Studies at UC Berkeley show that ... generosity for many is driven by a sincere desire to benefit others, said Robb Willer, a UC Berkeley sociologist who researches the ways individuals overcome selfishness to contribute to the social good. He has found that people have varying levels of altruism, depending on such things as their personality, parental influences and experience. Volunteering your time and giving money to charity tends to make people happier than spending money on themselves," Willer said. But for others, generosity pays. "It makes sense to be generous from a self-interested perspective," said Willer, who studies how people behave in groups. "If you're generous, you receive more respect, you have more influence and people cooperate with you more." Experiments Willer has conducted in five countries show that giving can be contagious. One of Willer's studies focused on users of the website freecycle.org, an online gift-giving community. Freecycle began in 2003 as an e-mail group in Tucson committed to reusing materials that would otherwise end up in landfills. Its only rule was that items be given without reciprocity or compensation. Freecycle has since grown to have more than 7 million members in 85 countries. The feeling of gratitude has driven the success of Freecycle, Willer found. "Giving in this community follows a pattern of contagious generosity, where if you received a gift from somebody else in the world, then you become more likely to give to somebody else in turn," he said.

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