E-Voting System Usability: Lessons for Interface Design, User Studies, and Usability Criteria

Introduction

Electronic Voting (e-voting) systems continue to be used in different countries and contexts around the globe, enabling governments to obtain information on citizens’ preferences more quickly and efficiently. Systems in use are both e-voting machines and remote e-voting systems. Four reasons can be stated why usability is important in e-voting systems. First, due to the election principle of universal suffrage, anyone who meets the voting age requirement¹ should be able to use these systems to cast his vote. This includes first time voters, elderly persons, and even those who do not frequently interact with technology. Second, a voter should be able to easily express his wishes. The interface design should neither cause him to make mistakes nor influence his decision. Poor interface design can easily cause a voter not to cast a vote for his desired candidate. Third, voters remain novices due to a lack of training and irregular interaction with these systems, since elections are held infrequently in many countries and contexts. As such, the learning that occurs from continuous interaction with systems over a period of time is less likely to occur. Finally, if the usability of e-voting systems is not considered, frustration is likely to occur, reducing acceptance among voters, and thus decreasing voter turnout. Usability issues are especially important in e-voting systems that provide verifiability and in particular when using cryptographic verifiability.

Verifiable voting systems have been discussed since their proposal by Cohen and Fischer (1985). We mainly distinguish e-voting systems which implement voter verifiable paper audit trails (VVPAT) and those using cryptographic means for verifiability. The premise is that individual voters are able to verify that their vote is cast as they intended, and stored as they cast it. In addition, voters and any interested parties are able to verify that all votes are tallied as stored. Voters will then have to carry out certain steps to verify votes, and may encounter unfamiliar terminology, such as encryption. However, verifiable systems are only beneficial if any voter who wants to verify his vote can do so without being a specialist. The German Federal Court Decision (2009) backs this stance, requiring that the correctness of all essential steps in the election are publicly examinable without having specialist knowledge. Verifiable e-voting systems are thus even more challenging from a usability point of view; however, the future of e-voting lies in verifiable e-voting as black box systems (where one has to trust that technical and organizational processes are correct, yet no way of testing this is provided) continue to face criticism (Alvarez & Hall, 2008, p. 31).

There is a lot of literature available on usability studies of e-voting systems. Researchers and developers of future e-voting systems should take this into account, especially if they address the most complex systems, namely verifiable and cryptographically-verifiable remote e-voting systems.

In this book chapter, we review existing literature on usability of e-voting systems. Note that the literature is primarily from a western perspective, specifically from American and European contexts. The literature is available either as user studies or usability reviews carried out by HCI experts and/or researchers. We summarize lessons learned for e-voting system interface design, user studies, and usability criteria, from which we extract relevant recommendations for the same. We argue for extensions in these three areas to take into account verifiable and cryptographically-verifiable e-voting systems.

The content of this book chapter is especially relevant to designers of e-voting systems for whom the information provided will form basic input for designing future e-voting systems, in particular, verifiable e-voting systems, where user interaction for verifiability is required, and therefore understanding is critical. Researchers who are interested in replicating user studies or carrying out their own studies will obtain invaluable information, as will researchers and practitioners who are interested in the usability of e-voting systems, and the criteria used to determine usability. Further we identify future research beneficial to researchers seeking open questions in this field.

The reader is advised that accessibility issues in e-voting systems will not be discussed, and are left for future work. However the Voluntary Voting Systems Guidelines (VVSG), which we review, addresses the evaluation of accessibility aspects of e-voting systems.