Browsing by Author "Everett, Sarah P."
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Item The usability of electronic voting machines and how votes can be changed without detection(2007) Everett, Sarah P.; Byrne, Michael D.The problems in the 2000 election in Florida focused national attention on the need for usable voting systems. As a result, the Help America Vote Act (HAVA) of 2002 provided funding for updating voting equipment and many states purchased direct recording electronic (DRE) systems. Although these electronic systems have been widely adopted, they have not been empirically proven to be more usable than their predecessors in terms of ballot completion times, error rates, or satisfaction levels for the average voter. The series of studies reported here provides usability data on DREs to compare with that of previous voting technologies (paper ballots, punch cards, and lever machines). Results indicate that there are not differences between DREs and older methods in efficiency or effectiveness. However, in terms of user satisfaction, the DREs are significantly better than the older methods. Paper ballots also perform well, but participants are much more satisfied with their experiences voting on the DREs. These studies also go beyond usability comparisons and test whether voters notice if their final ballots on the DRE reflect choices other than what the voters selected. Results indicate that over 60% of voters do not notice if their votes as shown on the review screen are different than how they were selected. Entire races can be added or removed from ballots and voter's candidate selections can be flipped and the majority of users do not notice. Beyond discovering that most voters do not detect the changes, these studies also identify several characteristics of the voter and the voting situation that are important in whether participants will or will not notice the changes. This means that attacks could be targeted to only those people who will most likely not notice the changes. The result is that malicious software installed on a DRE could steal votes right in front of voters with a low probability of being detected.Item Varying icon spacing changes users' visual search strategy: Evidence from experimental data, cognitive modeling, and eye-tracking(2005) Everett, Sarah P.; Byrne, Michael D.Users of modern GUIs routinely engage in visual searches for control items such as buttons and icons. The current research is intended to deepen our understanding of how the spacing between icons affects search times. Two experiments based on previous icon sets (Fleetwood & Byrne, 2002) were conducted in which the spacing between icons was systematically manipulated, and for which there was a computational cognitive model that predicted performance. Although the model's prediction that larger spacing would lead to slower search times was supported, there was an unanticipated finding: users were substantially slower than in similar experiments that employed consistent smaller spacing. The results were better fit with a model that employed a fundamentally different, less efficient search strategy. Eye-tracking data from a third experiment confirmed the effect of spacing on users' visual search behavior, but the system could not provide adequate information to explain the change in search behavior.