How Individual Preferences Get Aggregated in Groups - an Experimental Study

This paper experimentally investigates how individual preferences, through unrestricted deliberation, get aggregated into a group decision in two contexts: reciprocating gifts, and choosing between lotteries. In both contexts we find that median group members have a significant impact on the group decision, but particular other members also have some influence. Non-median members closer to the median tend to have more influence than other members. By investigating the same individual’s influence in different groups, we find evidence for relative position in the group having a direct effect on influence. We do not find evidence that group choice exhibits a shift in a particular direction that is independent of member preferences and caused by the group decision context itself. We also find that group deliberation not only involves bargaining and compromise, but it also involves persuasion: preferences tend to shift towards the choice of the individual’s previous group, especially for those with extreme individual preferences.