Factors affecting accuracy of eye witness testimony

• What is misleading information?

  - Information that is given to an eyewitness which may change or contaminate their memory of the event

  - E.g. Leading questions, post-event discussion
• Loftus and Palmer

  • Arranged for 45 PPs to watch film clips of car accidents and then asked them questions about the accident
  • In the critical question PPs were asked to describe how fast the cars were travelling: ‘About how fast were the cars going when they ___ each other?’ There were five groups of participants and each group was given a different verb in the critical question. One group had the verb hit, the others had contacted, bumped, collided, smashed
• Findings of Loftus and Palmer

  • The mean estimated speed was calculated for each participant group
  • The verb contacted resulted in a mean estimated speed of 31.8 mph (lowest)
  • The verb smashed, the mean was 40.5 mph (highest)
  • The leading question biased the eyewitness’s recall of an event
• Research on Post Event Discussion

  • Gabbert studied participants in pairs
  • Each participant watched a video of the same crime, but filmed from different points of view
  • This meant that each participant could see elements in the event that the other could not
  • Only one of the participants could see the title of a book being carried by a young woman
  • Both participants then discussed what they had seen before completing a test of recall
• Findings on research on Post Event Discussion

  • The researchers found that 71% of the participants mistakenly recalled aspects of the event that they did not see in the video but had picked up in the discussion
  • In a control group where there was no discussion overlap was 0%
  • This was evidence of memory conformity
• What occurs as a result of post event discussion?

  • Memory contamination- when co-witnesses to a crime discuss it with each other their eyewitness testimonies may become altered or distorted
  • This is because they combine information from other witnesses with their own memories.
  • Memory conformity- Gabbert concluded that witnesses often go along with each other either to win social approval or because they believe the other witnesses are right and they are wrong
  • Unlike with memory contamination the actual memory is unchanged
• AO3 Misleading Info: Real World Application

  • Has important practical uses in the criminal justice system
  • The consequences of inaccurate EWT can be very serious
  • Leading questions can have such a distorting effect on memory that police officers need to be very careful about how they phrase their questions when interviewing eyewitnesses
  • Improve the way the legal system works especially by protecting innocent people from faulty convictions based on unreliable EWT
• AO3 Misleading Info: Counterpoint to Application

  • The practical applications of EWT may be affected by issues with research
  • Loftus and Palmer’s PPs watched clips in a lab a very different experience from witnessing a real event (less stressful)
  • What eyewitnesses remember has important consequences in the real world but PPs responses in research do not matter in the same way so research PPs are less motivated to be accurate
  • Researchers are too pessimistic about the effects of misleading information and EWT may be more dependable than many studies suggest
• AO3 Misleading Info: Evidence against Substitution

  • EWT is more accurate for some aspects of an event than for others
  • PPs were shown a video clip and when they were later asked misleading questions their recall was more accurate for central details of the event than for peripheral ones
  • Presumably the PPs’ attention was focused on central features of the event and these memories were relatively resistant to misleading information
  • This suggests that the original memories for central details survived and were not distorted an outcome that is not predicted by the substitution explanation
• AO3 Misleading Info: Evidence challenging memory conformity

  • Post-event discussion actually alters EWT
  • Researchers showed their PPs film clips and there were two versions a robber’s hair was dark brown and it was light brown
  • PPs discussed the clips in pairs each having seen different versions
  • They did not report what they had seen or what they heard from the co-witness but a ‘blend’ of the two (e.g. an answer to the hair question ‘medium brown’)
  • Memory itself is distorted through contamination by misleading post-event discussion rather than the result of memory conformity
• AO3 Misleading Info: Demand Characteristics

  • Lab studies have identified misleading information as a cause of inaccurate EWT due to controlling variables
  • Some argue that many answers given by participants in lab studies are due to demand characteristics
  • Participants usually want to be helpful and not let the researcher down so they guess when they are asked a question they don’t know the answer to
• What is Anxiety?


