December 8, 2011
Researchers Nicola Lacetera, Mario Macis and Robert Slonim present evidence from a natural field experiment involving nearly 100,000 individuals on the effects of offering economic incentives for blood donations.
- Subjects who were offered economic rewards to donate blood were more likely to donate, and more so the higher the value of the rewards.
- They were also more likely to attract others to donate, spatially alter the location of their donations toward the drives offering rewards, and modify their temporal donation schedule leading to a short-term reduction in donations immediately after the reward offer was removed.
Although offering economic incentives, combining all of these effects, positively and significantly increased donations, ignoring individuals who took additional actions beyond donating to get others to donate would have led to an underestimate of the total effect, whereas ignoring the spatial effect would have led to an overestimate of the total effect. The researchers also find that individuals who received a reward by surprise were less likely to donate after the intervention than subjects who received no reward, suggesting that for some individuals a surprise reward adversely affected their intrinsic motivations. In the study, the researchers discuss the implications of these findings for understanding pro-social behavior.
Source: Nicola Lacetera, Mario Macis and Robert Slonim, "Rewarding Altruism? A Natural Field Experiment," National Bureau of Economic Research, December 2011.
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