When asked to volunteer their time to charity, Americans are likely to give more money.

Participants in an online survey read a statement about lung cancer and a cancer research foundation's mission. The participants who were asked to donate time eventually pledged more than those who weren't asked: $36.44 versus $24.46.

In the second test, the same researchers introduced undergraduate college students to HopeLab, a nonprofit organization that serves children with chronic illnesses. The average donation level was nearly five times higher for participants who were first asked about donating their time to the organization.

"Because time consumption is associated with emotional experiences, thinking about donating time reminds people of the happiness achieved through helping others," conclude the researchers, Wendy Liu at UCLA and Jennifer Aaker of Stanford University.

A third study replicated the findings of the first two and explored the feelings that arose when people thought about donating time.

"We argue that thinking about time activates goals of well-being and beliefs involving personal happiness. In contrast, thinking about money suppresses such emotional goals and instead activates goals of economic utility and beliefs about attainment of such goals," the authors write in the October issue of the Journal of Consumer Research.

They figure non-profits as well as for-profit organizations could benefit by incorporating the findings into their fund-raising strategies.