Eyewitness Skills and Juror Perceptions of Adults with Intellectual Disabilities

Abstract

Individuals with intellectual disabilities (ID) are at an increased risk of abuse and are thus more likely to come into contact with the criminal justice system (CJS). Research examining this group’s eyewitness skills is limited, particularly in relation to adults with ID, but it does suggest that they can be reliable and accurate witnesses. However, there remain significant gaps in the existing literature. The current research focused on three key areas of eyewitness testimony: investigative interviewing, line-up identification and juror perceptions. In the first study, adults with ID and mental age (MA) matched typically developing (TD) children, were shown two separate but similar eyewitness films. Recall occurred at three points: following a delay of around 45 minutes, a delay of one week and, for half of the participants, a further delay of one week. Participants were also asked to identify the two perpetrators (from the eyewitness films) from sequentially presented identification line-ups. Overall, the adults with ID recalled just as much information as the TD children, whilst producing few source monitoring errors, confabulations and contradictions. However, the adults with ID found the identification line-ups particularly challenging, evidenced by low identification accuracy rates, problems in recalling the non-biased line-up instructions and understanding the line-up’s purpose. In an investigation of the usefulness of cognitive measures (e.g., memory and language) in predicting eyewitness performance, facial and verbal memory were discovered to be significant predictors of amount of correct information recalled for both groups, but facial memory was not predictive of line-up identification accuracy. The second study examined how level of recall and provision of witness information affected mock jurors’ perceived credibility of evidence from witnesses with ID. This group were perceived to be honest and believable, but their evidence was not perceived to be very complete. Provision of witness information did not have a detrimental impact on perceived credibility. In summary, adults with ID can be reliable witnesses however, their ability to accurately identify a perpetrator from an identification line-up is impoverished. These results have important practical implications, not only with specific reference to the police investigation process, but also in relation to several aspects of the criminal justice system.

Date of Award	10 Mar 2020
Original language	English
Awarding Institution	University of Winchester
Supervisor	Rachel Wilcock (Supervisor), Wendy Kneller (Supervisor) & Genevieve Waterhouse (Supervisor)