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UBC Theses and Dissertations

Eyewitness identification in the developmentally delayed Rodgers, Marguerite


Developmentally delayed individuals are more likely to be witnesses to crime than the average population because of their increased vulnerability to sexual and physical assaults. Knowing how eyewitness memory in the developmentally delayed behaves in these types of situations would help police and the judicial system to ensure that these individuals are given fair access to the courts and that their testimony is considered appropriately. To examine eyewitness memory, 22 developmentally delayed participants and 23 control participants underwent a scripted interactive encounter with a confederate. One to two weeks following the interactive encounter, participants were interviewed about their memory for the event and were asked to identify the person they had dealt with in the interactive encounter. Half of the participants were shown target-present and half were shown target-absent sequential line-ups. The interview followed the step-wise interview structure (Yuille, Hunter, Joffe, & Zaparniuk, 1993), beginning with a free narrative, followed by open questions, and asking close-ended questions only if necessary. Leading questions, to test for suggestibility, were asked at the end of the interview, to ensure that they did not contaminate the majority of the interview. The interview was scored for number of action and descriptive details. Contrary to the literature, results indicate that developmentally delayed participants do not perform as well as controls with a target-present line-up, but no significant differences were found between participant groups with a targetabsent line-up. Further analysis showed that control participants performed significantly better than chance with the target-absent line-up, but developmentally delayed participants did not. A verbal overshadowing effect was evidenced for control participants, but not for developmentally delayed participants. Developmentally delayed participants performed well in the interview, showing accuracy rates similar to the control participants, although developmentally delayed participants provided fewer details than control participants. Developmentally delayed participants were vulnerable to one of the suggestive questions, but not both. These results are consistent with other research findings and are discussed in terms of their implications for the ability of developmentally delayed individuals to provide eyewitness testimony.

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