Section of Neuropsychology, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany; Unit of Neuropsychology, Clinic of Neurology, University Hospital, Zürich, Switzerland.
Section of Neuropsychology, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany.
Neuropsychologia. 2011 Apr;49(5):1294-1301. doi: 10.1016/j.neuropsychologia.2011.01.012. Epub 2011 Jan 12.
It is widely accepted that letter-by-letter reading and a pronounced increase in reading time as a function of word length are the hallmark features of pure alexia. Why patients show these two phenomena with respect to underlying cognitive mechanisms is, however, much less clear. Two main hypotheses have been proposed, i.e. impaired discrimination of letters and deficient processing of word forms. While the former deficit can easily be investigated in isolation, previous findings favouring the latter seem confounded. Applying a word reading paradigm with systematically manipulated letter orders in two patients with pure alexia, we demonstrate a word form processing deficit that is not attributable to sublexical letter discrimination difficulties. Moreover, pure alexia-like fixation patterns could be induced in healthy adults by having them read sentences including words with transposed letters, so-called 'jumbled words'. This further corroborates a key role of deficient word form processing in pure alexia. With regard to basic reading research, the present study extends recent evidence for relative, rather than precise, encoding of letter position in the brain.
人们普遍认为，逐字阅读和阅读时间随单词长度呈明显增加是纯失读症的显著特征。然而，为什么患者在认知机制方面会表现出这两种现象，其原因还不是很清楚。提出了两个主要假说，即字母辨别障碍和单词形式加工缺陷。虽然前者的缺陷很容易单独进行研究，但之前支持后者的发现似乎存在混淆。通过对两名纯失读症患者应用一种具有系统操纵字母顺序的单词阅读范式，我们证明了一种单词形式加工缺陷，这种缺陷不能归因于亚词汇字母辨别困难。此外，通过让健康成年人阅读包含字母换位的单词的句子，即所谓的“乱序词”，可以在他们身上诱导出类似纯失读症的注视模式。这进一步证实了单词形式加工缺陷在纯失读症中的关键作用。就基础阅读研究而言，本研究扩展了最近关于大脑中字母位置相对而非精确编码的证据。
