Previous neurophysiological and behavioural studies have shown that attention can be guided by the contents of working memory (WM), and that such guidance can be involuntary even when it is detrimental to the task at hand. In three experiments, this thesis investigated whether the guidance of visual attention from WM could be generalized from a specific stimulus or a task to a category. Experiment 1 tested whether maintaining a set of stimuli of a specific category in WM would influence participants' deployment of visual attention to favour other stimuli that belonged to the same category. Experiment 2 further manipulated the interval between the onset of a critical prime (i.e., a stimulus in the same category as the stimuli held in WM) and the target to determine whether the results of Experiment 1 were associated with the lack of time for attention to be focused onto the critical prime. In both experiments, the stimuli held in WM never appeared in the prime display. In Experiment 3, the identity of the prime was manipulated so that it matched the stimuli held in WM on half of the trials. The results showed that when the stimuli held in WM never reappeared in the prime display (Experiments 1 and 2) there was no evidence that maintaining specific stimuli in WM biased the distribution of attention to other stimuli within the same category. However, when the stimuli held in WM could reappear in the prime display on some trials (Experiment 3), the participants whose reaction times were relatively fast showed evidence for category-based WM guidance of attention when the critical prime item was a new stimulus in the same category as the stimuli held in WM. In contrast, the participants whose reaction times were relatively slow showed a non-spatially specific cost when the critical prime was one of the WM items than when it was a new item in the same category. These results showed that category-based WM could guide the deployment of visual attention under certain conditions. It further suggests that the relationship between WM and attention is more complex than what is outlined by the biased competition theory and related theories of attention.

Evidence is presented that supports the view that most models of short-term memory cannot account for the flexibility of the primary memory system. It is argued that the working memory model outlined by Baddeley and Hitch (1974) is, however, a potentially adequate model. Working memory, in this thesis, is depicted as a system that assembles 'constellations' consisting of the central executive and one or more sub-systems. This view suggests a formulation that is considerably more complex than the 1974 model. The empirical studies examine the role of the visuo-spatial scratch pad in the formation and maintenance of working memory constellations. It is concluded from these studies that the scratch pad is independent of the articulatory loop but is usually coupled to the central executive except during maintenance rehearsal. Furthermore, it can be used concurrently with the articulatory loop to process spatial aspects of highly verbal tasks. However a constellation consisting of the executive, the loop and the scratch pad is vulnerable to a wider range of interference effects than a simpler constellation. Paivio (1971) suggested that 'dual coding' leads to better memory performance, however, this is only the case when no distractors are present. The final two chapters present some speculations on how working memory research might proceed in the future. It is concluded that the current trend towards collecting convergent evidence and the emphasis on testing theory in applied situations should give us insights into memory that were not available to Ebbinghaus and other early memory researchers.

One of the best ways to increase memory performance on a task is to organize the to-be-remembered material (Postman, 1972). Throughout a number of experiments, the amount a subject organizes a list of words has been shown to be related to their overall recall performance (e.g., Mandler & Pearlstone, 1966). However, few studies have investigated whether other cognitive abilities are related to the organization of memory and whether these other abilities contribute to the relationship between organization and memory performance. In the present study subjects completed four sets of multitrial free recall and the consistency in which subjects recalled words (a measure of organization) was compared to performance on multiple measures of working memory capacity and fluid intelligence. I show that working memory capacity is related to the organization of memory particularly when subjects were told to use an organizational strategy and that fluid intelligence is related to organization regardless of strategy. Additionally, both working memory capacity and organization predict unique variance in immediate free recall performance.

Working memory (WM) refers to the information processing system that is responsible for the maintenance plus manipulation of information. WM is necessary for the performance of complex tasks, such as reasoning and comprehension. Until relatively recently, WM capacity was thought to be a fixed trait of the individual. However, research findings on the effects of WM training programs have demonstrated otherwise. Therefore, this dissertation examined the impact of WM training in college students with Attention-Deficit/Hyperactivity Disorder (ADHD) and Learning Disabilities (LD), two neuro-developmental disorders in which WM is impaired. The main objectives of this dissertation were to investigate training gains on the WM training program itself, transfer effects, and 2-month maintenance effects. College students with ADHD/LD, all of whom were registered with student disability services, were randomized to either the WM training program or a wait-list control group. Those who received WM training showed significantly greater improvements in the criterion WM measures (WAIS-IV Digit Span, CANTAB Spatial Span) and self-reported fewer ADHD symptoms and daily cognitive failures, compared to the control group. Analysis of participants who completed the follow-up assessment indicated that the gains in WM were maintained for at least 2 months after training. The dissertation is presented in four chapters. The introduction provides a broad overview of the research on WM, ADHD/LD, and WM training. The second chapter expands upon the methods used in the current study. The third chapter consists of a manuscript that will be submitted for publication. The fourth and final chapter summarizes the findings of the current study and discusses its implications for future research and clinical practice.

