加工速度和工作记忆在认知年老化过程中的作用

研究加工速度和工作记忆在认知能力年老化过程中的作用。被试为20-90岁的健康成人1350名,完成加工速度、工作记忆及一组认知能力测验,应用分层回归分析方法考查在年老化过程中加工速度和工作记忆对多项认知变量的作用量。结果表明,在年老化过程中,加工速度和工作记忆对认知变量的作用量分别约为87% 和76%;二者的综合作用量约为94%。说明加工速度和工作记忆在认知能力年老化过程中起决定作用     

青老年组不同难度下心算活动的脑功能磁共振成像研究

应用功能磁共振成像技术研究不同心算难度下脑区的活动以及年龄的影响。14名志愿者（20～29岁青年和60～69岁老年被试各7名）参加了该实验。实验任务为2个难度水平的连续减法心算,分别为1000—3和1000—17。结果表明：（1）心算加工激活了额叶和顶叶的许多脑区;（2）大脑左半球是心算加工的优势半球,但随着心算难度加大,大脑一侧化程度下降,而年老加剧了这一趋势;（3）青年组进行简单心算（1000—3）时,额中回未见明显激活,而老年组进行简单心算时,该脑区被明显激活。总体上,额叶和顶叶在心算活动中起着重要作用,而任务难度和年龄对心算加工时脑活动的影响以额中回区最为明显。     

心算加工年老化及其机制研究

以172名20－79岁成人为被试对心算加工的年老化过程及其机制进行了研究。任务为连续减法心算,依难度分为5种：1000－1、1000－3、1000－7、1000－13及1000－17。结果表明,年龄与心算难度存在明显的交互作用,且随着年龄增加,不同难度心算效率均以幂函数形式降低。结构方程建模分析发现心算加工年老化过程存在两个中介作用因子,即速度因子和非速度因子,且速度因子对非速度因子存在明显的正效应。     

基本心理能力老化的认知机制

基本心理能力老化机制是认知老化领域研究热点之一。横断研究与追踪研究表明, 感觉功能、加工速度、工作记忆等信息加工资源的衰退导致了基本心理能力的衰退。但由于相关研究不能进行因果推论, 基本心理能力老化的认知机制尚存在争论。因此本项目拟采用实验室研究和干预实验设计, 通过操纵感觉功能(知觉压力水平)、干预加工速度与工作记忆, 考察基本心理能力的年龄差异的变化, 以期为认知老化理论的深化和拓展提供实验依据。     

数字工作记忆广度的毕生发展及其作用因素

以10~90岁的1993名自愿者为被试完成该实验研究。结果表明：（1）在最简单的心算加工负荷下,数字工作记忆广度约为6±2;（2）在10至90岁范围内,测验的最高成绩在16~19岁组（即高中生组）,回归分析表明数字工作记忆广度随年龄的对数呈抛物线变化;（3）教育因素对成年人数字工作记忆广度的随龄化过程有重要作用;（4）与我们过去的研究结果相比较,发现数字工作记忆广度受心算加工负荷的影响显著     

工作记忆负荷和自动化提取对小学生加法心算策略执行效果的影响

本研究选取43名小学四年级学生(18名男生和25名女生)为实验被试,探究了工作记忆负荷和自动化提取对复杂加法心算策略效果的影响.结果显示:(1)工作记忆负荷对复杂加法心算策略的影响显著,即一项加法心算策略所需的工作记忆负荷越小,该策略的执行效果越好;(2)自动化提取对加法心算策略的影响显著,即一项加法心算策略所需自动化提取的程度越高,该策略的执行效果越好;(3)工作记忆负荷和自动化提取对加法心算策略效果的交互作用显著,表现为在自动化提取水平较高的情况下,工作记忆负荷的大小对心算策略执行效果的影响差异不显著;而在自动化提取水平较低的情况下,工作记忆负荷小的心算策略的执行效果显著优于工作记忆负荷大的心算策略的执行效果.     

认知作业年老化的比较研究

用言语—操作和人机对话两种方式完成１２项认知作业年老化比较研究,被试２４２人,４６－７５岁。结果表明：（１）一些作业（符号数字、视觉数字广度、听觉数字广度、词对联想学习、图象自由回忆和无意图形再认）成绩随年老明显下降,另一些作业（图象分类、卡片分类、心算和矩阵填图）成绩不随年老明显降低;（２）再次验证心算、符号数字、数字鉴别和计数四项非词语性作业速度随年老进行性减慢。     

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     

心算活动机制的研究

心算是一种重要的思维活动,是认知心理学的研究主题之一。心算活动具有明显的问题大小效应,其加工过程与工作记忆和长时记忆存在密切关系。此外,对心算的加工机制进行跨学科（认知心理学、神经科学等）的综合研究,是今后心算研究的主要方向。     

与年龄相关的认知速度减慢及学习改善过程

该工作应用人机对话方式完成心算、符号数字、数字鉴别和计数四项作业认知速度年老减慢及学习改善过程的研究,被试３５０人,４６—７５岁。研究结果表明：四项认知作业速度随年老进行性减慢;然而,老年人经学习训练认知作业速度可明显改善。上述变化程度与作业所需时间有密切关系,提示年老过程中枢信息加工过程速度的减慢快于外周感觉─运动过程速度的减慢,学习改善作用也可能主要是中枢过程速度的提高。     

PROCESSING SPEED, WORKING MEMORY, AND FLUID INTELLIGENCE:

Abstract— Processing speed, working memory capacity, and fluid intelligence were assessed in a large sample ( N = 214) of children, adolescents, and young adults (ages 7 to 19 years) Results of path analyses revealed that almost half of the age-related increase in fluid intelligence was mediated by developmental changes in processing speed and marking memory and nearly three fourths of the improvement in working memory was mediated by developmental changes in processing speed Moreover, even when age-related differences in speed, working memory and fluid intelligence were statistically controlled, individual differences in speed had a direct effect on working memory capacity which, in turn was a direct determinant of individual differences in fluid intelligence     

Influences on the efficiency of prospective memory in younger and older adults.

