Individual differences on complex memory spans predict a variety of higher-order cognitive tasks (e.g. reading comprehension, reasoning, following direction) as well as low-level attention tasks (e.g. Stroop, dichotic listening, antisaccade). The current study attempted to better determine the role of individual differences in complex memory span and episodic retrieval. Specifically, two experiments explored the possibility that individual differences in complex memory span reflect differences in the ability to successfully retrieve items from secondary memory via a cue-dependent search process. High and low complex span participants were tested in delayed (Experiment 1) and continuous distractor (Experiment 2) free recall with varying list-lengths. Across both experiments low spans recalled fewer items than high spans, recalled more previous list intrusions than high spans, and recalled at a slower rate than high spans. It is argued that low spans search through a larger set of items than high spans and, thus low spans episodic retrieval deficits are associated with an inability to use cues to guide a search and retrieval process of secondary memory. Implications for dual-component models of memory are discussed.

A latent variable approach was used to (1) examine the relationship between working memory capacity and fluid intelligence, (2) compare the relationship between fluid intelligence and two measures of working memory capacity (complex span and n-back), (3) identify higher-order personality factors and (4) determine the relationship between higher-order personality factors, working memory capacity and fluid intelligence. Confirmatory factor analysis followed by structural equation modeling described the complex span and n-back as highly correlated yet distinct constructs. Consistent with previous research, both measures correlated highly with fluid intelligence. Four higher-order personality factors best modeled the structure of personality. Moreover, these four factors had differential relationship to cognitive constructs. The current research provides a deeper understanding of the relationship between working memory capacity and fluid intelligence, including discrepancies considering the magnitude of the relationship between two types of working memory measures and fluid intelligence, and finally, the influence of a diverse personality structure on working memory capacity and fluid intelligence. Importantly, the study examined these relationships on a broad scale using multiple tasks at a latent level contributing to better understanding of the nature of working memory capacity - fluid intelligence relationship and the influence of personality on higher-order cognition.

To investigate whether multilingualism can be used to predict working memory in older adults this study has used a categorical variable as well as a continuous variable to measure multilingualism. This was done while also accounting for possible confounding variables such as intelligence. Furthermore, subjective memory was investigated regarding how it can be affected by multilingualism and if subjective memory is an accurate measure of objective memory. A positive correlation between the Ospan score and composite language score was found while correlations could not be found for subjective memory. However, according to the hierarchical multiple regressions that were done, composite language score was not a significant predictor of Ospan score when demographics and intelligence were accounted for, only intelligence could predict both Span and Ospan scores. In regards to subjective memory, it was found that composite language scores could predict subjective memory and that those who spoke four languages rated themselves worse than monolinguals. Working memory tasks could not, however, predict subjective memory. The conclusions that were made were that multilingualism does not have an effect on working memory capacity but that composite language score and quadrilingualism have an effect on subjective memory.

There has been little research exploring whether different memory processes (i.e. related to short term memory (STM), working memory (WM) and long term memory (LTM) may be differentially sensitive to representation and processing aspects of compound words. This study investigated how compound words are represented in STM in immediate serial recall tasks and in WM in complex span tasks that combine processing and storage demands. The simple span STM task was comprised of solely a list of memory words, whereas the two complex span WM tasks interleaved sentence processing between presentation of memory words. They varied in the presence of a pause after presentation of each memory word and before onset of the following distractor sentence for processing. The absence of a pause was intended to minimize opportunity for subvocal rehearsal, whereas the presence of a pause encouraged rehearsal. To increase chances of recombination errors for error analyses, lists of memoranda were manipulated so that each set (list) of four compound words contained one “lure” pair (e.g. pinstripe + warhead = pinhead) in which the modifier and head constituents from separate compound words could recombine to form a new, legal word. Recall performance was better in the simple span and complex span pause tasks compared to the complex span no pause task. Whole compound and left constituent frequencies played opposite roles, helping and harming, respectively. Error types reflecting decomposition of the compound words to their constituents were more common in simple span than in complex span. Omissions were more common in complex span. We discuss how different memory processes may be differentially sensitive to representation and processing aspects, and how recall of compound words is affected by various lexical variables. / Thesis / Master of Science (MSc)

