The results of the control tests in Experiment 1 suggest that the existence of the soaking cagemate is important to generate the door-opening helping behavior. However, it is possible that the existence of the cagemate is simply enough to generate the behavior, i.e., it might not be necessary that the cagemate is in a distressed situation. To elucidate the importance of a cagemate being distressed, we investigated whether helper rats learned to open the door to allow the cagemate go through the partition when the cagemate was not in water.