Testing Voters’ Understanding of a Security Mechanism Used in Verifiable Voting

Proposals for a secure voting technology can involve new mechanisms or procedures designed to provide greater ballot secrecy or verifiability. These mechanisms may be justified on the technical level, but researchers and voting officials must also consider how voters will understand these technical details, and how understanding may affect interaction with the voting systems. In the context of verifiable voting, there is an additional impetus for this consideration as voters are provided with an additional choice; whether or not to verify their ballot. It is possible that differences in voter understanding of the voting technology or verification mechanism may drive differences in voter behaviour; particularly at the point of verification. In the event that voter understanding partially explains voter decisions to verify their ballot, then variance in voter understanding will lead to predictable differences in the way voters interact with the voting technology. This paper describes an experiment designed to test voters’ understanding of the ‘split ballot’, a particular mechanism at the heart of the secure voting system Pret a Voter, used to provide both vote secrecy and voter verifiability. We used a controlled laboratory experiment in which voter behaviour in the experiment is dependent on their understanding of the secrecy mechanism for ballots. We found that a two-thirds majority of the participants expressed a confident comprehension of the secrecy of their ballot; indicating an appropriate level of understanding. Among the remaining third of participants, most exhibited a behaviour indicating a comprehension of the security mechanism, but were less confident in their understanding. A small number did not comprehend the system. We discuss the implications of this finding for the deployment of such voting systems.