For example - my father grew up in Kansas City in the 1930's. He told me once, how in looking back at that time/place and recalling the fact that when he rode the bus, he just expected that an elderly black woman would give up her seat to him-- a healthy young white boy. Now one of the things that I have always respected about my father is his sense of ethics and justice, and for as long as I can remember he supported Civil Rights, always seemed especially questioning of whatever those in power espoused. So it was quite shocking to me, when as a young adult he shared with me about how growing up in KC before the Civil Rights movement, he never once thought about the injustices that people of color faced every day, right in front of him. In fact, it took repeated exposure to the new ideas, before he could really "get" them -- but then once he did, he couldn't understand how he could have ever failed to see what was now so ridiculously obvious.
And that I think is how this whole desensitization thing works. In certain places in Japan, custom and tradition have taught that hunting dolphins for food is ok. There are lots of people there, who grew up with this supporting this practice. It is a significant ritual for some families that serves as a vehicle for bonding between the generations. When those of us not subject to this culture's particular desensitization veiw images depicting dophins being trapped in a cove and knifed to death, amidst a bloodied cove and beach and hear about the brutal massacre of families, and social groups, that leave young dolphins orphaned, we are rightly aghast. We are equally repulsed to learn about the murder of elephants for their tusks, the bush meat trade, China's skinning of cats and dogs to use their fur for clothing, the rape of young females in remote villiages in India as retribution for their father's crimes, because in each of those cases we can easily see the situation from a place of compassion-- identifying immediately with the victims. But when we have been taught from our earliest ages that a specific violence is normal, natural or necessary in order for us to live as we do, and when the people in our family or social group reinforce this idea, it is the extremely rare and extraordinary person who can still recognize that there is an injustice. However one such person who was able to do this, was Donald Watson. Living in the UK and visiting his uncle's farm as a small boy in the early 1900s, he was able to see the normalized violence, in spite of the fact that everyone else around him could not. Watscon went on to be one of the first people in the world to call himself vegan (in 1944).