Factors affecting EWT

    Cards (58)

    • Eyewitness testimony

      Evidence used in court concerning the identity of someone who has committed a crime
    • Factors that can influence eyewitness testimony
      • Misleading information
      • Leading questions
      • Post-event discussion
    • Leading questions
      Two explanations for their influence:
      1. Response bias explanation: wording of the question has no real effect on the participants memories, but influences how they decide to answer
      2. Substitution explanation: wording of the leading question actually changes the participants memory for the event
    • Loftus and Palmer (1974) found that the verb used in a question about the speed of cars in an accident influenced the participants' estimates of the speed
    • Loftus and Palmer (1974) also found that the verb used in a question influenced whether participants mistakenly reported seeing broken glass
    • Post-event discussion

      Can result in information being added after the event which will also bias the witness's memory
    • Memory contamination
      Witnesses become confused about what they witnessed themselves and what they have been told by others
    • Memory conformity
      Witnesses may go along with other people for social approval (normative social influence) or because they believe other witnesses have better information than they do (informational social influence)
    • Gabbet et al (2003) found that 71% of participants mistakenly recalled aspects of an event that they couldn't have seen, after discussing the event with another participant who had a different perspective
    • Research into factors affecting the accuracy of eyewitness testimony has informed police how to effectively interview eyewitnesses to avoid leading questions
    • Loftus and Palmers participants watched clips in a lab, which is very different from witnessing real life events (less stressful)
    • Foster et al (1994) identified that there are important consequences to eyewitness testimony in real life that can't translate to the research scenario
    • Skagerberg and Wright (2008) found participants' memory was distorted through contamination by misleading post-event discussion rather than being altered as a result of memory conformity
    • Anxiety
      Psychological and is associated with arousal
    • Arousal
      Physiological effects
    • Effects of anxiety on the accuracy of eyewitness testimony
      • Negative effect: anxiety creates arousal which prevents paying attention to important cues, so recall is worse
      • Positive effect: the fight or flight response increases alertness and improves memory because we become more aware of cues in the environment
    • Yerkes-Dodson law (inverted u)

      Performance increases with arousal (or anxiety) until a certain point and then it decreases
    • Deffenbacher (1983) meta-analysis found inconsistent findings of the effect of anxiety on the accuracy of eyewitness testimony, and used the Yerkes Dodson law to explain this
    • Weapon focus effect
      In violent crimes where a weapon is involved, anxiety may focus the witness on the weapon rather than other details of the event
    • Johnson and Scott (1976) found that participants were less accurate at identifying a person when a weapon was present compared to when no weapon was present
    • Pickrel (1998) found eyewitness testimony was less accurate with highly unusual conditions, suggesting weapon focus effect is due to unusualness rather than anxiety
    • Christianson and Hubinette (1993) found that people who had been subjected to the greatest anxiety showed more detailed and accurate recall than onlookers, suggesting anxiety has a positive effect on recall
    • Who conducted the first experiment on memory distortion in 1974?
      Loftus and Palmer
    • What was the main task for participants in Loftus and Palmer's first experiment?
      Estimate the speed of cars in films
    • How many conditions were participants divided into during Loftus and Palmer's first experiment?
      5 conditions
    • What verb was used in the question asked to participants in Loftus and Palmer's first experiment?
      Hit
    • What was the mph reported when the verb 'contacted' was used?
      31.8 mph
    • What was the mph reported when the verb 'smashed' was used?
      40.8 mph
    • What were the findings of Loftus and Palmer's second study regarding broken glass?
      • 32% in smashed condition reported broken glass
      • 14% in hit condition reported broken glass
      • 13% in control condition reported broken glass
    • How many participants were involved in Loftus and Palmer's second study?
      150 participants
    • What question was asked to Group 1 in Loftus and Palmer's second study?
      How fast were the cars going when they smashed each other?
    • What was the control condition in Loftus and Palmer's second study?
      No questions about speed were asked
    • What was the percentage of participants in the smashed condition who reported seeing broken glass?
      32%
    • Who conducted the study in 2003 that involved participants watching a crime video?
      Gabbert et al
    • What was the main finding of Gabbert et al's study regarding discussion among participants?
      71% recalled aspects not seen in video
    • What was the percentage of participants in the control group who recalled aspects not seen in the video?
      0%
    • What did Skagerberg and Wright (2008) find about memory distortion?
      It was due to misleading post-event discussion
    • What are the key findings from Loftus and Palmer's studies and Gabbert et al's study?
      • Loftus and Palmer: Verbs influence speed estimates
      • Smashed condition reported more broken glass
      • Gabbert et al: Discussion leads to false memories
      • 71% recalled unseen aspects after discussion
    • Who conducted the study on human memory in 1976?
      Johnson and Scott
    • What was the setting of Johnson and Scott's experiment?
      Participants were in a waiting room
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