The researchers analyzed the pattern of emotions conveyed when leaders spoke about their rival group and examined speeches given at three points in time before a specific act of aggression. They compared the results with the content of speeches delivered by leaders whose groups engaged in nonviolent acts of resistance such as rallies and protests.
Among leaders of groups that committed aggressive acts, there was a significant increase in expressions of anger, contempt and disgust from 3 to 6 months prior to the group committing an act of violence. For nonviolent groups, expressions of anger, contempt and disgust decreased from 3 to 6 months prior to the group staging an act of peaceful resistance.
Matsumoto says the findings suggest a leader's emotional tone may cause the rest of the group to share those emotions, which then motivates the group to take part in violent actions.
"For groups that committed acts of violence, there seemed to be this saturation of anger, contempt and disgust. That combination seems to be a recipe for hatred that leads to violence," Matsumoto said.
Anger, contempt and disgust may be particularly important drivers of violent behavior because they are often expressed in response to moral violations, says Matsumoto, and when an individual feels these emotions about a person or group, they often feel that their opponent is unchangeable and inherently bad.
Of course, domestically, in a society with strong legal protections for the freedom of speech, there is little that authorities can do with this kind of information. The leader who is driving the movement, quite possibly intentionally, doesn't actually rely on overt direct threats to achieve his objective, so it may be impossible to take direct legal action against a potentially violent group's leader. Violence seems to be driven more by the emotional subtext and framing in the speeches than by the particular calls to action themselves.
On the other hand, this analysis could be useful in formulating counterpropoganda initiatives designed to defuse the violent frenzy (or call for non-violent resistance) that a movement's charismatic leader is trying to whip up. Anti-terrorism rhetoric, presumably, ought to focus on defusing anger, destabilizing the sense of superiority that makes contempt possible, and densensitizing movements members to whatever it is that has incited their disgust. More succinctly, counterterrorist rhetoric ought to focus on a message of forgiveness, humility, and tolerance.