when we see a group of people being dehumanized, is that act one of choice?

Ehrlich gives us some interesting things to think about this week in terms of how people from different ethnic groups are dehumanized, and how that is often the first step towards ethnoviolence. When you read Chapter 1, you see information that children learn their prejudices as early as age three or four. When you read Chapter 3, you see that it can be quite common even in the workplace to treat people who are different as if they are not even there, that they are objects or resources, but not people. 

My question for you this week is: when we see a group of people being dehumanized, is that act one of choice? Or is it something that has become so ingrained in the minds of those who do it that it is second-nature to them? Or is it some combination of both? Can you provide a specific example to illustrate your point?