Blood donations are a famous oft-cited case of where we might get less of something of we pay more for it. Now it seems the problem is just with cash, not with payment; apparently we dislike an appearance of being paid, not payment itself:
We set up … a survey administered to 467 blood donors in an Italian town, and find that donors are not reluctant to receive compensation in general: A substantial share of respondents declared they would stop being donors if paid a small amount of cash, but we do not find such effects when a voucher of the same nominal value is offered instead. The aversion to direct cash payments is particularly marked among women and older respondents, while there are neither gender nor age differences in the response to the voucher.
More here.
People tend to have an irrational and dualistic view of trade. On the one hand, people see money as dehumanizing and exploitative. On the other hand, they get a feeling of warmth from exchanging gifts, and they see how two parties trading in kind can both be better off as a result.
By avoiding cash and presenting the deal as a trade-in-kind, we avoid the senseless prejudice that causes money to be viewed as dehumanizing and exploitative. The brain can then focus on the positive benefits of trade as a result.
So, yes, higher value vouchers would probably attract more donors, but the higher the value, the less flexible it has to be - the more it needs to be a voucher for a specific service, to avoid it being interpreted as money and again invoking all the prejudice.
Donated two days ago - our vampires have cookies! They are really good gourmet cookies but my physical reward is still limited to just cookies and juice (and sometimes soup) and the occasional shiny pin at milestones. I'm a Canuck, so blood donation and plasma donation and the like has always been voluntary unpaid. The 1.5 - 2 hours for the appointment and travel is considered to be paid time by my employer and I get free transportation to the clinic with coworkers as part of a "friendly" corporate challenge (how friendly can it be when it involves BLOOD, I ask you? :P ) but I was a donor long before that so all it influences is the timing of my donations.
I would probably still donate if donors got real, non-cookie incentives to donate but I wouldn't be as *happy* about it and I would definitely not spend as much time wheedling others into trying donation. Social bragging rights are a good incentive. I could see being ok with having my name entered into a draw but not with a direct handout, even if said handout was a lottery ticket. Odd, when I think about it -why should it feel different? It does, though.
Thank you for an interesting item and for the link.