Marinelli Chiara V, Traficante Daniela, Zoccolotti Pierluigi
Neuropsychology Research Centre, IRCCS Santa Lucia Rome, Italy.
Department of Psychology, Catholic University of Milan Milan, Italy ; NeuroMI - Milan Center for Neuroscience Milan, Italy.
Front Psychol. 2014 Dec 2;5:1353. doi: 10.3389/fpsyg.2014.01353. eCollection 2014.
The locus of the deficit of children with dyslexia in dealing with strings of letters may be a deficit at a pre-lexical graphemic level or an inability to bind orthographic and phonological information. We evaluate these alternative hypotheses in two experiments by examining the role of stimulus pronounceability in a lexical decision task (LDT) and in a forced-choice letter discrimination task (Reicher-Wheeler paradigm). Seventeen fourth grade children with dyslexia and 24 peer control readers participated to two experiments. In the LDT children were presented with high-, low-frequency words, pronounceable pseudowords (such as DASU) and unpronounceable non-words (such as RNGM) of 4-, 5-, or 6- letters. No sign of group by pronounceability interaction was found when over-additivity was taken into account. Children with dyslexia were impaired when they had to process strings, not only of pronounceable stimuli but also of unpronounceable stimuli, a deficit well accounted for by a single global factor. Complementary results were obtained with the Reicher-Wheeler paradigm: both groups of children gained in accuracy in letter discrimination in the context of pronounceable primes (words and pseudowords) compared to unpronounceable primes (non-words). No global factor was detected in this task which requires the discrimination between a target letter and a competitor but does not involve simultaneous letter string processing. Overall, children with dyslexia show a selective difficulty in simultaneously processing a letter string as a whole, independent of its pronounceability; however, when the task involves isolated letter processing, also these children can make use of the ortho-phono-tactic information derived from a previously seen letter string. This pattern of findings is in keeping with the idea that an impairment in pre-lexical graphemic analysis may be a core deficit in developmental dyslexia.
诵读困难儿童在处理字母串方面存在缺陷，其根源可能在于词前字素层面的缺陷，或者是无法将正字法信息与语音信息相联结。我们通过两项实验对这些不同假设进行评估，实验中考察了刺激可发音性在词汇判断任务（LDT）和强制选择字母辨别任务（赖克-惠勒范式）中的作用。17名四年级诵读困难儿童和24名同龄对照阅读者参与了这两项实验。在词汇判断任务中，向儿童呈现4、5或6个字母的高频、低频单词、可发音的假词（如DASU）和不可发音的非词（如RNGM）。当考虑超可加性时，未发现组别与可发音性交互作用的迹象。诵读困难儿童在处理字符串时存在障碍，不仅是可发音刺激的字符串，不可发音刺激的字符串也如此，单一的全局因素能够很好地解释这一缺陷。在赖克-惠勒范式中获得了互补的结果：与不可发音的启动刺激（非词）相比，两组儿童在可发音启动刺激（单词和假词）的情境下进行字母辨别时准确率都有所提高。在这个需要辨别目标字母和竞争字母但不涉及同时处理字母串的任务中，未检测到全局因素。总体而言，诵读困难儿童在将字母串作为一个整体同时进行处理时表现出选择性困难，这与字母串的可发音性无关；然而，当任务涉及孤立字母处理时，这些儿童也能够利用从先前看到的字母串中获得的正字-语音-构词信息。这一研究结果模式与词前字素分析受损可能是发育性诵读困难的核心缺陷这一观点相符。