The influence of 4 factors on age-related declines in prospective memory (PM) was considered in 2 experiments. The results of the experiments reveal that age-related differences in PM were not moderated by the degree of match between the nature of processing required in the ongoing activity and the defining features of the PM cue. Age-related differences in the accuracy of PM responses were primarily attributable to an increase in the number of omission errors committed by older adults. Age-related differences in PM were somewhat independent of the ability to recall the PM cues and intentions following task performance and were mediated by the cognitive resources of processing speed, inhibitory control, and working memory.     

Decomposing adult age differences in symbol arithmetic

A componential analysis was conducted to determine the locus of adult age differences in symbol arithmetic. Measures of the duration of two proposed components, substitution of digits for symbols and the addition or subtraction of the digits resulting from these substitutions, were obtained from 52 young adults and 52 older adults. Tests of working memory, perceptual speed, motor speed, and associative learning were also administered to all subjects. The results were most consistent with an interpretation postulating that the speed of many different cognitive processes decreases with increased age. Considerable age-related variance remained in the measures of symbol arithmetic performance after statistical control of working memory and associative learning performance, casting doubt on alternative hypotheses of the source of age-related differences in this task.     

Age-related deficits in generation and manipulation of mental images: I. The role of sensorimotor speed and working memory.

The authors investigated age-related slowing of information processing in mental imagery tasks. Eighty-five healthy adults (ages 18 to 77) performed a visual, sensorimotor, reaction-time task; a visual-perceptual choice reaction task; and 3 mental imagery tasks that varied in apparent difficulty and involved stimuli at 2 levels of graphic complexity. Age was associated with prolongation of response time across all tasks and both levels of stimulus complexity. Accuracy of response was adversely affected by increase in stimulus complexity in all tasks, whereas it was negatively related to age only on the tasks with substantial mental imagery requirements. Slowing of information processing and reduction in accuracy were mediated by declines in working memory but not by decrease of sensorimotor speed.     

Patterns and Predictors of Adult Age Differences in Mental Imagery

Adult age differences in, and predictors of, component imagery processes were examined across a broad elderly adult age range (65-86 years). Relative to younger adults, older adults were slower and less accurate on tasks of image generation, maintenance, scanning, and rotation. Ability to maintain mental images in particular was compromised by older age. Manipulations of stimulus complexity produced inconsistent differential age effects across tasks. Processing speed and sensorimotor functioning were prominent predictors of performance and age-related variance in all imagery components, with smaller contributions from working memory and executive function. These findings suggest that age-related decrements in individual imagery processes depend primarily on how quickly information can be processed and on the neurophysiological integrity of the ageing brain.     

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.     

Age-related deficits in generation and manipulation of mental images: II. The role of dorsolateral prefrontal cortex.

The authors investigated neural substrates of age-related declines in mental imagery. Healthy adult participants (ages 19 to 77) performed a series of visual-spatial mental imagery tasks that varied in apparent difficulty and involved stimuli of varying graphic complexity. The volumes of the dorsolateral frontal cortex (DLPFC) and posterior visual processing areas were estimated from magnetic resonance imaging scans. The volume of the DLPFC and the fusiform cortex, working-memory capacity, and performance on the tasks involving image generation and manipulation were significantly reduced with age. Further analyses suggested that age-related deficits in performance on mental imagery tasks may stem in part from age-related shrinkage of the prefrontal cortex and age-related declines in working memory but not from age-related slowing of sensorimotor reaction time. The volume of cortical regions associated with modality-specific visual information processing did not show a consistent relationship with specific mental imagery processes.     

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.     

Contents Index Volume 8

In a group of 62 young and 75 older subjects, LISREL models were used to predict ordered list recall from age category, self-reported strategy use and selected cognitive abilities. It was found that: (a) age differences in the strategies of associating and repetition/testing were completely explained by speed of mental processing and associative memory; (b) only these two age-related strategies were efficacious strategies, the one not age-related strategy (concentrating) was not; (c) a large proportion of the age-related variance in list recall performance was mediated by speed and associative memory; and (d) this influence of speed and associative memory on ordered list recall was partly mediated by strategies. These results support a moderate version of the production deficiency explanation of memory aging, in which age differences in efficacious strategy use are explained by age differences in basic cognitive abilities.     

The effects of age and professional expertise on working memory performance

Differences in professional choice and experience may explain age differences in working memory performance of elderly people. The aim of this study was to examine whether expertise and prolonged practice in verbal and visuo‐spatial abilities reduce age differences in laboratory working memory tasks. The effects of age and expertise on working memory performance were examined in three age groups in two different experiments. Firstly, the role of visuo‐spatial expertise was analysed by examining age differences in architects. Secondly, people with extensive experience in verbal abilities (literary people) were tested in order to evaluate the effect of professional verbal experience. Architects and literary people outperformed a group of unselected age peers on tasks related to professional expertise only, but not on general working memory tests. There was no interaction between age and experience, suggesting that professional experience does not increase differences between experts and non experts and cannot modulate age‐related effects. Copyright © 2008 John Wiley & Sons, Ltd.