Data from: Dispositional free riders do not free ride on punishment

Strong reciprocity explains prosocial cooperation by the presence of
individuals who incur costs to help those who helped them (‘strong
positive reciprocity’) and to punish those who wronged them (‘strong
negative reciprocity’). Theories of social preferences predict that in
contrast to ‘strong reciprocators’, self-regarding people cooperate and
punish only if there are sufficient future benefits. Here, we test this
prediction in a two-stage design. First, participants are classified
according to their disposition towards strong positive reciprocity as
either dispositional conditional cooperators (DCC) or dispositional free
riders (DFR). Participants then play a one-shot public goods game, either
with or without punishment. As expected, DFR cooperate only when
punishment is possible, whereas DCC cooperate without punishment.
Surprisingly, dispositions towards strong positive reciprocity are
unrelated to strong negative reciprocity: punishment by DCC and DFR is
practically identical. The ‘burden of cooperation’ is thus carried by a
larger set of individuals than previously assumed.