Laboratory Simulation: Most commonly used, where participants view an event and later describe it's details (recall) or identify from a lineup (recognition).
Eyewitness Research Variables
Independent Variables:
Estimator Variables: Present during the crime and cannot be changed (e.g., age of witness).
System Variables: Can be manipulated to impact accuracy (e.g., lineup procedures).
Dependent Variables:
Recall of the event/crime.
Recall of the perpetrator.
Recognition of the perpetrator.
Recall of Event/Perpetrator
Two types of recall:
Open-Ended Recall: Witness recounts details without prompts.
Direct Question Recall: Witness answers specific questions.
Recall assessed by:
Amount of information reported.
Type of information reported.
Accuracy of information reported.
Recognition of the Perpetrator
Typically done through lineups:
Can include voice or clothing lineups.
Recognition is assessed by:
Accuracy of decisions.
Types of errors made.
Interviewing Eyewitnesses
Goal: To obtain accurate accounts.
Common impediments by police:
Interruptions during free recall.
Short or leading questions.
Pre-determined question order.
Memory can be contaminated by other witnesses (memory conformity).
Hypnosis
Used for hypnotically refreshed memory, including:
Age regression and various techniques to elicit details.
Although it can generate more details, these details are as likely to be inaccurate.
Highly suggestive, and information derived is often inadmissible in court.
Example: Martensville Satanic Panic case.
Misinformation & Wording Effects
The Misinformation Effect: Incorporating inaccurate information presented after witnessing into memory.
Example: Car crash experiment with different question phrasing ("hit" vs. "smashed").
Factors leading to memory errors:
Acceptance of misinformation.
Source misattribution.
Memory impairment.
Implications of Misinformation
Witnesses may inadvertently incorporate unknown information from questions (e.g., "Did you see the gun?").
Misinformation Acceptance Hypothesis: Participants guess based on what they believe the interviewer expects.
Source Monitoring: Identifying the source of memories accurately can be challenging.
Individual Differences in Memory Distortion
Suggestibility varies by:
Age (children and depressed individuals are more suggestible).
IQ and working memory (higher IQ and working memory correspond to less suggestibility).
Autobiographical memories can be reconstructed to maintain self-esteem.
Eyewitnesses and Earwitnesses
Eyewitness recall is often lacking in detail; descriptors such as gender and clothing are common.
Voice Identification: Limited research; factors affecting accuracy include short samples and accents.
McGurk Effect: The phenomenon illustrating the interaction between hearing and vision in speech perception.
Types of Recall Protocols
Free Recall: Open-ended request for all memories.
Narrative Elaboration: Utilizes picture cues to prompt memory retrieval.
Comprehensive Narrative Elaboration Technique (CNET): Multistep procedure with visual cues focusing on various memory components.
Cognitive Interview
Techniques include:
Context reinstatement.
Encouraging comprehensive reporting.
Reversing order of reporting.
Changing perspectives.
Generally enhances accurate information retrieval but could yield more false information than standard interviews.
Lineup Procedures
Types of Lineups:
Target-present or target-absent lineups.
Live lineups vs. photo arrays; photo arrays being more common due to practicality.
Sequential vs. Simultaneous Lineup: Sequential lineups lead to more accurate rejections.
Biased Lineups
A biased lineup may suggest a specific suspect:
Risks include foil and clothing biases.
Importance of accuracy in multi-feature identification for reliability.
Witness Confidence
A small positive correlation exists between witness confidence and accuracy.
Consider the speed of decision and interval between event and identification.
Confidence can be manipulated through post-identification feedback.
Estimator Variables
Age: Older adults generally have fewer correct identifications.
Race: Witnesses tend to remember faces of their own race better (cross-race effect).
Weapon Focus: Witness attention on a weapon decreases focus on the perpetrator.
Eyewitness Expert Testimony
Controversy exists around the reliability and applicability of eyewitness research.
Disagreements include:
Variability of results across studies.
Use of laboratory simulations.
The “common sense” applicability of findings.
Legal Guidelines in the U.S. for Eyewitness Testimony
Conduct lineups with an unaware administrator.
Inform witnesses that the perpetrator may not be present.
Ensure the suspect does not stand out.
Record witness confidence at the time of identification.
Sophonow Inquiry in Canada
Addressed wrongful conviction; made recommendations for the handling of eyewitness evidence:
Videotaping lineup procedures.
Sequential photo lineups.
Avoid discussing identifications with witnesses.
Additional Resources
Study on earwitness reliability
Insights from Picking Cotton
Eyewitness Testimony & DNA Exonerations documentation