The effects of crime type and evidence strength on jury verdicts and juror decision making

Carleton University undergraduate students role played mock jurors in a simulated sexual assault or robbery trial. Juries were randomly assigned to one of the cells of a 3 x 2 (3 levels of evidence x 2 types of crime) between groups design with the restriction of ten juries per condition. Juries were presented with an audio visual synopsis of the trial and then deliberated to a verdict of innocence or guilt.In the strong evidence condition juries that tried the robbery case returned significantly more guilty verdicts than juries that tried the sexual assault case. More specifically, ninety percent of the juries that tried the strong robbery case returned guilty verdicts as opposed to fifty percent of the juries that tried the strong evidence sexual assault case. However, when the evidence was weak or moderate jury verdicts did not differ across crime type. When the evidence was moderately strong female jurors who tried the sexual assault case were significantly more likely to return guilty verdicts than female jurors who tried the robbery case. The implications of these findings are discussed.