Factors affecting eyewitness testimony

• what 3 factors affect the accuracy of eyewitness testimony?

  1. Misleading information including leading questions
  2. Post event discussion
  3. Anxiety
• loftus and Palmer - aim


  To see if leading questions affect the accuracy of EWT
• procedure of loftus and Palmer 


  Used an independant measures design comprised of 45 student participants. Asked Ps to watch footage of a car accident. After watching, they were then asked to describe what they had seen as if they were actual eyewitnesses. Asked 10 specific questions about events leading up to accident. one question would be the critical question
• what was the critical question used in loftus and Palmer? How was it manipulated for each condition?


  "How fast were the cars going when they ... Eachother?" The verb would be changed in each condition. Different verbs used were: hit, smashed, bumped, contacted and collided.
• what was the IV and DV in loftus and Palmer's study?

  IV=change in verb for each group

  DV=average speed in mph was calculated for each group
• what were the results of loftus and Palmer's study?


  "Smashed" produced highest estimation - mean average of 40.8mph - in group which used.

  "Contacted" produced lowest estimation - mean average of 31.8mph
• conclusions of loftus and Palmer's study 


  Leading question used distorts accuracy of eyewitness testimony, with an eyewitness using schemas to confabulate
• what did loftus and Palmer's second experiment focus on?


  Post-event information
• Procedure of loftus and Palmer's second study

  used 150 Ps. Split Ps into 3 groups. All 3 groups watched short clip of a car accident. After watching, they were asked a question about the speed of the car. In condition 1, the verb "smashed" was used, in condition 2 the verb "hit" and in the last condition was the control condition so there was no misleading information. Ps returned week later and asked new critical question: "did you see any broken glass?"
• results of loftus and Palmer's second study 


  Post event information impacted accuracy of testimony.

  16/50 in "smashed" condition reported broken glass compared to 7/50 in "hit" condition
• was there broken glass in the clip in loftus and Palmer's second experiment?


  NO - verb "smashed" had altered the perception of the incident, Ps recalled broken glass that wasn't present
• conclusions of loftus and Palmer's second experiment?


  Post-event information can permanently affect memory
• why does loftus and Palmer's research lack population validity?


  Only used limited sample of students being unable to make generalisations from
• Schacter et al


  Elderly people have more problems recalling the source of their information, even though their memory isnt impaired when compared to younger participants, making elderly more prone to be influenced by misleading information = age could be an individual difference which may impact on results of research into misleading information
• why does loftus and Palmer's research lack ecological validity?


  Conducted in controlled way, procedures were artificial. Watching a clip of a car accident isn't the same as experiencing a real accident as it wold have a different level of emotional arousal.

  Furthrmore they were told to watch the clip which may have improved their recall compared to a real life events which would've been spontaneous. Due to this, generalisations from findings cannot be applied to real life eyewitness testimony
• Yuille and cutshall 


  Argued that being an eyewitness to a real life event would actually improve your recall. Looked at witnesses of real bank robbery in Canada, after trial had ended they asked witnesses what they could recall from the event, using 2 leading questions to attempt to distort the accuracy of recall. Despite being asked 4 months after the incident, they were still highly accurate in the level of detail recalled. = Contradicts that leading questions can affect accuracy of eyewitness testimony
• Larooy 


  Found that, when interviewing children, the more times the witness is re-interviewed the higher the chance that something the interviewer has said will be incorporated in their recall. a leading question could further alter their account = further research support for idea that post event information affects eyewitness testimony
• what did gabbert et al believe regarding how post event information can affect eyewitness testimony?


  When co-witnesses of a crime discuss it with each other, their EWT ay become contaminated. This is because they combine misinformation from other witnesses with their own memories
• procedure of gabbert's study on post event information 


  Carried out experiment where eyewitnesses - young and old adults - watched short film of girl stealing money from a wallet. They took part individually or in pairs. Those in pairs were led to believe that they were watching the same film as their co-witnesses. However, each co-witness was actually seeing a different perspective. (As would realistically be the case) Only one witness of each pair actually saw the crime
• what did the 2 conditions in gabbert have to do after watching the short film?


  Those in pairs - discussed event together

  Finally all eyewitnesses individually completed questionnaire relating to memory of what they had seen
• results of gabbert's study on post event information 


  71% of eyewitnesses who had discussed event with a co-witness mistakenly recalled information they hadn't witnessed but which had been mentioned during post event discussion when completing questionnaire.

  Control group with no discussion, found 0% of eyewitnesses recalled information they hadn't witnessed.

