The impact of politicians’ behaviors on hate speech spread: hate speech adoption threshold on Twitter in Japan

Abstract

In this paper, we hypothesized that a leading politician’s behavior signaling support for the ideas of hate groups will increase hate speech by shifting social norms. To examine the hypotheses, in particular, to quantify the social norms shift, the study utilized an adoption threshold measure based on Twitter retweet networks. Our empirical study focused on the hate speech spread effect of an announcement by Yuriko Koike, Governor of Tokyo, declining to participate in a memorial ceremony for Korean massacre victims. The results support the hypothesis: after Koike’s announcement, adoption thresholds of hate speech users were significantly lowered, while the number of hate speech users increased. Further, this study compared the effect of Koike’s announcement to the effect of a North Korean missile launch, a national security threat to Japan. The average hate speech adoption threshold was lower after Koike’s announcement than after the missile launch, suggesting that a leading politician’s behavior could have a greater impact on shifting norms of prejudice than even a nationally threatening event.