Group Size, Decision Rules, and Communication in Legislative Bargaining

How many members of a group or decision making body should be re- quired to agree to an action that changes the status quo? One? Two? A Majority? Or perhaps all members of the group? We conduct three exper- iments designed to investigate the eects of dierent majority requirements on bargaining outcomes in small and large groups. In particular, we use a Baron-Ferejohn protocol and investigate the eects of decision rules on delay (number of bargaining rounds needed to reach agreement) and measures of \fairness" (inclusiveness of coalitions, equality of the distribution within a coalition). In addition, we evaluate the effect of free-form communication in multilateral bargaining games. We find that larger groups and unanimity rule are associated with signicantly larger decision making costs in the sense that first round proposals more often fail, leading to more costly delay. In contrast, communication reduces decision costs signicantly under both, majority and unanimity rules. Communication increases the probability of individually accepting a proposal, and this in turn makes overall proposals more likely to be passed.