14410779731257090974

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14410779731257090974

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

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