fascinating. this details some psych studies that conclude that ones perception of relative wealth can directly affect their level of compassion, with the better off being far less empathetic, and that holding true regardless of absolute level of wealth but depending on perceived level of wealth relative to a group in your immediate context.
How Wealth Reduces Compassion: Scientific American
http://www.scientificamerican.com/article.cfm?id=how-wealth-reduces-compassion
(via Instapaper)