Eyewitness Testimony Flashcards
Miscarriages of Justice
Eyewitness testimony errors involved in 75% of DNA exoneration cases
Eyewitness mistaken identification
Eyewitness testimony is important
May be only evidence available if forensic is absent
Witnesses can identify and describe suspects to help with future investigations
Eyewitness Testimony is persuasive
Eyewitness Testimony 78%
Fingerprints 70%
Polygraph 53%
Handwriting 34%
Jurors, judges and general public have limited knowledge of factors affecting eye witness testimony (Magnussen et al 2010)
Eyewitness Testimony is error prone
Recorded crime on TV (Buckhout,1980)
2000 people rang in, but 1800 made incorrect ID.
Megreya & Burton (2008)
Innocent suspect number 4 being chosen the most.
Why are eyewitness unreliable?
Decision to attend to and encode stimulus properties - Poor encoding
Incorporate into internal representation (Schema) - Stereotypes and prejudice.
Integrate representation with additional information & regenerate representation (visualise) - Misleading information
Response - demand characteristics
Factors that affect eyewitness accuracy
Eyewitness factors: emotional state, intoxication
Perpetrator factors: disguise, facial distinctiveness
Situtation factors: exposure duration, distance, retention interval
System variables: size, structure, and selection of fillers.
Cognitive interviews: procedures and training
Encoding:
Ornstein et al, 2006
Holst and Pezdek 1992
We remember more of an event, the more we know about it in advance (Ornstein et al, 2006)
We remember more information that is consistent with our scripts (Holst and Pezdek, 1992).
Change Blindness
Change blindness correlates with memory (Levin et al 2002) - Primed 65% versus not primed (12.5%).
Explanations (Simons,2000)
Overwriting, first impressions, nothing is stored, storage but no comparison and feature combination (Dog & Duck combined).
Situation and perpetrator factors
Duration of exposure (Memon et al 2003)
distance from incident (Lindsay et al 2008)
Awareness of the incident
Facial distinctiveness (Busey & Tunnicliff, 1999)
Disguises (Patterson & Baddeley, 1977).
Perps change of appearance and disguises
- Offender’s changed appearance and disguises
Study phase: Participants viewed a staged robbery. For 1/2 of the particpants the robber wore knit pullover cap.
Test phase: Identified perpetrator from video lineup 45% no hat group vs 27% hat group.
Witness Factors
High stress negatively impacts memory (Deffenbacher et al, 2004)
- Soldier Study (Morgan et al 2004).
Ageing effect (Memon et al 2003).
Witness Intoxication
Reduced attentional capacity
Alcohol myopia theory suggests that alcohol increases focus on central detail (Josephs,1990).
Storage
Retention interval: delay decreases the amount of information that can be recalled
Post event suggestion
- Exposure to media report
- Co-witness discussions
- Choice blindness
Retention Interval:
Face Recognition (Wells et al 2006)
Event details
Face Recognition
- Immediate, longer delays
- Fewer correct Ids
- Increase in false Ids
Event details
- Immediate vs 4 week delay
- Reduction in number of recalled facts
- % error consistent
Woman assaulted 36 years ago.
Post event suggestion & misinformation
Many witnesses will see or read news of events.
- Recall vs what really happened
- Proneness to false memory associated with personality traits (Ost, Granhag & Hjelmsater, 2007).
Delay between event and information plays a role in acceptance of misleading suggestions -
Susceptibility of memories to retroactive interference increase as memories are forgotten (Reyna, 1995)
Post event suggestion & misinformation P2.
86% of witness discuss their memory with co-witnesses
- Causes conformity (Gabbert et al 2004)
- Can cause misinformation (Wright et al, 2000).
Difficulty detecting manipulation of a choice they made (Sagana et al, 2014).
Blindness for recognition decisions, this is the person you selected.
39 - 68% of detections remained undetected
Many people think they would be able to detect this manipulation
Eyewitness Memory Typical reporting
Reported . Accuracy
Gender 100% 100%
Age . 55% . 38%
Speech . 15% 84%
Height . 75% . 44%
Verbal Overshadowing
Most common: Hair Style
Less common: eye colour and eye shape, nose mouth and teeth.
Rarely mentioned cheek, chin and forehead
Verbal Overshadowing Pt.2
When describing a face you become less accurate at recognising it subsequently (Schooler et al, 1990) reduction of 26%
(Meissner & Brigham, 2001) more likely to occur when identification immediately followed the description.
Verbal Shadowing: Why does this occur? Schooler et al, 1990
No relationship between description quality and recognition performance.
Specific to verbal description, mentally revisualising the face does not interfere with recognition.
Expert Processing
Unconscious
Non-verbal
Holistic
Good for face perception
Inexpert Processing
Conscious Verbal Featural Bad for face perception Small Perceptual field
