| dc.description.abstract | In social dilemmas entailing a conflict between self-interest and the interest of the collective there is often uncertainty about the size of the resource (resource uncertainty). In Common Pool Resource(CPR) dilemmas there is uncertainty about the size of the resource pool and in public-good (PG) dilemmas there is uncertainty about the provision threshold. Previous research has found that people underconditions of resource uncertainty overestimate the size of the resource and thereby request too much. The present thesis aimed at distinguishing between three possible explanations of this phenomenon.A perceptual explanation suggests that the effect is due to that subjects perceive a positive relationship between measures of central tendency and variability. Under increasing resource uncertainty thiswould thus lead subjects to overestimate the size of the resource and thereby request too much. Another possible explanation assumes that subjects weigh the upper and lower bound of the resource size inorder to make an estimate. It is further suggested that subjects fall victim of an outcome-desirability bias and overweigh the upper bound of the interval resulting in an upward shift of their estimates. Athird possible explanation takes into account that interdependence may play a role for the effect of resource uncertainty to occur. In line with the so-called constrained-egoism hypothesis, adhering to anequal-share fairness norm, may feel less compelling when the size of the resource is uncertain.In Experiment 1 of Study I we replicated previous findings in a standard CPR dilemma. Subjects requested more from the resource with increasing levels of resource uncertainty. Furthermore,overharvesting occurred in both an individual condition where outcomes only depended on a single individual as well as in a group condition where outcomes depended on the group, but not in a conditionwhere subjects guessed the size of the resource. These results spoke in favor of an explanation in terms of an outcome-desirability bias rather than a perceptual or a egoism bias. In Experiment 2 weobtained the same pattern of results in a step-level CPR dilemma. In Study II information about the size of the resource was given as a sequence of numbers representing previous resource sizes. The numbers were presented both sequentially and simultaneously. Theeffect of resource uncertainty was found to be less pronounced when subjects had access to all information at the same time (simultaneous presentation) as opposed to sequential presentation.Study III investigated size estimates and requests from an uncertain resource in a common-pool resource dilemma and in contributions in a public-good dilemma with an uncertain provision thresholdwhen participants are informed about others´ pessimistic estimates of the resource size or provision threshold. Supporting outcome-desirability bias participants cooperated more, rather than less, whenthey were informed about others´ estimates. These results were also replicated in Experiment 3 where the outcome did not depend on others´ requests or contributions. Study IV, Experiment 1 investigated situations in where all members of a group did or did not have access to the same information about resource size. In line with an outcome desirability bias hypothesisit was demonstrated that participants with certain information lowered their requests when knowing that subsequent players had uncertain information about the resource size. Experiment 2 compared agroup condition without fate control with an individual condition. Lending further support for the outcome-desirability bias explanation, overharvesting occurred in equal magnitude in both conditions.In conclusion, the results from all four studies strongly support an explanation of the effects of resource uncertainty in terms of an outcome-desirability bias. | en |