  A state of physical and emotional arousal. Emotions include having worried thoughts and feelings of tension
• Anxiety can have a negative effect on recall: Weapon focus effect

  • Anxiety creates physiological arousal in the body which prevents us paying attention to important cues so recall is worse
  • One approach to studying anxiety and EWT is to look at the effect of the presence of a weapon which creates anxiety
  • This leads to a focus on the weapon reducing a witness’s recall for other details of the event
• Research that anxiety has a negative effect on recall

  • Johnson and Scott made their PPs believe they were taking part in a lab study
  • While seated in a waiting room participants in the low anxiety condition heard a casual conversation in the next room and saw a man walk past them carrying a pen and with grease on his hands
  • Other participants overheard a heated argument accompanied by the sound of breaking glass and a man walked out of the room holding a knife covered in blood. This was the high-anxiety condition
• Findings on research that anxiety has a negative effect on recall

  • The participants later picked out the man from a set of 50 photos 49% who had seen the man carrying the pen were able to identify him
  • PPs who had seen the man holding the knife was 33%
  • The tunnel theory of memory argues that people have enhanced memory for central events. Weapon focus as a result of anxiety can have this effect
• Anxiety can have a positive effect on recall: Fight or Flight

  • Witnessing a stressful event creates anxiety through physiological arousal within the body
  • The fight or flight response is triggered increasing alertness
  • This may improve memory for the event as we become more aware of cues in the situation
• Research that anxiety has a positive effect on recall

  • Researchers conducted a study of an actual shooting in a gun shop. The shop owner shot a thief dead. There were 21 witnesses and 13 took part in the study
  • They were interviewed 4-5 months after the incident and interviews were compared with the original police interviews at the time of the shooting
  • Accuracy was determined by the number of details reported in each account and the witnesses were also asked to rate how stressed they had felt at the time of the incident and whether they had any emotional problems since the event
• Findings on the research that anxiety has a positive effect on recall

  • The witnesses were very accurate in their accounts and there was little change in the amount recalled or accuracy after five months (some details were less accurate, such as recollection of the colour of items and age/height/weight estimates)
  • Those PPs who reported the highest levels of stress were most accurate (about 88% compared to 75% for the less-stressed group)
  • This suggests that anxiety does not have a detrimental effect on the accuracy of eyewitness memory in a real world context and may even enhance it
• Yerkes and Dodson's Law

  • The relationship between emotional arousal and performance looks like an ‘inverted U’
  • 21 studies of EWT were reviewed and noted contradictory findings on the effects of anxiety and Yerkes-Dodson Law was used to explain findings
  • When witnessing a crime we are emotionally and physiologically aroused
  • Lower levels of anxiety produce lower levels of recall accuracy and then memory becomes more accurate as the level of anxiety increases
  • There is an optimal level of anxiety and if a person experiences more arousal their recall declines
• Yerkes and Dodson's Curve


  Labelled

  
• AO3 Anxiety: Unusualness not anxiety

  • Johnson and Scott's study may not have tested anxiety
  • PPs focused on the weapon maybe because they were surprised rather than scared
  • Researcher conducted an experiment using scissors, a handgun, a wallet or a raw chicken as items in a hairdressing salon video (where scissors would be high anxiety, low unusualness)
  • Eyewitness accuracy was significantly poorer in the high unusualness conditions (chicken and handgun)
  • The weapon focus effect may be due to unusualness rather than anxiety so tells us nothing specifically about the effects of anxiety on EWT
• AO3 Anxiety: Support for negative effects

  • Research on weapon focus, finding negative effects on recall
  • The researchers used an objective measure (heart rate) to divide participants into high and low anxiety groups
  • 17% in high anxiety group recalled correctly and 75% remembered in the low anxiety group
  • Anxiety clearly disrupted the PPs ability to recall details
  • High level of anxiety does have a negative effect on the immediate eyewitness recall of a stressful event
• AO3 Anxiety: Support for positive effects

  • Researcher interviewed 58 witnesses to actual bank robberies in Sweden
  • Some of the witnesses were directly involved (e.g. bank workers) and some were indirectly involved (e.g. bystanders)
  • Researchers assumed that those directly involved would experience the most anxiety
  • It was found that recall was more than 75% accurate across all witnesses
  • The direct victims (most anxious) were even more accurate
  • Findings from actual crimes confirm that anxiety does not reduce the accuracy of recall for eyewitnesses and may even enhance it.
• AO3 Anxiety: Limitation of Yerkes-Dodson Law

  • The inverted-U theory appears to be a reasonable explanation of the contradictory findings linking anxiety with both increased and decreased eyewitness recall
  • It ignores the fact that anxiety has many elements – cognitive, behavioural, emotional and physical
  • It focuses on just the physical arousal and assumes this is the only aspect linked to EWT
  • But the way we think about the stressful situation (cognitive) may also be important