Social preferences are stable over long periods of time

We measure people's pro-social behavior, in terms of voluntary money and labor contributions to an archetypical public good, a bridge, and in terms of voluntary money contributions in a public good game, using the same non-student sample in rural Vietnam at four different points in time from 2005 to 2011. Two of the observed events are actual voluntary contributions (one in terms of money and one in terms of labor), one is from a natural field experiment, and one is from an artefactual field experiment. Despite large contextual variations, we find a strong positive and statistically significant correlation between voluntary contributions, whether correcting for other covariates or not. This suggests that pro-social preferences are fairly stable over long periods of time and contexts.