Working memory (WM) refers to the information processing system that is responsible for the maintenance plus manipulation of information. WM is necessary for the performance of complex tasks, such as reasoning and comprehension. Until relatively recently, WM capacity was thought to be a fixed trait of the individual. However, research findings on the effects of WM training programs have demonstrated otherwise. Therefore, this dissertation examined the impact of WM training in college students with Attention-Deficit/Hyperactivity Disorder (ADHD) and Learning Disabilities (LD), two neuro-developmental disorders in which WM is impaired. The main objectives of this dissertation were to investigate training gains on the WM training program itself, transfer effects, and 2-month maintenance effects. College students with ADHD/LD, all of whom were registered with student disability services, were randomized to either the WM training program or a wait-list control group. Those who received WM training showed significantly greater improvements in the criterion WM measures (WAIS-IV Digit Span, CANTAB Spatial Span) and self-reported fewer ADHD symptoms and daily cognitive failures, compared to the control group. Analysis of participants who completed the follow-up assessment indicated that the gains in WM were maintained for at least 2 months after training. The dissertation is presented in four chapters. The introduction provides a broad overview of the research on WM, ADHD/LD, and WM training. The second chapter expands upon the methods used in the current study. The third chapter consists of a manuscript that will be submitted for publication. The fourth and final chapter summarizes the findings of the current study and discusses its implications for future research and clinical practice.

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This study examines how undergraduate students use hand gestures to offload cognitive demands on their working memory (WM) when they are engaged in three major proving activities: reading, presenting, and constructing proofs of mathematical conjectures. Existing research literature on the role of gesturing in cognitive offloading has been limited to the context of elementary mathematics but has shown promise for extension to the college level. My framework weaves together theoretical constructs from mathematics education and cognitive psychology: gestures, WM, and mathematical proofs. Piagetian and embodied perspectives allow for the integration of these constructs through positioning bodily activity at the core of human cognition. This framework is operationalized through the methodology for measuring cognitive demands of proofs, which is used to identify the set of mental schemes that are activated simultaneously, as well as the places of potential cognitive overload. The data examined in this dissertation includes individual clinical interviews with six undergraduate students enrolled in different sections of the Introduction to Proofs course in Fall 2021 and Spring 2022. Each student participated in seven interviews: two WM assessments, three proofs-based interviews, a stimulated recall interview (SRI), and post-interview assessments. In total, 42 interviews were conducted. The participants' hand gesturing and mathematical reasoning were qualitatively analyzed. Ultimately, students' reflections during SRIs helped me triangulate the initial data findings. The findings suggest that, in absence of other forms of offloading, hand gesturing may become a convenient, powerful, although not an exclusive offloading mechanism: several participants employed alternative mental strategies in overcoming the cognitive overload they experienced. To better understand what constitutes the essence of cognitive offloading via hand gesturing, I propose a typology of offloading gestures. This typology differs from the existing classification schemes by capturing the cognitive nuances of hand gestures rather than reflecting their mechanical characteristics or the underlying mathematical content. Employing the emerged typology, I then show that cognitive offloading takes different forms when students read or construct proofs, and when they present proofs to the interviewer. Finally, I report on some WM-related issues in presenting and constructing proofs that can be attributed to the potential side effects of mathematical chunking. The dissertation concludes with a discussion of the limitations and practical implications of this project, as well as foreshadowing the avenues for future research. / Doctor of Philosophy / In this study, I examined how undergraduate students can rely on their hand gesturing to reduce the cognitive complexity of mathematical proofs. Specifically, I studied gestures produced by students when they are engaged in various kinds of proving activities: reading for comprehension, reading for validation, presenting, and constructing proofs of mathematical conjectures. During the experiments, the participants were not given pencils/paper, calculators, or any other and other figurative materials. Therefore, they had to rely on their imagination, working memory, and hand gestures to make progress on the tasks. Results suggest that students' hand gestures have a beneficial effect in navigating cognitive challenges associated with mathematical proofs. Moreover, I show that this effect takes different forms depending on the proving activity in which the student engages. Finally, I report on some memory-related issues in presenting and constructing proofs. The dissertation concludes with a discussion of the limitations and practical implications of this project, as well as foreshadowing the avenues for future research.

