Inoculating voters against misinformation in greenspace ballot measures

Public agencies responsible for conservation, parks, and recreation (CPR) increasingly rely on voter-approved ballot measures to secure funding for greenspace acquisition and preservation. These campaigns are vulnerable to misinformation, yet few studies have examined how to protect voters from false claims in this context. Drawing on inoculation theory, this experimental study tested whether proactive inoculation messages can buffer voters against misinformation targeting a real CPR-focused ballot measure, the 2022 King County, Washington Proposition No. 1 Conservation Futures Levy. A mixed-design survey experiment (N = 400) randomly assigned registered voters to one of four conditions: misinformation only, general inoculation, detailed inoculation, or combined inoculation. Outcome measures included perceived fairness of the referendum, perceived tax increase, word-of-mouth (WOM) intentions, change in voting decision, and susceptibility to misinformation. Detailed inoculation and combined inoculation significantly preserved perceived fairness and reduced perceived tax burden following misinformation exposure, whereas general inoculation alone did not produce significant protective effects. Participants receiving detailed inoculation, alone or combined with a general inoculation message, were significantly less likely to perceive the misinformation as believable, reliable, trustworthy, and accurate than those exposed to misinformation alone. No significant condition differences were observed for WOM intentions or voting decision change. These findings suggest that inoculation messages containing specific refutations of misinformation are more effective than general forewarnings alone in the CPR ballot-measure context. This study extends inoculation theory to voting and direct-democracy settings and offers practical guidance for public-sector CPR providers seeking to proactively protect voters from campaign misinformation.