Group Decision-Making in Ultimatum Bargaining:
An Experimental Study∗
Alexander Elbittar†, Andrei Gomberg‡ and Laura Sour§
June 8, 2004
Abstract
Many rent-sharing decisions in a society are result from a bargaining process between groups
of individuals (such as between the executive and the legislative branches of government, between
legislative factions, between corporate management and shareholders, etc.). The purpose of this
work is to conduct a laboratory study of the effect of different voting procedures on group
decision-making in the context of ultimatum bargaining. An earlier study (Bornstein and Yaniv,
[2]) has suggested that when the bargaining game is played by unstructured groups of agents,
rather than by individuals, the division of the payoff is substantially affected in favor of the
ultimatum-proposers. Our theoretical arguments suggest that one explanation for this could be
implicit voting rules within groups. We propose to explicitly structure the group decision-making
as voting and study the impact of different voting rules on the bargaining outcome.