In the news, we’re seeing a number of reports concerning “vote flipping.” The story, as typically reported, is that voters are attempting to vote for one candidate but observe that the machine “flipped” their vote to the other candidate. For touch-screen voting machines, the most likely cause of this issue is miscalibration of the screens (or, perhaps, a voter who is significantly taller or shorter than the person who did the calibration, since different angles of view require different calibrations). I wrote a detailed explanation of this issue two years ago.

UPDATE: Barbara Ballard, a usability expert with Little Spring Designs offers some excellent advice about how to configure touch screen button layouts to minimize or eliminate the parallax issues that seem to induce or exacerbate vote flipping.

A related issue concerns reports of vote flipping on the Hart InterCivic eSlate voting machine. These machines do not have touch-sensitive screens, so therefore poor calibration cannot explain the voter confusion. Since my home county uses eSlates, I went to vote early, this morning, and paid careful attention to how the user interface works. For those unfamiliar with eSlates, the voter’s primary interface to the machine is a dial-wheel and an “Enter” button, which operates in a manner that would be quite familiar to users of Apple’s iPod. You turn the wheel and it highlights successive entries. You press the Enter button and it indicates your selection graphically. Using some HTML tables, I’ve attempted to recreate the salient details below.

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