Koji Murata

Accentuation of Bias in Jury Decision-Making

We investigated the bias accentuation effect of group decision-making. Previous studies have shown that individuals were more likely to endorse the guilty verdict when the prosecution evidence was presented in a temporal order (story condition) than when the same evidence was presented in a nontemporal order (witness condition). We expected that group deliberation would accentuate this biasing effect of evidence order through a majority-wins process. Sixty-six 3-person groups engaged in a mock jury task either in the story or witness condition. As predicted, group deliberation accentuated the difference in the verdict judgments between the two conditions through a majority-wins/leniency asymmetry process. This accentuation effect was not moderated by how juries deliberated (evidence-driven vs. verdict-driven). Some theoretical and practical implications of these findings were discussed.