认知与发展心理学研究室知识库

视听整合指个体将来自视觉和听觉通道的信息组合在一起形成一个知觉判断的过程。视听整合能力对于个体阅读能力的获得具有重要作用。目前有关发展J胜阅读障碍视听整合能力的研究大多是在拼音文字中展开的，发现阅读障碍存在语言层面和感知觉层面的视听整合缺陷。但是，阅读障碍跨通道加工缺陷与单通道加工缺陷的关系尚不清楚。汉字不同于拼音文字，缺乏形音对应规则;并且汉语阅读障碍的视觉单通道、听觉单通道缺陷具有不同于拼音文字阅读障碍的特点。因此，汉语阅读障碍的视听整合具有其独特表现。目前，对于汉语发展性阅读障碍视听整合能力的研究依然欠缺。

本研究结合行为实验和脑成像技术系统地考察了汉语发展性阅读障碍儿童在语言层面和感知觉层面的视听整合特点。结果表明:

(1)语言层面的行为实验结果显示，阅读障碍儿童在视听一致、视听不一致条件下对视觉文字判断的表现差于同年龄对照组儿童;排除阅读障碍儿童在视觉单通道加工上和对照组儿童的差异后，两组儿童在视听一致、视听不一致条件下的表现无差异。阅读障碍儿童在视听一致、视听不一致条件下对听觉字音判断的表现差于对照组儿童;排除阅读障碍儿童在听觉单通道加工上和正常儿童的差异后，两组儿童在视听一致、视听不一致条件下的表现无差异。然而，语言层面的行为研究还发现，阅读障碍儿童在视听一致条件下对听觉字音判断的表现存在反应速度上的缺陷，并且，该缺陷与其听觉单通道加工能力无关。脑成像实验结果显示，阅读障碍儿童的左侧颖上回对视听关系一致的文字和字音的激活反应显著高于正常儿童。

(2)感知觉层面的行为实验结果显示，阅读障碍儿童在跨通道条件下对视觉光栅判断的表现差于对照组儿童，排除阅读障碍儿童在视觉单通道加工上和对照组儿童的差异后，两组儿童在视听条件下的表现无差异。阅读障碍儿童在跨通道条件下对听觉纯音判断的表现与对照组儿童无差异。脑成像实验结果显示，阅读障碍儿童的左侧颖上回对同时出现的光栅和纯音的激活反应显著低于正常儿童。

以上结果表明，汉语发展性阅读障碍儿童的视听整合能力缺陷不只存在于语言层面，在一般感知觉层面上也有所反映。该缺陷可能受其单通道缺陷影响。阅读障碍儿童的视听整合缺陷具有异常的神经基础。

The ability of audiovisual integration refers to the competence that combines information across the visual and auditory modalities to generate a perceptual judgment. It plays an important role in the development of reading ability. Studies in alphabetic languages have evidenced that dyslexics have impaired audiovisual integration ability in both language and sensory processes. However, the relationship between the deficits in audiovisual integration and in unimodal processes remains controversial. In contrast to alphabetic languages, Chinese is a writing system without grapheme-to-phoneme correspondence. Many studies demonstrated that cognitive and neural mechanisms in unimodal processing in Chinese children with dyslexia are different from that of alphabetic dyslexia. Hence, Chinese dyslexics might have its unique characteristics in audiovisual integration dysfunction. However, studies on audiovisual integration ability in Chinese dyslexics were very few.

The present study adopted behavioral measurements and functional magnetic resonances imaging (fMRI) technique to systematically investigate the audiovisual integration ability in both language and sensory processes in Chinese children with dyslexia. The results showed that,

(1)Behavioral data about language processing showed that, when deciding whether one character presented in the screen is real or not under audiovisual situation or judging one character pronunciation is real or not, dyslexic children's peg0formance was worse than that of the chronological age-matched (CA) children in the congruent and incongruent conditions. After removing the difference between the two groups in unimodal visual and unimodal auditory processing, the performance of dyslexics was equal to that of controls in the congruent and incongruent conditions. However, the difference in reaction rate under the congruent condition was independent of dysclxics' unimodal al7ility. The fMIZI data provided evidence that dyslexic children showed greater superior temporal gyrus (STG) activity than CA controls for congruent character and Chinese character pronunciation pairs.

(2)Behavioral data about sensory processing showed that, when decide whether orientation of a grating is left or right, or determine whether a pure tone sounds gh" or "low", dyslexic children's performance was worse than the chronological age-matched children only in the direction discrimination task. After removing the difference between the two groups in unimodal visual process, no significant difference was found between dyslexics and controls.

In summary, the present study showed that Chinese children with dyslexia have audiovisual integration deficits at both the language and sensory levels. It is noteworthy that, integration deficit in dyslexia is related to their unimodal visual deficit, and unimodal auditory deficit. Besides, evidence showing different brain activation in the left STG between Chinese dyslexia and controls supported functional abnormality in audiovisual integration deficits in Chinese children with dyslexia.