研究者对ADHD心理机制的认识一直未能达成一致。以反应抑制缺陷理论为代表的ADHD单一执行功能缺损的理论并不能很好地解释ADHD的缺损，采用能将各种执行功能进行分离的简单神经心理学范式来探索执行机制并不是好的做法，近年来，更多的研究者开始关注ADHD的复杂信息加工能力，尤其是工作记忆的缺损。工作记忆是对信息的短时在线存储和加工，包括缓冲器和中央执行机制，中央执行的功能尤为复杂。大量证据虽证实了ADHD的工作记忆缺陷，却没有进一步深入探索这种缺损的具体机制，简单归因于一般性的缺损。工作记忆具有相对复杂的加工机制，为数不多的研究为ADHD的工作记忆特异性缺陷提供了证据，通过对比阅读障碍进行研究更有价值。鉴于此，本研究中，首先探索ADHD和阅读障碍儿童在言语和非言语记忆刷新任务上是否存在选择性受损，若受损，进一步根据记忆刷新的过程机制及其影响因素，探索不同变量对两种障碍的记忆加工是否存在特异性影响。另外，鉴于以往研究中发现ADHD儿童在热执行功能任务中的成绩能明显改善，研究也将对比ADHD和阅读障碍儿童在冷热记忆刷新任务上的表现差异。在研究一中，结果发现了两种障碍不同的缺损机制。在言语任务上，ADHD儿童和阅读障碍儿童均存在明显落后，而在图形任务上，阅读障碍儿童则是正常的，ADHD儿童则表现出明显缺损。阅读障碍儿童的言语编码能力存在明显受损，甚至在不卷入更新操作的更新0次任务上的成绩也存在明显落后。在更新操作上，随着更新难度的增大，ADHD儿童和阅读障碍儿童的成绩下降的幅度都明显大于正常儿童，反映出了更大的更新操作的困难，说明了障碍儿童记忆容量的限制，以及对记忆表征快速高效操作的困难。阅读障碍儿童图形记忆刷新成绩的正常表明了阅读障碍儿童是一种基于语言加工缺陷的特异性障碍，以语音回路能力的缺损为主。而ADHD儿童在视觉材料上的严重受损则说明其在对抽象图形材料的编码、复述和操作上的困难。在研究二中，研究发现在言语编码水平ADHD儿童和阅读障碍儿童成绩的缺陷。这说明ADHD儿童在由“自下而上”自动化加工完成的低级语音编码加工水平并不存在缺损，阅读障碍的这一表现可能与任务本身相关。在语音短时延迟水平，ADHD儿童和正常儿童的成绩不但没有下降，反而略有升高，而阅读障碍儿童成绩出现明显下降。这说明在短时延迟期间，ADHD儿童的语音复述能力是正常的，被迅速复述的语音表征不但没有减弱，甚至得到巩固。而编码困难和复述困难是影响阅读障碍的成绩缺陷的因素。但在语音长时延迟水平，ADHD儿童的成绩出现了急剧下滑，ADHD儿童的注意缺损导致了复述频次的降低，从而影响了再认的成绩。在视空间编码水平，发现了ADHD儿童的缺陷，却没有发现阅读障碍儿童的缺陷。ADHD儿童的缺陷与基于视觉注意的特征捆绑加工有关。在视空间短时复述期间，ADHD儿童的成绩便明显下降（8.6%），表明了其视空间复述机制的缺损。这与基于注意的视空间复述机制缺陷有关。另外，虽然阅读障碍儿童的视空间编码能力正常，但在视空间复述上，尤其是在长时间复述上，成绩下降非常明显，表明阅读障碍儿童在利用语音回路辅助视空间编码复述上的缺陷。在前摄干扰n-back任务中，结果发现ADHD儿童成绩因受到前摄干扰的影响大幅下滑（26.4%），阅读障碍儿童和正常控制组儿童的成绩也有下降，两者差异并不明显，这说明ADHD儿童更加容易受到前摄干扰的影响，这是导致其记忆加工缺陷的重要原因，而阅读障碍儿童尽管其语音编码和复述能力受损，但这并不影响其抵抗前摄干扰的能力。在表征搜索任务中，并没有发现ADHD儿童和阅读障碍儿童在表征搜索能力上的缺陷。这说明两组障碍的基于选择性注意的表征搜索机制并不存在明显受损。研究三对比了被试在同样难度的趣味和枯燥记忆刷新任务上的表现，结果发现ADHD儿童在趣味记忆刷新任务上的成绩有明显提高，相反，阅读障碍儿童和正常儿童的成绩则几乎没有变化。表明ADHD儿童对奖励和惩罚有着特殊的敏感性，他们的动机和情绪卷入补偿了执行功能缺陷导致的成绩下降。尽管阅读障碍儿童在完成趣味任务的动机也明显加强，但成绩并没有得到明显提高，说明动机的加强对于阅读障碍儿童的言语记忆刷新功能并没有实质性的促进作用，这与两种障碍工作记忆缺损的不同机制有关。总之，研究表明，ADHD和阅读障碍在工作记忆上存在特异性受损，阅读障碍的缺陷主要表现在语音回路的功能上，而ADHD的缺陷则主要体现在执行机制和视空间模板的功能上。

Researchers didn’t achieve consistence about the psychological mechanism of attention deficit hyperactivity disorder (ADHD) as yet. The essential deficit of ADHD can not be well interpreted by the single executive function (EF) deficit theory which is represented by the behavioral inhibition theory. It is unadvisable to explore the executive mechanism of ADHD through simple nuropsychological measurements because of the separation of EF. These years complex information processing ability, especially working memory (WM), has been more focused on. Working memory is capability of temporary information storage and processing comprised of two short-term buffers and central executive (CE). CE is the most complicated and important component of WM. WM problems of ADHD have been found by lots of studies, though none give a in-depth exploration of the explicit mechanism of this deficit, just simply contribution of the general deficit.A few studies supported the especial deficit of WM of ADHD, so it will be more valuable to compare ADHD and reading disorder (RD) in WM. Basing on it in this study, firstly whether the selective deficit in the verbal and nonverbal working memory updating task can be found in the ADHD and RD children will be investigated. If so, some variables which maybe influence the two disorders’ memory processing will be explored next according to the course of memory updating and related influence factors. Besides, the different exhibitions in the cold and warm memory updating tasks of two disorders will be investigated considering the improvement in warm EF tests in ADHD ever been found before.The results of study 1 support different deficit mechanism of two disorders. In the verbal task, ADHD and RD show lower performance than control group. But the finding is different in the nonverbal aspect, ADHD children show deficit while RD group not. The ability of phonological encoding deficit is found in RD