Fragaszy Dorothy Munkenbeck, Kuroshima Hika, Stone Brian W
Psychology Department, University of Georgia, Athens, Georgia, United States of America.
Psychology Department, Kyoto University, Kyoto, Japan.
PLoS One. 2015 Oct 6;10(10):e0140033. doi: 10.1371/journal.pone.0140033. eCollection 2015.
Effective vision for action and effective management of concurrent spatial relations underlie skillful manipulation of objects, including hand tools, in humans. Children's performance in object insertion tasks (fitting tasks) provides one index of the striking changes in the development of vision for action in early life. Fitting tasks also tap children's ability to work with more than one feature of an object concurrently. We examine young children's performance on fitting tasks in two and three dimensions and compare their performance with the previously reported performance of adult individuals of two species of nonhuman primates on similar tasks. Two, three, and four year-old children routinely aligned a bar-shaped stick and a cross-shaped stick but had difficulty aligning a tomahawk-shaped stick to a matching cut-out. Two year-olds were especially challenged by the tomahawk. Three and four year-olds occasionally held the stick several inches above the surface, comparing the stick to the surface visually, while trying to align it. The findings suggest asynchronous development in the ability to use vision to achieve alignment and to work with two and three spatial features concurrently. Using vision to align objects precisely to other objects and managing more than one spatial relation between an object and a surface are already more elaborated in two year-old humans than in other primates. The human advantage in using hand tools derives in part from this fundamental difference in the relation between vision and action between humans and other primates.
有效的行动视觉和对同时存在的空间关系的有效管理是人类熟练操纵物体（包括手持工具）的基础。儿童在物体插入任务（装配任务）中的表现为早期生活中行动视觉发展的显著变化提供了一个指标。装配任务还考察了儿童同时处理物体多个特征的能力。我们研究了幼儿在二维和三维装配任务中的表现，并将他们的表现与之前报道的两种非人类灵长类动物成年个体在类似任务中的表现进行比较。两岁、三岁和四岁的儿童通常能将条形棒和十字形棒对齐，但将战斧形棒与匹配的切口对齐时会有困难。两岁的儿童在处理战斧形棒时尤其困难。三岁和四岁的儿童在试图对齐时，偶尔会将棒举离表面几英寸，通过视觉将棒与表面进行比较。研究结果表明，在利用视觉实现对齐以及同时处理二维和三维空间特征的能力方面存在异步发展。在两岁的人类中，利用视觉将物体精确地与其他物体对齐以及处理物体与表面之间的多种空间关系，已经比其他灵长类动物更为精细。人类在使用手持工具方面的优势部分源于人类与其他灵长类动物在视觉与行动关系上的这种根本差异。
