工作记忆新探:基于个体差异的研究

近年来对工作记忆的研究开始关注个体差异的理论分析。经典的工作记忆模型得到了发展,引入情境缓冲系统作为多成分模型的一部分,这是对个体经验的重视。传统衡量个体差异的主要指标短时记忆容量(组块)、智力(g)等逐步被工作记忆指标发展替代:如执行性注意控制、工作记忆广度等。工作记忆的个体差异本质上是否与智力的差异具有同构性的焦点引起了广泛关注。在今后的研究中,关于领域一般性与特殊性的及神经生理学等方向可能是厘清工作记忆个体差异的主流趋势。     

第二语言语义提取中的工作记忆效应

本文报告一项针对工作记忆容量是否制约中国英语学习者第二语言语义提取效率的实验。实验考查了工作记忆广度中的个体差异是否抑制学习者对第二语言单词语义信息的提取问题,还探索了工作记忆广度和第二语言词汇知识水平的相关性。研究以通用容量工作记忆模型为基础,采用运算广度的工作记忆测试,得出工作记忆广度对单词语义信息的提取没有显著抑制作用的结果。结果还显示工作记忆广度与第二语言词汇知识水平之间没有显著的线性关系。     

人类工作记忆广度个体差异的机制

人类工作记忆广度个体差异的机制是研究者关注的一个热点问题,研究者在大量行为实验的基础上,提出了许多解释人类工作记忆广度存在个体差异的模型和理论:Daneman和Carpenter的资源分享模型;Towse和Hitch的任务转换假设;Engle及其同事提出的工作记忆广度的注意控制理论;Lustig的基于抑制的理论;以及Daily等人的资源激活模型。本文对这些模型和理论观点进行了论述、分析和评价,指出了以往研究存在的不足和未来研究应该注意的问题。     

认知负荷和控制性注意对工作记忆广度任务成绩的影响

通过stroop干扰实验严格筛选被试,考察了控制性注意能力不同的被试在加工部分认知负荷不同的工作记忆广度任务中的成绩。结果表明：任务复杂性和加工速度对工作记忆广度任务成绩有重要影响,任务越复杂或加工速度越快,被试的工作记忆广度任务成绩越低;在复杂的和加工速度快的工作记忆广度任务中,控制性注意能力高的被试成绩要好于控制性注意能力低的被试,但在简单的和加工速度慢的任务中两者成绩没有显著差异。     

干扰、工作记忆与一般流体智力

工作记忆与复杂认知任务之间的关系已成为工作记忆研究领域的热点问题。大量研究表明,工作记忆广度不仅是评价工作记忆能力的一种指标,而且也是衡量一个人的高级认知能力的预报因子。本文从工作记忆的本质以及工作记忆与一般流体智力之问的关系人手,分析了干扰不仅是影响工作记忆容量个体差异的关键因素,而且也在工作记忆与一般流体智力的关系中起着重要的影响作用。     

加工时间和加工速度对工作记忆广度的影响

对工作记忆广度机制的四个模型:资源共享模型、任务转换假说、干扰说和时间资源共享模型进行了检验。以60名大学本科生为被试,完成工作记忆广度任务和转换任务。结果表明:加工时间和加工项目数不是影响工作记忆广度的主要因素;工作记忆广度受到加工速度的影响;工作记忆广度和线索-任务转换代价呈显著的负相关关系。结果支持时间资源共享模型,工作记忆广度取决于注意在加工和存储之间快速、灵活的转换。     

工作记忆广度：资源限制、记忆消退还是转换机制？

为了检验工作记忆广度有限性的3种假说,即资源限制假说、记忆消退假说和转换机制假说,实验要求被试首先完成一项转换效率任务,然后完成工作记忆广度任务。结果发现,加工负荷对工作记忆广度具有重要影响,保持时间不影响工作记忆广度,转换效率与工作记忆广度也没有显著相关。实验结果支持工作记忆广度受认知资源限制的观点     

8岁到成年期工作记忆广度的发展

工作记忆与认知能力、智力和学习能力有密切的联系.本研究采用横断研究的方法,测量了213名8岁到成年期被试的数字、词语和视空间工作记忆广度,探查了工作记忆广度的发展情况.结果发现,数字工作记忆广度在此期间持续增长,词语广度在18岁达到最高,视空间工作记忆广度在14-16岁达到高峰.不同任务的工作记忆广度具有相似的发展趋势,但工作记忆的平均广度分数与Pascual-Leone模型的预测并不一致.     

