Tweets That Matter: Evidence From a Randomized Field Experiment in Japan

Although election campaigns are increasingly utilizing social media, only a few studies have investigated their effects experimentally. To fill this gap in the literature, we conducted a field experiment to examine the effects of a campaign that used Twitter during the 2013 House of Councillors election in Japan. The treatment was exposure to tweets from Tōru Hashimoto, the mayor of Osaka and co-leader of the Japan Restoration Party, who has the largest number of Twitter followers among Japanese politicians. Participants assigned to the treatment group followed Hashimoto and the two placebos, whereas those assigned to the control condition followed only the two placebos. They followed the politicians continuously for approximately one month. Pre- and posttreatment measures were collected using online surveys, and treatment compliance was continuously checked via Twitter application programming interface (API). Following Hashimoto on Twitter during the election campaign had a positive impact on feelings toward Hashimoto. This effect was not mediated by issue knowledge or the evaluation of Hashimoto’s personal traits, and no effects were observed on voting. These findings suggest that repeated exposure to a politician’s messages on Twitter may only result in a mere exposure effect, which nevertheless generates favorable overall attitudes about the politician.