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Copyright © 2012 Pearson Canada Inc.5 - 1 Chapter 5 Eyewitness Testimony.

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Presentation on theme: "Copyright © 2012 Pearson Canada Inc.5 - 1 Chapter 5 Eyewitness Testimony."— Presentation transcript:

1 Copyright © 2012 Pearson Canada Inc.5 - 1 Chapter 5 Eyewitness Testimony

2 Copyright © 2012 Pearson Canada Inc.5 - 2 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

3 Copyright © 2012 Pearson Canada Inc.5 - 3 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

4 Copyright © 2012 Pearson Canada Inc.5 - 4 The Stages of Memory Encoding Storage Retrieval

5 Copyright © 2012 Pearson Canada Inc.5 - 5 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

6 Copyright © 2012 Pearson Canada Inc.5 - 6 Studying Eyewitness Issues Eyewitness issues can be studied using a variety of methods: – Archival data – Naturalistic observation – Laboratory simulations

7 Copyright © 2012 Pearson Canada Inc.5 - 7 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)

8 Copyright © 2012 Pearson Canada Inc.5 - 8 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

9 Copyright © 2012 Pearson Canada Inc.5 - 9 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

10 Copyright © 2012 Pearson Canada Inc.5 - 10 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

11 Copyright © 2012 Pearson Canada Inc.5 - 11 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)

12 Copyright © 2012 Pearson Canada Inc.5 - 12 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)

13 Copyright © 2012 Pearson Canada Inc.5 - 13 Explaining the Misinformation Effect Three theories attempt to explain the misinformation effect: – Misinformation acceptance hypothesis – Source misattribution hypothesis – Memory impairment hypothesis

14 Copyright © 2012 Pearson Canada Inc.5 - 14 Facilitating Eyewitness Recall Procedures used in the investigative process to aid eyewitness recall include: – Hypnosis – Cognitive Interview – Enhanced Cognitive Interview

15 Copyright © 2012 Pearson Canada Inc.5 - 15 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

16 Copyright © 2012 Pearson Canada Inc.5 - 16 Cognitive Interview Based on memory retrieval techniques: – Reinstating the context – Reporting everything – Recalling event in different orders – Changing perspectives

17 Copyright © 2012 Pearson Canada Inc.5 - 17 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

18 Copyright © 2012 Pearson Canada Inc.5 - 18 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)

19 Copyright © 2012 Pearson Canada Inc.5 - 19 Recall of the Culprit Descriptions of culprits by eyewitnesses are lacking in detail and accuracy Gender, hair, clothing, and height are commonly reported descriptors

20 Copyright © 2012 Pearson Canada Inc.5 - 20 Recognition Memory Recognition memory can be tested in a number of ways: –Live lineups or photo arrays –Video surveillance records –Voice identification

21 Copyright © 2012 Pearson Canada Inc.5 - 21 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

22 Copyright © 2012 Pearson Canada Inc.5 - 22 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

23 Copyright © 2012 Pearson Canada Inc.5 - 23 Accurate Identification Decisions Type of Lineup Guilty Culprit Present Correct Decision Target- Present YesCorrectly identify culprit/ Correct Identification Target- Absent NoCorrectly reject lineup/ Correct Rejection

24 Copyright © 2012 Pearson Canada Inc.5 - 24 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

25 Copyright © 2012 Pearson Canada Inc.5 - 25 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

26 Copyright © 2012 Pearson Canada Inc.5 - 26 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)

27 Copyright © 2012 Pearson Canada Inc.5 - 27 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

28 Copyright © 2012 Pearson Canada Inc.5 - 28 Increasing Voice Identification Having longer versus shorter voice samples leads to greater accuracy 5 - 28

29 Copyright © 2012 Pearson Canada Inc.5 - 29 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

30 Copyright © 2012 Pearson Canada Inc.5 - 30 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”

31 Copyright © 2012 Pearson Canada Inc.5 - 31 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

32 Copyright © 2012 Pearson Canada Inc.5 - 32 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

33 Copyright © 2012 Pearson Canada Inc.5 - 33 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

34 Copyright © 2012 Pearson Canada Inc.5 - 34 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

35 Copyright © 2012 Pearson Canada Inc.5 - 35 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

36 Copyright © 2012 Pearson Canada Inc.5 - 36 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


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