Center for Visual Cognition, Department of Psychology, Copenhagen University, O. Farimagsgade 2A, DK-1353 Copenhagen K, Denmark.
Neuropsychologia. 2011 Jul;49(9):2283-98. doi: 10.1016/j.neuropsychologia.2011.04.028. Epub 2011 May 4.
It is commonly assumed that number reading can be intact in patients with pure alexia, and that this dissociation between letter/word recognition and number reading strongly constrains theories of visual word processing. A truly selective deficit in letter/word processing would strongly support the hypothesis that there is a specialized system or area dedicated to the processing of written words. To date, however, there has not been a systematic review of studies investigating number reading in pure alexia and so the status of this assumed dissociation is unclear. We review the literature on pure alexia from 1892 to 2010, and find no well-documented classical dissociation between intact number reading and impaired letter identification in a patient with pure alexia. A few studies report strong dissociations, with number reading less impaired than letter reading, but when we apply rigorous statistical criteria to evaluate these dissociations, the difference in performance across domains is not statistically significant. There is a trend in many cases of pure alexia, however, for number reading to be less affected than letter identification and word reading. We shed new light on this asymmetry by showing that, under conditions of brief exposure, normal participants are also better at identifying digits than letters. We suggest that the difference observed in some pure alexic patients may possibly reflect an amplification of this normal difference in the processing of letters and digits, and we relate this asymmetry to intrinsic differences between the two types of symbols.
通常认为，纯失读症患者的数字阅读能力完好无损，这种字母/单词识别与数字阅读之间的分离强烈限制了视觉单词处理的理论。如果字母/单词处理确实存在选择性缺陷，那么这将强烈支持存在专门的系统或区域专门用于处理书面单词的假设。然而，迄今为止，尚未对研究纯失读症患者数字阅读的研究进行系统回顾，因此这种假设的分离状态尚不清楚。我们回顾了 1892 年至 2010 年期间关于纯失读症的文献，并未发现患有纯失读症的患者在数字阅读完好无损和字母识别受损之间存在有充分记录的经典分离。有几项研究报告了强烈的分离，数字阅读的损伤程度低于字母阅读，但当我们应用严格的统计标准来评估这些分离时，跨领域的表现差异在统计学上并不显著。然而，在许多纯失读症患者中，存在一种趋势，即数字阅读比字母识别和单词阅读受影响更小。我们通过表明，在短暂暴露的情况下，正常参与者也更善于识别数字而不是字母，为这种不对称性提供了新的视角。我们认为，在一些纯失读症患者中观察到的差异可能反映了字母和数字处理中这种正常差异的放大，我们将这种不对称性与两种类型符号之间的内在差异联系起来。
