Speech-processing capacity in young and older adults: a dual-task study

Adult age differences in processing speech were examined with a dual-task paradigm. Subjects listened to spoken passages for later recall while performing a concurrent reaction time task intended to index cognitive capacity usage on the speech memory task. Age differences in secondary task decision latencies were eliminated when subgroups of young and older subjects were matched on working memory span. These findings are interpreted as showing that an age-related reduction in working memory efficiency contributes to age differences in processing discourse for memory.     

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.     

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)。     

Age-related differences in irrelevant-speech effects

Three experiments examined age-related differences in irrelevant-speech effects. Younger and older adults were required to recall short prose texts or lists of semantically related words presented visually together with distractor speech. In all experiments, older adults made more semantically related intrusion errors from the irrelevant speech than younger adults. Results of a source memory test suggested that these age-related differences in interference are most likely due to both inhibitory deficits and source-monitoring problems. The results lend partial support to the inhibition deficit theory of cognitive aging.     

Domain-specific and domain-general constraints on word and sequence learning

The relative influences of language-related and memory-related constraints on the learning of novel words and sequences were examined by comparing individual differences in performance of children with and without specific deficits in either language or working memory. Children recalled lists of words in a Hebbian learning protocol in which occasional lists repeated, yielding improved recall over the course of the task on the repeated lists. The task involved presentation of pictures of common nouns followed immediately by equivalent presentations of the spoken names. The same participants also completed a paired-associate learning task involving word–picture and nonword–picture pairs. Hebbian learning was observed for all groups. Domain-general working memory constrained immediate recall, whereas language abilities impacted recall in the auditory modality only. In addition, working memory constrained paired-associate learning generally, whereas language abilities disproportionately impacted novel word learning. Overall, all of the learning tasks were highly correlated with domain-general working memory. The learning of nonwords was additionally related to general intelligence, phonological short-term memory, language abilities, and implicit learning. The results suggest that distinct associations between language- and memory-related mechanisms support learning of familiar and unfamiliar phonological forms and sequences.     

Adult Age Differences in Tower of Hanoi Performance: Influence From Demographic and Cognitive Variables

We examined performance in a five-disk version of the Tower of Hanoi (TOH) puzzle, assumed to reflect executive functioning, in population-based samples ranging in age from 35 to 85 years (N ?=?2798). Univariate analyses revealed significant age effects across three TOH measures as reflected by an age-related increase in moves to solution, a gradual slowing of performance, and an increase in rule violations with advanced age. The age-related influence was eliminated, or reduced considerably, when controlling for demographic and cognitive background variables. Across the dependent measures, Block Design and a measure of episodic memory (recall) were the consistent predictors. No effects of education were detected, while significant gender differences, favoring males, were observed for two TOH measures. Taken together, the results suggest that age-related deficits observed in TOH performance reflects an age-related impairment in visuospatial ability in addition to impairments in executive functions.     

The role of age and inhibitory efficiency in working memory processing and storage components

In this study, we examined the extent to which inhibitory efficiency accounted for age-related decline in the processing and storage components of working memory. Older and younger adults performed a sequential task, which served as an index of deletion-type inhibition (the ability to suppress no-longer-relevant information). The reading span task was used to measure working memory components by examining processing accuracy, processing time, and end-word recall of sentences presented. Reduced inhibitory efficiency, which was poorer in older adults, predicted age-related decline in recall, over and above the effects of processing speed. Similar results were observed for processing accuracy, although the age effect in this component was marginal. These results highlight the important role of deletion-type inhibition in explaining age-related decline in working memory performance, particularly in the storage component, and extend previous research by examining this relationship at a componential level.     

The role of age and inhibitory efficiency in working memory processing and storage components

In this study, we examined the extent to which inhibitory efficiency accounted for age-related decline in the processing and storage components of working memory. Older and younger adults performed a sequential task, which served as an index of deletion-type inhibition (the ability to suppress no-longer-relevant information). The reading span task was used to measure working memory components by examining processing accuracy, processing time, and end-word recall of sentences presented. Reduced inhibitory efficiency, which was poorer in older adults, predicted age-related decline in recall, over and above the effects of processing speed. Similar results were observed for processing accuracy, although the age effect in this component was marginal. These results highlight the important role of deletion-type inhibition in explaining age-related decline in working memory performance, particularly in the storage component, and extend previous research by examining this relationship at a componential level.     

Mind racing: The influence of exercise on long-term memory consolidation

Over time, regular exercise can lower the risk for age-related decline in cognition. However, the immediate effects of exercise on memory consolidation in younger adults have not been fully investigated. In two experiments, the effects of exercise were assessed on three different memory tasks. These included paired-associate learning, procedural learning and text memory. Results indicate that performance on procedural learning and situation model memory was increased with exercise, regardless of if participants exercised before or after encoding. No benefit of exercise was found for paired-associate learning. These findings suggest that intense exercise may benefit certain types of memory consolidation.     

