Flexible and goal-driven behaviour requires a process by which the appropriate task-set is selected and maintained in a privileged state of activation. This process can be conceptualised as loading a task-set into a procedural working memory (PWM) buffer. Task switching experiments, which exercise this process, reveal “switch costs”: increased reaction times and error rates when the task changes, compared to when it repeats. The process of loading a task-set into PWM may be one source of these costs. The switch cost is reduced with preparation, suggesting that at least some of the processes involved in a successful change of task can be achieved in advance of the stimulus. The aim of this thesis was to investigate the properties of PWM, and its contribution to task-set control. One account of PWM distinguishes between the level at which recently exercised (but currently irrelevant) task-sets are represented, and the level at which only the currently relevant task-set is maintained in a most active state. To distinguish between these levels of representation, and to assess the extent to which the process of getting a task-set into a most-active state (loading it into the PWM buffer) is subject to a capacity limit at each level, the experiments varied the number of tasks participants switched among (Experiments 1 and 2), and the complexity of individual task-sets (Experiments 3-6) in a task-cueing paradigm. In Experiments 1 and 2, participants switched among three or five tasks, in separate sessions. There was no effect of the number of tasks on the switch cost, or its reduction with preparation, provided that recency and frequency of task usage were matched. When recency and frequency were not matched, there appeared to be a larger switch cost with five tasks at a short preparation interval, suggesting that the time consumed by getting a task-set into a most active state is influenced by its recency and frequency of usage, not the number of alternatives per se. However, Experiment 3 showed that the time required to select an S-R mapping within a task-set does increase as a function of the number of alternatives (even when stimulus frequency and recency are matched), suggesting that representation of the most active task-set in a PWM buffer is subject to a strict capacity limit. Experiments 4-6 further investigated the capacity limit of this PWM buffer, and found that task-set preparation was more effective for task-sets that are less complex (i.e. specified by fewer S-R rules). These findings suggest that only very few S-R rules can be maintained in a most active state in the PWM buffer. Finally, Experiments 7-9 investigated whether S-R rules are represented phonologically for task-set maintenance and preparation, by manipulating the phonological properties of the stimulus terms. But task-cueing performance was not affected by the name length (Experiment 7) or phonological similarity (Experiments 8 and 9) of the stimulus terms. These results suggest that phonological representations of S-R rules do not make a functional contribution to task-set control, possibly because the rules are compiled into a non-linguistic PWM. The results of these experiments are discussed in terms of a procedural working memory which is separate from declarative working memory, and distinguishes between two levels of task-set control: the level of task-sets, which are maintained in a capacity unlimited state of representation, and the level at which the currently relevant task-set is maintained in a most-active but highly capacity limited state of representation.

Although studies are conducted on economical gains due to BI system adoption, limited knowledge is available on factors which influence BI system usage. Identifying these factors is necessary for organisations because this may enable the design of effective BI systems, thus increasing the chance of firms adopting them to realise the actual value inherent in the exploitation of BI systems. The purpose of this study is, therefore, to investigate factors which influence BI system usage. The investigation employed constructs derived from three theoretical frameworks, namely technology acceptance model (TAM), task-technology fit (TTF) and social cognitive theory (SCT) as follows: intention to use, perceived usefulness, perceived ease use, task characteristics, technology characteristics, task-technology fit and computer self-efficacy. To test the hypotheses, data was collected by administering the study to 682 BI system users in a South African financial institution, SA-Bank, wherein 193 usable responses were received. The findings of the study with partial least squares (PLS) analysis indicated support for the joint use of constructs from the three theoretical frameworks, explaining 65% of BI system usage variance. Furthermore, the perceived usefulness of a BI system reflected a stronger influence as a factor of BI system usage over the beliefs that the system was easy to use, and the belief that it was aligned to the performance of business tasks. An unusual outcome in this study was the lack of influence of computer self-efficacy on BI system usage. Nonetheless, the study extended validation of the use of constructs derived from the three theoretical frameworks for a BI technology in the context of SA-Bank, thereby contributing to theory. Finally, the results of hypothesis testing suggested a starting point for practitioners towards designing BI systems, and recommendations and suggestions are included in this report.

