Bleeding Ballots: Exploring the Cognitive Limit of Voters in a Two-Ballot System

• In Event: How Ballot Structure Contributes to Voter Errors and Omissions

Abstract

Ballot designs have been demonstrated to affect voting behavior and influence the ability of voters to cast their ballots accurately. When a ballot imposes significant cognitive costs and overburdens voters' cognitive load, voters are more likely to make a mistake when casting a ballot, unintentionally casting ballots for non-preferred candidates. This article aims to provide evidence and quantify the extent of misvoting in mixed-member electoral systems, where voters are required to cast two ballots. Specifically, it examines the complications that arise from the use of inconsistent numbering schemes between these ballots, particularly when the number assigned to a party on the party list ballot does not match the party's candidate number on the constituency ballot. This discrepancy is expected to increase the cognitive burden on voters, as they are forced to remember two distinct numbers when the number of the preferred party and the preferred constituency candidate does not overlap. Consequently, an inconsistent numbering scheme leads to a higher incidence of voting error.

To assess the impact of inconsistent numbering schemes in a two-ballot system, this study utilized cross-sectional data from the 2023 Thai national election. In line with expectations and as an indication of misvoting, I find evidence that minor parties on the party list ballot receive a boost in vote shares when their numbers coincide with those of major candidates on the constituency ballot. To provide further evidence of voter error, I utilize precinct-level data to conduct a spatial regression discontinuity design, demonstrating that the vote share for minor parties significantly decreases when moving from an electoral district where the party's number coincides with that of a major candidate to a nearby district that lacks a number match with a major candidate. This suggests that a portion of the electorate has limited capacity to process complicated ballot designs or does not invest the time to gather information about the ballot.

Furthermore, this article examines demographic factors affecting the degree of misvoting. I find that electoral districts with rural locations, a larger proportion of poorly educated voters, and lower internet penetration experience a larger vote boost for minor parties on the party list ballot when their numbers align with those of major candidates on the constituency ballot. Finally, I explore the effectiveness of various campaign strategies that major parties utilized to mitigate misvoting due to an inconsistent numbering scheme.

Author

• Songkhun Nillasithanukroh, University of Arkansas