Logic says that our charity dollars would do the most good if we donated them to organizations that were the most effective — that is, if we treated donations like investments. But it turns out that’s not how people generally behave when it comes to charitable giving: Donors tend to act more on emotion than rationality when choosing organizations to support. New research from Wharton marketing professor Deborah Small examines why that’s so. Her paper is titled, “ Impediments to Effective Altruism: The Role of Subjective Preferences in Charitable Giving ,” and was coauthored with Jonathan Z. Berman, Alixandra Barasch and Emma E. Levine. Small recently spoke with Knowledge at Wharton about the paper and its implications for donors and organizations. An edited transcript of the conversation follows. Knowledge at Wharton: It seems that many of us rely more on our hearts than our minds when it comes to picking charities. What is it about acting with our emotions that causes problems with charitable giving?…