Merely increasing bids increases charitable donation

Amid a sea of requests for aid, what factors affect decisions to donate? Here, we investigate the efficacy of a manipulation of choice architecture to affect giving: increasing the number of bids available to donors to increase how much they give. Across six experiments (N = 6,153), participants recruited online responded to single- or multiple-bid donation requests. Viewing multiple bids for aid increased both intention to donate and actual donation without decreasing the proportion of people who donated at all. We rule out previously documented heuristics (i.e., 1/n, fairness), anchoring, and agency as explanations for our effect. Finally, we replicate our effect in a natural experiment (N = 10,000 donors): Presenting donors, giving their own money, with multiple bids increased the average donation by $8.77 (a 19.7% increase). Our findings have theoretical implications for invigorating prosocial behavior and offer practical suggestions for how charitable organizations can better engineer solicitations for aid. (PsycInfo Database Record (c) 2025 APA, all rights reserved).