To investigate whether the classic bystander effect is unique to humans, the effect of bystanders on rat helping was studied. In the presence of rats rendered incompetent to help through pharmacological treatment, rats were less likely to help due to a reduction in reinforcement rather than to a lack of initial interest. Only incompetent helpers of a strain familiar to the helper rat exerted a detrimental effect on helping; rats helped at near control levels in the presence of incompetent helpers from an unfamiliar strain. Duos and trios of potential helper rats helped at superadditive rates, demonstrating that rats act nonindependently with helping facilitated by the presence of competent-to-help bystanders. Furthermore, helping was facilitated in rats that had previously observed other rats’ helping and were then tested individually. In sum, the influence of bystanders on helping behavior in rats features characteristics that closely resemble those observed in humans.

为了研究经典的旁观者效应是否是人类独有的，我们研究了旁观者对老鼠帮助的影响。当老鼠无法通过药物治疗提供帮助时，老鼠不太可能提供帮助，因为强化程度减少，而不是缺乏最初的兴趣。只有辅助鼠熟悉的品系的无能辅助者才会对帮助产生有害影响。在来自不熟悉品系的无能助手存在的情况下，老鼠的帮助水平接近控制水平。潜在的辅助老鼠的二人组和三人组以超加和率提供帮助，这表明老鼠在有能力提供帮助的旁观者的存在下会非独立地提供帮助。此外，先前观察到其他老鼠的帮助并随后进行单独测试的老鼠的帮助得到了促进。总之，旁观者对老鼠帮助行为的影响具有与人类观察到的特征非常相似的特征。