Working Memory and Learning in Early Alzheimer’s Disease

Cognitive deficits associated with early Alzheimers disease (AD) have been recently operationalised in terms of an acquisition deficit and the research supporting this view is presented. However, there is still debate concerning the nature of this deficit and how underlying cognitive processes may be detrimentally affecting the ability to acquire new information in early AD. This review argues that the pattern of cognitive deficits contributing to the acquisition impairment in early AD patients may be readily interpreted within the context of a working memory model. Isolating the component processes of working memory that underlie the acquisition deficit in early AD patients will aid in the design of clinical applications that are focussed at enhancing the ability to acquire new information in everyday life.     

A structural analysis of working memory and related cognitive skills in young children

The aim of this study was to investigate the functional organisation of working memory and related cognitive abilities in young children. A sample of 633 children aged between 4 and 6 years were tested on measures of verbal short-term memory, complex memory span, sentence repetition, phonological awareness, and nonverbal ability. The measurement model that provided the best fit of the data incorporates constructs that correspond to the central executive, phonological loop, and episodic buffer subcomponents of working memory, plus distinct but associated constructs associated with phonological awareness and nonverbal ability.     

But I thought it was Mickey Mouse: the effects of new postevent information on 18-month-olds' memory

Two experiments examined the effects of postevent information on 18-month-olds' event memory. Experiment 1 (N=60) explored whether children's memory was reinstated when action information was eliminated from the reinstatement and only object information was introduced. Experiment 2 (N=48) examined children's recall when either (a). information about the objects' target actions was replaced with new action information or (b). the original training objects were replaced with new objects. In an elicited-imitation paradigm, children were trained to perform six target actions, watched a video reinstatement 10 weeks later, and were tested for recall 24 h after reinstatement. Two results were found. First, a video reminder eliminating action information reinstated children's memory as effectively as a video containing object and action information. Second, children were reminded of their past training when during reinstatement action information was preserved and new objects were presented but were not reminded when object information was preserved and new actions were presented.     

Strategy choices in simple and complex addition: Contributions of working memory and counting knowledge for children with mathematical disability

Groups of first-grade (mean age = 82 months), third-grade (mean age = 107 months), and fifth-grade (mean age = 131 months) children with a learning disability in mathematics (MD, n = 58) and their normally achieving peers (n = 91) were administered tasks that assessed their knowledge of counting principles, working memory, and the strategies used to solve simple (4+3) and complex (16+8) addition problems. In all grades, the children with MD showed a working memory deficit, and in first grade, the children with MD used less sophisticated strategies and committed more errors while solving simple and complex addition problems. The group differences in strategy usage and accuracy were related, in part, to the group difference in working memory and to group and individual differences in counting knowledge. Across grade-level and group, the switch from simple to complex addition problems resulted in a shift in the mix of problem-solving strategies. Individual differences in the strategy mix and in the strategy shift were related, in part, to individual differences in working memory capacity and counting knowledge.     

Category specificity in normal episodic learning: applications to object recognition and category-specific agnosia

Studies of patients with category-specific agnosia (CSA) have given rise to multiple theories of object recognition, most of which assume the existence of a stable, abstract semantic memory system. We applied an episodic view of memory to questions raised by CSA in a series of studies examining normal observers' recall of newly learned attributes of familiar objects. Subjects first learned to associate arbitrarily assigned colors or textures to objects in a training phase, and then attempted to report the newly learned attribute of each object in a recall task. Our subjects' pattern of recall errors was similar both quantitatively and qualitatively to the identification deficits among patients with CSA for biological objects. Furthermore, errors tended to reflect conceptually and structurally based confusions. We suggest that object identification involves recruitment and integration of information across distributed episodic memories and that this process is susceptible to interference from objects that are structurally similar and conceptually related.     

The effects of noise and gender on children's episodic and semantic memory

The main objectives in the present study were to examine meaningful irrelevant speech and road traffic noise effects on episodic and semantic memory, and to evaluate whether gender differences in memory performance interact with noise. A total of 96 subjects, aged 13-14 years (n = 16 boys and 16 girls in each of three groups), were randomly assigned to a silent or two noise conditions. Noise effects found were restricted to impairments from meaningful irrelevant speech on recognition and cued recall of a text in episodic memory and of word comprehension in semantic memory. The obtained noise effect suggests that the meaning of the speech were processed semantically by the pupils, which reduced their ability to comprehend a text that also involved processing of meaning. Meaningful irrelevant speech was also assumed to cause a poorer access to the knowledge base in semantic memory. Girls outperformed boys in episodic and semantic memory materials, but these differences did not interact with noise.     

Effects of age and anxiety on episodic memory: selectivity and variability

Selective age-related differences in source memory relative to item memory, and individual differences in memory performance in relation to anxiety were explored with high- and low-anxious subjects screened from normal young and elderly adults. They were read false facts about the locations of well-known and unknown sights in a male or female voice. Intentional and incidental learning instructions were administered for source memory. Selective age-related deficits in source memory were observed under both encoding conditions. Higher level of anxiety was related to lower memory performance only in the old group; this relation was stronger in source recall. The findings suggest that the presence of such selectivity is unrelated to the tradeoff between item encoding and source encoding. Anxiety affects the variability, and mediates the selectivity of age effects on episodic memory.     

Confidence judgments in event recall: developmental progression in the impact of question format

Two studies were conducted to examine developmental progression in children's and adults' ability to adequately monitor their own attempts to recall event details as well as the dependence of such metamemorial competencies on question formats. Eight and 10-year-old children as well as adults (Study 1, N=116; Study 2, N=60) rated their confidence when responding to specific questions about an observed event. Confirming most recent results, children and adults gave higher confidence ratings after correct than after incorrect answers. This ability, however, was limited to an unbiased question format. When being asked misleading questions, children's ability to differentiate was undermined, as reflected in equally high confidence judgments after correct and incorrect answers, even when the interview contained a mix of misleading and unbiased questions. When the interviewer "bombarded" the children with an uninterrupted series of misleading questions, children's difficulties appeared to be even more pronounced. These findings highlight the importance of the way in which questions are asked, and point to age-related progression in the relative impact of questioning style.     

Differential memory-preserving effects of reminders at 6 months

Although reactivation and reinstatement reminders differ procedurally, differences in their memory-preserving effects have been described as artifactual. In three experiments, we examined this conclusion. One hundred and twelve 6-month-olds learned an operant task, forgot it, received a reactivation or reinstatement reminder to recover the inactive memory, and were tested after increasing delays until they forgot it again. In Experiments 1a and 1b, a single reactivation reminder extended infants' memory of an operant mobile task for 2 weeks after reminding, but a single reinstatement extended it for 4 weeks, when testing was discontinued. In Experiment 2, a single reinstatement extended 6-month-olds' memory of an operant train task for 19 weeks after reminding, when infants were almost 1 year old. After reactivation, infants remember this task for only 2 weeks. The finding that the memory-preserving effect of reinstatement is greater by an order of magnitude suggests that procedural differences between the two reminders have functional significance.     

Capacity,strategies, and metamemory: tests of a three-factor model of memory development

Multiple measures of three of the factors (capacity, strategies, and metamemory) hypothesized to cause improvements in memory with age were obtained from 179 children in kindergarten to second grade (younger: ages 5-8) or third and fourth grade (older: ages 8-11) during nine sessions of testing. Confirmatory factor analysis was computed separately for each age group. Results suggested that the fit of the three-factor model was statistically significantly better than a one-factor, general memory model for both age groups. However, the fit indices were borderline, and there was not sufficient evidence for a metamemory factor for younger children. The factors that influence memory performance may differ with age.