Transfer from number to size reveals abstract coding of magnitude in honeybees

Number discrimination has been documented in honeybees. It is not known, however, whether it reflects, as in vertebrates, the operating of an underlying general magnitude system that estimates quantities irrespective of dimensions (e.g., number, space, time) and format (discrete, continuous). We trained bees to discriminate between different numerical comparisons having either a 0.5 (2 vs. 4; 4 vs. 8) or 0.67 ratio (2 vs. 3; 4 vs. 6). Bees were then tested for spontaneous choice using comparisons with identical numbers but different sizes. Irrespective of the ratio of stimuli, bees trained to select the smaller numerical quantity chose the congruent smaller size; bees trained to select the larger numerical quantity chose the congruent larger size. This finding provides the evidence for a cross-dimensional transfer between discrete (numerical) and continuous (spatial) dimensions in an invertebrate species and supports the hypothesis of a cognitive universality of a coding for general magnitude.已有研究证实蜜蜂具备数量辨别能力。但目前仍不清楚，这种能力是否如同脊椎动物那般，依赖于一套底层的通用量级系统（general magnitude system）：该系统能够对数量进行估算，且不受维度（如数量、空间、时间）与呈现形式（离散、连续）的限制。本研究训练蜜蜂对两组不同的数量对比进行辨别：一组比例系数为0.5（2对4、4对8），另一组为0.67（2对3、4对6）。随后，研究团队使用数量相同但尺寸不同的对比刺激，对蜜蜂开展自发选择测试。无论刺激的比例系数如何，经过训练选择较小数量的蜜蜂，会优先选择尺寸匹配的更小刺激；而经过训练选择较大数量的蜜蜂，则会优先选择尺寸匹配的更大刺激。该发现为无脊椎动物物种中离散（数量）与连续（空间）维度间的跨维度迁移（cross-dimensional transfer）提供了实证依据，并佐证了“通用量级编码具有认知普遍性”的假说。