Researchers at the University of Chicago report what they call the first evidence of “empathy-driven helping behavior” in rats.
The experiments, designed by psychology graduate student and first author Inbal Ben-Ami Bartal with co-authors Decety and Peggy Mason, placed two rats that normally share a cage into a special test arena. One rat was held in a restrainer device — a closed tube with a door that can be nudged open from the outside. The second rat roamed free in the cage around the restrainer, able to see and hear the trapped cagemate but not required to take action.
The researchers observed that the free rat acted more agitated when its cagemate was restrained, compared to its activity when the rat was placed in a cage with an empty restrainer. This response offered evidence of an “emotional contagion,” a frequently observed phenomenon in humans and animals in which a subject shares in the fear, distress or even pain suffered by another subject.
While emotional contagion is the simplest form of empathy, the rats’ subsequent actions clearly comprised active helping behavior, a far more complex expression of empathy. After several daily restraint sessions, the free rat learned how to open the restrainer door and free its cagemate. Though slow to act at first, once the rat discovered the ability to free its companion, it would take action almost immediately upon placement in the test arena.
A follow-up study presented the free rat with two restrainers: one containing another rat and one containing a pile of chocolate chips. To the researcher’s surprise, the free rat was as likely to free the restrained rat first and share the chocolate as he/she was to eat the chocolate first. (I can’t say I’d do the same.)
Interestingly, neither the UC press release, nor the other coverage I’ve seen mentions a much earlier study on possible empathy-driven helping behavior in rats, summarized by Mark Bekoff and Jessica Pierce in their book Wild Justice: The Moral Lives of Animals (see page 96):
Another early study in 1962 by George Rice and Priscilla Gainer titled “‘Altruism’ in the Albino Rat” showed that rats would help other rats in distress. One rat was suspended in air by a harness and a neighboring rat could press a lever to lower the suspended rat. The suspended animal would typically squeak and wriggle in distress. The rats were apparently made uncomfortable by signs of distress in a fellow rat, and would act to alleviate the distress by pressing the lever. Empathy likely motivated the ‘altruistic’ response.
That we continue to be surprised by pro-social behavior in social mammals… continues to be surprising. I hope to revisit this topic in a post sometime soon.
(Be sure to watch the video of the experimental procedure on the University of Chicago press release link.)