Hazelwood, L., & Brigham, J. C. (1998). The effects of juror anonymity on jury verdicts. Law and Human Behavior, 22, 695-713.
This study examined the effects of anonymity on jurors’ verdicts and on jurors’ feelings of accountability for their jury’s verdicts. Twenty four-person anonymous juries and 20 four-person nonanonymous juries rendered individual and group verdicts for three student defendants charged with selling drugs on a school campus. When unanimous guilty verdicts were reached, juries imposed one of five punishments. Finally, jurors completed postdeliberation opinion and accountability questionnaires. As predicted, anonymous juries showed a higher rate of conviction (70%) than did nonanonymous juries (40%) when the evidence against the defendant was strong, supporting the hypothesis that anonymity would have a greater effect for situations in which there was relatively strong evidence of the defendant’s guilt. Anonymous juries imposed the harshest punishment (expulsion) significantly more often than did nonanonymous juries. Contrary to predictions from differential self-awareness theory, anonymous juries did not report feeling less accountable than did nonanonymous juries. However, anonymous juries did see the process as significantly more fair than did identifiable juries.
Very large effect of evidence strength on jury verdicts. Anonymous juries tended to convict more often (15%), especially when evidence was overwhelming. Anonymity not related to sentence severity, but anonymous juries more often imposed the harshest punishment.