Factors affecting eyewitness testimony

• Eyewitness testimony


  The account witnesses tell the police/court about an incident/crime they have seen
• It is more accurate to refer to eyewitness memory rather than eyewitness testimony when we study how accurate their recall is
• Eyewitness memory


  1. Encoding the details of the event and the people involved in the LTM

  2. Retaining the information in the LTM

  3. Retrieving the memory of the event
• Eyewitness memory might be inaccurate due to partial or distorted encoding, lost or distorted memories, interference, and lack of retrieval cues
• Unreliable eyewitness memory could lead to wrongful arrests, imprisonment or execution
• Leading questions


  Questions asked in such a way to suggest an expected answer
• Leading question


  • Did you see the man crossing the road?
• Non-leading question


  • Did you see anybody crossing the road?
• Post-event discussion (PED)


  • The original memory of an event might be distorted through discussion of this event with other people (conformity effect)
  • Memory can also be distorted by repeated interviews
• Witnesses go along with each other either to gain approval or because they think the other witness is right and they are wrong (memory conformity)
• Anxiety and eyewitness testimony


  Accuracy is poor at high and low levels of anxiety, and is best at moderate levels
• Loftus & Palmer - misleading Q

  • investigate how info provided to witness after event influences memory of it
  • 45 american students shown vid of car crash
  • asked question about the car crash the word varied - what was the speed of the car when contacted/hit/bumped/collided/smashed
  • Results: contacted- 32mph, hit- 34 mph, bumped- 38 mph, collided- 40mph, smashed- 41mph
  • shows wording of question can affect accuracy of answer
• Loftus & Palmer - misleading info

  150 american ps used to investigate whether post event info could alter ps memory before it stored in LTM

  • grp 1 asked - how fast cars going when they smashed

  grp 2 - asked same but hit

  grp 3 - control- asked nothing

  • ps came week later and asked 10 Q , one of them did you see any broken glass
  • those who thought car travelling faster (smash condition) more likely to report seeing broken glass than ps in other conditions

  shows influence of misleading info lasts over time
• Conformity effect
• Gabbert et al (2003)


  • 2 groups of Ps watched the same crime scene but from different angles, then were asked to recall the event either alone or in pairs. 71% of witnesses who had discussed the event reported at least one wrong detail acquired during the discussion
• Wright et al, 2000


  • Pairs of participants saw an identical crime, except that half saw an accomplice with the thief and half did not. After discussing the crime, 75% of the pairs exhibited conformity
• This shows that witnesses go along with each other either to gain approval or because they think the other witness is right and they are wrong. This is memory conformity
• Weapon focus


  The effect where the presence of a weapon distracts the witness away from the person holding it
• Pickel (1998)


  • Ps watched a vid of scene from hair salon
• This suggests that the weapon focus effect is caused by the unusualness rather than the high level of anxiety
• Johnson and Scott (1976)


  • Ps heard a discussion in an adjoining room. Condition 1: a man exited with a pen and greasy hands (low anxiety). Condition 2: a man exited with a paperknife and bloody hands (high anxiety). Condition 1 were 49% accurate, Condition 2 were 33% accurate
• The weapon distracted the witness away from the person holding it. This supports the weapon focus effect
• Lab experiments have weaknesses, but the results are important because it is impossible to expose participants to real danger for ethical reasons. Another strength is that the Evs are controlled whereas in natural situations they can affect people's memory of the crime and their recall
• EWT irl - Yuille and Cutshall


  13 people witnessed armed robbery where robber shot and killed.

  witnesses interviewed 4 mnths after event and interview included 2 misleading questions

  ps able to accurately recall event.

  ps who experienced highest stress aso most accuate

  shows high anxiety doesnt always mean decrease in recall
• EWT irl - Chritinson & Hubittett

  • questioned 58 witnesses of real life bank robberies
  • those threatened in some way had improved recall and remembered more details
  • shows weapon focus isnt so influential irl and recall doesnt decrease due to anxiety
• Studies of Eyewitness Testimony (EWT)

  • Most research has been conducted in a lab, so has low ecological validity
  • In real life, witnesses would know their testimony has consequences, so they might be more careful
  • By watching a video, people do not become as emotionally aroused as they would for a real-life accident
  • In real life, witnesses would be interrogated by the police, who are perceived as authority figures, which may influence their testimonies
  • Small, ethnocentric samples have been used, so low population validity
• These studies do not show whether the original memory is only temporarily distorted or whether the distortion is permanent, but later research indicates the distortion is permanent
• Not every participant responded in the same way, e.g. in Wright et al., 2000, 25% of participants did not alter their memory, showing that individual characteristics influence their behaviour
• Rhodes, 2000 found that participants between the age of 18-45 were more accurate in their recall than participants aged above 55
• Based on the findings of these studies, the police have changed the way they interview witnesses to avoid leading questions and ask the witnesses not to talk about their recall of the event witnessed with others