Scientific American, February:
Money is an incentive to work hard, but it also promotes selfish behavior. Those conclusions may not be surprising, but psychologists at the University of Minnesota recently found that merely thinking of money makes people less likely to give help to others.
The researchers got people to think about money by showing them words related to money, having them handle play money, or revealing a poster with pictures of money on it. They then got the subjects to perform tasks which had nothing to do with money, but assessed social behavior. The result: people who think about money are less helpful and also less likely to seek help from others.
Science, November 17. [Link]