Rats are less likely to help a trapped companion if there are other rats around that aren’t helping, according to a new study from the University of Chicago. In other words, rats may also exhibit the social-psychological “bystander effect”.

In 1964, 28-year-old Kitty Genovese was brutally murdered while walking home, at night, in New York City. According to a sensationalized article published in New York Times at the time, there were 38 witnesses who watched the stabbings but did not intervene, nor did they call the police until after the attacker had fled. The original article was exaggerated but it is still referenced not only in the media but also in psychology textbooks, mostly because it serves as a parable for an important psychological effect. There was no helping Kitty Genovese, but maybe something good could come out of the story.

The effect is now called the Bystander Effect, and it hypothesizes that individuals are less likely to offer help to a victim when there are other people present. The greater the number of participants, the more the perceived responsibility is diffused among the group, and people are less likely to act. This is still an area of active research and the theory is challenged by some studies but now, things just got even more intriguing: because it seems that the bystander effect isn’t only limited to humans.

The study started in 2011, when Peggy Mason, professor of neurobiology, found that rats consistently free their trapped companions, even giving up on a bit of chocolate for them. The empathy of rats has been demonstrated in several later studies, and it’s already a well established phenomenon.

But Mason also found that when rats are treated with anti-anxiety medication, they are less likely to free a trapped peer because they are less likely to feel its anxiety. In another study, researchers found that rats were hesitant to save strangers, and only freed trapped rats they were familiar with. Rat empathy is remarkably similar to human empathy, maybe in more ways than we’d like to admit.

However, it was only recently that First author John Havlik, then an undergraduate student at the University of Chicago, brought this up in a lab meeting.

“My students had been bugging me to do this experiment for years,” said Mason. “But it wasn’t until John came along and would not let the idea go that we took the plunge.”

Havlik took on the task of testing the Bystander Effect on rats, but it wasn’t easy. First, he had to ensure that some of the rats wouldn’t help. This is where he used previous anti-anxiety medication research to turn some rats into passive bystanders. He then tested the effect of other rats, to see if they were less likely to intervene and help their peers if passive bystanders were nearby. They were.

“It’s worse to have a non-responsive audience than to be alone,” Mason said. “The rats try helping, but it’s just not a rewarding experience because the other rats don’t appear to care. It’s as though the rat was saying to himself, ‘I helped yesterday and no one cared. Not doing that again.’ “

Empathy is contagious

The thing is, we don’t really know if the bystander effect is real, and exactly how it manifests itself. It seems that both in rats and in humans, the group tends to accentuate behavior, but it’s not always clear what that behavior is.

Mason tried something different: she recreated the same scenario, but without drugging mice. In other words, the rats weren’t forced to be passive bystanders, they were bystanders who made their own choices.

Contrary to what was expected, teams of rats were actually more likely to help than solo rats.

“At first, I thought the experiment had failed,” Havlik said. “But after doing more research into human studies, we realized that behavior has actually been mirrored in people, too.”

This seemingly goes against everything we know about the Bystander Effect but as it turns out, a surveillance footage study published just last year found that humans actually helped in more than 90% of violent encounters.

The thing is — as is often the case in psychology research — we don’t fully understand the effect. But whatever the implications may be, the takeaway is that humans are not the only ones manifesting this type of behavior. Rats seem to be every bit as empathetic and chaotic as us.

“The reason we see these patterns of helpfulness goes deeper than the lessons we learned in kindergarten about being nice to each other,” said study co-author Maura Jacobi, MD, a 2020 graduate of the University of Chicago Pritzker School of Medicine and co-first author of the study. “This is a phenomenon that’s not exclusive to humans.”

Journal Reference: J.L. Havlik el al., “The bystander effect in rats,” Science Advances (2020). advances.sciencemag.org/lookup … .1126/sciadv.abb4205