Researchers from the University of California, Berkeley, found people perceive tainted or "dirty" money as less valuable, and feel the money has less purchasing power.

Social scientists from Berkeley, conducted a study to challenge the popular belief "all money is green," and that people would go to any lengths to attain it. According to the new study, scientists discovered the source of money does matter to people. They perceive tainted or "dirty" money as less valuable, and feel this money has less purchasing power.

"Our work suggests morality is an important force shaping economic decision-making," said Jennifer Stellar, a doctoral student in psychology and lead author of the study. "Though we often think $50 is $50, these results demonstrate that when money takes on negative moral associations, its value is diminished."

During the study, scientists examined the psychological thinking behind tainted money, like social responsibility, investing and the boycotting of taint-produced goods.

"People possess powerful motivations to view themselves as fundamentally good and moral," said Robb Willer, associate professor of sociology at Stanford University and co-author of the paper. "We find this motivation is so great that it can even lead people to disassociate themselves from money that has acquired negative moral associations."

For the study, 59 student participants were asked to take part in a raffle contest for a prize of $50. The students were divided into two groups, namely, "neutral money" and "immoral money." The "neutral money" group was told the prize was sponsored by retail giant Target while the "immoral money" group was told that the money was sponsored by Walmart.

The second group was also told about the 2005 lawsuit by the International Labor Rights Forum that alleged Walmart had failed to meet internationally mandated labor standards, and that the prize money may be linked to this.

Both groups were given as many as 70 tickets and said they could fill in as many tickets as they wanted with their names and contact details, and drop them in the raffle draw. Students belonging to the "immoral money" group filled in far lesser tickets than the "neutral money" group, proving that the source of money does matter to people.

The study was published in an online issue of the journal Social Psychological and Personality Science.