认知与发展心理学研究室知识库

个体整合视觉文字及其听觉语音之间对应关系的能力与其阅读水平紧密相关。Blomert(2011)提出不能形成字母一语音的早期自动化整合是发展性阅读障碍者的核心缺陷。然而，对于发展性阅读障碍者是否存在形音整合缺陷的问题仍存在争论。在发现阅读障碍者存在形音整合缺陷的研究中，视听刺激均是同时或接近同时呈现的，而未发现阅读障碍者存在形音整合缺陷的研究中，视听刺激呈现的时间间隔相对较长，这提示我们视听刺激时间间隔可能是导致研究结果不一致的原因。对正常被试的研究发现，视听刺激时间间隔对形音整合的影响随年龄、阅读经验及正字法知识等因素的变化而不同。那么，对于汉语发展性阅读障碍儿童这一特殊的被试群体，视听刺激呈现的时间间隔对其形音整合效应有怎样的影响呢?是否与对正常被试的影响不同呢?

针对上述问题，本研究操纵了视听刺激呈现的时间间隔C Stimulus Onset Asynchrony, SOA)，在行为层面和神经层面上，考察了视听刺激呈现的时间间隔对汉语阅读障碍儿童形音整合效应的影响。研究中采用三种SOA水平，分别为:视听刺激同时呈现(SOA=0)，视觉领先听觉刺激200ms呈现(SOA=200ms)，视觉领先听觉激SOOms呈现((SOA=SOOms)。在行为层面，以正确率和反应时为指标，在神经层面上，利用ERP技术，以早期的P2, N2成分为测量指标。结果发现:

（1)行为层面上，视听刺激时间间隔对阅读障碍儿童形音整合的影响模式与 同年龄对照组儿童不同，这种差异主要表现在正确率上。正常儿童在SOA=0和SOA=200时表现出整合效应，在SOA=500时整合效应消失;而阅读障碍儿童则是在三种SOA条件下均表现出整合效应，说明阅读障碍儿童可能具有更大的形音整合时间窗。

(2)在神经层面上，视听刺激时间间隔对阅读障碍儿童形音整合的影响模式也与同年龄对照组儿童不同，这种差异主要表现在P2成分上。正常儿童在视听刺激同时呈现时，在P2, N2成分上均表现出了早期的形音整合效应，并且这种整合效应在视听刺激不同步呈现(SOA=200ms或SOA=5OOms)时消失。而阅读障碍儿童在视听刺激同时呈现时，仅在N2 成分上表现出早期的形音整合效应，在视觉领先听觉刺激200ms呈现时，仅在P2成分上表现出早期的形音整合效应。另外，ERP研究还发现，当视听刺激同时呈现时，阅读障碍儿童在P2成分上的整合效应值显著弱于同年龄对照组儿童，而当视听刺激不同步呈现(SOA=200ms或SOA=500ms )，两组儿童的整合效应值没有显著差异。

综上所述，视听刺激时间间隔对汉语阅读障碍儿童形音整合的影响模式可能与正常儿童不同。汉语阅读障碍儿童可能对同时呈现的形音一致刺激的早期整合加工存在缺陷。

The ability to integrate the information between visual words and auditory speech is closely related to the development of reading ability. Blomert (2011) suggests that a failure to integrate letters and speech sounds into automated audio-visual objects is a core defect of developmental dyslexia. However, the results have been mixed. Studies supporting Blomert's idea are usually found to present the audiovisual stimuli simultaneously or nearly simultaneously, whereas studies challenging Blomert's idea usually have relatively longer stimulus onset asynchronies between audiovisual stimuli. So, the effect of stimulus onset asynchrony (SOA) on between audiovisual integration of dyslexia remains unknown. Besides, it has been proved that the effect of SOA on the multisensory integration will be influenced by age, reading experience and orthographic background. Based upon the above-mentioned information, this study aimed at examining the effect of SOA on the multisensory integration of Chinese children with and without developmental dyslexia, and checking out if there is any difference on the effect of SOA between the two groups of children.

To investigate the effects of SOA on audiovisual integration of Chinese children with and without dyslexia, the present study manipulated the intervals between audio and visual stimuli, with the audiovisual stimuli being presented simultaneously (SOA=0), visual stimuli being presented 200ms before auditory stimuli (SOA=200ms), visual stimuli being presented 5OOms before auditory stimuli (SOA=5OOms). Results were recorded by behavioral measurements and event-related potentials (ERPs) technique. The results showed that:

(1) Behavioral results showed that the effect of SOA on the multisensory integration of dyslexia is different from that of typically developing children. Typically developing children exhibited word-phonetic integration when the audiovisual stimuli being presented simultaneously (SOA=0) and visual stimuli being presented 200ms before auditory stimuli (SOA=200ms). However, dyslexia children exhibited word-phonetic integration on all three SOA conditions, indicating that dyslexia children may have an extended temporal window for integrating word-phonetic.

(2) ERP results also revealed that the effect of SOA on the early word-phonetic integration of dyslexia is different from that of typically developing children. For the typically developing children, the congruent audiovisual stimuli induce bigger amplitude of wave of P2，N2 than ones of baseline stimuli only when the audiovisual stimuli being presented simultaneously (SOA=0). As for dyslexia children, the congruent audiovisual stimuli induce bigger amplitude of wave of N2 when the audiovisual stimuli being presented simultaneously (SOA=0) but bigger amplitude of wave of P2 when the visual stimuli being presented 200ms before auditory stimuli (SOA=200ms). In addition, the integration effect of P2 of dyslexia was of significant difference to that of typically developing children only when the audiovisual stimuli being presented simultaneously (SOA=0).

In sum, the effects of SOA on multisensory integration of word-phonetic were different for dyslexia and normal children. Chinese children with developmental dyslexia exhibited early word-phonetic integration defect only when the audiovisual stimuli are presented simultaneously.