Psychologists have analyzed the speeches of rousing leaders like Hitler and Gandhi for their emotional content, assessing how much fear, joy, sadness and so on were present. They then tested whether the levels of emotion could predict whether a certain speech preceded violence or nonviolence. They discovered the following emotions, particularly combined, could ignite violence: Anger: The speaker gives the audience reasons to be angry, often pointing out who should be held responsible for that anger. Contempt: The outgroup is deemed inferior to the ingroup, and thus unworthy of respect. Disgust: The outgroup is described as so revolting they are undeserving of even basic humane treatment.