京都大学 / 新制・課程博士 / 博士(教育学) / 甲第24988号 / 教博第297号 / 新制||教||221(附属図書館) / 京都大学大学院教育学研究科教育学環専攻 / (主査)教授 齊藤 智, 教授 MANALO Emmanuel, 准教授 高橋 雄介 / 学位規則第4条第1項該当 / Doctor of Philosophy (Education) / Kyoto University / DGAM

The intent of this thesis is to examine the psychometric properties of a complex span task (CST) developed to measure working memory capacity (WMC) using measurements obtained from a sample of 68 undergraduate students at the University of Central Florida. The Grocery List Task (GLT) promises several design improvements over traditional CSTs in a prior study about individual differences in WMC and distraction effects on driving performance, and it offers potential benefits for studying WMC as well as the serial-position effect. Currently, the working memory system is composed of domain-general memorial storage processes and information-processing, which involves the use of executive functions. Prior research has found WMC to be associated with attentional measures (i.e., executive attention) and the updating function, and unrelated to the shifting function. The present study replicates these relationships to other latent variables in measures obtained from the GLT as convergent and discriminant evidence of validity. In addition, GLT measures correlate strongly with established measures of WMC. Task reliability is assessed by estimates of internal consistency, pairwise comparisons with a cross-validation sample, and an analysis of demographic effects on task measurements.

L’objectif principal de cette thèse est d’examiner et d’intervenir auprès des déficits de la mémoire de travail (MdeT) à l’intérieur de deux populations cliniques : la maladie d’Alzheimer (MA) et le trouble cognitif léger (TCL). La thèse se compose de trois articles empiriques. Le but de la première expérimentation était d’examiner les déficits de MdeT dans le vieillissement normal, le TCL et la MA à l’aide de deux versions de l’empan complexe : l’empan de phrases et l’empan arithmétique. De plus, l’effet de «l’oubli» (forgetting) a été mesuré en manipulant la longueur de l’intervalle de rétention. Les résultats aux tâches d’empan complexe indiquent que la MdeT est déficitaire chez les individus atteints de TCL et encore plus chez les gens ayant la MA. Les données recueillies supportent également le rôle de l’oubli à l’intérieur de la MdeT. L’augmentation de l’intervalle de rétention exacerbait le déficit dans la MA et permettait de prédire un pronostic négatif dans le TCL. L’objectif de la deuxième étude était d’examiner la faisabilité d’un programme d’entraînement cognitif à l’ordinateur pour la composante de contrôle attentionnel à l’intérieur de la MdeT. Cette étude a été réalisée auprès de personnes âgées saines et de personnes âgées avec TCL. Les données de cette expérimentation ont révélé des effets positifs de l’entraînement pour les deux groupes de personnes. Toutefois, l’absence d’un groupe contrôle a limité l’interprétation des résultats. Sur la base de ces données, la troisième expérimentation visait à implémenter une étude randomisée à double-insu avec groupe contrôle d’un entraînement du contrôle attentionnel chez des personnes TCL avec atteinte exécutive. Ce protocole impliquait un paradigme de double-tâche composé d’une tâche de détection visuelle et d’une tâche de jugement alpha-arithmétique. Alors que le groupe contrôle pratiquait simplement la double-tâche sur six périodes d’une heure chacune, le groupe expérimental recevait un entraînement de type priorité variable dans lequel les participants devaient gérer leur contrôle attentionnel en variant la proportion de ressources attentionnelles allouée à chaque tâche. Les résultats montrent un effet significatif de l’intervention sur une des deux tâches impliquées (précision à la tâche de détection visuelle) ainsi qu’une tendance au transfert à une autre tâche d’attention divisée, mais peu d’effets de généralisation à d’autres tâches d’attention. En résumé, les données originales rapportées dans la présente thèse démontrent un déficit de la MdeT dans les maladies neurodégénératives liées à l’âge, avec un gradient entre le TCL et la MA. Elles suggèrent également une préservation de la plasticité des capacités attentionnelles chez les personnes à risque de développer une démence. / The principal aim of this dissertation is to investigate and intervene upon working memory (WM) impairments in two clinical populations: Alzheimer’s disease (AD) and mild cognitive impairment (MCI). The dissertation is comprised of three empirical articles. The goal of the first study was to examine WM impairments in normal aging, MCI and AD using two versions of the complex span task: sentence span and operation span. In addition, the effect of forgetting was assessed by manipulating the length of the retention interval. Results indicate impaired WM on complex spans in MCI and, to a greater extent, in AD. Data also support a role for forgetting within WM. Increasing the retention interval augmented deficit in persons with AD, and showed potential in predicting a negative prognosis in those with MCI. The objective of the second article was to investigate the feasibility of a computerized cognitive training paradigm for the attentional control component of WM in healthy older individuals and those with MCI. Data from this experiment revealed positive effects of the intervention for both groups. However, the absence of a control group limited interpretation of results. Based on those data, the third article aimed to implement a double-blind randomized controlled study of training of attentional control in MCI with executive deficits. This involved a dual-task paradigm comprised of a visual detection task and a visual alpha-arithmetic judgment task. While the control group performed simple dual-task practice over six one-hour sessions, the experimental group received variable-priority training, in which participants managed their attentional control by varying the proportion of attentional resources allocated to each task. Results show a significant effect of intervention on one of the two tasks involved (accuracy on the visual detection task) and a trend for transfer to another task of divided attention, but little generalization to other tasks of attention. In summary, the original data reported in this thesis demonstrates WM impairment in age-related disorders, with a gradient between MCI and AD, and suggest preserved plasticity of attentional capacities in persons at risk of developing dementia.

