Interpersonal trust has long been known to influence cooperation. This
study tested the hypothesis that one's degree of trust in others will
influence the extent to which one reacts to the presence of fear (or
the possibility of receiving no payoff for cooperative actions) in a p
ayoff matrix. The hypothesis was formally tested with public goods gam
es and resource dilemma games, with fear manipulated. Results support
the hypothesis: when fear was present, high trusters cooperated more f
requently than low trusters; when absent, high and low trusters cooper
ated at the same rate. The findings held across both games. However, t
he effects of fear within each game were not straightforward: removing
fear from the resource dilemma increased low trusters' cooperation ra
tes, but removing fear from the public goods game decreased high trust
ers' cooperation rates. Results imply that discussion of the role of t
rust in cooperation must consider whether the particular dilemma conta
ins an element of fear.