Apparently, as Doig reports, there is actually a theory to explain the self-absorbed behavior and lack of concern exhibited by urbanites. "The linchpin of this theory is the Bystander Effect, which suggests that our failure to react is caused by the urban environment. It was first established in 1968 after the notorious murder of Kitty Genovese, the young Queens woman who was killed while dozens of witnesses looked on."
"But in the decades since, our knowledge of the Bystander Effect has evolved even further. Now we can even predict which people - in which cities - are most likely to help out a stranger."
Of comfort to urbanites, Doig points out that the causes for the Bystander Effect have little to do with morality. Two causes, stimulus overload and ambiguity, have a lot to do with the impacts of density. Other causes may be uncertainty about what to do, or fear of intervening.
What's curious, though, is that "the Bystander Effect varies so greatly from city to city - if you're in a place where people are apt to intervene, you probably will too. And if you're not, you won't."