Trading Votes for Votes: An Experimental Study∗

Trading votes for votes is believed to be ubiquitous in committees and legislatures, and yet we know very little of its properties. We return to this old question with a laboratory experiment and a simple theoretical framework. We posit a family of minimally rational trading rules such that pairs of voters can exchange votes when mutually advantageous. Such rules always lead to stable vote allocations—allocations where no further improving trades exist. Our experimental data show that stability has predictive power: vote allocations in the lab converge towards stable allocations, and individual vote holdings at the end of trading are in line with our theoretical predictions. However, there is only weak support for the dynamic trading rules themselves, and although trading is frequent final outcomes show significant inertia around pre-trade outcomes. JEL Classification: D70, D72, P16