加工速度、工作记忆与液态智力发展的关系

有关儿童液态智力 (fluid intelligence) 发展的年龄特征早已有了较明确的一致性结论。然而,儿童液态智力发展的机制问题到现在仍知之甚少。早期零星的研究观察到,随着儿童年龄的增长,其信息加工速度变快,工作记忆能力和液态智力亦提高。由此可推测,对儿童液态智力与加工速度、工作记忆能力关系的考察有助于阐明儿童液态智力发展的机制问题。 近10多年已有不少研究分别探讨了液态智力与加工速度、液态智力与工作记忆的关系,并已开始同时探讨液态智力与加工速度和工作记忆的关系。但令人惊讶的是,有关儿童液态智力发展与加工速度、工作记忆关系问题的综合探讨几成空白,到目前为止,仅有极少量的研究 (Fry 和Hale, 1996; Miller和Vernon, 1996) 探讨了这一问题,其中Fry 和Hale (1996) 还提出了一个模型 (the developmental cascade model) 试图解释儿童液态智力发展的机制,随后Fry 和Hale (2000)进一步阐明并坚持了这一观点。Fry 和Hale的观点是,儿童液态智力的发展取决于儿童工作记忆能力的发展,而工作记忆能力的发展又进一步取决于儿童信息加工速度能力的发展。这就是说,加工速度和工作记忆是儿童液态智力发展的两个关键因素,其中加工速度又是第一作用因素。Fry 和Hale (1996, 2000) 提出了她们的观点后,后续研究在国际上仍十分少见。但来自于发展领域之外的研究似乎不支持Fry 和Hale (1996, 2000)的观点。研究发现(Conway et al., 2002),仅工作记忆能很好预测液态智力的变化,而加工速度不能很好预测液态智力的变化。 该研究从南京市中小学随机选取了243名10到18岁的健康儿童（男生127名,女生116名）。所有被试共完成7项任务,包括2项液态智力任务测试（瑞文标准推理测验和卡特尔文化公平智力测验,以原始分作为数据分析指标）、3项加工速度任务测试（数字抄写、字母串比较和符号串比较）、2项工作记忆任务（数字工作记忆和视空间工作记忆）。验证性因素分析发现这7项任务所测量的正是液态智力、加工速度和工作记忆这3个因子,且这3个因子间存在显著的相关。但随后的结构方程模型分析表明,从工作记忆到液态智力间存在显著路径,但从加工速度到液态智力并不存在显著路径,工作记忆几乎可完全解释儿童液态智力的发展变化（85.4%）,且可以解释81.6%的加工速度的发展变化量。仅当不考虑工作记忆这一因素时,加工速度才能解释50%的液态智力的发展变化。这表明,工作记忆是儿童液态智力发展的基础,而加工速度则不是。这一结果在以三个变量的平均标准分数为基础所进行的层级回归分析 (hierarchical regression analyses)中亦得到了证实。 总体上,该研究并不支持Fry 和Hale (1996, 2000)的观点。工作记忆是儿童液态智力发展的关键因素,而加工速度则不是。加工速度与液态智力存在显著相关,其原因可能在于,加工速度反映的是儿童液态智力的同一年龄内个体差异而不是年龄间差异（即发展性变化）。本研究同时对工作记忆之所以是儿童液态智力发展的基础的可能原因进行了讨论。     

The Roles of Working Memory Updating and Processing Speed in Mediating Age-related Differences in Fluid Intelligence

ABSTRACT

This study was conducted to investigate the relative roles of working memory updating (updating) and processing speed in mediating age-related differences in fluid intelligence. A sample of 142 normal adults between 18 and 85 years of age performed a set of updating, processing speed, and fluid intelligence tasks. Hierarchical regression analyses indicated that the proportion of unique age-related variance in updating measures was related to the complexity of speed measures. There was a larger proportion of unique age-related variance in updating measures after controlling for the variance in simpler speed measures. Moreover, structural equation modeling showed that updating mediated almost all the age-related effects on fluid intelligence. These results suggest that updating, but not speed, is the critical mediator between age and fluid intelligence. In addition, the speed mediation of age-related differences in fluid intelligence as indicated by previous studies is at least partially derived from the executive component of speed measures.     

