • Wells and Olsen 2003 found no differences between males and females despite a different focus.
  • 23. Real world
    • Wells and Olsen 2003 found that EWT testimony may be mistaken, this is supported by DNA exoneration cases.
  • 24.
    • Post event information
  • 25. Broken glass
    • Misleading questions affect storeage.
    • Loftus stop and yield
    • Bekerian and Bowers
  • 26. Review
    • Activity 4 p 27 fill in the blanks.
    • Explain why studies of EWT have been criticised as lacking in validity. 5 marks. (spec 1)
    • task 3 extended writing. 12 marks
  • 27.
    • Anxiety
    • Age of witness
  • 28. Anxiety
    • Deffenbacher et al meta analysis shoed anxiety reduced accuracy of EWT.
    • Christianson and Hubinette 1993 foudn anxiety increased accuarcy in real life bank robberies
    • Yerkes-Dodson law: accuracy is best under moderate arousal.
  • 29. WEAPONS FOCUS
  • 30. Weapons focus
    • Loftus 1979a . Identified weapons focus. There were 2 conditions:
    • In both conditions participants heard a discussion in an adjoining room.
    • In both condition 1 a man emerged holding a pen with grease on his hands.
    • In condition 2 the discussion was more heating and a man emerged holding a paper knife covered in blood.
  • 31. findings
    • When asked to identify the man from 50 photos, participants in condition 1 were 49% accurate compared with 33% accuracy in condition 1.
  • 32. conclusions
    • This suggests that the weapon may have distracted attention from the man and might explain why eyewitnesses sometimes have poor recall for certain details of a crime.
  • 33. Meta analysis
    • Steblay 1992 found that the presence of a weapon reduces the chance of correct identification of person holding the weapon.
    • Loftus 1987 monitored eye movements and found that the presence of the weapon causess attention to be physically drawn towards the weapon and away from the face.
  • 34. RM
    • Meta analysis
  • 35. Applications
    • Riniolo et al EWT from titanic was accurate.
  • 36. Age of witness
    • Yarney describe young woman , younger participants more confident no age differences.
    • Mermon et al older people less accurate when delay was one week.
    • Own age bias. Anastasi and Rhodes.
  • 37. Clip to view
    • Basketball.
  • 38. Individual differences
    • Alcohol impairs attention. Clifasefi et al 2006
  • 39.
    • Lab v field experiments.
  • 40. Laboratory experiment
    • IV manipulated to observe effect on DV, controlled.
    • (+) Can draw causal conclusion.
    • (+) Confounding variables minimized.
    • (+) Can be easily replicated.
    • (-) Artificial, contrived situation.
    • (-) Investigator and participant effects.
  • 41. Field experiment
    • Investigate causal relationships in more natural surroundings.
    • IV directly manipulated by experimenter to observe effect on DV.
    • (+) Usually higher ecological validity than lab experiment.
    • (+) Avoids some participant effects.
    • (-) Less control.
    • (-) More time-consuming.
  • 42. To do
    • RM 3.9
    • RM 3.10