Beyond the tax deduction, what motivates people to give money to charity? With Americans donating hundreds of billions of dollars to causes every year, it’s a question that directly affects nonprofits, and new academic research is trying to offer a clearer answer.

People may have internal or external reasons for behaving charitably, or they may be motivated by some blend of the two. One external incentive to give money is recognition, and charities tap into that by offering cards, gifts and special mentions on programs and websites. But a study published this year in The Journal of Marketing found that recognition seems to work only for a small subset of people — those who feel that it’s important to express their moral values to others, said Karen Winterich, an assistant marketing professor at Pennsylvania State University and one of the study’s authors.

People whose moral values are more internalized (for example, because of their religious beliefs) don’t need the promise of future recognition to be persuaded to donate, said Professor Winterich. This means charities may want to reconsider their spending levels on things like award dinners and gifts, she said.