The rules matter: an experimental study of the effects of electoral systems on shifts in voters' attention

Using a computerized process tracing program, we conduct an experimental study of the effects of single-member district (SMD) and closed-list proportional representation (PR) electoral systems on information acquisition and processing by voters. We find that subjects in the closed-list PR system access less of the available candidate information compared to subjects in the SMD electoral system, and that subjects assigned to the SMD electoral system utilize a dimension-based information search pattern (i.e., they acquire information about multiple candidates/parties on the same dimension). The findings indicate that voters' attention to political information is structured in part by the rules of their electoral system. We also find that subjects assigned to the PR electoral system were more likely to vote for their party than subjects assigned to the SMD electoral system. Our study has implications for research in voting behavior in SMD and PR systems as well as cognitive theories of information processing.