copyright © 2012 pearson canada inc.5 - 1 chapter 5 eyewitness testimony

Copyright © 2012 Pearson Canada Inc. 5 - 1

Chapter 5

Eyewitness Testimony


Learning Objectives

• Independent and dependent variables in eyewitness research

• The misinformation effect• Cognitive interview• Lineup procedures and how they can be

biased• Expert testimony on eyewitness issues• Recommendations for collecting eyewitness

evidence


The Role of Memory

• Eyewitness testimony relies on encoding, storing, and recalling information

• Storing memories requires several steps including attention, encoding, short-term memory, and long-term memory

• Not all memories pass successfully through these stages and problems may occur at each stage


The Stages of Memory

Encoding

Storage

Retrieval


Types of Eyewitness Memory• There are two types of memory retrieval

that eyewitnesses perform:

– Recall memory: Reporting details of a previously witnessed event/person

– Recognition memory: Determining whether what is currently being viewed/heard is the same as the previously witnessed item/person


Studying Eyewitness Issues

• Eyewitness issues can be studied using a variety of methods:– Archival data – Naturalistic observation– Laboratory simulations


Types of Eyewitness Independent Variables

• Two types of independent variables in eyewitness research:

– Estimator variables: Present at the time of the crime and cannot be changed (e.g., age of witness)

– System variables: Can be manipulated to increase (or decrease) eyewitness accuracy (e.g., lineup procedure)


Recall of the Event/Culprit

• Recall of the crime event can take two forms:

– Open ended recall/free narrative: Witnesses are asked to recount what they witnessed without being prompted

– Direct question recall: Witnesses are asked specific questions about the event/culprit


Types of Eyewitness Dependent Variables

• There are three general dependent variables used in eyewitness studies:– Recall of the event– Recall of the culprit– Recognition of the culprit


Interviewing Witnesses

• Police officers may impede the interview process by:– Interrupting witnesses during free recall– Asking short specific questions which

may not get at critical information– Asking questions not relevant to what

the witness is currently describing


The Misinformation Effect

• Occurs when a witness is provided with inaccurate information about an event after it is witnessed and incorporates the ‘misinformation’ in their later recall (Loftus, 1975)


Misinformation Studies: Results

• Participants who are given misinformation provide different reports than those who receive no misleading information

• Subtle differences in phrasing of the question (e.g., using ‘smashed’ instead of ‘hit’), may bias witness’ responses (Loftus & Palmer, 1974)


Explaining the Misinformation Effect

• Three theories attempt to explain the misinformation effect:– Misinformation acceptance

hypothesis– Source misattribution

hypothesis– Memory impairment hypothesis


Facilitating Eyewitness Recall

• Procedures used in the investigative process to aid eyewitness recall include:– Hypnosis– Cognitive Interview– Enhanced Cognitive Interview


Hypnosis

• Can be used to facilitate retrieval of memories. However, memories may or may not be accurate

• Greater information is recalled when participants close their eyes (Perfect et al., 2008)

• Information obtained under hypnosis is not usually admissible in court


Cognitive Interview

• Based on memory retrieval techniques:– Reinstating the context– Reporting everything – Recalling event in different orders – Changing perspectives


Enhanced Cognitive Interview

• The following components were added to the original Cognitive Interview (Fisher & Geiselman, 1992):– Rapport building– Supportive interviewer behaviour– Transfer of control – Focused retrieval– Witness compatible questioning


Cognitive Interview: Results

• Cognitive interviews elicit more information than “standard police interviews”, without an increase in inaccurate information (Memon & Bull, 1991)

• Unclear which components elicit this increase in accurate information (Kebbell & Wagstaff, 1998)


Recall of the Culprit

• Descriptions of culprits by eyewitnesses are lacking in detail and accuracy

• Gender, hair, clothing, and height are commonly reported descriptors


Recognition Memory

• Recognition memory can be tested in a number of ways:

