Scarf Damian, Boy Karoline, Uber Reinert Anelisie, Devine Jack, Güntürkün Onur, Colombo Michael
Department of Psychology, University of Otago, Dunedin 9054, New Zealand;
Department of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, D-44780 Bochum, Germany.
Proc Natl Acad Sci U S A. 2016 Oct 4;113(40):11272-11276. doi: 10.1073/pnas.1607870113. Epub 2016 Sep 16.
Learning to read involves the acquisition of letter-sound relationships (i.e., decoding skills) and the ability to visually recognize words (i.e., orthographic knowledge). Although decoding skills are clearly human-unique, given they are seated in language, recent research and theory suggest that orthographic processing may derive from the exaptation or recycling of visual circuits that evolved to recognize everyday objects and shapes in our natural environment. An open question is whether orthographic processing is limited to visual circuits that are similar to our own or a product of plasticity common to many vertebrate visual systems. Here we show that pigeons, organisms that separated from humans more than 300 million y ago, process words orthographically. Specifically, we demonstrate that pigeons trained to discriminate words from nonwords picked up on the orthographic properties that define words and used this knowledge to identify words they had never seen before. In addition, the pigeons were sensitive to the bigram frequencies of words (i.e., the common co-occurrence of certain letter pairs), the edit distance between nonwords and words, and the internal structure of words. Our findings demonstrate that visual systems organizationally distinct from the primate visual system can also be exapted or recycled to process the visual word form.
学习阅读涉及掌握字母与发音的对应关系（即解码技能）以及视觉识别单词的能力（即正字法知识）。虽然解码技能显然是人类独有的，因为它们基于语言，但最近的研究和理论表明，正字法处理可能源自对视觉回路的扩展适应或重新利用，这些视觉回路是为了识别我们自然环境中的日常物体和形状而进化出来的。一个悬而未决的问题是，正字法处理是仅限于与人类相似的视觉回路，还是许多脊椎动物视觉系统共有的可塑性的产物。在这里，我们表明，与人类在3亿多年前就分道扬镳的鸽子，能够进行正字法单词处理。具体而言，我们证明，经过训练以区分单词和非单词的鸽子，能够识别出定义单词的正字法属性，并利用这些知识识别它们从未见过的单词。此外，鸽子对单词的字母组合频率（即某些字母对的常见共现情况）、非单词与单词之间的编辑距离以及单词的内部结构很敏感。我们的研究结果表明，与灵长类动物视觉系统在组织上不同的视觉系统，也可以被扩展适应或重新利用来处理视觉单词形式。