The roles of working memory updating and processing speed in mediating age-related differences in fluid intelligence

This study was conducted to investigate the relative roles of working memory updating (updating) and processing speed in mediating age-related differences in fluid intelligence. A sample of 142 normal adults between 18 and 85 years of age performed a set of updating, processing speed, and fluid intelligence tasks. Hierarchical regression analyses indicated that the proportion of unique age-related variance in updating measures was related to the complexity of speed measures. There was a larger proportion of unique age-related variance in updating measures after controlling for the variance in simpler speed measures. Moreover, structural equation modeling showed that updating mediated almost all the age-related effects on fluid intelligence. These results suggest that updating, but not speed, is the critical mediator between age and fluid intelligence. In addition, the speed mediation of age-related differences in fluid intelligence as indicated by previous studies is at least partially derived from the executive component of speed measures.     

Working memory – not processing speed – mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms

Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self‐report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes.     

儿童青少年时期加工速度和执行功能在流体智力发展中的作用

以7~15岁儿童青少年为研究对象,考察加工速度和执行功能对流体智力的影响。研究结果表明,随着年龄的增长,感觉运动加工速度、知觉加工速度对流体智力从具有直接影响到只通过执行功能中的记忆更新成分产生间接影响,但这种影响存在年龄间的差异。在童年中期（7~9岁）,知觉加工速度对流体智力不仅具有直接的预测作用,还通过记忆更新对其产生间接的影响。童年晚期（10~12岁）,感觉运动加工速度和知觉加工速度不再对流体智力具有直接预测作用,都是通过记忆更新和抑制/转换合成成分间接对流体智力起作用。青春期（13~15岁）,知觉加工速度对流体智力只通过记忆更新产生间接影响。     

工作记忆、加工速度与流体智力的发展

近几年有关认知发展心理机制的研究成为一个认知发展领域一个颇引人注目的内容．这些研究探讨了年龄、工作记忆、加工速度与流体智力之间的关系。研究发现．在流体智力的发展过程中,工作记忆可能比加工速度发挥着更直接、更一般的作用,而加工速度则对工作记忆的发展起直接调节作用。     

The influence of complex working memory span task administration methods on prediction of higher level cognition and metacognitive control of response times

Participants between the ages of 18 and 80 were tested on a complex working memory span task that was administered either using a typical experimenter-paced method or using a method in which the processing component was presented at a fixed, limited-pace presentation rate. Path analyses revealed that even after controlling for individual differences in general processing speed, the limited-pace task predicted unique variance in episodic memory, executive functioning, and fluid intelligence, whereas the experimenter-paced task did not. For the experimenter-paced task, slower responses on the processing component of the task were associated with better recall, but only when individual differences in processing speed were controlled. These findings suggest that metacognitive control of response times affects recall from working memory span tasks, as well as the relationship between span task recall and high-level cognition. These results support resource-sharing explanations of working memory and suggest that limiting processing times using computer pacing of complex span tasks can be an effective way to efficiently measure working memory capacity.     

The influence of temporal resolution power and working memory capacity on psychometric intelligence

According to the temporal resolution power (TRP) hypothesis, higher TRP as reflected by better performance on psychophysical timing tasks accounts for faster speed of information processing and increased efficiency of information processing leading to better performance on tests of psychometric intelligence. An alternative explanation of individual differences in psychometric intelligence highlights individual differences in working memory (WM) capacity which has been found to be closely associated with psychometric intelligence. A latent variable approach was applied on the data of 200 participants ranging in age from 18 to 30 years and spanning a large range of levels of psychometric intelligence. Functional relationships were examined among TRP, WM capacity, as well as reasoning and speed of processing as two important aspects of psychometric intelligence. As predicted by the TRP hypothesis, the relation between TRP and psychometric intelligence was mediated by WM capacity supporting the view that higher TRP leads to better coordinated mental operations which, in turn, result in higher psychometric intelligence. The results are discussed against the background that WM capacity and psychometric reasoning are hardly dissociable from each other and that the specific factors limiting WM capacity and accounting for the mediation effect need to be identified in future research.     

