The programme of research described in this dissertation examines the potential prejudicial impact of gruesome evidence on mock juror decision making. The dissertation provides a model of the cognitive and emotional processes by which gruesome evidence can influence mock juror judgments. Five studies will be presented which have examined the influence of gruesome verbal (written) and visual evidence. Four studies utilised mock trial or simulation methodology utilising written trial transcripts and undergraduate students as mock jurors. Results suggest that gruesome evidence can cause emotional reactions in mock jurors and that mock jurors who are exposed to gruesome evidence are more likely to find the defendant culpable (in criminal cases) and liable (in civil cases). The studies evaluated a model which outlines the cognitive and affective processes by which gruesome evidence might influence juror emotion and decision making. Gruesome evidence presented verbally, such as verbal descriptions of the victim??s injuries, may bias juror decisions toward conviction. Increased estimates of the guilt of the defendant may result when gruesome information is present, especially when the inculpatory evidence is weak overall. Photographic evidence, irrespective of whether this evidence is neutral or gruesome, can increase the likelihood of conviction. Admitting gruesome photographic evidence, rather than excluding this evidence, may increase the inculpatory value that jurors ascribe to prosecutorial evidence via the influence of gruesome evidence on the emotional state of jurors. Further, although exposure to any photographs had similar effects on mock juror affect, emotional reactions to gruesome photographic evidence appeared to lead to changes in the assessment of evidence and to an increased likelihood of conviction or liability when compared with neutral and no photographs. The implications of the results for policy, practice and research are discussed.

The programme of research described in this dissertation examines the potential prejudicial impact of gruesome evidence on mock juror decision making. The dissertation provides a model of the cognitive and emotional processes by which gruesome evidence can influence mock juror judgments. Five studies will be presented which have examined the influence of gruesome verbal (written) and visual evidence. Four studies utilised mock trial or simulation methodology utilising written trial transcripts and undergraduate students as mock jurors. Results suggest that gruesome evidence can cause emotional reactions in mock jurors and that mock jurors who are exposed to gruesome evidence are more likely to find the defendant culpable (in criminal cases) and liable (in civil cases). The studies evaluated a model which outlines the cognitive and affective processes by which gruesome evidence might influence juror emotion and decision making. Gruesome evidence presented verbally, such as verbal descriptions of the victim??s injuries, may bias juror decisions toward conviction. Increased estimates of the guilt of the defendant may result when gruesome information is present, especially when the inculpatory evidence is weak overall. Photographic evidence, irrespective of whether this evidence is neutral or gruesome, can increase the likelihood of conviction. Admitting gruesome photographic evidence, rather than excluding this evidence, may increase the inculpatory value that jurors ascribe to prosecutorial evidence via the influence of gruesome evidence on the emotional state of jurors. Further, although exposure to any photographs had similar effects on mock juror affect, emotional reactions to gruesome photographic evidence appeared to lead to changes in the assessment of evidence and to an increased likelihood of conviction or liability when compared with neutral and no photographs. The implications of the results for policy, practice and research are discussed.

abstract: In a trial, jurors are asked to set aside their emotions and make judgments based solely on evidence. Research suggests jurors are not always capable of this, particularly when exposed to gruesome photographic evidence. However, previous research has not looked at the potentially moderating effect of when and for how long jurors are exposed to emotionally disturbing photographs, nor how many photographs they see. In two experiments I tested the impact of the timing of and extent of exposure to gruesome photographs on jurors’ emotions, verdicts, and punishment recommendations. In Study 1, I investigated the effect of timing and exposure duration to a single gruesome photograph of a victim in a murder case (no exposure, brief early exposure, brief late exposure, and prolonged exposure) on mock jurors’ emotions and case judgments. Prolonged exposure (relative to no or brief exposure, regardless of timing) increased disgust, which in turn was associated with harsher punishment. Contrary to previous research, the photograph manipulation did not influence verdicts. The results were mixed and inconclusive regarding brief early versus late exposure. In Study 2, I compared repeatedly viewing a single gruesome photograph to viewing a set of four similar, but unique gruesome photographs—holding the exposure time constant—to assess the impact of quantity of photos on jurors’ emotions and case judgments. Viewing multiple gruesome photos (relative to no photos) led to increase in guilty verdicts through increased disgust, replicating previous research. Viewing a single gruesome photo (relative to no photo) led to increase in guilty verdicts through disgust, differing from Study 1 findings. Viewing multiple gruesome photos and a single gruesome photo led to more disgust, compared to viewing no photo. However, differing from Study 1, gruesome photographs did not lead to an increase in punishment recommendations. There were no significant differences between exposure to a single or multiple gruesome photos on disgust, verdicts, or punishments. Overall, greater exposure to gruesome evidence led to increased disgust and punitiveness, relative to those with less exposure. However, jurors with greater exposure to the same or different photographs did not differ in reported emotions, verdicts, or punitiveness. / Dissertation/Thesis / Masters Thesis Psychology 2020