工作记忆广度与汉语句子语境效应的关系

采用计算机快速系列视觉呈现技术,以反应时为指标,利用命名法,从工作记忆容量个体差异的角度,探讨汉语句子阅读中的语境效应。本研究将句子的语境效应分为两个来源：一个是自动激活扩散的词汇之间的语义启动,另一个是相互作用的句子水平的主题启动。结果表明：词汇间的语义启动不受工作记忆容量的影响,并且不易受到无关记忆任务的干扰。句子水平的主题启动会受到工作记忆容量的影响：工作记忆广度较高的读者能出现主题水平的语境效应,但是在无关记忆任务的干扰下,句子主题水平的语境效应消失;低广度的读者在无外部记忆负荷和有外部记忆负荷两种条件下都没有出现主题水平的语境效应。工作记忆容量对那些需要较多认知资源的加工过程产生显著的影响,实验结果符合工作记忆容量限制理论     

问题表征、工作记忆对小学生数学问题解决的影响

以104名小学六年级学生为被试, 采用4个相对独立的研究探讨了工作记忆广度、问题表征方式与小学生数学应用题解决的关系。结果表明：(1)言语工作记忆广度只影响高难度应用题的解决, 在低难度、中等难度的应用题解决上, 高、低言语工作记忆广度者不存在显著差异; (2)视觉-空间工作记忆广度对低难度、中等难度、高难度应用题的解决都存在影响; (3)问题表征方式影响数学应用题的解决, 应用题的解题成绩与问题表征方式的使用有关; (4)言语工作记忆广度对应用题的表征方式没有影响, 高、低言语工作记忆广度者在三种难度水平应用题的表征方式上不存在显著差异; (5)视觉-空间工作记忆广度对应用题的表征方式存在影响, 高、低视觉-空间工作记忆广度者在三种难度水平应用题的表征方式上均存在组间差异。     

Word length and phonological similarity effects in simple, complex, and delayed serial recall tasks: implications for working memory

Some current models of working memory argue that a passive short-term store is not involved in more dynamic working memory tasks. Other models argue that standard short-term memory and working memory tasks rely on common storage facilities. We examine these issues by exploring two signature effects of passive short-term storage in simple span, complex span, and Brown-Peterson tasks. The finding that all three tasks show word length and phonological similarity effects suggests that common processes or storage mechanisms are involved in all tasks. The implications for models of working memory are discussed.     

Word length and phonological similarity effects in simple,complex, and delayed serial recall tasks: Implications for working memory

Some current models of working memory argue that a passive short-term store is not involved in more dynamic working memory tasks. Other models argue that standard short-term memory and working memory tasks rely on common storage facilities. We examine these issues by exploring two signature effects of passive short-term storage in simple span, complex span, and Brown-Peterson tasks. The finding that all three tasks show word length and phonological similarity effects suggests that common processes or storage mechanisms are involved in all tasks. The implications for models of working memory are discussed.     

The structure of working memory abilities across the adult life span

The present study addresses three questions regarding age differences in working memory: (1) whether performance on complex span tasks decreases as a function of age at a faster rate than performance on simple span tasks; (2) whether spatial working memory decreases at a faster rate than verbal working memory; and (3) whether the structure of working memory abilities is different for different age groups. Adults, ages 20-89 (n = 388), performed three simple and three complex verbal span tasks and three simple and three complex spatial memory tasks. Performance on the spatial tasks decreased at faster rates as a function of age than performance on the verbal tasks, but within each domain, performance on complex and simple span tasks decreased at the same rates. Confirmatory factor analyses revealed that domain-differentiated models yielded better fits than models involving domain-general constructs, providing further evidence of the need to distinguish verbal and spatial working memory abilities. Regardless of which domain-differentiated model was examined, and despite the faster rates of decrease in the spatial domain, age group comparisons revealed that the factor structure of working memory abilities was highly similar in younger and older adults and showed no evidence of age-related dedifferentiation.     

On the interpretation of working memory span in adults

Experimental research into children's working memory span has shown that retention duration contributes substantially to span performance, while processing efficiency need not be related to concurrent memory load (Towse, Hitch, & Hutton, 1998). These findings have been used to argue for a model of working memory span that emphasizes time-based forgetting rather than the popular resource-sharing or tradeoff framework. The present paper considers whether adults perform working memory span tasks in a qualitatively different way. Data from reading span and operation span tasks show that adults' performance can be distinguished from that of children, but also that a task-switching model of working memory span can explain some important aspects of performance.     

Differential constraints on the working memory and reading abilities of individuals with learning difficulties and typically developing children

This study examined the factors that constrain the working memory span performance and reading ability of individuals with generalized learning difficulties. In the study, 50 individuals with learning difficulties (LD) and 50 typically developing children (TD) matched for reading age completed two working memory span tasks. Participants also completed independent measures of the processing and storage operations involved in each working memory span task and Raven's Coloured Progressive Matrices. The results showed that despite an equivalent level of working memory span, the relative importance of the constraints on working memory differed between the groups. In addition, working memory span was not closely related to word recognition or sentence comprehension performance in the LD group. These results suggest that the working memory span performance of LD and TD individuals may reflect different working memory limitations and that individuals with generalized learning difficulties may approach cognitive tasks in a qualitatively different way from that of typically developing individuals.     

