Constituency Diversity, District Magnitude and Voter Co-ordination

Why are voters in some electoral constituencies able to successfully co-ordinate their balloting decisions on viable party offerings, while those in other constituencies are not? Prior work on voter co-ordination failures has focused on institutional and elite-level explanations. This article demonstrates that characteristics of the voting constituencies themselves – specifically their socio-demographic diversity – can play an important role in shaping voters’ collective ability to co-ordinate around viable party offerings. It synthesizes theories of collective decision making from the field of organizational psychology with theories of institutions as incentive structures to argue that diversity inhibits collective co-ordination in some contexts, but not others. In so doing, the article offers a new causal mechanism that links diversity and district magnitude to party system size. The argument is tested using a cross-national analysis of tens of thousands of voters across lower house elections in twelve countries.