Exposure to Countering Messages Online: Alleviating or Strengthening False Belief?

Posting countermessages is commonly used as a strategy to combat false rumors spreading online. The effectiveness of countermessage exposure has been investigated in past studies, but little is known about its repercussions. The aim of this study was to contribute to the understanding of rumor control by investigating the factors impacting the effectiveness of countermessage exposure. A total of 164 participants were asked to judge the believability of rumor and factual tweets before and after countermessage exposure in a web-based experiment. Two forms of countermessage were compared to examine the effects of countermessages on belief change in the target tweets. One was subjective countermessages based on personal experiences, and the other was objective countermessages based on evidence. The results showed that objective countermessages reduced belief in rumor tweets, whereas subjective countermessages strengthened false beliefs. In addition, the half of the participants who were exposed to objective countermessages randomly mixed with subjective countermessages formed negative attitudes not only toward the rumor tweets but also toward the factual tweets. The results also showed gender differences in response to countermessage exposure; women tended to be more susceptible to countermessages and changed their beliefs regarding the target tweets negatively after the exposure. We discuss the practical implications of the results associated with the adverse effects of countermessage exposure.