Individual differences in working memory: introduction to the special section.

This special section includes a set of 5 articles that examine the nature of inter- and intraindividual differences in working memory, using working memory span tasks as the main research tools. These span tasks are different from traditional short-term memory spans (e.g., digit or word span) in that they require participants to maintain some target memory items (e.g., words) while simultaneously performing some other tasks (e.g., reading sentences). In this introduction, a brief discussion of these working memory span tasks and their characteristics is provided first. This is followed by an overview of 2 major theoretical issues that are addressed by the subsequent articles--(a) the factors influencing the inter- and intraindividual differences in working memory performance and (b) the domain generality versus domain specificity of working memory--and also of some important issues that must be kept in mind when readers try to evaluate the claims regarding these 2 theoretical issues.     

How does the severity of a learning disability affect working memory performance?

Working memory performance was examined in children aged 11-12 years who had borderline, mild, and moderate learning disabilities. Comparisons with children of average abilities were used to determine whether those with more severe learning disabilities had greater impairments in working memory. Seven measures of working memory span were used to assess temporary phonological short-term storage (digit span, word span), temporary visuo-spatial short-term storage (pattern span, spatial span), and temporary short-term storage with additional processing, or central executive, demands (listening span, odd one out span, reverse digit span). Children with mild and moderate learning disabilities were impaired on all measures of working memory compared to children of average abilities. Children with borderline learning disabilities were just as good as children with average abilities on visuo-spatial and complex span tasks, but showed an impairment on phonological span tasks. Children with moderate learning disabilities were indistinguishable from children with mild learning disabilities on simple span tasks, but were significantly poorer than the mild group on the more demanding complex span tasks. For the group as a whole, working memory was strongly related to mental age.     

How does the severity of a learning disability affect working memory performance?

Working memory performance was examined in children aged 11-12 years who had borderline, mild, and moderate learning disabilities. Comparisons with children of average abilities were used to determine whether those with more severe learning disabilities had greater impairments in working memory. Seven measures of working memory span were used to assess temporary phonological short-term storage (digit span, word span), temporary visuo-spatial short-term storage (pattern span, spatial span), and temporary short-term storage with additional processing, or central executive, demands (listening span. odd one out span, reverse digit span). Children with mild and moderate learning disabilities were impaired on all measures of working memory compared to children of average abilities. Children with borderline learning disabilities were just as good as children with average abilities on visuo-spatial and complex span tasks, but showed an impairment on phonological span tasks. Children with moderate learning disabilities were indistinguishable from children with mild learning disabilities on simple span tasks, but were significantly poorer than the mild group on the more demanding complex span tasks. For the group as a whole, working memory was strongly related to mental age.     

Complex span and n-back measures of working memory: A meta-analysis

Working memory is a construct of primary relevance to many areas of psychology. Two types of tasks have been used to measure working memory, primarily in different research areas: Complex span tasks are commonly used in behavioral studies in the cognitive and individual-differences literature, whereas n-back tasks have been used more frequently in cognitive neuroscience studies investigating the neural underpinnings of working memory. Despite both categories of tasks being labeled as “working memory” measures, previous empirical studies have provided mixed evidence regarding the shared amount of overlapping processes between complex span and n-back tasks. The present meta-analysis showed that the complex span and n-back tasks are weakly correlated, although significant heterogeneity across studies was observed. A follow-up analysis of unpublished data indicated that the sample composition affects the relationship between the complex span and n-back tasks, following the law of diminishing returns. Finally, a separate meta-analysis indicated that the simple span and n-back tasks are correlated to the same extent as are the complex span and n-back tasks. The present findings indicate that the complex span and n-back tasks cannot be used interchangeably as working memory measures in research applications.     

The Measurement of Verbal Working Memory Capacity and Its Relation to Reading Comprehension

Ninety-four subjects were tested on the Daneman and Carpenter (1980) reading span task, four versions of a related sentence span task in which reaction times and accuracy on sentence processing were measured along with sentence-final word recall, two number generation tasks designed to test working memory, digit span, and two shape-generation tasks designed to measure visual-spatial working memory. Forty-four subjects were retested on a subset of these measures at a 3-month interval. All subjects were tested on standard vocabulary and reading tests. Correlational analyses showed better internal consistency and test-retest reliability of the sentence span tasks than of the Daneman-Carpenter reading span task. Factor analysis showed no factor that could be related to a central verbal working memory; rotated factors suggested groupings of tests into factors that correspond to digitrelated tasks, spatial tasks, sentence processing in sentence span tasks, and recall in sentence span tasks. Correlational analyses and regression analyses showed that the sentence processing component of the sentence span tasks was the best predictor of performance on the reading test, with a small independent contribution of the recall component. The results suggest that sentence span tasks are unreliable unless measurements are made of both their sentence processing and recall components, and that the predictive value of these tasks for reading comprehension abilities lies in the overlap of operations rather than in limitations in verbal working memory that apply to both.