– Live lineups or photo arrays

– Video surveillance records

– Voice identification


Lineup Identification

• Witnesses are frequently asked to identify a culprit from a lineup

• Lineups contain the suspect (who may or may not be guilty) who is placed among a set of individuals who are known to be innocent for the crime in question, called foils or distractors


Estimating Identification Accuracy

• To accurately assess the rate at which real witnesses will correctly identify culprits, two types of lineups are needed in research:

– Target-present lineup: Lineup contains the culprit

– Target-absent lineup: Lineup contains an innocent suspect


Accurate Identification Decisions

Type of

Lineup

Guilty Culprit

Present

Correct Decision

Target- Present

Yes Correctly identify culprit/

Correct Identification

Target-

Absent

No Correctly reject lineup/

Correct Rejection


Lineup Procedures

• Simultaneous lineup: A common lineup procedure that presents all lineup members at one time to the witness

• Sequential lineup: Lineup members are presented serially to the witness

• Showup: Only the suspect is shown to the witness

• Walk-by: Witness is taken to a public location where the suspect is likely to be


Types of Lineup Judgments

• Two types of judgments may be used in lineup procedures:– Relative judgment: Comparing lineup

members to one another and choosing

the one who looks most like culprit– Absolute judgeent: Each member is

compared to the witness’s memory of the culprit


Lineup Procedure Effectiveness

• Sequential lineups increase the likelihood of a correct rejection compared to the simultaneous procedure (Lindsay & Wells, 1985)

• However, recent research suggests that the superiority of sequential over simultaneous lineups may be the product of methodological factors (McQuinston-Surrett et al., 2006)


Biased Lineups

• Biased lineups: Suggest who the police suspect and thereby who the witness should identify

• Types of biases that increase false identification:– Foil bias– Clothing bias– Instruction bias


Increasing Voice Identification

• Having longer versus shorter voice samples leads to greater accuracy

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Decreasing Voice Identification

• Whispering

• Disguising the voice

• Unfamiliar accents

• Placing the target voice near the end of the lineup

• Showing the face along with the voice

• Using a larger number of foils


Witness Confidence

• A small positive correlation exists between a witness’s confidence and their identification accuracy

• Confidence can be manipulated with post-identification feedback

• Mock-jurors do not appear sensitive to “inflated confidence”


Estimator Variables• Age

– Younger and older adults (over age 60) produce comparable correct identification rates (from target-present lineups)

– Older adults produce lower correct rejection rates (from target-absent lineups) compared to younger adults


Estimator Variables

• Race– Witnesses are able to remember faces of

their own race more accurately than faces of other races, known as the cross-race effect

• Cross-race effect may relate to:– Attitudes– Physiognomic homogeneity– Interracial contact


Estimator Variables

• Weapon focus: The phenomenon of a witness’ attention being focused on the culprit’s weapon rather than on the culprit

• Attempts to explain this phenomenon:

– Cue-Utilization hypothesis

– Unusualness hypothesis


Eyewitness Expert Testimony

• There is some controversy regarding the application of research on eyewitness issues to the courts

• Points of contention include:

– Reliability of results across studies

– Applicability of laboratory simulations to real life situations

– Brief exposure to culprit


Identification Guidelines

• The person who conducts the lineup should not be aware of who is the suspect

• Eyewitnesses should be informed the culprit may not be present in the lineup

• The suspect should not stand out • A clear statement regarding a witness’ confidence

should be taken at the time of the identification


Sophonow Inquiry: Recommendations for Canada

• The lineup procedure should be videotaped or audiotaped

• Officers should inform witnesses that it is just as important to clear innocent suspects

• The photo lineup should be presented sequentially

• Officers should not discuss a witness’ identification with him or her

copyright © 2012 pearson canada inc.5 - 1 chapter 5 eyewitness testimony

Documents

pearson canada

types of eyewitness

recall memory

eyewitness research

eyewitness studies

eventculprit slide

eyewitness evidence

eyewitness accuracy