How to hire helpers? Evidence from a field experiment

How to hire voluntary helpers? We shed new light on this question by reporting a field experiment in which we invited 2859 students to help at the ‘ESA Europe 2012’ conference. Invitation emails varied non-monetary and monetary incentives to convince subjects to offer help. Students could apply to help at the conference and, if so, also specify the working time they wanted to provide. Just asking subjects to volunteer or offering them a certificate turned out to be significantly more motivating than mentioning that the regular conference fee would be waived for helpers. By means of an online-survey experiment, we find that intrinsic motivation to help is likely to have been crowded out by mentioning the waived fee. Increasing monetary incentives by varying hourly wages of 1, 5, and 10 Euros shows positive effects on the number of applications and on the working time offered. However, when comparing these results with treatments without any monetary compensation, the number of applications could not be increased by offering money and may even be reduced.