L’objectif principal de cette thèse est d’examiner et d’intervenir auprès des déficits de la mémoire de travail (MdeT) à l’intérieur de deux populations cliniques : la maladie d’Alzheimer (MA) et le trouble cognitif léger (TCL). La thèse se compose de trois articles empiriques. Le but de la première expérimentation était d’examiner les déficits de MdeT dans le vieillissement normal, le TCL et la MA à l’aide de deux versions de l’empan complexe : l’empan de phrases et l’empan arithmétique. De plus, l’effet de «l’oubli» (forgetting) a été mesuré en manipulant la longueur de l’intervalle de rétention. Les résultats aux tâches d’empan complexe indiquent que la MdeT est déficitaire chez les individus atteints de TCL et encore plus chez les gens ayant la MA. Les données recueillies supportent également le rôle de l’oubli à l’intérieur de la MdeT. L’augmentation de l’intervalle de rétention exacerbait le déficit dans la MA et permettait de prédire un pronostic négatif dans le TCL. L’objectif de la deuxième étude était d’examiner la faisabilité d’un programme d’entraînement cognitif à l’ordinateur pour la composante de contrôle attentionnel à l’intérieur de la MdeT. Cette étude a été réalisée auprès de personnes âgées saines et de personnes âgées avec TCL. Les données de cette expérimentation ont révélé des effets positifs de l’entraînement pour les deux groupes de personnes. Toutefois, l’absence d’un groupe contrôle a limité l’interprétation des résultats. Sur la base de ces données, la troisième expérimentation visait à implémenter une étude randomisée à double-insu avec groupe contrôle d’un entraînement du contrôle attentionnel chez des personnes TCL avec atteinte exécutive. Ce protocole impliquait un paradigme de double-tâche composé d’une tâche de détection visuelle et d’une tâche de jugement alpha-arithmétique. Alors que le groupe contrôle pratiquait simplement la double-tâche sur six périodes d’une heure chacune, le groupe expérimental recevait un entraînement de type priorité variable dans lequel les participants devaient gérer leur contrôle attentionnel en variant la proportion de ressources attentionnelles allouée à chaque tâche. Les résultats montrent un effet significatif de l’intervention sur une des deux tâches impliquées (précision à la tâche de détection visuelle) ainsi qu’une tendance au transfert à une autre tâche d’attention divisée, mais peu d’effets de généralisation à d’autres tâches d’attention. En résumé, les données originales rapportées dans la présente thèse démontrent un déficit de la MdeT dans les maladies neurodégénératives liées à l’âge, avec un gradient entre le TCL et la MA. Elles suggèrent également une préservation de la plasticité des capacités attentionnelles chez les personnes à risque de développer une démence. / The principal aim of this dissertation is to investigate and intervene upon working memory (WM) impairments in two clinical populations: Alzheimer’s disease (AD) and mild cognitive impairment (MCI). The dissertation is comprised of three empirical articles. The goal of the first study was to examine WM impairments in normal aging, MCI and AD using two versions of the complex span task: sentence span and operation span. In addition, the effect of forgetting was assessed by manipulating the length of the retention interval. Results indicate impaired WM on complex spans in MCI and, to a greater extent, in AD. Data also support a role for forgetting within WM. Increasing the retention interval augmented deficit in persons with AD, and showed potential in predicting a negative prognosis in those with MCI. The objective of the second article was to investigate the feasibility of a computerized cognitive training paradigm for the attentional control component of WM in healthy older individuals and those with MCI. Data from this experiment revealed positive effects of the intervention for both groups. However, the absence of a control group limited interpretation of results. Based on those data, the third article aimed to implement a double-blind randomized controlled study of training of attentional control in MCI with executive deficits. This involved a dual-task paradigm comprised of a visual detection task and a visual alpha-arithmetic judgment task. While the control group performed simple dual-task practice over six one-hour sessions, the experimental group received variable-priority training, in which participants managed their attentional control by varying the proportion of attentional resources allocated to each task. Results show a significant effect of intervention on one of the two tasks involved (accuracy on the visual detection task) and a trend for transfer to another task of divided attention, but little generalization to other tasks of attention. In summary, the original data reported in this thesis demonstrates WM impairment in age-related disorders, with a gradient between MCI and AD, and suggest preserved plasticity of attentional capacities in persons at risk of developing dementia.

