Relatively few studies have investigated the impact of communication modality (e.g., video vs. print) on political action intentions, as well as what motivates external observers to act when both the victim and perpetrator of injustice are out-group members. The present research experimentally investigated the influence of communication modality of an injustice (text vs. video), where all parties were out-group members, on observers' sympathy, anger, social cohesion to victims, and political action intentions. Participants reported greater intentions to politically act in the video condition, relative to print, which was explained by increased anger in the video condition. In addition, both sympathy and anger were positively related to social cohesion to the out-group, but only anger was associated with political action intentions.
Glasford, Demis. 2013. "Seeing is believing: communication modality, anger, and support for action on behalf of out-groups." Journal of Applied Social Psychology (October): 2223-30. http://onlinelibrary.wiley.com/doi/10.1111/jasp.12173/abstract