Abstract: The ability of distance perception enables us to estimate the distance between objects and thereby interact efficiently with the world. Theoretically, the vision should perceive the distance accurately. While it has been largely found that the perceived distance is distorted, to adapt to act on the objects. Previous studies have revealed that the physical relation between objects and the categorical relation between objects can influence the perception of distance. Nevertheless, due to that individuals are always socially interact, the social relation is always perceived between two objects, and how this information modulate distance perception is still unknown. The present study is aimed to explore how the social cooperation information influence the distance perception, given that this kind of social relation is core to dominate our interaction. To address the above question, we manipulated the cooperation information by presenting two chasers and one common target to perform cooperative or individual chases. Subjects were required to estimate the distance between two chasers when the agents stopped moving. The perceived distance of cooperative chases was compared with the individual chases. To assess whether the perceived distance was expanded or compressed by the cooperation information, the perceived distance of both cooperative chases and individual chases were also compared with that of the random motion, wherein the two chasers moved randomly (Experiment 1). In our used chasing scenes, the behaviors of chasers responded to those of the target continuously, and thus it is critical to take into consideration of the target (or goal) when understanding the interactions. That is to say, if the prey becomes invisible, the observer will be hard to get the intents of the chasers though they are still moving in exactly the same way with the presence of target. Hence, we also established a direct manipulation of the goal-directedness of one chaser’s movements to disrupt cooperation information (Experiment 2), to control for possible low-level physical properties and further examine whether the observed effect in Experiment 1 was reasoned by the social information. It was found that: (1) The perceived distance was influenced by the social cooperation information, and the perceived distance of cooperative chases was farther than both individual chases and random motion, but there was no different between individual chases and random motion; (2) When the social cooperation information was disrupted through making the target invisible, even the physical relation between two chases was kept the same as before, no significant defense was found across cooperative chases, individual chases and random motion; namely, if the social cooperation information is not present, the above effects vanishes. Therefore, the current study indicated that the perceived distance between two objects with social cooperation is expanded and such effect can’t be explained by the low-level properties, suggesting that the social relation information also modulates the perception of distance between objects. This finding is consistent with the view in which the high-level information can penetrate into low-level processes. In addition, the current finding could help us understand more about how the social information interacts with the perception of distance.

Key words: Social Cooperation, Distance Perception, Social Interaction, Chasing Scene

摘要： 为探讨社会合作信息对距离知觉的影响，本研究通过两个实验，采用动态追逐场景，对两个追逐者之间的交互模式(或合作或单独追逐同一目标)与追逐目标的存在与否进行了操作。结果发现，相比随机运动和单独追逐，存在合作关系的两个追逐者间的距离被知觉得更远，即存在距离的扩张效应(实验1)，且该效应不能由底层的物理特征所解释(实验2)。该结果揭示，社会合作信息使得知觉距离被扩张，其可帮助理解视觉的适应性机制。

关键词: 社会合作, 距离知觉, 社会交互, 追逐场景