Factors affecting EWT

• What is eye-witness testimony (EWT)?


  An account given by a person of an event they have witnessed
• What is the greatest cause of wrongful convictions in the USA?

  EWT misidentification
• What percentage of convictions overturned through DNA testing involve faulty EWT?


  More than 75%
• Why is it important to understand the factors affecting EWT?


  To improve EWT and reduce wrongful convictions
• What are some factors that affect EWT?


  • Misleading information (after the crime)
  • Anxiety (during the crime)
• What is misleading information in the context of EWT?


  Information that affects a witness after witnessing the crime
• What is post-event discussion?


  • Discussion among witnesses after the crime
  • Can contaminate testimony
  • May create false memories
  • Leads to source-monitoring errors
• What did Gabbert (2003) find regarding post-event discussion?


  71% of participants gave information they hadn't seen due to discussion
• What term did Gabbert use to describe the phenomenon where witnesses' memories conform to each other?


  Memory conformity
• What are leading questions in the context of EWT?


  Questions that suggest a desired answer through their phrasing
• What was the aim of Loftus & Palmer's (1974) study?


  To assess how misleading questions influence speed estimates of car accidents
• What were the procedures of Loftus & Palmer's experiment 1?


  • 45 university students watched 7 video clips of car crashes
  • Participants wrote accounts and answered specific questions
  • Key question involved estimating vehicle speed with different verbs
• What were the five verbs used in Loftus & Palmer's study to assess speed estimates?


  'Smashed', 'Collided', 'Bumped', 'Hit', 'Contacted'
• What were the mean speed estimates for the verb 'Smashed' in Loftus & Palmer's study?


  40.5 mph
• What did Loftus & Palmer's experiment 2 investigate?


  The effect of leading questions on the recall of broken glass
• How many participants were in Loftus & Palmer's experiment 2?


  150 participants
• What were the findings regarding broken glass in Loftus & Palmer's experiment 2?


  Participants in the 'smashed' condition were twice as likely to recall false memories of broken glass
• What were the conclusions of Loftus & Palmer's experiments?


  • Leading questions affect speed estimates
  • Leading questions can create false memories
  • Memory is reconstructed
• What are the strengths and weaknesses of Loftus & Palmer's study?


  Strengths:

  • High control of extraneous variables
  • Valid and reliable empirical data

  
  

  Weaknesses:

  • Low ecological validity
  • Demand characteristics
• What did Loftus (1979) find regarding leading questions?


  98% of participants correctly identified the color of the wallet despite misleading questions
• What did Loftus & Zanni (1975) find regarding phrasing of questions?


  More participants reported seeing a broken headlight when asked with "the broken headlight"
• What did Yuille & Cutshall (1986) find regarding real witnesses and leading questions?


  Real witnesses were not influenced by leading questions four months after the robbery
• What are the practical applications of research into EWT?


  • Improved questioning techniques by police
  • Ensures accurate recall of information
  • Reduces chances of wrongful convictions
• What are the strengths and weaknesses of laboratory studies in EWT research?

  Strengths:

  • Greater control of extraneous variables
  • Valid and reliable empirical data

  
  

  Weaknesses:

  • Low ecological validity
  • Lacks mundane realism
• What is anxiety in the context of EWT?


  A state of emotional arousal due to real or anticipated threat
• How can anxiety affect EWT?


  Anxiety can have both positive and negative effects on memory recall
• What is the weapon focus effect?


  Attention is drawn to a weapon, hindering recall of other details
• What is the tunnel theory of memory?


  We focus on central details and forget less important ones
• What did Johnson & Scott (1978) find regarding anxiety and weapon presence?


  Participants were less accurate in describing the criminal when a knife was present
• What alternative explanation did Mitchell et al (1998) provide for the weapon focus effect?


  It may be due to surprise at seeing an unusual item, not anxiety
• How can anxiety have positive effects on recall?


  Stress can increase alertness and improve memory
• What did Yuille & Cutshall find regarding stress and recall in their study?


  Witnesses who reported more stress were the most accurate
• What did Christianson et al (1993) find regarding anxiety and recall in bank robberies?


  Tellers had the best recall due to being directly threatened
• What is the Inverted U Hypothesis (IUH)?


  • Performance improves with increased arousal to a point
  • Beyond the optimum point, performance declines
  • Moderate anxiety is associated with better recall
• What did Deffenbacher (2004) find regarding anxiety and EWT performance?


  EWT performance increases with anxiety to a point, then declines
• What is a weakness of the Inverted U Hypothesis?


  It is difficult to test and lacks empirical evidence
• What is a potential ethical issue with inducing anxiety in EWT studies?


  It could cause psychological harm to participants