Co-Witness Influences on Eyewitness Identification Accuracy

Transcription

1 The International Research Centre for Investigative Psychology Co-Witness Influences on Eyewitness Identification Accuracy Dara Mojtahedi, Dr Maria Ioannou, Dr Laura Hammond

2 The Problem with Eyewitness Statements Influences approximately 75-84% of false convictions (Scheck et al.,2000) One of the least reliable forms of evidence used for conviction (Wells et al., 1998) In approximately 48% of cases of misidentification, the real perpetrator went on to commit more crimes (Cardozo, 2009)

3 Yet Eyewitness Statements are Still Heavily Influential in the Court Room There is still a strong tendency for police officers and jurors to believe that eyewitness statements are more reliable than research shows (Cutler & Penrod, 1995) 87% police officers stated that eyewitness statements provide the major lead in most investigation (Kebbell & Milne, 1998) Most important factor in almost 1 in 5 criminal cases (Coupe & Griffiths, 1996) Should we reassess the validity of eyewitness testimonies as a safe source of evidence?

4 Reasons for False Eyewitness Testimonies Inaccurate memory encoding (Cowan, 1988; Craik, Govoni, Naveh- Benjamin, & Anderson, 1996) Memory decay (Ebbinghaus, 1985) Poor interviewing techniques (Loftus, Miller, & Burns, 1978) Pressure to perform (Wells et al., 2000) If individuals can be influenced by investigators, then why not by other eyewitnesses?

5 Co-witness Conformity 38% of misidentification cases involved more than one eyewitness (Cardozo, 2009) Social conformity: - Informational influence: obtaining information from a group and accepting it as accurate information about reality (Kaplan & Miller, 1987). - Informational influence is at its strongest when an individual is uncertain about the task or topic at hand (Suls & Wheeler, 2000). - Research has found that social conformity can influence an individuals answers when recalling information (Gabbert, Memon, Allan, & Wright, 2004), however little research investigates this relationship through the context of witnessing a crime.

6 Gender Differences in Conformity Women found to conform more than men (Eagly, 1978) However this has been attributed to gender bias tasks (Sistrunk & McDavid, 1971) Very little evidence of gender differences in conformity of crime eyewitnesses

7 Present Study Aim & Objectives Aim To investigate the effects of social conformity on crime eyewitness statements Objectives i. To identify if a group discussion amongst eyewitnesses prior to giving individual statements could influence their statements ii. To identify if there is a significant gender difference in eyewitness conformity rates

8 Sample 90 participants (47 male, 43 female) Age range: (mean= 28.19, SD=8.088) Three (independent) groups: a. Condition A (N=30): Group discussion of the crime in the presence of a confederate, prior to giving a statement. b. Condition B (N=35): Group discussion of the crime, prior to giving a statement, no confederate. c. Condition C= (N=25): No group discussion permitted (control group)

9 The footage CCTV footage of a violent fight breaking out inside of a bar. Man in the dark top is the first to attack and instigator of the fight. Due to the fight occurring unexpectedly in the corner of the screen and not the centre, participants in the pilot study stated that they didn t see it coming, eliciting natural behaviour.

10 Procedure Condition A: Participants were placed into groups of five true participants + one confederate. Participants watched the CCTV footage collectively in their groups. After the footage, participants were allocated two minutes to discuss amongst each other who they believed had started the fight. The confederate had been instructed to purposely argue that the wrong man had started the fight. Participants were then interviewed privately and asked to identify who they saw start the fight. Participants were given the option to answer with unsure.

11 Procedure Condition B: Participants were placed into a group of five true participants. Participants watched the CCTV footage collectively in their groups. After the footage, participants were allocated two minutes to discuss amongst each other who they believed had started the fight. Participants were then interviewed privately and asked to identify who they saw start the fight. Participants were given the option to answer with unsure.

12 Procedure Condition C: Participants were placed into a group of five true participants. Participants watched the CCTV footage collectively in their groups. Participants were instructed not to discuss the footage with other group members at any time. After the footage finished, participants were then interviewed privately and asked to identify who they saw start the fight. Participants were given the option to answer with unsure.

13 Results: Confederate effect Chi-squared test of independence found that there was a significant relationship between the presence of a confederate and false eyewitness identification x 2 (4, N = 90) = , p =.004. Condition A: 73% identified the wrong man as the offender Condition B: 40% identified the wrong man as the offender Condition C: 32% identified the wrong man as the offender

14 Results: Group Discussion and Conformity Looked at the groups rather than individual participants Three conformity levels: - Unanimous (all five participants identified the same suspect as the offender) - Majority (four participants identified the same suspect as the offender) - No conformity (less than four participants identified the same suspect as the offender)

15 Results: Group Discussion and Conformity Cross tabulation of the data found that when no group discussion was permitted 100% of the groups showed no group conformity, with a significant standard residual of 1.9. However in the conditions that permitted group discussion, 76.9% of the groups showed group conformity with 30.8% if the groups displaying unanimous conformity. The data suggests that discussing the event with other co-witnesses can impact an individuals final eyewitness statement.

16 Results: Gender Differences in Cowitness Conformity The Chi-square test for independence found that there was no significant relationship between gender and conformity x² (2, N = 30) = 3.232, p =.199. Gender Answer man in yellow Unsure man in black male Count Expected Count % within Gender 77.8% 0.0% 22.2% female Count Expected Count % within Gender 66.7% 16.7% 16.7%

17 Summary The data indicates that eyewitnesses of a crime can be influenced by the views of other co-witnesses when recalling a crime. The data suggests that the false account of one eyewitness can thus have a negative impact on the identification accuracy of other eyewitnesses. The data indicates that there are no gender differences in conformity rates amongst crime eyewitnesses.

18 Implications of Findings The data suggests that eyewitnesses are at risk of taking on false information about an event as reality. Therefor police investigators must uphold interventions to prevent the accounts of eyewitnesses from being contaminated by others (including the investigators). The findings indicate that eyewitness testimonies are not always a reliable source of evidence and we must acknowledge this, especially in the court rooms.

19 Limitations Reduced pressure to perform Absence of shock The participants were shown a clear view of the fight when in reality, eyewitnesses do not always get a clear view Ambiguity of the task

20 Future Research The use of first person footage to offer a more realistic simulation of witnessing a crime Individual differences and eyewitness conformity using FIRO Investigating the group dynamics of eyewitness behaviour Cultural differences in eyewitness behaviour

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