“it's a lot easier to overcome any trigger-finger hesitations you might have with a disturbing trick: don't think of the person you're killing as a human being. Instead, mentally transform the person into a disposable subhuman abstraction. History's worst atrocities are usually preceded by language that equates human beings with insects, vermin, even objects. Slaves were referred to as stock. Native Americans were called savages. Rwanda's perpetrators of genocide depicted Tutsi as cockroaches
Nazis referred to Jews as rats and depicted them on posters as lice.

But in most of the worst acts of human cruelty and abuse, the perpetrators tried to create social distance between themselves and their victims. Unable to change the temporal, spatial, or experiential aspects of killing, the focus remained on devaluing the lives of the "enemy" It helped overcome the perpetrators' human instinct, our aversion to killing.” - Brian Klaas, Corruptible, Page 216