News Release

Like humans, rats are less likely to help victims in the presence of unhelpful bystanders

The bystander effect in rats

Peer-Reviewed Publication

American Association for the Advancement of Science (AAAS)

A study in rats demonstrates that the bystander effect - a phenomenon in which individuals are less likely to help someone in need with other bystanders around - exists in a non-human species. Furthermore, while rats were less likely to rescue a rodent in need when surrounded by unhelpful bystanders, John Havlik and colleagues also observed that they were more likely to take action when their fellow bystanders were willing helpers. This finding aligns with recent evidence in humans, suggesting bystander behavior may either inspire others to act or suppress their will to intervene. "In the context of recent events worldwide, these results may inform our understanding of both the failure of police to help injured protesters and the ready offering of help by protesters to their injured peers," says Havlik. Research that led to the discovery of the bystander effect in humans was inspired by the 1964 murder of Catherine (Kitty) Genovese, whose death was reportedly witnessed by more than 35 of her neighbors, none of whom intervened (although the account was later deemed inaccurate). To investigate whether rats also exhibit the bystander effect, John Havik et al. gave two rats a low dose of the anti-anxiety drug midazolam. This did not anesthetize or incapacitate them, but reduced their level of interest in helping. These incompetent helpers were planted near potential helpers that encountered another rat trapped in a restrainer. In contrast to control rats, rats paired with incompetent helpers failed to consistently help release the distressed rat on subsequent days after opening the door once. Incompetent bystander rats only influenced the non-impaired bystanders if they belonged to a strain the non-impaired bystanders were familiar with (essentially, if they were part of their "in-group"). Havlik et al. suggest their findings in rats undermine conventional wisdom that the bystander effect occurs when an individual assumes others are responsible for taking action, lessening their own sense of responsibility. Instead, this phenomenon may stem from less cognitive mammalian processes.


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