Abstract
The high importance of career-oriented motivations within the group of young volunteers and recent evidence that volunteering can improve employment opportunities, suggest that job references can motivate young adults to take up a social engagement, but not necessarily to carry it out regularly, with high intensity for a long period of time. We hypothesize that job references with information on individual engagement can motivate new volunteers to perform at a higher level compared to traditional references without individual performance information. In order to test this hypothesis, we implement both types of reference in a series of field experiments in which younger volunteers assist older citizens in completing tasks with their smartphone or tablet computer. The preliminarily results confirm that providing detailed performance information with the certificate increases the volume of individual volunteer work. The strength of this motivational effect varies depending on the underlying performance assessment mechanism (bonus system, single bet, repeated betting).

Keywords
job references, virtual volunteering, nonmonetary incentives, habit formation, intergenerational cooperation, performance assessment mechanism