Aging and Individual Variation in Interhemispheric Collaboration and Hemispheric Asymmetry

ABSTRACT

Thirty younger (Mean Age = 19.9 years) and 20 older adults (Mean Age = 74.7 years) performed Physical and Name Identity letter-matching tasks (matches were either within or between hemispheres) to study age-related changes in 1) the efficiency with which the two hemispheres interact with each other and 2) hemispheric asymmetry. In order to determine whether age-related effects were associated with differences in cognitive resources, the same individuals completed a set of memory span tasks. Performance on the letter-matching tasks indicated that the costs of interhemispheric collaboration were greater for older than for younger participants. However, within the older group, the advantage of spreading processing across both hemispheres increased as memory span decreased, suggesting that older individuals who are challenged by cognitive complexity are more likely to show increased benefits from between-hemisphere processing than individuals who are not so challenged. There was also an overall left visual field/right hemisphere advantage for the younger but not for the older group, suggesting greater age-related declines in right- than left-hemisphere function.     

Hebb learning, verbal short-term memory, and the acquisition of phonological forms in children

Recent work using the Hebb effect as a marker for implicit long-term acquisition of serial order has demonstrated a functional equivalence across verbal and visuospatial short-term memory. The current study extends this observation to a sample of five- to six-year-olds using verbal and spatial immediate serial recall and also correlates the magnitude of Hebb learning with explicit measures of word and nonword paired-associate learning. Comparable Hebb effects were observed in both domains, but only nonword learning was significantly related to the magnitude of Hebb learning. Nonword learning was also independently related to individuals' general level of verbal serial recall. This suggests that vocabulary acquisition depends on both a domain-specific short-term memory system and a domain-general process of learning through repetition.     

The effects of print exposure on sentence processing and memory in older adults: Evidence for efficiency and reserve

The present study was an examination of how exposure to print affects sentence processing and memory in older readers. A sample of older adults (N = 139; Mean age = 72) completed a battery of cognitive and linguistic tests and read a series of sentences for recall. Word-by-word reading times were recorded and generalized linear mixed effects models were used to estimate components representing attentional allocation to word-level and textbase-level processes. Older adults with higher levels of print exposure showed greater efficiency in word-level processing and in the immediate instantiation of new concepts, but allocated more time to semantic integration at clause boundaries. While lower levels of working memory were associated with smaller wrap-up effects, individuals with higher levels of print exposure showed a reduced effect of working memory on sentence wrap-up. Importantly, print exposure was not only positively associated with sentence memory, but was also found to buffer the effects of working memory on sentence recall. These findings suggest that the increased efficiency of component reading processes that come with life-long habits of literacy buffer the effects of working memory decline on comprehension and contribute to maintaining skilled reading among older adults.     

Education does not protect against age-related decline of switching focal attention in working memory

In this experimental study, effects of age and education on switching focal attention in working memory were investigated among 44 young (20-30 years) and 40 middle-aged individuals (50-60 years). To this end, a numeric n-back task comprising two lag conditions (1- and 2-back) was administered within groups. The results revealed a comparable increase of reaction time as a function of lag across age groups, but a disproportionate decrease of accuracy in the middle-aged relative to the young group. The latter effect did not interact with education, which challenges the cognitive reserve hypothesis. Moreover, the high-educated middle-aged participants showed a greater increase of reaction time as a function of lag than their low-educated counterparts. Apparently, they were not able to sustain their relatively high response speed across conditions. These results suggest that education does not protect against age-related decline of switching focal attention in working memory.     

Short-term longitudinal change in cognitive performance in later life.

Changes in mean performance on memory, information processing, and intellectual ability tasks over a 3-year period were examined. The sample consisted of 328 community-dwelling men and women (from an original sample of 484 individuals) aged 55-86 years. Ss completed tasks yielding measures of verbal processing time, working memory, implicit memory, vocabulary, verbal fluency, world knowledge, reading comprehension, word recall, and text recall. The results showed significant average decline on working memory, verbal fluency, and world knowledge. There were also interactions for 2 processing time measures and working memory, showing greater decline in the earlier-born cohort group than in the later-born cohort group. A step-down analysis revealed that covarying declines in other variables, including processing time, did not eliminate significant declines in working memory, verbal fluency, and world knowledge.     

Working Memory Demands and Semantic Sensitivity for Prose in Mild Alzheimer's Disease

The debate continues with regard to whether degradation of semantic knowledge or deficits in information processing lead to impaired memory performance in patients with Alzheimer's disease (AD). This study examined the effects of semantic content and working memory demands on the recall and recognition abilities of patients with mild AD. Nineteen patients with probable AD and 19 demographically matched normal control participants were asked to remember prose passages that varied in semantic content (high, medium, and low level of idea importance) and working memory demands (narrative and expository passages). Compared to the controls, patients with mild AD lost the ability to recall prose in a manner consistent with the semantic structure of the passages as the demands on working memory increased. Furthermore, as the demands on working memory increased, patients recognized information in a manner that suggested their initial processing was of isolated details rather than by semantic structure. This study provides support for the hypothesis that information processing deficits contribute to impaired semantic processing in patients with mild AD.     