It is well established that repeated testing is more beneficial for durable learning than repeated studying of the same material, a phenomenon known as the testing effect. This study sought to investigate the role of working memory capacity (WMC) in relation to the learning process and the difficulty of the material to be learned when using a test-enhanced learning method. As between subject manipulation, participants (n = 99, M = 25.62 years of age) were divided into two groups, one using repeated studying and one using alternated testing and studying. A material of two difficulty levels, as well as immediate and delayed retention tests, was used in each condition as within subject manipulation. Further, an n-back task was used to measure WMC. Results from mixed model ANOVAs showed no significant impact of WMC on either the learning process or retention in relation to the difficulty of the material. The testing condition performed significantly higher than the studying condition on the retention tests. The testing effect is further cemented as a promising method for practical application in the educational sector regardless of both WMC and difficulty level. / Det är väl etablerat att upprepad testning är mer fördelaktigt för hållbar inlärning än upprepad instudering av samma material, ett fenomen känt som testeffekten. Denna studie ämnade undersöka arbetsminnets roll i relation till inlärningsprocessen och svårighetsgrad av material med testbaserat lärande som metod. Som mellangruppsmanipulation delades deltagare (n = 99, M = 25.62 år gamla) in i två grupper, en som upprepade gånger studerade materialet och en som alternerade studerande med tester. Ett material med två svårighetsgrader och ett direkt samt fördröjda retentionstester användes som inomgruppsmanipulation. Vidare användes ett n-backtest som mått på arbetsminneskapacitet. Resultat visade ingen signifikant inverkan av arbetsminne på varken inlärningsprocessen eller retention i relation till svårighetsgrad av material. Testbetingelsen presterade signifikant högre på retentionstest än studiebetingelsen. Testeffekten fastställs ytterligare som lovande metodik för praktisk applikation i utbildningssektorn oberoende av både arbetsminneskapacitet och svårighetsgrad.