Date of Award


Degree Type


Degree Name

Doctor of Psychology


School of Psychology


Faculty of Community Services, Education and Social Sciences

First Advisor

Dr Alfred Allan

Second Advisor

Dr Maria Allan


Previous research has shown that a number of characteristics of trial participants (extralegal variables) can and do influence juror’s judgements. This is of importance as only the legally relevant facts of the case should be considered during a trial. The present study investigates the influence of victim characteristics on the juror decision making process during deliberation and the judgements made about the victim, crime and defendant in a mock jury setting, as well as investigating mock juror gender differences. A representative sample of people eligible for jury duty in Western Australia viewed a video vignette depicting a trial, in which the mental disorder label (no label, schizophrenia, depression, intellectual disability) was varied. Deliberations were videotaped and subject to an analysis in conjunction with pre and post test questionnaire measuring victim characteristics. A 4x2x2 repeated measures ANOVA was used to analyse the data, in addition to the analysis of the deliberations. The qualitative findings suggest that mock jurors invested relatively much time in some mental disorder labels may function as extralegal variables. This inference is supported by the quantitative findings in this study. The mental disorder label assigned to the victim had an impact on mock jurors’ perception of the likeability, reliability and honesty of the victim, the responsibility for the crime and the guilt of the defendant, often interacting with mock juror gender and deliberation. However, no clear pattern of bias against or in favour of any specific victim could be discerned. There was slightly more evidence of a negative bias than a positive bias towards the no label and schizophrenia victims, while the opposite was true for the depression and intellectual disability victims.