Jurors' perceptions of the influence of extra-evidential factors on their decision making : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University

Abstract

One of the major assumptions underlying the jury system is that juries' verdicts are based exclusively on the evidence presented in court. However, many have challenged this assumption and claim that a number of extra-evidential factors influence jurors' decision making. The present research was designed to investigate jurors' perceptions of the influence of various extra-evidential factors related to the defendant, the lawyers and the judge on their decision making, and to examine possible relationships between jurors' perceptions of the trial participants and their evaluations of the defendant, and the lawyers and their cases. Structured interviews were conducted with sixty-nine respondents who had served on a jury within the last three years, and the data collected was statistically analysed using a .05 level of statistical significance. The results indicated that respondents perceived that some of the extra-evidential factors investigated had influenced their decision making, and relationships were also found between some of these factors and respondents' evaluations. The implications of the results are limited by various methodological considerations, particularly relating to the sample and the nature of the data, but the results do suggest that extra-evidential factors may influence jurors' decision making, and that this is an area worthy of further investigation.