The literature suggests working memory can have a significant effect on children's academic success. A number of working memory training programmes have been developed as tools for helping children to boost their working memory and learning ability. The reliability and validity of this body of evidence has been challenged recently with questions raised as to whether such programmes actually do boost working memory or show any subsequent impact upon learning. The thesis contains an evaluative systematic review examining eight studies from the last decade that explore the effects of working memory training on working memory, literacy and numeracy. The review found significant near and far transfer effects for improvements to working memory with differences in the pattern of these improvements. The assertion that working memory training leads to improvements in other areas such as literacy and numeracy is also challenged. The thesis also contains an examination of the efficacy of a paired whole class working memory intervention in delivering improvements in the working memory, literacy and numeracy skills of primary aged school children. The pre-experimental design tested the impact of the intervention on the working memory, literacy and numeracy of a sample of forty-one Year 4 children. The data demonstrated a significant positive immediate effect of the programme on verbal working memory recall and processing and visual-spatial working memory processing and recall. No significant immediate effects of the programme were found on numeracy or literacy. Finally a critical appraisal of concepts of evidence based practice and a review of the literature regarding the dissemination of research and notions of research impact is presented. The implications of the current research for professional practice is explored in terms of the care that must be taken by educational professionals in offering up working memory training programmes as solutions to academic underachievement in children.

The current study explored the relationship between working memory (WM) and reading performance in 50 typically-developing third-grade students, as well as the effect of WM-training on their WM, reading fluency, and reading comprehension skills. Half of the sample was randomly assigned to the experimental group, while the other half was placed in the control group. Children in both groups participated in a battery of WM and reading assessments preceding and following three weeks of computer game play. The children in the experimental group played a WM-training computer game for about 10 minutes a day (Monday-Friday) for three weeks, while children in the control group played a computer game that required sustained attention, but did not have a WM component. It was hypothesized that WM performance would predict reading performance, such that better WM ability would be associated with better reading ability. Furthermore, it was predicted that WM span would mediate the relationship between reading fluency and reading comprehension. In terms of WM training, it was hypothesized that WM training would significantly improve the experimental group's performance on the measures of WM, reading fluency, and reading comprehension relative to the control group. Results indicated that WM ability significantly predicted performance on measures of reading fluency and reading comprehension at pre-test; however, WM performance was not observed to mediate the relationship between reading fluency and reading comprehension despite being closely associated with both skills. Finally, although children in the experimental group did not show improvements in WM performance relative to those in the control group on transfer tasks, they did demonstrate improvements in reading fluency and reading comprehension. The findings of this study not only suggest that WM ability is closely related to reading skills, but also that WM training may serve as another route to further improve and develop students' literacy abilities.

Phonological working memory (PWM) is the mind's capacity for maintaining and manipulating representations of the sounds important for speech when they are not actively being perceived. It is believed to be a critical component supporting typical language acquisition and vocabulary development, as well as second-language learning. Despite the success of the theoretical framework traditionally used to conceptualize PWM, consensus on its instantiation in the brain remains elusive. In this thesis, I will describe a series of studies designed to interrogate the functionality of the brain regions supporting PWM. In Chapter 1, we compare activation patterns from a canonical PWM task, nonword repetition, to nonword discrimination, a matched task designed to engage core PWM functions, but for the purpose of comparing stimuli, not repeating them. We replicate the findings that PWM during nonword repetition engages speech cortices and show that these cortical regions are also reliably engaged in nonword discrimination, in individual subjects. In Chapter 2, we directly assess the extent to which conjunctive activation between language and working memory paradigms can be interpreted as shared functionality. We find that despite the ability to localize regions in which the majority of subjects show conjunction of significant activation between tasks, the pattern similarity between tasks within those regions vary. We find no pattern similarity between language and spatial working memory, and marginal similarities between language and verbal working memory. Verbal working memory and spatial working memory conjunctions localize a similar network to the multiple demand network and find highly similar patterns of activation in these regions across working memory tasks. Finally, in Chapter 3, we investigate the functional properties of brain areas supporting PWM by comparing activation between nonword repetition, language, verbal working memory, and spatial working memory tasks. We find that PWM shares support with areas involved in spoken language perception, as well as regions engaged by working memory tasks that lie outside of the core language network. Taken together, these studies give a detailed account of the neural bases of PWM, through the lens of shared functionality between this capacity, language, and other domains of working memory.