Mapping the developmental constraints on working memory span performance

This study investigated the constraints underlying developmental improvements in complex working memory span performance among 120 children of between 6 and 10 years of age. Independent measures of processing efficiency, storage capacity, rehearsal speed, and basic speed of processing were assessed to determine their contribution to age-related variance in complex span. Results showed that developmental improvements in complex span were driven by 2 age-related but separable factors: 1 associated with general speed of processing and 1 associated with storage ability. In addition, there was an age-related contribution shared between working memory, processing speed, and storage ability that was important for higher level cognition. These results pose a challenge for models of complex span performance that emphasize the importance of processing speed alone.     

Thought suppression,intelligence, and working memory capacity

The importance of individual differences in intelligence and working memory capacity in predicting the ability to intentionally suppress thoughts was investigated. Sixty participants completed a thought suppression task, and measures of working memory capacity (OSPAN), fluid intelligence (Raven's Matrices), and crystallised intelligence (the National Adult Reading Test). As predicted, the results indicated that more effective thought suppression was independently related to higher working memory capacity and greater fluid intelligence, but was unrelated to crystallised intelligence. The findings have theoretical implications for understanding the mechanisms underlying a failure to inhibit unwanted intrusions and clinical implications for disorders involving high levels of intrusive thoughts and memories.     

工作记忆和感觉运动速度在心算加工年老化过程中的作用

对心算加工年老化研究有助于阐明认知老化规律,然而有关心算老化的少量研究结果仍存在不一致甚至矛盾之处。导致这种不一致的原因十分复杂,表面上看,不同认知老化研究所采用的统计方法不尽相同导致了结果的歧异。例如,在心算的年老化研究中,有的研究结论基于群体的数据分析,如层级回归分析(hierarchical regres-sion analyses)或方差分析,如Sahhouse和Coon(1994);另有一些研究先对每一个体数据作线性回归分析,如此得到斜率和截距(分别表示心算的中枢加工时间和外周感觉运动时间),然后再行层级回归分析或方差分析,如Al-len等(1992,1997)。这两类统计分析所得的结果很不一致。从理论上看,只要所采用的统计方法是合理的,统计方法的不尽相同应不会导致矛盾。但在实际情况下,统计分析误差增加了结论不一致的可能性,从而增大了揭示心算老化复杂性规律的难度。事实上,心算活动的年龄差异可能来自于记忆、加工速度等不同认知资源的老化差异。为了深入探讨这一问题,我们进一步研究了工作记忆和感觉运动速度在心算加工年老化过程中的作用。被试共161人,20—79岁,身体健康,受教育年限12年以上,以10岁段划分为6个年龄组,组间文化程度基本匹配。被试任务包括：(1)连续减法心算,分别为1000—3、1000—7、1000—13及1000—17等4种,在排除了被试看屏幕和按键的感觉运动时间后得到心算所需的时间;(2)数字计算工作记忆,根据工作记忆对信息同时进行加工和储存的特点,要求被试计算完题后再回忆答案,以获得工作记忆广度指标;(3)“数字复制”(digit copying),以获得感觉运动速度指标。实验在386微机上进行。对所得数据分别进行了上述群体数据与个体数据分析。两种数据分析方法得到了相同的结果,一致表明,在控制工作记忆与感觉运动速度的年龄差异后,心算活动的年龄差异显著降低。而且,控制感觉运动速度的年龄差异后心算活动年龄差异的降低程度要大于控制工作记忆的年龄差异后心算活动年龄差异的降低程度。这说明,感觉运动速度在心算加工年老化过程中发挥了更大作用。但是,工作记忆与感觉运动速度二者的年龄差异并不能完全解释心算活动的年龄差异,表明心算加工的年老化存在其特殊性过程,不支持认知老化的普遍减慢假说(genenalized slowing hypotllesis)。     

