Public image is a strong motivator when it comes to charitable giving, according to a study by three researchers from Duke, Tel Aviv, and Columbia Universities, reports The Economist. But providing monetary incentives for people to donate time, money, or blood can actually be counterproductive when the giving is motivated by a desire for the donor to “look good” in the public eye, the article says.

In the paper, “Doing Good or Doing Well? Image Motivation and Monetary Incentives in Behaving Prosocially,” which will be published in the March 2009 edition of the American Economic Review, researchers found that donors were more likely to give more when their efforts were announced publicly to a group.