Eye witness testimony

• Eye witness testimony - description given by people of an event they have experienced, including that given in a criminal trial by individuals present at the time of the crime

  It includes the identification of people as well as details such as speed of vehicles, weather conditions.
• Factors affecting accuracy of EWT:

  • Anxiety
  • Misleading information (leading questions and post event discussion)
• Anxiety - a state of emotional and physical arousal in response to stress, involving worry, tension, increased heart rate etc.
• It is not clear whether the effects of anxiety make eyewitness recall better or worse, there is evidence for both.
• Johnson and Scott - investigated the effects of anxiety on EWT using participants who believed they were waiting to take part in a laboratory experiment, sitting in a waiting room
• Johnson and Scott study

  Two conditions:

  • Low anxiety Condition - Participants overheard a casual conversation in the next room about an equipment failure. A person then emerged from the room holding a pen with grease on his hands
  • High anxiety Condition - participants overheard a heated and hostile exchange between people in next room. Crashing chairs, a man emerged holding a paper knife covered in blood
• Johnson and Scot study

  After the condition of either low or high, participants were shown 50 photos and asked to identify the person who had come out of the laboratory. P's in the low anxiety condition identified the person 49% of the time whereas p's in the high anxiety condition identified the person 33% of the time.

  Suggesting anxiety makes EWT less accurate
• Tunnel theory of memory - explains that people have enhanced recall for central events (weapon) but less accurate details of peripheral details (faces) due to narrow focus of attention on the source of anxiety. Weapon focus as a result of anxiety can have this effect, making EWT less reliable
• Johnson and Scott findings

  Could be explained by unusualness rather than anxiety.

  P's focussed on the knife because they were surprised by it.

  So weapon focus may be due to unusualness rather than anxiety and so tells us little about the effects of anxiety on EWT.
• Valentine and Mesout - study that supports anxiety reduces accuracy of EWT.

  Studied visitors to the 'Horror Labyrinth' at the London Dungeon.
• Valentine and Mesout

  Procedure - P's worse wireless heart monitors and completed a questionnaire to measure their anxiety.

  Findings - researchers found that those who experienced high anxiety were less likely to identify an acoter that they met on the visit than those with low anxiety
• Yuille and Cutshall - procedure

  Carried out a study of interviews of 13 witnesses to an attempted theft from a gun shop in Vancouver during which the shopkeeper shot and killed a thief
• Yuille and Cutshall - findings

  4 months later, witness accounts remained highly accurate in comparison to what they had told police immediately after the event and those who reported the highest levels of stress at the time were the most accurate
• Yuille and Cutshall - conclusion

  Suggests that anxiety does not have a detrimental effect on the accuracy of recall of a real life event and may actually enhance
• Misleading questions consists of leading questions and post event discussion
• Leading questions - questions which suggest a certain answer because of the way they are phrased
• Loftus and Palmer - procedure

  Investigated the effects of participants hearing different words when asked about their memory of a car crash.

  They were shown 30 second clip of two cars colliding and then asked about the speed of the cars travelling
• Loftus and Palmer

  The question was 'How fast the cars were going when they...'

  The conditions/words used were hit, smashed, collided, bumped and contacted

  A week later, participants were asked if they had seen any broken glass on the road (there was none)
• Loftus and Palmer - findings

  Found the average estimated speed was found to increase as the strength of the verb increase.

  For 'smashed' it was almost 10mph faster than for 'contacted'
• Findings for Loftus and Palmer

  Smashed - 40.5 mph - 32% reported they saw glass

  Collided - 39.3 mph

  Hit - 34 mph - 14% reported they saw glass

  Bumped - 38.1 mph - 34% reported they saw glass

  Contacted - 31.8
• Loftus and Palmer - conclusion

  Shows that leading questions can bias memory, suggesting that eyewitness testimony may not be reliable
• AO3 - Loftus and Palmer

  Considerable implications in eyewitness testimony, suggesting eyewitness testimony is not reliable
• AO3 - Loftus anf Palmer

  Highly controlled and replicable laboratory study which strongly suggests a cause and effect relationship between leading questions and speed estimate
• AO3 - Loftus and Palmer

  Difficulties in generalising the findings of the study to real life witness testimony situations.

  The participants knew they were in a study and the their answers didn't matter. They would have little emotional involvement with the crashes

  Suggesting Loftus and Palmer may be too pessimistic about EWT
• Post Event Discussion - when witnesses discuss what they have seen with others who may also have witnessed the event, possibly leading to contamination of their eyewitness testimonies
• Gabert et al - procedure

  Asked pairs of participants to watch videos of the same crime, but from different view points, showing slightly different details of the crime. They then discussed together what they had seen, before individually completing recall tests
• Gabert et al - findings

  71% of participants recalled events they had not seen in the video but picked up from conversation.

  In control group (had no chance to discuss what they had seen), none recalled events that were not in the video thy had watched
• Gabert et al - conclusion

  Suggests that post event discussion can affect the accuracy of EWT, because witnesses may agree with each other about things they have not actually seen.

  This memory conformity may be due to a desire for social approval or because they trust each other
• Some researcher have found that the effects of post event discussion can be reduced if participants are warned of their impact. If participants are warned that they should forget anything they hear in a discussion.

  Important practical application suggesting that this procedure should be used by police and courts to improve reliability
• Criticism of research into eye witness testimony

  Loftus and Palmer focused on memories of peripheral details.

  Fruzetti suggested that it is much harder to distort EWT by misleading post event information for key details than it is for minor details sick as presence of broken glass

  Lowers internal validity
• Criticism of research into eye witness testimony

  Laboratory experiments have the advantage that they allow us to draw conclusion about cause and effect but lack external validity