发展性阅读障碍与知觉加工

近年来许多行为实验和神经生理学实验都发现 ,发展性阅读障碍与基本知觉障碍有关。在视觉领域研究者提出了巨细胞障碍假设 ,这种假设认为阅读障碍者视觉神经系统中的巨细胞障碍导致他们对某种类型的视觉刺激加工存在困难 ,进而影响阅读。在听觉领域研究发现阅读障碍者加工快速、系列、短暂呈现的声音刺激存在障碍。研究者认为阅读障碍者加工快速刺激输入障碍反映了普遍的时间知觉障碍。这方面的研究发展非常迅速 ,理论观点非常明确 ,并且直接与内在的神经机制相联系 ,形成了与传统的“语言障碍”理论迥然不同的“知觉障碍”理论。“知觉障碍”理论综合了行为、认知和神经等多个层次的研究 ,反映了神经科学发展所带来的巨大影响和认知加工模块化理论的渐渐衰退。

DEVELOPMENTAL DYSLEXIA AND PERCEPTUAL PROCESSING

Many behavioral and neurophysiological studies in recent years found that developmental dyslexia is related to deficits in basic perceptual processing. The magnocellular theory, proposed mostly by researchers working in the visual processing field, postulates that dyslexia is the result of a deficit in the magnocellular part of the visual system. This magnocellular system respondes to rapid changes in visual stimulation and a deficit here would lead the brain to confuse neural activities attributed to different fixations between saccades during text reading. A similar deficit also existes in the auditory domain, where dyslexics show difficulties in processing rapid, sequential, and transit sounds. It is believed that a general impairment in temporal processing underlies dyslexics poor performance in reading. Theories emphasizing the role of basic perceptual processing in reading impairment is in contrast with theories that focus on the deficits in the linguistic domain, reflecting the significant advancement in cognitive neuroscience and the decline of the modular approaches.