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小学儿童汉字认知N170的发展研究
其他题名Development of visual character processing as revealed by N170 effects in Chinese children
曹晓华
2009-11
其他摘要

        研究阅读获得过程中视觉词形相关脑活动的变化对理解阅读加工的本质具有重要作用。ERP研究发现字词视觉认知在颖枕区激活N170成分。此N170成分被认为与正字法加工过程有关,并表现出左侧化。大量此类研究是针对字母语系进行探讨,但采用字母文字很难确定正字法与读音对N170偏侧化和敏感性的确切作用。而汉字作为语标语系,读音和正字法可以分别操纵,因而可以分别测量两个因素的作用,但目前关于汉字N170的研究还不充分。
        从发展的角度探讨N170成分是理解此成分本质的一个重要途径,最近对字母语系的N170发展进行了少量研究,但结果很不一致,而汉字认知的N170发展研究缺乏。更重要的是,以前的研究很少关注字词阅读发展中的重要年龄阶段一小学阶段。本研究对小学二年级、四年级、六年级儿童和大学生汉字认知N170成分的偏侧化和敏感性发展进行探讨。
        本研究包括两个实验,采用颜色匹配判断的内隐阅读任务,被试为小学二年级(平均7. 3岁)、四年级(平均9. 3岁)、六年级(平均11. 5岁)和大学生(平均24. 4岁)。实验一采用人脸图形、汉字和物体线条图为材料,探讨汉字与其它刺激间的类别选择性发展。实验二采用符合正字法的真字、伪字和不符合正字法的笔划组合为材料,探讨N170的偏侧化和正字法敏感性发展。
主要研究发现如下:
        (1)儿童汉字认知相关的N170成分从双侧化向左侧化发展,左侧化在小学六  年级才开始出现。
        (2)汉字认知中,各年级汉字和线条图激活的N170差异都显著,表明N170对 汉字与线条图的类别选择性在小学二年级已经出现。
        (3)汉字认知中,只有六年级和大学生的汉字和笔划组合激活的N170在左侧差异显著,提示N170对汉字与笔划组合的类别选择性在小学六年级开始    形成。
        (4)六年级的N170正字法敏感性效应与大学生没有明显差异,提示汉字N170的正字法敏感性六年级基本成熟。
本研究首次探讨四个年龄阶段汉字诱发N170成分的相关特征,为理解汉字认知早期成分发展的神经机制提供了实验数据。

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  Investigations of functional changes that occur during reading acquisition in cortical regions associated with the perception of visual words are important to understand the nature of reading processing.Previous Event-related Potentials (ERPs) studies of adult readers have demonstrated that letter strings elicited larger N170 component than control stimuli. This relatively specialized ERP component, often shown to be largest over the left occipito-temporal region, is believed to be associated with orthographic processing. However, this claim is confounded by a phonological factor, since pronunciation and orthography is virtually undistinguishable in alphabetic scripts. In contrast, in written Chinese, orthography and phonology can be separately manipulated,  while unfortunately only very few studies have been conducted using Chinese characters.
    Intuitionly, investigation of N170 changes along with literacy development is vital for understanding of the nature of this reading-related brain activity. While quite a few of studies with alphabetic children have been reported (results are largely inconsistent though), there is essentially no such kind of ERP study conducted in Chinese children. In particular, how it develop in the primary school children.
    In the current study, we examined the development of N170 elicited by Chinese characters, in terms of its hemispheric laterality and category/orthography sensitivity,in primary school children as well as adult readers. A context--irrelated color matching task was used, in which participants were required to compare the color of a target stimulus with that of a preceding cue stimulus.
    The study includes two experiments. Twenty 20a grade children (10 females, mean age 7.33士0.53 years), twenty 4th grade children (10 females, mean age 9.34士0.54years), twenty 6th grade children (10 females, mean age 11.55士0.36,years) and 13 young adults (7 females, mean age 24.4士0.43  years) participated in the experiments. All subjects were native Chinese. The first experiment was to explore the development of category selectivity of N170 component, by use of Chinese characters, faces, and line-drawings of common bjects. The second experiment used Chinese characters, pseudowords and stroke combinations to detect the development of orthographic sensitivity of this component.
The main foundings and conclusions are as follows:
    (1) The N170 sensitive to Chinese characters shifted from bilateral to left-lateralized during development of literacy. Specifically, left lateralization effect did not emerge until the 6th grade children.
    (2) The N170 amplitudes evoked by Chinese characters was significantly larger than  that by line-drawings of common objects in all four groups, suggesting that the  category selectivity of N170 elicited by characters emerges as early as the 20d  grade children.
    (3) The N170 amplitudes evoked by Chinese characters was significantly larger than  that by stroke combinations in the 6`h grade children and adults readers, and this  effect was found only on the left hemisphere. These results suggest that  orthographic sensitivity effect does not emerge until the 6`h grade children.
    (4) The left-lateralized N170 effect of orthographic sensitivity did not differ significantly between the 6th grade children and adult readers, suggesting that orthography in the 6th children has already well developed.
    This study, for the first time, charaterized N170 effects associated with reading of Chinese characters in four groups from 2nd grade children to college students,providing important empirical insights into the neural basis of the development of early stages of Chinese character processing.

学科领域心理学
关键词汉字 N170 儿童 偏侧化 敏感性
学位类型博士
语种中文
学位专业认知神经科学
学位授予单位中国科学院研究生院
学位授予地点北京
文献类型学位论文
条目标识符http://ir.psych.ac.cn/handle/311026/21779
专题健康与遗传心理学研究室
作者单位中国科学院心理研究所
推荐引用方式
GB/T 7714
曹晓华. 小学儿童汉字认知N170的发展研究[D]. 北京. 中国科学院研究生院,2009.
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