Friedmann Naama, Lukov Limor
Language and Brain Lab, School of Education, Tel Aviv University, Tel Aviv, Israel.
Cortex. 2008 Oct;44(9):1146-60. doi: 10.1016/j.cortex.2007.09.005. Epub 2008 Mar 4.
Individuals with surface dyslexia read via grapheme-to-phoneme conversion due to a deficit in the lexical route. A deficit in the lexical route can be caused by impairments at several different loci. In the current study we identify three subtypes of developmental surface dyslexia, each caused by impairment at a different locus on the lexical route, and each showing a different pattern of performance in various tasks. All three subtypes show the classical pattern of reading aloud, with regularizations and difficulty in reading words that have more than a single possible conversion to a phoneme string, but they differ in their performance in lexical decision and homophone comprehension. The first subtype, input surface dyslexia, results from a deficit to the orthographic input lexicon, and entails poor performance in lexical decision and comprehension tasks. The second subtype, orthographic lexicon output surface dyslexia, in which the orthographic input lexicon is accessible but its output to the phonological output lexicon and to the semantic system is impaired, allows normal lexical decision, but causes impaired comprehension of homophones. The third subtype, interlexical surface dyslexia, caused by a selective deficit in the connection between the orthographic input lexicon and the phonological output lexicon but with intact access from the orthographic input lexicon to the semantic system, allows normal performance in lexical decision and comprehension tasks. Seventeen Hebrew-speaking individuals with developmental surface dyslexia aged 10-43 participated in the study, eight of them showed the first pattern, three showed the second pattern, and six displayed the third pattern. Another result of the study pertains to the importance of the lexicality of the result of grapheme-to-phoneme conversion for each target word. Some words, when read via grapheme-to-phoneme conversion, can potentially be read as other words (such as "now" in English, which can be sounded as the word "know"), we term these words potentiophones. The results indicate that potentiophones yield the highest error rate in reading aloud for all the participants with surface dyslexia.
表层失读症患者由于词汇通路受损，通过字母到音素的转换来阅读。词汇通路受损可能由几个不同位点的损伤引起。在本研究中，我们识别出三种发育性表层失读症亚型，每种亚型由词汇通路上不同位点的损伤引起，并且在各种任务中表现出不同的模式。所有这三种亚型都表现出经典的大声朗读模式，对有多种可能转换为音素串的单词进行规则化处理且阅读困难，但它们在词汇判断和同音异形词理解任务中的表现有所不同。第一种亚型是输入性表层失读症，由正字法输入词典缺陷导致，在词汇判断和理解任务中表现较差。第二种亚型是正字法词典输出性表层失读症，其中正字法输入词典可访问，但它向语音输出词典和语义系统的输出受损，允许正常的词汇判断，但导致同音异形词理解受损。第三种亚型是词间表层失读症，由正字法输入词典和语音输出词典之间的连接选择性缺陷引起，但从正字法输入词典到语义系统的访问完好，在词汇判断和理解任务中表现正常。17名年龄在10至43岁之间的希伯来语发育性表层失读症患者参与了该研究，其中8人表现出第一种模式，3人表现出第二种模式，6人表现出第三种模式。该研究的另一个结果涉及每个目标单词字母到音素转换结果的词汇性的重要性。有些单词通过字母到音素转换阅读时，可能会被读成其他单词（例如英语中的“now”，可以发音为“know”这个词），我们将这些单词称为潜在同音词。结果表明，对于所有表层失读症患者，潜在同音词在大声朗读时产生的错误率最高。
