The present study examined whether rats help their cagemates in an aversive situation. We used water to produce a
situation of distress. The results in Experiment 1 showed that rats quickly learned to open the door to rescue their
cagemate from the soaked situation. In addition, the three control tests (the pool, empty, and object tests) showed that
the distressed cagemate is necessary to induce the door opening behavior and that even if the door-opening behavior occurred with no cagemate, the latency was extremely prolonged when compared to that in the door opening sessions. Similarly, in Experiment 2, the rats did not open the door when the cagemate was not distressed even when it was next to the door. These results suggest that the door-opening behavior was motivated to liberate the cagemate from the distressing situation and thus that rats can behave prosocially (Mogil 2012; Panksepp and