Langford et al. examined empathy in rodents using an approach based in neuroscience. They reported that (1) if two mice experienced pain together, they expressed greater levels of pain-related behavior than if pain was experienced individually, (2) if experiencing different levels of pain together, the behavior of each mouse was modulated by the level of pain experienced by its social partner, and (3) sensitivity to a noxious stimulus was experienced to the same degree by the mouse observing a conspecific in pain as it was by the mouse directly experiencing the painful stimulus. The authors suggest this responsiveness to the pain of others demonstrated by mice is indicative of emotional contagion, a phenomenon associated with empathy, which has also been reported in pigs. One behaviour associated with fear in rats is freezing. If female rats experience electric shocks to the feet and then witness another rat experiencing similar footshocks, they freeze more than females without any experience of the shocks. This suggests empathy in experienced rats witnessing another individual being shocked. Furthermore, the demonstrator's behaviour was changed by the behaviour of the witness; demonstrators froze more following footshocks if their witness froze more creating an empathy loop.