The power of fiction is to create empathy … A newspaper could tell you that one hundred people, say, in an airplane, or in Israel, or in Iraq, have died today. And you can think to yourself, “How very sad,” then turn the page and see how the Wildcats fared. But a novel could take just one of those hundred lives and show you exactly how it felt to be that person… You could taste that person’s breakfast, and love her family, and sort through her worries as your own, and know that a death in that household will be the end of the only life that someone will ever have. As important as yours. As important as mine. – Barbara Kingsolver 
Paul Slovic has written about “psychic numbing” as a possible answer to the question “Why do good people ignore mass murder and genocide?” Acknowledging that the answer to this question is unlikely to be straightforward, Slovic (p.80) focuses on one particular aspect of the answer, “… that the statistics of mass murder or genocide, no matter how large the numbers, fail to convey the true meaning of such atrocities. The numbers fail to spark emotion or feeling and thus fail to motivate action. Genocide in Darfur is real, but we do not “feel” that reality.”
His argument is rooted in the now common idea that humans have two systems of thinking, one intuitive and automatic, and the other slow and contemplative. The same idea is the subject of Daniel Kahneman’s recent Thinking, Fast and Slow. The slow and contemplative System 2 likely values every life more or less equally. Should we not feel just as unhappy we hear that one person has died in Syria as we do when we hear that the death toll there has risen from 2,000 to 2,001? We don’t, of course, and Slovic locates one reason in the fast and intuitive System 1. System 1, he argues, evolved to deal with immediate “present, visible, immediate dangers” not “distant, mass murder.” We can feel the reality of an immediate danger or an immediate personal tragedy but we have enormous difficulty feeling the danger or the tragedy of large-scale events. We cannot feel 100 times worse when 100 people die than we do when one dies. Several kinds of “psychic numbing” has now been documented in a number of experiments that Slovic marshals on behalf of his argument.
What is to be done? Images and narrative enlist our emotions far more effectively than do statistics documenting the large scale of any disaster. Charitable organizations have long tried to focus our attention on one hungry child, even when the child is one of many at risk. Reading Barbara Kingsolver’s novel The Poisonwood Bible (or, better yet, listening to Kingsolver herself read the text in the audiobook version) will give you a far better sense of what happened in the Congo in the early 1960s than any history. And, as the quote that begins this piece illustrates, she is well aware of what she is trying to do.
Beyond art, however, Slovic (pp. 91-92) believes that:
… we cannot depend only upon our moral feelings to motivate us to take proper actions against genocide. That places the burden of response squarely upon the shoulders of moral argument and international law. The genocide convention was supposed to meet this need, but it has not been effective. It is time to reexamine this failure in light of the psychological deficiencies described here and design legal and institutional mechanisms that will enforce proper response to genocide and other crimes against humanity.
 Barbara Kingsolver, High Tide in Tucson, (Harper Perennial, 1996) 231, cited in Slovic (200), p. 87.
 Daniel Kahneman, Thinking Fast and Slow (Farrar, Strauss and Giroux, 2011)