An article in Science by Nicola Lacetera, Mario Macis, and Robert Slonim summarizes their research on economic incentives and blood donation (abstract; PDF). Contrary to previous studies, the researchers found that various incentives, from gift cards to a day off, increased blood donation:
Overall, 18 of the 19 distinct incentive items offered in observational and field experimental studies increased blood donations, and the effects were larger for items of higher monetary value; only one reward offer, a free cholesterol test, had no effect. When data were available (for 15 of the items), no effect on blood safety was detected. Finally, although temporary rewards might affect long-term motivations, no post intervention effects on donations were found, including any negative effects deriving from potential motivation loss.
In Freakonomics, we mentioned Richard Titmuss‘s landmark 1970 study on blood donations, which found that offering money for blood actually hurt donations. The new research urges a policy overhaul:
The position and guidelines of the World Health Organization (WHO) and several national blood collection agencies for nearly 40 years have been based on the view that offering economic incentives to blood donors is detrimental to the quantity and safety of the blood supply. The guidelines suggest that blood should be obtained from unpaid volunteers only.
However, whether economic incentives positively or negatively affect blood donations (and other prosocial activities) has remained the subject of debate since the positions were established.
Evidence consistent with the WHO position came originally from uncontrolled studies using nonrandom samples and, subsequently, from surveys and laboratory studies indicating that economic incentives can “crowd out” (decrease) intrinsic motivations to donate and can attract “worse” donors.