Understanding pre-trial publicity : an examination of biases in mock juror and jury decision-making

Six empirical studies were designed with the following three objectives: 1) To evaluate the influence of pre-trial information on individual impression formation and culpability evaluation; 2) To investigate jury group discussions and determine the impact of pre-trial publicity on the content and style of the deliberative process and, 3) To examine the processing of evidence and the pattern of PTP biases. Study 1 investigated whether knowledge that an individual is a criminal will produce more negative evaluations on traits associated with a criminal stereotype - specifically, a trait associated with criminal appearance. Results indicated that evaluative ratings were more negative when the information processed prior to rating suggested criminality. Study 2 investigated whether a particular form of legitimate pre-trial information would bias the impression formed but also forensically relevant dimensions such as target culpability. Results indicated that participants exposed to an elaborately worded indictment made significantly more negative attributions about the defendant’s character, culpability and the crime event. Study 3 sought to examine the effect of delay between exposure to the negative pre-trial information and subsequent evaluation. Exposed participants were not any more likely to ascribe negative characteristics to the defendant than control participants but they remained more likely to assert that the defendant was guilty. Study 4a and 4b investigated the impact of information valence. In Study 4a, results indicated that participants exposed to positive PTP were significantly less likely to reach a guilty verdict than those exposed to negative PTP. Study 4b included a control group and more a more forensically relevant form of positive PTP. However, results reflected a seemingly counter-intuitive increase in ‘guilty’ verdicts for mock jurors exposed to positive PTP and this ‘overcorrection’ was discussed with reference to Wegner and Petty’s (1997) Flexible Correction Model. Study 5 sought to examine the impact of negative PTP on the content and style of jury group deliberations. Initial analysis of individual pre-deliberation verdicts demonstrated the standard PTP effects. Juries comprising members who had been exposed to negative PTP appeared more likely to reach a guilty verdict. Results suggested that for juries exposed to negative PTP deliberations displayed a higher instance of successful pro-prosecution interruptions during their discussions. Study 6 examined differences in predecisional distortion for mock jurors exposed to negative PTP versus control participants. Predecisional distortion occurs when jurors bias new evidence in favour of their current leading party rather than evaluate this information for its actual probative properties. Predecisional distortion scores for participants exposed to negative PTP reflected a pro-prosecution bias. The effect of prejudicial PTP on verdict outcomes was mediated by predecisional distortion in the evaluation of testimony. To summarise, the results of initial studies appear to indicate that to elicit an effect pre-trial information needs to be sufficiently extreme to prime a broadly negative impression that is also consistent with a pro-prosecution preference. This pro-prosecution preference than promotes the predecisional distortion such that the evaluation of evidence carries a built-in pro-prosecution bias that ultimately results in an elevated conviction rate. Mock jurors exposed to negative pre-trial publicity are less likely to report the use of the publicity information (than participants receiving positive information), appear more likely to reach a guilty verdict at a lower certainty threshold and retain their negative impression even when reaching a not guilty verdict. This may render them susceptible to the subsequent persuasion in favour of a guilty verdict during deliberations. Findings in this thesis also suggest that deliberations do not necessarily attenuate the PTP effect.EThOS - Electronic Theses Online ServiceGBUnited Kingdo