Investigating the Effects of Investigative Interview techniques and Defendant IQ on Mock Jurors’ Judgements based on Confession Evidence.

Westwood, Corrin (2017) Investigating the Effects of Investigative Interview techniques and Defendant IQ on Mock Jurors’ Judgements based on Confession Evidence. Manchester Metropolitan University. (Unpublished)

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Abstract

Confession Evidence is one of the most valuable forms of evidence to jurors (Leo and Cutler, 2016). Research has shown that the risk of obtaining a false confession is increased when coercive interviewing techniques are used with a defendant with low IQ (Garrett, 2008). This research aimed to investigate whether mock jurors are aware of coercive interviewing techniques and the risks of these when used with a potentially vulnerable suspect. Questionnaires were used to study the effects of ‘Interview Technique’ and ‘Defendant IQ’ on mock jurors’ ‘Perceptions of Confession Evidence’ and ‘Judgements of Guilt’. 172 participants were presented with a police interview extract and an ‘Offender Profile’, in order to manipulate the independent variables ‘Interview technique’ and ‘Defendant IQ’, before filling out a questionnaire. A 2x2 independent MANOVA was conducted to analyse data. Results indicated that participants in the US condition were more likely to perceive the confession as false but gave higher ratings of guilt compared to UK conditions. Defendant IQ did not seem to effect mock jurors’ perceptions of confession evidence but they gave higher ratings of guilt for ‘Average IQ’ defendants compared to ‘Low IQ’ defendant conditions. Results revealed that ‘Interview technique’ and ‘Defendant IQ’ are important factors involved in mock jurors’ judgements. Further study is required to gain a comprehensive understanding of all potential factors involved in the process of juror judgement-making.