高功能孤独症幼儿空间工作记忆的组块加工缺陷

Chunking processing of spatial working memory in autism preschool children

孤独症谱系障碍者存在空间工作记忆加工缺陷,其具体受损环节尚不明确。组块是一种有效的策略性信息编码方式,是空间工作记忆的关键环节。高度结构化的刺激容易形成高水平组块,因此,刺激结构化程度对记忆效果的影响能够反映个体的组块加工能力。研究采用Sternberg空间工作记忆任务、Corsi空间广度任务,加入刺激结构化因素,考察高功能孤独症幼儿是否存在组块加工缺陷,并探讨组块加工是否直接影响到空间工作记忆容量。实验1采用Sternberg空间工作记忆任务,结果表明,ASD幼儿存在明显的组块加工缺陷。在易于组块的高结构化条件下,健康幼儿的记忆成绩明显较高,而ASD幼儿在高、低结构化条件下的记忆成绩并无显著差异。实验2采用Corsi空间广度任务,结果显示,不论高、低结构化条件,ASD幼儿的空间工作记忆容量均显著低于健康幼儿。但ASD幼儿由于存在组块加工缺陷,在高、低结构化条件下的记忆成绩差异较健康幼儿小。因此,ASD幼儿的组块能力一定程度上影响了空间工作记忆容量。此外,记忆存储器的异常可能也是ASD幼儿空间工作记忆容量不足的重要原因。研究表明,ASD幼儿的空间组块缺陷主要由于弱中央统合的认知风格,他们缺乏自上而下的组块加工动机,难以主动对刺激形成高水平组块编码,从而影响记忆效果。

Autism spectrum disorder （ASD） individuals are confirmed to have deficits in spatial working memory, but the specific impaired element is still undefined. Chunking is an effective form of strategic encoding that involves the recoding of a set of data into a compressed, efficient form and can extend working memory capacity. Spatial chunking is a key segment of the spatial working memory processing. Structured stimuli significantly encourage chunking, lessening working memory demand and significantly improving working memory performance. In this study, we used the Sternberg spatial working memory task and the Corsi＇s spatial span task, manipulated the structure of stimulus＇ spatial arrangement. In this method, we investigated the chunking processing of autism preschool children, and evaluated the relationship between spatial chunking and spatial working memory capacity in ASD. All participants were recruited in a integrated kindergarten, including 15 ASD children and 18 typical developing children. Age range from 4.5 to 7 years old. Participants were matched in age, verbal intelligence and nonverbal intelligence. In experimentl, participants were required to remember several stimulus＇ positions which are presented simultaneously, and only judge one position of them. The accuracy of participants were recorded. In experiment2, stimulus participants were presented one by one, participants were required to remember several stimulus＇ positions, and repeat the stimulus positions in the same order. Experiments were manipulated into 2 conditions. In the high-structured condition, all sequences followed a structured rule such that locations were organized as familiar shape components, involving symmetry and parallel sides, and were thus more easily organized into higher-level patterns. In the low-structured condition, locations were organized as irregular figures. The results in experimentl proved that ASD children existing chunking deficits. First of all, healthy children performed significant better than ASD Children in high-structured condition, F（1,31） = 18.21, p 〈 0.001, η p 2 = 0.370. But there was no difference in low-structured condition between the 2 groups, F（1,31） = 0.87, p = 0.358, ηp2 = 0.027. Besides, healthy children performed significant better in high-structured condition comparing with the low-structured condition （p 〈 0.001）. In contrast, ASD Children didn＇t show any difference in the 2 conditions （p = 0.245）. This proved that the high-structured arrangement encouraged high-level chunking in typical developing children. But ASD children were insensitive in the structured arrangement of stimulus and can＇t apply chunking strategy effectively. According to the results in experiment 2, the spatial capacity of ASD children was significantly lower than healthy children no matter in high- or low-conditions [F（1,31） = 41.68, p 〈 0.001, ηp2 = 0.573; F（1,31） = 12.65, p = 0.001, ηp2 = 0.290]. High-structured arrangement significantly improved the spatial working memory capacity in typical developing children （p 〈 0.001）, but also influenced ASD children to some extent （p = 0.041）. Chunking deficits influenced spatial capacity in ASD children, abnormal memory storage is also an important factor. In summary, ASD children showed impairment in chunking in spatial working memory, cognitive style of weak central coherence plays a crucial role in spatial chunking. Besides, attention control and executive function have indirect effect in spatial working memory processing in other domains. These findings not only provide inspiration for developing cognitive intervention model, but also provide a breakthrough to the neurophysiological mechanism studies in ASD.