Why Money messes with your mind

Dough, wonga, greenbacks, cash. Just words, you might say, but they carry an eerie psychological force. Chew them over for a few moments, and you will become a different person. Simply thinking about words associated with money seems to makes us more self-reliant and less inclined to help others. And it gets weirder: just handling cash can take the sting out of social rejection and even diminish physical pain.

http://www.newscientist.com/article/mg20127001.200-why-money-messes-with-your-mind.html?full=true