Resource stock levels in common-pool resources have received little attention by academic research so far, and the results delivered are inconclusive as of yet. Furthermore, the reactions of users to resource changes, and the related variations in the levels of cooperation are still mostly unknown. In this paper we present the result of an experimental study that aims to test the effect of both resource changes and stock levels on harvesting behavior. We conducted common-pool resource laboratory experiments, using a student sample, with different resource stock levels, in order to test for differences in harvesting behavior, and presenting them just a payoff table, to minimize framing effects. We also collected further personal data and we tried to define what goal the students chose for themselves during the game. Our results suggest that, at least without framing the experiment, the resource levels do not induce different behavior, while other-related preferences seem to play a major role.