Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command.

中文翻译：

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人类快速扫视眼动表明数量感知是自动和直接的

快速眼跳是对显着和生态上重要的视觉刺激（如动物和面部）的快速自动眼动反应。区分朋友、敌人或猎物的数量也可能具有进化优势。在这项研究中，参与者被要求快速扫视两个阵列中更多的阵列。参与者可以以高准确度和极快的速度区分数字，最快可达 190 毫秒。与非常低或非常高的数字相比，中等数字更可能引起快速眼跳。声音反应的反应时间（在单独的实验中收集）较慢，不依赖于数值范围，并且仅与缓慢而不是快速扫视相关，指向不同的系统。我们观察到的短扫视反应时间令人惊讶，因为使用数量估计的区分被认为需要相对复杂的神经回路，通过顶叶和前额叶皮层传递几个信息。我们的结果表明，可以在单个前馈信息传递中生成快速数字驱动的扫视，该系统招募原始系统，该系统穿过皮层层次结构并将数字信息快速转换为扫视命令。