Murphy Melissa M, Mazzocco Michele M M
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Dev Neuropsychol. 2008;33(3):345-64. doi: 10.1080/87565640801982429.
Mathematical learning disabilities (MLD) have been reported for elementary school age girls with fragile X syndrome who do not have mental retardation. Yet girls with fragile X demonstrate age-appropriate rote math skills, sometimes outperforming other children with MLD. We examined whether MLD and strengths in rote math skills persist during middle school among girls with fragile X. Middle school children were individually administered the Ranking Proportions Task (RPT), which involves fractions and decimals. Such problems, although difficult for many students, yield different performance profiles between children with versus without MLD. We hypothesized that girls with fragile X would outperform children with MLD on rote skills (e.g., naming decimals) despite conceptual difficulties, regardless of effects of FSIQ. To address the influence of fragile X versus MLD or FSIQ, several comparison groups were included. Children from a normative sample outperformed girls with fragile X on conceptual, but not rote, skills. However, their performance resembled that of children with MLD on conceptual skills, such as identifying equal quantities with different symbols (e.g., 0.5 and 1/2). Fragile X syndrome provides a compelling model of the heterogeneity of MLD, as the associated profile resembles that of both children with or without MLD. In terms of applications to serving girls with fragile X, it is important to consider that efficient rote skills may not only fail to enhance math achievement, they may hinder achievement by masking underlying conceptual deficiencies.
已有报道称，患有脆性X综合征的小学适龄女童存在数学学习障碍（MLD），但她们并无智力迟钝。然而，患有脆性X综合征的女童表现出与年龄相符的死记硬背式数学技能，有时比其他患有数学学习障碍的儿童表现更好。我们研究了患有脆性X综合征的女童在中学阶段是否仍存在数学学习障碍以及死记硬背式数学技能方面的优势。对中学生个体进行了排序比例任务（RPT）测试，该任务涉及分数和小数。这类问题虽然对许多学生来说都很困难，但在有数学学习障碍和没有数学学习障碍的儿童之间会产生不同的表现特征。我们假设，患有脆性X综合征的女童尽管存在概念理解困难，但在死记硬背技能（如说出小数）方面会比患有数学学习障碍的儿童表现更好，且不受全量表智商（FSIQ）的影响。为了研究脆性X综合征与数学学习障碍或全量表智商的影响，我们纳入了几个对照组。来自常模样本的儿童在概念技能方面比患有脆性X综合征的女童表现更好，但在死记硬背技能方面并非如此。然而，他们在概念技能方面的表现与患有数学学习障碍的儿童相似，比如识别用不同符号表示的等量（如0.5和1/2）。脆性X综合征为数学学习障碍的异质性提供了一个引人注目的模型，因为其相关特征与有或没有数学学习障碍的儿童的特征都相似。在为患有脆性X综合征的女童提供服务的应用方面，重要的是要考虑到高效的死记硬背技能不仅可能无法提高数学成绩，还可能通过掩盖潜在的概念缺陷来阻碍成绩的提高。
