The researchers worked with the charity, Freedom from Hunger, to send out two nearly identical letters.
In the first experimental wave, the control group received an emotional appeal focused on a specific beneficiary, along with a narrative explaining how FFH ultimately helped the individual. The treatment group received a similar emotional appeal (trimmed by one paragraph), with an added paragraph about scientific research on FFH’s impact. The second wave was identical in design, except that the treatment group narrative included more specifics on the research, and briefly discussed randomized trials and their value as impact assessment tools.
They found that adding the scientific data didn’t have an impact on whether someone donated and how much they donated in the full sample. However, the full sample includes previous donors as well as those who had never donated before.
There was a significant difference when they looked at just those who had previously made a donation. (I have inserted a paragraph break to the original text to provide easier reading)
We find that presenting positive information about charitable effectiveness increases the likelihood of giving to a major U.S. charity for large prior donors, but turned off small prior donors. This heterogeneity is important, we believe, and is consistent with a model in which large donors (holding all else equal, including income and wealth) are more driven by altruism and small donors more driven by warm glow motives.
Altruistic donors, we posit, are more driven by the actual impact of their donation, and thus information to reinforce or enhance perceived impacts will drive higher donations. On the other hand, for warm glow donors, information on impacts may actually deter giving by distracting the letter recipient from the emotionally powerful messages that typically trigger warm glow and instead put forward a more deliberative, analytical appeal which simply does not work for such individuals.
Now whether the results for a large national human services charity will be consistent for a smaller, regional cultural charity, is uncertain. The fact that larger donors may be motivated by evidence of effectiveness and smaller donors by emotional appeal and turned off by effectiveness data is definitely something to think about.