More than 100 countries allow people to vote directly on policies in direct democracy elections (e.g., 2016 Brexit referendum). Politicians are often responsible for writing ballot language, and voters frequently encounter ballot measures that are difficult to understand. We examined whether eye movements from a small group of individuals can predict the consequences of ballot language on large-scale voting decisions. Across two preregistered studies (Study 1: N = 120 registered voters, Study 2: N = 120 registered voters), we monitored laboratory participants' eye movements as they read real ballot measures. We found that eye-movement responses associated with difficulties in language comprehension predicted aggregate voting decisions to abstain from voting and vote against ballot measures in U.S. elections (total number of votes cast = 137,661,232). Eye movements predicted voting decisions beyond what was accounted for by widely used measures of language difficulty. This finding demonstrates a new way of linking eye movements to out-of-sample aggregate-level behaviors.
Keywords: decision making; direct democracy; eye movements; open data; open materials; preregistered; voting.