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Examining the influence of others on joint actions could clarify the basal mechanisms underlying social coordination in non-human animals. The joint Simon task is used for this purpose, and some non-human animals have demonstrated the joint Simon effect. However, previous investigations have only demonstrated the effect among familiar dyads despite the potential importance of social relationships for task performance. In this study, we investigated joint Simon effects using two rat strains (Wistar and Long-Evans) that differ in appearance. We performed exploratory testing to examine whether familiarity between dyads affects the size of the joint Simon effect. We compared the joint Simon effects that emerged when subjects (N = 8) were paired with familiar cagemates to when they were paired with stranger non-cagemates. After discrimination training, the rats performed the joint Simon task with two auditory stimuli (2 and 4 kHz tones). Rats showed a significant joint Simon effect when paired with a cagemate partner, replicating earlier findings. Although rats showed a greater compatibility effect when paired with cagemates than with non-cagemates, the small sample size and repeated dyads warrant cautious interpretation. Our findings suggest that the attention of rats is drawn to adjacent partners during a joint task, even in the absence of explicit benefits. The exploratory results on familiarity suggest the possibility that perceived similarity between partners induces a larger joint Simon effect in rats.探究他人对联合行动的影响，有助于阐明非人类动物社会协调的潜在基本机制。为此，学界常采用联合西蒙任务（joint Simon task）开展相关研究，已有部分非人类动物被证实可表现出联合西蒙效应。然而过往研究仅在熟悉配对组中验证了该效应，尽管社会关系对任务表现或具有潜在重要意义。本研究选用外观存在差异的两种大鼠品系——Wistar与Long-Evans，探究联合西蒙效应。我们通过探索性实验，检验配对双方的熟悉程度是否会影响联合西蒙效应的强度。我们对比了两种配对情境下的联合西蒙效应：其一为实验对象（样本量N=8）与熟悉的同笼伙伴配对，其二为与陌生的非同笼伙伴配对。在完成辨别训练后，大鼠需完成包含两种听觉刺激（2kHz与4kHz纯音）的联合西蒙任务。当与同笼伙伴配对时，大鼠表现出显著的联合西蒙效应，这一结果重复了此前的研究发现。尽管相较于与非同笼伙伴配对，大鼠在与同笼伙伴配对时呈现出更强的相容性效应，但由于样本量较小且存在重复配对组，对该结果的解读需保持审慎。本研究结果表明，即便不存在明确的收益，大鼠在联合任务中也会将注意力投向相邻的同伴。此次关于熟悉度的探索性结果提示，伙伴间的感知相似性或许可诱导大鼠产生更强的联合西蒙效应。