Laboratory of Systems Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai, Japan.
Department of Sensory Science, Kawasaki University of Medical Welfare, Okayama, Japan.
Sci Rep. 2018 Oct 26;8(1):15878. doi: 10.1038/s41598-018-33349-3.
A functional category is a set of stimuli that are regarded as equivalent independently of their physical properties and elicit the same behavioral responses. Major psychological theories suggest the ability to form and utilize functional categories as a basis of higher cognition that markedly increases behavioral flexibility. Vaughan claimed the category use in pigeons on the basis of partition, a mathematical criterion for equivalence, however, there have been some criticisms that the evidence he showed was insufficient. In this study, by using a group reversal task, a procedure originally used by Vaughan, we aimed to gather further evidence to prove the category use in animals. Macaque monkeys, which served as subjects in our study, could efficiently perform the task not only with familiar stimulus sets as Vaughan demonstrated but also with novel sets, and furthermore the task performance was stable even when the number of stimuli in a set was increased, which we consider as further evidence for the category use in animals. In addition, by varying the timing of the reversal, we found that a category formation takes place soon after encountering new stimuli, i.e. in a few blocks of trial after a novel stimulus set was introduced.
功能类别是一组被视为等价的刺激物，它们独立于其物理属性，引发相同的行为反应。主要的心理理论表明，形成和利用功能类别是提高行为灵活性的更高认知能力的基础。沃恩（Vaughan）声称鸽子具有类别使用能力，其依据是分区，这是等价的数学标准，但也有一些批评认为他所展示的证据不足。在这项研究中，我们通过使用群组反转任务（group reversal task），一种最初由沃恩（Vaughan）使用的程序，旨在收集更多证据证明动物具有类别使用能力。作为我们研究对象的猕猴不仅能够像沃恩（Vaughan）所展示的那样，使用熟悉的刺激集有效地完成任务，还能够使用新的刺激集，而且即使在一个刺激集中的刺激数量增加时，任务表现也很稳定，我们认为这是动物具有类别使用能力的进一步证据。此外，通过改变反转的时间，我们发现类别形成发生在遇到新刺激后不久，即在引入新的刺激集后的几个试验块中。
