The free rat was agitated when its cagemate was trapped, which the researchers say is evidence of "emotional contagion," a lower form of empathy in which animals share in the fear or distress of another animal. But what happened next was much more like true empathy. Although the rats were agitated, they didn't freak out, freeze or become overwhelmed with fear, which is one possible reaction to emotional contagion. Instead, they coolly circled the container, bit it, clawed at it and generally spent time near it, even reaching through holes to touch (and comfort?) the trapped rat.