Eyewitness Testimony

1
Eyewitness Testimony

• Reconstructive memory
• Schema driven errors
• Effect of leading questions
• Other factors
• Weapon focus
• Effects of anxiety/arousal
• Retrieval cues

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2
Reconstructive Memory

• Bartlett (1932)
• Memory is not a direct record of what was
  witnessed
• What is encoded and how it is retrieved depends
  on
• Information already stored in memory
• How this info is understood, structured and
  organised

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3
Reconstructive Memory

• Schemas
• Knowledge structures that relate to commonly
  encountered objects, situations or people
• Enable us to predict events, make sense of
  unfamiliar circumstances, organise our own
  behaviour
• Act as filters to perception recall

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4
Computer Information Processing
BANG!
Can you wreck a nice beach?
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5
Schema Driven Processing
Yes. I can recognise speech.
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6
Bartlett (1932)
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Bartlett (1932)
7
Bartlett (1932)

• War of the Ghosts
• When recalled by UK PPs
• Shorter
• Less detailed
• Some details changed (e.g. seal hunting changed
  to fishing)
• More Western structure

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8
EWT Schema Driven Errors

• Witnesses to crimes filter information during
  acquisition recall
• Their schematic understanding may influence how
  info is both stored retrieved
• Distortions may occur without the witness
  realising

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9
EWT Schema Driven Errors

• Past experiences
• Assumptions about what usually happens
• Stereotypes beliefs about crime criminals

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10
EWT Leading Questions

• Loftus (1970s onwards)
• Effect of leading questions on recall
• Leading questions introduce new information
• Leading info may activate wrong schemas in
  witness mind
• Consequently, witness may recall events
  incorrectly

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11
EWT Leading Questions

• Loftus studies using film/video/slides road
  accidents
• How fast were cars going when they hit or
  when they smashed?
• Smashed led to higher speed estimates
• Did you see a/the broken headlight?
• The produced more affirmative (incorrect)
  responses

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12
EWT Leading Questions

• Loftus research usually lab based
• Restricted samples (students)
• Artificial stimuli (slides, videos, not real
  events)
• Potential for demand characteristics to influence
  responses
• No legal/moral consequences for inaccurate answers

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13
EWT Leading Questions

• EWT most affected by leading Qs when
• Witness believes questioner knows more than them
• Witness does not realise they may be misled
• Leading information is peripheral, not central
• Leading information is not blatantly incorrect

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14
EWT Weapon Focus

• When a weapon is used to threaten a victim, their
  attention is likely to focus on it
• Consequently, their recall of other information
  is likely to be poor

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15
EWT Arousal Effects

• Memory is most effective at moderate arousal
  levels
• If the witness was in a state of extremely low or
  high arousal then recall may be poor

performance
arousal
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16
EWT Retrieval Cues

• Recall typically takes place in a different
  context to acquisition
• Lack of retrieval cues (state and context) can
  inhibit recall
• Reconstruction of the events (either imagination
  or simulation) can lead to enhanced recall

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