Abstract
Charitable giving depends on individuals' abilities to make altruistic decisions. Previous studies suggest that altruism involves recruitment of neural resources in regions including social processing, reward/reinforcement learning, emotional response, and cognition. Despite evolutionary and social benefits to altruism, we know that humans do not always engage in altruistic behavior, like charitable giving. Understanding the underlying processes leading to decisions to donate is vital to improve prosocial community engagement. The present study examined how characteristics of the charitable giving opportunity influence an individual's decision to give and the neural engagement underlying these features. Twenty-nine participants subjectively rated ten charities on their value, effectiveness, and the subject's personal chance of donating. Participants then completed an fMRI task requiring them to decide to donate to certain charities given the probability of the donation helping, their personal preference for the charity, and whether the donation came at cost to themselves. There was a significant reduction in donating when the probability of helping was low versus high, and subjects were significantly less likely to donate to their lowest-rated charities. Further, probability of a donation being helpful and how much the subject favored a charity moderated PCC and left IFG engagement. Interestingly, reward neurocircuitry did not demonstrate similar sensitivity to these variations. These results may suggest individuals engage motivated reasoning to justify failure to donate, while donations are driven by emotion mentalizing that focuses on the welfare of others. This may provide valuable insight into how to engage individuals in altruistic giving.