By Michael Marshall
Anil Kumar / Alamy
Rats will often help their fellows if they are in distress, but they can be influenced not to – if other rats seem uninterested in the situation. This so-called bystander effect has been studied in humans for 50 years. That it also exists in rats suggests it has deep evolutionary roots.
However, the bystander effect doesn’t mean what many people have understood it to: that a person in distress is unlikely to receive help. The opposite is true.
Research into the bystander effect was prompted by the 1964 murder of Catherine “Kitty” Genovese in New York City. A New York Times article claimed that 38 witnesses saw the killing unfold for over 30 minutes but didn’t help or raise the alarm. It was a shocking story, though it later emerged that most did not see enough to know what was happening.
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Psychologists soon found laboratory evidence that people were less likely to help if they were part of a crowd than if they were alone, says Peggy Mason at the University of Chicago in Illinois. But this had to be done in an artificial way using “confederates” – researchers instructed not to help.
Mason’s team has now shown the same effect in rats. The team trapped one rat in a plastic tube that could only be opened from the outside by a second rat. Lone rats are quick and eager to help. “The only reason the rat does this is because it feels good,” says Mason. “We’re not giving any food.”
This changed when additional rats were introduced. These “confederate” rats had been given midazolam, which reduced their emotional response to the trapped rat, so they didn’t try to help. Now the original rat became less likely to assist. This was the bystander effect in action.
However, the team also performed a twist on the experiment, by introducing additional rats that weren’t drugged, but which hadn’t seen the tube before. These naive rats made the experienced rats more likely to help. “If you’re alone, it feels dicey to go in and intervene,” says Mason. “But if there’s three of you, that’s mitigated.”
This helps explain a 2019 study of surveillance footage of real-life altercations, which found that bystanders helped in over 90 per cent of cases – and that they were more likely to help if they were part of a group.
Mason says emotionally unengaged bystanders really can suppress others from helping, as the laboratory studies show. But in reality, if you do get attacked and there are people around, they will probably help you, she says.
Journal reference: Science Advances, DOI: https://doi.org/10.1126/sciadv.abb4205
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