After pointing out the evolutionary reasons for moral outrage's existence - to shame & punish wrongdoers - this 2017 Nature paper describes a psychological framework (triggering stimuli -> Responses -> Outcomes) for understanding how online social networks "change the expression of moral outrage and its social consequences?&quo;…

outrage explodsd... because it allowed us to make the story about ourselves... we could effortlessly and instantaneously join a global conversation... attracted more agreement from our following than resentment, and invigorated our social capital. We were putting our best face forward, aligning ourselves with an ethical and moral high ground, virt…