  60% of Ps in co-witness condition who hadnt actually seen crime themself still claimed girl was guilty. These findings were similar in all ages
• conclusions of gabbert's study on post event information 


  Study shows that we need to take seriously the possibility that co-witnesses can produce distortions in what eyewitnesses report about an event
• what is the main limitation about gabbert's study on post event information?


  It isn't entirely clear whether distortions obtained reflect problems with memory or whether they reflect social pressure from the co-witnesses (memory conformity)
• skagerberg and wright 


  Supports effects of post event discussion. 60 eyewitnesses to criminal events were asked to complete a questionnaire. Their answers indicated that 58% of those who had witnessed a crime along with 1 or more co-witnesses had discussed the event with at least 1 co-witness. General crime details and suspect details were the most common areas of discussion. Suggests PED is an important factor when considering one's EWT and its accuracy
• Eakin et al 


  Showed Ps slides of a maintenance man stealing money and a calculator. Eyewitness memory was impaired by post event discussion. Memory was impaired even when eyewitness was warned immediately about the presence of misleading information and told to disregard it. Supports gabbert's findings, suggests post event information given to Ps can distort their memory
• bodner et al 


  Challenges eakin's findings, found that effect of post event discussion can be reduced if Ps were warned of its detrimental effects. Recall was more accurate when Ps were warned about anything a co-witness may say as second hand information, and to only recall memory they had of the event. Goes against idea that a persons memory is always distorted by post event discussion
• what is an important application of research into the effects of post event discussion?


  Suggests how police should handle witnesses of crimes, importance of educating them about effects of discussion on EWT. Based on findings of research, police should separate eyewitnesses immediately and interview them individually, as well as warn witnesses about dangers of discussing the event with others as it could have an effect on whether the real perpetrator is taken into custody and prosecuted
• what are the economic implications of inaccurate EWT?


  If there are inaccuracies in a persons testimony, then case may not result in prosecution and would be a waste of time and money attempting to get a conviction. Or - worst case scenario - the wrong person is convicted
• aims of Johnson and scott


  To discover if anxiety during a witnessed incident effects accuracy of later identification
• what is anxiety?


  A state of emotional and physical arousal, including physical changes like increased heart rate and sweating, and emotional changes like fear and worry
• how is anxiety believed to affect eyewitness testimony?


  Anxiety can decrease accuracy of eyewitness testimony because of distraction/arousal (tunnel vision effect) or accuracy can be better because of increased alertness
• what was the procedure of Johnson and Scott's experiment?


  Group 1 - low-key discussion in lab about equipment failure. Person emerges with greasy hands holding a pen.

  Group 2 - heated and hostile discussion in lab, smashed glass and crashing of chairs. Man emerges with paper knife covered in blood.

  Both groups of Ps were then asked to identify the person leaving the lab out of 50 photos
• Findings of Johnson and Scott's study 


  No weapon (pen) condition - correctly identified man 49% of the time

  Weapon condition - correctly identified man holding knife 33% of the time
• conclusions of johnson and Scott's study


  Presence of a weapon - known as weapon focus - reduces accuracy of EWT, as weapon distracts attention from appearance of perpetrator. It induces fear or anxiety and heightens accurate detail of central details of an incident, but reduces memory of peripheral details
• what is an ethical issue with Johnson and Scott's study?


  Participants were deceived about nature of study and exposed to a man with a bloody knife, which increases stress far beyond everyday life and so they may not leave the experiment in the same physical and emotional state as before
• why does Johnson and Scott's study lack ecological validity?


  Procedures were staged and cannot be compared to the experience of a real incident where anxiety may be higher. Therefore this research may not be considered useful in explaining the effects of anxiety in EWT
• loftus et al - scientific evidence for weapon focus effect


  Ps were asked to observe a person either pointing a gun at them or handing a check to a cashier and subsequently recieving cash. Researchers recorded their eye movements, Ps made more eye fixations and looked longer at the gun than at the check. In addition, Ps memory was worse in the gun condition than check condition
• Christianson and hubinette - procedure 


  shows generalisations cannot be made from Johnson and Scott's study. Questioned 110 witnesses who witnessed a total of 22 actual bank robberies. Some witnesses were bystanders in the bank at the time, others were employees of the bank who were directly threatened
• Christianson and hubinette - findings 


  Actual victims were more accurate in their recall and remembered more details about the robber's clothing, behaviour and weapons used compared to the bystanders. This was still the case even 15 months after. Concluded that memory is more accurate in highly stressful situations if they occur in real life rather than a lab setting
• what individual differences weren't considered in research regarding anxiety?


  Those more susceptible to anxiety had some things in common: tended to show more empathy and are good at identifying with other peoples moods. Personality factors could also play a part