Buckhout, R., Weg, S., Reilly, V., & Frohboese, R. (1977). Jury verdicts: Comparison of 6- vs. 12-person juries and unanimous vs. majority decision rule in a murder trial. Bulletin of the Psychonomic Society, 10, 175-178.
A total of 180 jurors from the Kings County, New York, Jury Assembly room served as mock jurors in a murder trial presented on videotape. Subjects were randomly assigned to cells of a 2 by 2 design which varied jury size (6 vs. 12) and verdict decision rule (majority vs. unanimous). An ANOVA showed that jury verdicts became more severe as a result of deliberating in the smaller jury and under majority rule. The majority decision rule clearly resulted in more convictions. Empirical support for the smaller size jury effect was limited. There were 3 x more convictions in 5/6 majority juries compared with unanimous juries; unanimous juries hung much more often. More variability on convicting charge for smaller juries and non-unanimous juries.