Psychology

1
Psychology the Law

• Eyewitness Testimony
• Why are they wrong?
• Judging if they are mistaken
• Judging if they are lying
• Improving testimony
• My research ?

2
Most experts agree that the primary cause of
false convictions is inaccurate eyewitness
identification

• Why are they wrong?
• Acquisition
• Storage
• Retrieval

3
Acquisition

• Duration of crime
• Viewing conditions
• Victim vs. bystander
• Expectations
• Own-race bias

4
Storage

• Reconstructive memory

Correct Picture ID Accurate Questions
75 Misleading Questions 41
Loftus, Miller Burns, 1978

• Source Monitoring

5
Retrieval

• Relative Decision Model
• Witnesses compare all the people presented in
  the lineup to each other and then select the
  person that is most similar to the culprit
• Strong form
• Weak form

6
Target Present Target Absent
Target Present
Target Absent
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External Validity

• True rate of TP vs. TA lineups in the real world
  is currently unknown
• Lab studies 50 TP, 50 TA
• If all lineups were TP in the real world, an
  innocent suspect would never be chosen

8
Reduce False Positive IDs

• 1. Expert testimony regarding factors known to
  decrease eyewitness accuracy
• 2. Improving the validity of methods used to
  collect eyewitness ID evidence
• Match to description vs. Match to photo
• Witness Admonishment
• Include some TA lineups
• Blind lineup administrators
• Obtain witness confidence before giving feedback
• Sequential vs. simultaneous lineups
• Photo ID supplemented with voice ID

9
Judging if eyewitnesses are mistaken

• Confidence ? Accuracy
• Signs of inaccuracy
• Increase decision time
• Comparing faces vs. seeing one pop out
• Process of elimination
• Verbalization problem
• Accuracy in ID from lineup after verbalization
  (38) versus no-verbalization (64)

10
Judging if eyewitnesses are lying

• Experience ? better at detecting deception
• Polygraph
• Control question test
• Guilty knowledge test
• 10-15 inaccuracy

11
My research first year project

• Eyewitness accuracy in the real world DNA
  evidence as ground truth for eyewitness
  accuracy rates

12
External Validity

• True rate of TP vs. TA lineups in the real world
  is currently unknown
• Lab studies 50 TP, 50 TA
• If all lineups were TP in the real world, an
  innocent suspect would never be chosen

13
Innocence Project

• Purpose exonerate wrongfully convicted
• 61 of first 70 exonerations contained mistaken
  identification

Innocence Project, 2001
14
Predictions
From Laboratory Study Meta-Analysis
Steblay et al., 2001
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Method

• Background screening at SDPD and DA
• 352 cases coded at SDPD crime lab
• ? 160 linked to cases at DA office
• ? 70 coded to date
• Case selection
• March 2000, known victim, known suspect, at least
  1 source of evidence

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Case Characteristics

• Avg. of 2.3 witnesses/case
• 58 victims of the crimes
• ID Procedures Used

17
ID Accuracy
18
ID Accuracy in Lineups
19
DNA evidence lineup type

?2(10) 20.7, p lt .05
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Surprising?

• Results inconsistent with lab studies
• Case selection
• Attention in real world
• Nature of crimes

• Data are preliminary
• Questions generalizations from laboratory
  studies