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.

学界已证实蜜蜂具备数量辨别能力。然而目前尚不清楚，这种能力是否如同脊椎动物一般，依托于一套通用量级系统（general magnitude system）运作——该系统可不受维度（如数量、空间、时间）与呈现形式（离散、连续）的限制，对数量进行估算。我们通过两类比例的数量对比任务训练蜜蜂：一类比例为0.5（即2与4、4与8的对比），另一类比例为0.67（即2与3、4与6的对比），要求蜜蜂完成数量辨别。随后，我们采用数量相同但尺寸不同的对比任务，测试蜜蜂的自发选择偏好。无论刺激物的比例如何，经过训练选择较小数量的蜜蜂，会优先选择尺寸更小的匹配刺激；而经过训练选择较大数量的蜜蜂，则会优先选择尺寸更大的匹配刺激。这一发现为无脊椎动物中离散（数量）与连续（空间）维度间的跨维度迁移提供了实验证据，并支持了通用量级编码具有认知普适性的假说。