The unique contributions of the facilitation of procedural memory and working memory to individual differences in intelligence

Individual differences in working memory account for a substantial portion of individual differences in complex cognitive processes (e.g., comprehension) and fluid intelligence. However, a large portion of the variance in fluid intelligence and comprehension is unexplained. The current investigation was conducted to evaluate whether individual differences in the facilitation of procedural memory accounts for unique variance in intelligence not accounted for by working memory. To measure variability in the facilitation of procedural memory, we used a task that required participants to first classify exemplars of two categories; facilitation was then operationalized by subsequent improvements in the speed of classifying new exemplars from those categories (i.e., an operation-specific memory procedure). Three measures of each focal construct (facilitation in procedural memory, working memory, comprehension and fluid intelligence) were administered to 256 participants. We used structural equation modeling to examine the relationships among these latent variables. Working memory did account for variance in fluid intelligence and comprehension, but most important, individual differences in facilitation of procedural memory accounted for unique variance in fluid intelligence and comprehension.     

Cognitive Mediators of Age-Related Differences in Language Comprehension and Verbal Memory Performance

The present study tried to specify how much processing speed, working memory capacity, and inhibition capability contribute to the effects of aging on language performance. An individual-differences approach was used to examine the component processes that predict performance in language comprehension and verbal long-term memory tasks. A total of 151 participants aged 31-80 completed language processing tasks and a battery of tasks designed to assess processing speed, working memory, and resistance to interference. Latent-construct structural equation modeling was used to examine the relationships of these factors and age to different types of language tasks. The best fit model showed first that all the significant relationships between age and language performance are mediated through reductions in speed, resistance to interference, and working memory; this confirms the validity of the general factor approach of age-related differences in cognitive performance. The best fit model, however, also showed that the contribution of speed and resistance to interference is indirect and mediated by working memory, which appears to play a crucial role in explaining age-related differences in language performance.     

Working memory and phonological processing as predictors of children’s mathematical problem solving at different ages

The study explored the contribution of working memory (WM) to mathematical problem solving in younger (8-year-old) and older (11-year-old) children. The results showed that (1) significant age-related differences in WM performance were maintained when measures of phonological processing (i.e., digit naming speed, short-term memory, phonological deletion) were partialed from the analysis; (2) WM predicted solution accuracy of word problems independently of measures of problem representation, knowledge of operations and algorithms, phonological processing, fluid intelligence, reading, and math skill; and (3) a second-order WM factor was correlated with problem solving, suggesting that a general or executive system underlies age-related performance. The results were interpreted as support for the notion that the executive system was an important predictor of age-related changes in problem solving beyond the contribution of math and reading skills, and this system operates independently of the phonological system and domain-specific knowledge in predicting solution accuracy.     

The role of processing resources in age-related prospective and retrospective memory within old age

This study investigated the role of processing speed and working memory in prospective and retrospective memory (i.e., free recall) performance within old age. The aim was to examine age-related differences in both memory domains within the age range of 65 to 80 years. The sample consisted of 361 older adults from Wave 1 data of the Zurich Longitudinal Study on Cognitive Aging. Using structural equation modeling, prospective memory, free recall, working memory, and processing speed were identified as latent constructs. Age effects were found to be larger for prospective memory than for free recall. Furthermore, when controlling for individual differences in working memory and processing speed, unique age effects remained for prospective, but not retrospective, memory performance. Results indicate that, within old age, prospective memory represents a distinct memory construct that is partially independent of age-related individual differences in speed of processing, working memory, and retrospective memory.     

