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Monday, March 25, 2013

How to get people to donate blood

If you want people to do something, is it better to tell them what wonderful things will happen if they do as you ask, or what terrible things will happen if they don’t? In other words, should you entice or threaten? That’s a question Eileen Chou from the University of Virginia and Keith Murnighan of Northwestern University set out to answer, at least with respect to blood donation.

There are chronic shortages in the supply of blood available for transfusions. Hopefully, the need for donated blood will someday be eliminated by the development of artificial blood. In the meantime, however, the Red Cross is working on getting more people to donate blood. To that end, they took a close look at the messaging used to encourage people to donate blood.

The authors sent 3500 undergraduates one of five different emails soliciting blood donations. One email merely stated the time and place at which the recipient could donate blood. The other four were framed as either saving lives (gains to be made if the subject accedes to the request) or preventing deaths (losses to be suffered if the person doesn’t comply). In addition, each version was presented either as being urgent or moderately important.

Here’s the urgent, loss prevention message:
Don’t delay. Help prevent someone from dying! Each year, 4.5 million Americans would die without blood transfusions. Every second, 2 people could die waiting for blood. Every pint that you donate can help them avoid dying. Don’t delay! Help prevent unnecessary deaths.
And the moderate need, gain message: 
Act now. Help save someone’s life! Every day, many people could be saved by donated blood. Every pint that you donate can help them stay healthy. Act now! Promote healthy lives.
I haven’t included the other two variations, but you get the idea. Which message would be more likely to drive you to the donation site? It turns out that the ‘prevent a death’ message was far more successful than the ‘save a life’ message. More than three times as many people showed up to donate blood after receiving the ‘loss’ message than did for the ‘gain’ message. Interestingly, the degree of need did not seem to matter very much. Perhaps, people already have a sense of how essential it is to donate blood.

This greater desire to prevent loss versus to achieve gain has been documented in other arenas. The authors of this study performed a second study in which they tested whether requests to prevent a charity from no longer being able to provide services would elicit more or fewer contributions than requests to increase that charity’s services. Again, people were more charitable to prevent losses.

I guess the lesson from this data is that if you want someone to do something, give them the doomsday scenario and not the possible utopia their actions could create.



Chou, E., & Murnighan, J. (2013). Life or Death Decisions: Framing the Call for Help PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0057351.