Check it to Protect it: Understanding the Behaviors Driving Ballot Verification

This study sought to understand the factors influencing voters to verify their paper ballots produced by an electronic Ballot Marking Device (BMD). To tackle this question, 60 undergraduate students from Rice University participated in mock elections where their votes on the electronic BMD displayed their selections accurately, but then a subset of their votes on the printed ballots were altered. After the system printed the paper ballot, two user interface (UI) interventions aimed at improving ballot verification rates were displayed in the following sequence: (1) a digital-based prompt instructing voters to “Carefully check your printed ballot. Take your time. Make sure everything is correct” and asked the question, “Are your printed selections correct?” requiring an on-screen response of “Yes” or “No,” and (2) a paper-based prompt requiring voters to handscribe their signature, a checkmark, or a sentence on the paper ballot. The results revealed that the paper-based intervention did not influence ballot verification performance, as all participants who detected at least one anomaly destroyed their compromised ballots after encountering the digital-based intervention. The overall detection rate on the digital-based intervention was high, with 88% of voters detecting changes in their ballots, suggesting that this ballot verification intervention was an effective countermeasure to encourage voters to check their paper ballots. The findings from this study can inform voting system design guidelines that motivate voters to independently audit their own ballot for anomalies.