Image concerns in pledges to give blood: Evidence from a field experiment

We use a field experiment to study how social image concerns affect a commonly used strategy to attract new donors: pledges to engage in a charitable activity. While waiting for their appointment, visitors to a local government office are offered sign-ups for blood donations in a crowded waiting room. We randomly vary the visibility of the pledge to donate and the organization for which blood donations are solicited (charitable vs. commercial). Our setting provides natural variation in who observes the pledge. We do not find that visibility increases pledges to donate. Exploring heterogeneity in treatment effects, we find that visibility increases pledges when participants are observed by friends or family. Almost all subjects renege on their pledge.