Research Unit Behavioural Physiology, Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee 2, Dummerstorf, Germany.
Anim Cogn. 2012 Jul;15(4):567-76. doi: 10.1007/s10071-012-0485-y. Epub 2012 Mar 29.
The ability to establish categories enables organisms to classify stimuli, objects and events by assessing perceptual, associative or rational similarities and provides the basis for higher cognitive processing. The cognitive capabilities of farm animals are receiving increasing attention in applied ethology, a development driven primarily by scientifically based efforts to improve animal welfare. The present study investigated the learning of perceptual categories in Nigerian dwarf goats (Capra hircus) by using an automated learning device installed in the animals' pen. Thirteen group-housed goats were trained in a closed-economy approach to discriminate artificial two-dimensional symbols presented in a four-choice design. The symbols belonged to two categories: category I, black symbols with an open centre (rewarded) and category II, the same symbols but filled black (unrewarded). One symbol from category I and three different symbols from category II were used to define a discrimination problem. After the training of eight problems, the animals were presented with a transfer series containing the training problems interspersed with completely new problems made from new symbols belonging to the same categories. The results clearly demonstrate that dwarf goats are able to form categories based on similarities in the visual appearance of artificial symbols and to generalise across new symbols. However, the goats had difficulties in discriminating specific symbols. It is probable that perceptual problems caused these difficulties. Nevertheless, the present study suggests that goats housed under farming conditions have well-developed cognitive abilities, including learning of open-ended categories. This result could prove beneficial by facilitating animals' adaptation to housing environments that favour their cognitive capabilities.
分类能力使生物体能够通过评估感知、联想或理性相似性来对刺激物、物体和事件进行分类，并为更高层次的认知处理提供基础。在应用动物行为学中，农场动物的认知能力越来越受到关注，这一发展主要是由基于科学的努力来改善动物福利所驱动的。本研究通过在动物围栏内安装自动化学习设备，研究了尼日利亚矮山羊（Capra hircus）对感知类别的学习能力。13 只群居山羊在封闭经济的方法下接受训练，以区分在四选一设计中呈现的人工二维符号。这些符号属于两类：一类，黑色符号，中间有开口（奖励）；另一类，相同的符号，但填充黑色（不奖励）。从第一类中选择一个符号，以及从第二类中选择三个不同的符号来定义一个辨别问题。在训练了 8 个问题后，向动物呈现一个转移系列，其中包含训练问题，以及与同一类别中属于新符号的全新问题穿插在一起。结果清楚地表明，矮山羊能够根据人工符号的视觉外观相似性形成类别，并对新符号进行概括。然而，山羊在辨别特定符号方面存在困难。这些困难很可能是由于感知问题引起的。尽管如此，本研究表明，在农场条件下饲养的山羊具有发达的认知能力，包括开放式类别学习。这一结果可能通过促进动物适应有利于其认知能力的饲养环境而变得有益。