Can longitudinal changes in processing speed explain longitudinal age changes in fluid intelligence?

The processing-speed theory of cognitive aging contends tha age-related declines in intellectual function reflect the consequences of age-related slowing of processing speed. Cross-sectional data support this assumption. The association between 4-year changes in processing speed and 4-year changes in fluid intelligence was examined with a sample of 417 older adults. Changes in processing speed correlated .53 with changes in fluid intelligence. The difference in the explanatory power of processing speed regarding age-related differences and age-related changes is discussed with reference to other longitudinal studies and methodological considerations.     

抑制和加工速度与液态智力的年老化

研究抑制能力和加工速度在液态智力年老化过程中的相对作用。被试为142名18~85岁健康成年人,完成包括抑制优势反应、加工速度和液态智力共13项测验。分层回归分析显示,抑制能力与年龄相关的特异性变异,在控制简单的速度变量时较控制复杂的速度变量时更大;结构方程分析表明,对液态智力年老化的中介作用,当选取较复杂的速度变量时加工速度的作用更大,而当选取较简单的速度变量时抑制能力的作用更大。研究结果表明,在液态智力的年老化过程中,除了加工速度的作用之外,抑制能力也起重要的中介作用。该结果为认知年老化的抑制理论和执行衰退假说提供了认知行为学研究的证据,并且对加工速度理论作了有益的补充和修正     

Individual and age-related differences in children’s working memory

The purpose of this study was to investigate the degree to which age-related and individual differences in children’s working memory (WM) are due to a general or task-specific capacity system. Experiment 1 correlated children’s (N=146; age range 5–19 years) verbal and visual-spatial working memory performance with various intelligence and achievement measures. The results supporting a general system were that (1) visual-spatial and verbal WM measures were significantly intercorrelated with and without age partialed out and (2) both verbal and visual-spatial WM measures were significantly correlated with diverse achievement and intelligence measures. Experiment 2 compared three age groups (N=192; 7-, 10-, and 13-year-olds) on working-memory performance tasks under initial, enhanced (cued), and maintenance conditions. The results supporting a general capacity system were that (1) age-related performance differences in WM were found on all conditions and not isolated to specific processes, (2) the maintenance measures (high-load condition) predicted the variance better in age-related performance than process measures, and (3) although individual differences in WM performance reflected two independent operations, these operations produced similar correlations to achievement within age groups. Overall, the results support a general capacity explanation of age-related and individual differences in children’s WM performance.     

Latent change models of adult cognition: are changes in processing speed and working memory associated with changes in episodic memory?

The authors used 6-year longitudinal data from the Victoria Longitudinal Study (VLS) to investigate individual differences in amount of episodic memory change. Latent change models revealed reliable individual differences in cognitive change. Changes in episodic memory were significantly correlated with changes in other cognitive variables, including speed and working memory. A structural equation model for the latent change scores showed that changes in speed and working memory predicted changes in episodic memory, as expected by processing resource theory. However, these effects were best modeled as being mediated by changes in induction and fact retrieval. Dissociations were detected between cross-sectional ability correlations and longitudinal changes. Shuffling the tasks used to define the Working Memory latent variable altered patterns of change correlations.     

Cognitive Mechanisms Underlying Decrements in Mental Synthesis in Older Adults

The extent and nature of age-related differences in mental synthesis was examined in light of Baddeley's working memory model and resource theories. Mental synthesis performance of 30 young, young-old, middle-old and old-old adults was examined using a dual-task experiment and individual differences approach. Age-related differences in mental synthesis were shown, with an unprecedented heightened decrement evident after the age of 85. The central executive was not a mechanism of this decline. Executive function, speed of information processing, and working memory capacity were mechanisms underlying this decline, and together accounted for 86% of the age-related variance in mental synthesis. Environmental support enhanced mental synthesis.