Kameda, T., & Sugimori, S. (1995). Procedural influence in two-step group decision making: Power of local majorities in consensus formation. Journal of Personality and Social Psychology, 69, 865-876.
Procedural influence in consensus formation across multiple subgroups was examined. When a cross-sectional decision must be established by a joint conference of all members, 2 consensus procedures are conceivable. The 2-stage procedure encourages each subgroup to coordinate its members’ opinions prior to the joint conference; discussion follows 2 steps, first at the subgroup and then at the entire group level. In contrast, the single-stage procedure calls for the joint conference immediately to minimize the opportunities for opinion exchange at subgroups. It was predicted and confirmed that, compared with the single-stage method, the 2-stage procedure enhanced the power of local majorities at the subgroup level and hampered the tendency for the global majorities to prevail in the final decision. Numerical simulations further explored theoretical implications of distinguishing the local and global majorities for collective decision making.
<1>Juries that initially discussed case in 3-person subgroups with a local majority favoring life sentence in 1 subgroup never opted for death penalty and generally hung; juries that met once as a whole generally opted for the death penalty. Global majority/local minority jurors much more likely to change opinion than other members. <2>Replicated in 2nd study.