group. In the updating operating, ADHD and RD children reveal greater decline when the difficulty of the updating rises that reflects the abnormality of updating. Normal performance in the nonverbal updating task indicates that RD is a kind of disorder based on the special deficit of language processing related to the phonological loop. The deficit in the nonverbal task of ADHD indicates that ADHD children’s difficulty in the encoding, rehearsal and operating of the abstract nonverbal materials.The results of study 2 reveal that ADHD and RD children don’t show significant deficit in the verbal encoding aspect. It suggests that the normal ability of verbal encoding of ADHD is because the elementary verbal encoding is accomplished by the “bottom to up” automatic processing in which ADHD is normal while the performance of RD maybe relate with the task design. As to short time delay aspect, ADHD and control group don’t decline while RD does greatly. It indicates that in the short time delay interval, the ability of phonological rehearsal of ADHD is normal, the phonological representation being rehearsed quickly doesn’t fade away, even clearer. The difficulty of encoding and rehearsal are the disadvantage to RD, which contribute to the worse performance. But in the long time delay interval, ADHD group show greater decline than others, which can be interpreted that the attention deficit of ADHD causes the lower frequency of rehearsal, then leads to the worse performance of recognition.We find that ADHD children behave worse in the visual space encoding task while RD not. The visual space encoding deficit of ADHD is related to the feature-binded processing which bases on the visual attention. In the short term rehearsal of visual space aspect, the significant decline（8.6%）of ADHD illustrates the deficit of visual space rehearsal mechanism in ADHD, which is know as ＂attention-based rehearsal＂. In addition, even though the normal performance in the visual space encoding task, RD children perform worse in the delay task, especially in the long interval task suggesting that RD children show deficit in the usage of phonological loop to assist visual space rehearsal.The results of proactive interference n-back task indicate that the performance of ADHD declines greatly (26.4%) because of the proactive interference, while RD and control children decline a little and no difference has been found between RD and control group. It suggests that ADHD children are more influenced by proactive interference which greatly does harm to memory processing, while the bad phonological encoding and rehearsal ability of RD don’t relate to the ability to control proactive interference.No significant deficit has been found in ADHD and RD in searching task. It suggests that the two disorders have normal representation searching mechanism of selective attention. In study 3, ADHD and RD children finished both fun memory updating task and same difficulty boring memory updating task. The results show the great improvement of ADHD in the fun task while no changes to RD and control. It suggests that ADHD children are more sensitive to the reinforcement and punishment, the involvement of motive and emotion makes up the performance deficit caused by the EF dysfunction. Although RD and control children motivate more in fun task too, the performance don’t improve, suggesting that great motive involvement doesn’t facilitate the verbal memory updating of RD, it indicates the different deficit mechanisms of working memory of two disorders.In conclusion, this research suggests that the deficit of working memory is different between ADHD and RD; it is more related to the function of phonological loop in RD and more related to the EF and visuospatial sketchpad in ADHD.