Le développement de la mémoire de travail : perspectives dans le cadre du modèle de partage temporel des ressources

Working memory has a central role in cognitive development and its capacity is among the best predictors of high-level cognition and school achievement. Within the Time-Based Resource Sharing (TBRS) model, three main factors account for the development of working memory capacity. In this paper, we will review the main empirical evidence sustaining the impact of two of these factors on cognitive development. First, the amount of attention available for cognitive functioning might increase during childhood. Thus, for the same activities, older children would be able to process information faster than younger children. Within working memory span tasks, because the level of activation of memory traces decreases during the processing steps, any reduction of the duration of these steps directly diminishes the time during which the traces decay, and consequently increases the time available for reactivation or refreshing before the next processing step. These two effects jointly induce a stronger activation of the memory traces and a better recall of the to-be-maintained items. Second, because the main hypothesis of the TBRS model is that attention switches to refresh memory traces from processing to maintenance during the processing episodes, the efficiency of the refreshing mechanism should have a direct and strong impact on working memory functioning. An increase in the efficiency of this refreshing during childhood means that older children should take a greater advantage from the short pauses left free between each processing step. The level of activation of the memory traces would be then higher for older than for younger children, resulting in the classically observed increase in span. As a consequence, age-related changes in the efficiency of the refreshing could play a central role in working memory development.     

The relationship between executive function and verbal memory in Parkinson's disease

A growing body of evidence suggests that the various cognitive symptoms found in Parkinson's disease (PD) are secondary to executive dysfunction. Studies addressing this possibility for memory impairment specifically have not included measures of working memory nor have they ruled-out potential mediating variables such as overall level of cognitive impairment or depression. The purpose of this study was to include measures of these variables in determining the relationship between multiple aspects of executive function and delayed verbal recall in 32 idiopathic PD patients. Results were consistent with the original hypothesis and further suggest that working memory is a key factor in recall memory and may mediate the relationship between other executive measures and recall in PD.     

Developmental differences in memory for temporally neutral and temporally tagged information

Forty children (ages 7 and 11 years) listened to stories and then answered questions about temporally neutral and temporally tagged information appearing in them (e.g., “Linda is smart” vs “Linda ate an apple”). Number of presentations and free recall of the stories were manipulated to study age-related changes in the effects of additional processing on memory for the two kinds of information. Older children exhibited overall better memory, but with additional processing that difference was larger for temporally neutral than for temporally tagged information. The observed interactions among age, additional processing, and kind of information demonstrated the importance of the distinction between temporally neutral and temporally tagged information for developmental studies of memory for prose.     

Task experience and children's working memory performance: a perspective from recall timing

Working memory is an important theoretical construct among children, and measures of its capacity predict a range of cognitive skills and abilities. Data from 9- and 11-year-old children illustrate how a chronometric analysis of recall can complement and elaborate recall accuracy in advancing our understanding of working memory. A reading span task was completed by 130 children, 75 of whom were tested on 2 occasions, with sequence length either increasing or decreasing during test administration. Substantial pauses occur during participants' recall sequences, and they represent consistent performance traits over time, while also varying with recall circumstances and task history. Recall pauses help to predict reading and number skills, alongside as well as separate from levels of recall accuracy. The task demands of working memory change as a function of task experience, with a combination of accuracy and response timing in novel task situations being the strongest predictor of cognitive attainment.     

Type of stimulus mediates the relationship between working-memory performance and type of precocity

The relationship between type of stimulus (numeric and verbal) and type of precocity (mathematical and verbal) was examined in tasks designed to tap three aspects of working memory: encoding, capacity, and manipulation of information. The tasks included semantic categorization, odd-even categorization, recall of five-item lists after semantic categorization, and recall of items in a continuous paired-associates task. Correlations between task performance and the mathematical and verbal portions of the Scholastic Aptitude Test (SAT-M and SAT-V) were computed for gifted youth. There were no sex differences in the performance measures or in the pattern of correlations between performance and SAT scores. The analysis revealed positive relationships between SAT-M scores and numeric categorization latency, recall in the continuous paired-associate task with words and digits, and recall of digit lists. SAT-V scores were related only to word recall in the continuous paired-associate task and recall of word lists. In the working-memory tasks used, mathematical precocity is more strongly related to performance than is verbal precocity. The relationship is especially strong with numeric stimuli, even when the numeric stimuli are simply items to be remembered. The relationship between type of stimulus and type of precocity suggests underlying differences between verbally and mathematically precocious youth in how different types of stimuli are represented in memory.