The New York Times has a column here discussing the issue of the effect of great literature on a reader: specifically, does it make us more moral?
What all fiction does is pull the reader into another person’s view of reality, either through a first person narrator, or a third person narrator who describes what the characters are thinking.
It’s hard to overestimate the importance of this in our video culture. We see what characters say and do on a screen, but cannot see inside their minds. Only books take us inside the minds of characters.
As a high school English teacher for 37 years, my avid readers seemed to be more aware of the complexities of both moral issues and social situations. I put this down to their exposure to hundreds—indeed, thousands—of viewpoints different from their own. I rarely saw a violent avid reader, or an avid reader who was a simplistic thinker. And I've always thought the ability to process the world in a complex way is at the heart of morality.