[greeneggs]

Do you have any links? For example, Dupas writes,

"The third finding from recent pricing studies is that people need not have paid for something to value it. Households are as likely to use their bednet when they get it for free as when they have to pay for it (4, 7–9). People are as likely to use their water filter if they paid a lower price for it (2). This is surprising for two reasons. First, standard economic theory suggests that charging nontrivial user fees should help target products to those who need them the most—and thus those most likely to put them to appropriate use. But this reasoning breaks down when people face credit constraints and their ability to pay is lower than their willingness to pay. When those who could use a product the most are too poor to pay cash for it, higher prices screen out the poor, not just those with lower health returns from using the product (9). Second, it is often thought that the act of paying itself makes people value a product or service more; the feeling of “guilt” from having spent money on something that is left unused would make people more diligent users. However, experimental studies designed to test the importance of this psychological phenomenon suggest that this consideration is not important when it comes to essential health (2, 7, 10). The cost of poor health seems a good enough incentive to put products to good use."

Pascaline Dupas, "Getting essential health products to their end users: Subsidize, but how much?" Science 345:1279-1281, 2014. http://www.sciencemag.org/content/345/6202/1279.full.pdf?key...