Do people donate to charities because altruism makes them feel good about themselves, or because of social pressure to donate? It matters because altruistically motivated giving benefits both the giver and the charity, since the giver enjoys giving, while social pressure motivated giving benefits only the charity. A new study from Stefano DellaVigna, John List, and Ulrike Malmendier uses a randomized field experiment and a structural model to estimate the extent to which giving to door-to-door charities is motivated by each:

We find evidence that both altruism and social pressure affect door-to-door charitable giving. We estimate that about half of donors would prefer not to be contacted by the fund- raiser either because they would prefer not to donate, or because they would prefer to donate less. We estimate a social pressure cost of turning down a giving request of $1 to $4, depending on the type of charity…. On average, we estimate the welfare effect of the door-to-door campaigns in our sample to be negative.

If their study is taken to be representative of door-to-door fundraisers, the authors claim that the welfare loss incurred by those being solicited for donation is in the hundreds of millions of dollars. Do we need a pigouvian tax for door-to-door charities?