Ditz Helen M, Nieder Andreas
Animal Physiology, Institute of Neurobiology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
Animal Physiology, Institute of Neurobiology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
Proc Biol Sci. 2016 Mar 30;283(1827):20160083. doi: 10.1098/rspb.2016.0083.
The ability to estimate number is widespread throughout the animal kingdom. Based on the relative close phylogenetic relationship (and thus equivalent brain structures), non-verbal numerical representations in human and non-human primates show almost identical behavioural signatures that obey the Weber-Fechner law. However, whether numerosity discriminations of vertebrates with a very different endbrain organization show the same behavioural signatures remains unknown. Therefore, we tested the numerical discrimination performance of two carrion crows (Corvus corone) to a broad range of numerosities from 1 to 30 in a delayed match-to-sample task similar to the one used previously with primates. The crows' discrimination was based on an analogue number system and showed the Weber-fraction signature (i.e. the 'just noticeable difference' between numerosity pairs increased in proportion to the numerical magnitudes). The detailed analysis of the performance indicates that numerosity representations in crows are scaled on a logarithmically compressed 'number line'. Because the same psychophysical characteristics are found in primates, these findings suggest fundamentally similar number representations between primates and birds. This study helps to resolve a classical debate in psychophysics: the mental number line seems to be logarithmic rather than linear, and not just in primates, but across vertebrates.
估计数量的能力在动物界广泛存在。基于相对较近的系统发育关系（以及因此等效的脑结构），人类和非人类灵长类动物的非语言数字表征显示出几乎相同的行为特征，这些特征遵循韦伯 - 费希纳定律。然而，具有非常不同端脑组织的脊椎动物的数量辨别是否表现出相同的行为特征仍然未知。因此，我们在一个类似于先前用于灵长类动物的延迟样本匹配任务中，测试了两只食腐鸦（小嘴乌鸦）对从1到30的广泛数量范围的数字辨别能力。乌鸦的辨别基于一个类似数字系统，并显示出韦伯分数特征（即数量对之间的“刚好可察觉差异”与数值大小成比例增加）。对表现的详细分析表明，乌鸦的数量表征是在对数压缩的“数字线”上进行缩放的。因为在灵长类动物中也发现了相同的心理物理学特征，这些发现表明灵长类动物和鸟类之间在数字表征上基本相似。这项研究有助于解决心理物理学中的一个经典争论：心理数字线似乎是对数的而不是线性的，并且不仅在灵长类动物中如此，在整个脊椎动物中也是如此。