Motivado pelo fato de que a escolha correta da forma preênsil para mãos robóticas antropomórficas representa aspectos relevantes no planejamento de estratégias de manipulação de objetos, este trabalho: desenvolve um algoritmo de pegas de objetos compatíveis com a tarefa a ser realizada e um método computacional de ajuste de superelipsóides a superfícies de objetos sintéticos 3D para modelar as primitivas resultantes do estágio de segmentação manual do objeto. Essa representação volumétrica contempla as atrativas propriedades de um modelo compacto, controlável e intuitivo, capaz de modelar uma ampla variedade de geometrias simétricas básicas a partir de 11 parâmetros. Tendo em vista que a acomodação de superelipsóides a nuvens de pontos caracteriza desafios típicos de mínimos quadrados, um breve estudo sobre o método numérico de Levenberg-Marquardt, utilizado na minimização da função objetivo adotada, se mostrou necessário para maximizar a sua eficiência. O desempenho e a eficiência do programa computacional desenvolvido foram demonstrados na modelagem experimental de cinco primitivas organizadas em diferentes configurações. As pequenas distorções, consideradas aceitáveis para a proposta do trabalho, evidenciaram a robustez da representação de formas elementares empregando superelipsóides sem deformações. Encerrada a etapa de modelagem das primitivas, um método de auto-aprendizagem supervisionada interpreta as informações de forma e tamanho de tais formas básicas para sugerir a pega de uma das primitivas que compõem o objeto e a forma preênsil compatível com a tarefa desejada. / Motivated by the fact that the correct choice of prehensile form for anthropomorphic robotic hand describes relevant aspects in planning strategies of object manipulation, this work develops an algorithm of grasping objects to match the task requirements and a computational method capable of fitting superellipsoids to surfaces of synthetic 3D objects to model the resulting primitives from the manual segmentation stage of the object. This volumetric representation describes the attractive properties of a compact, controllable and intuitive model, which is capable of modeling a wide variety of standard geometric solids by using eleven parameters. Since the superellipsoid fitting process characterizes typical least squares problems, a brief review about Levenberg-Marquardt numerical method, employed for the adopted objective function minimization, was necessary to maximize its efficiency. The performance and efficiency of the developed program were demonstrated in the experimental modeling of five symmetrical primitives shapes organized in several configurations. The small distortions, considered acceptable to the work proposal, confirm the robustness of representing elementary shapes employing superellipsoids without deformations. After finishing the primitive modeling stage, a supervised learning method interprets the size and shape information of such basic shapes to suggest the grasp of one constituent single parts and the task-compatible prehensile form.

Postural control is the skill developed allowing body equilibrium and orientation, allowing for an efficient interaction with the environment. This skill is developed from birth; the first major landmark is the maintenance of an upright stance of a child, followed by the skill to walk freely (Shumway-Cook & Woollacott, 1985). A second important development occurs between the ages of 7-10 years-old when children start to demonstrate adult-like postural control (Riach & Hayes, 1987). While adults and older adults have shown increased automaticity in postural control in a dual-task (DT) (Potvin-Desrochers, Richer, & Lajoie, 2017), children have not yet been studied. The purpose of this experiment was to determine if children aged 6-7, 8-9, and 10-11 years old would demonstrate better postural stability, and greater postural automaticity in a DT condition than in a postural task (PT). To verify this, children were asked to stand still on a force platform in a PT or in a DT condition (PT with concurrent cognitive task). Results showed that older children had better postural stability, as demonstrated by a smaller sway area (7.20 cm2), reduced sway variability (0.60 cm), and a slower MV of sway (4.70 cm/s) than younger children (12.37 cm2, 0.78 cm, 6.60 cm/s). Older children also had a higher MPF in the PT (0.24 Hz) than in the DT (0.16 Hz). A wavelet transformation revealed a greater contribution of the ultra-low frequency band in the PT (49.9%) than in the DT (46.8%) across all children. These results demonstrated that older children were more stable than younger children. The smaller contribution to the ultra-low band in the DT may be an indication that children rely less heavily on their visual system in the DT. This research shows that children do not demonstrate automaticity of postural control between the ages of 6-11 years.

Despite the widespread adoption of task-based language teaching in English as a foreign/second language (EF/SL), task difficulty has continued to be a controversial issue in task-based assessment. This research explores how feasible it is to implement a task-based approach to testing within the existing Chinese National English Curriculum (CNEC). The central problem that the study has addressed is how task difficulty can be established through the use of a theoretically-motivated analytic scheme, grounded in contemporary task research. The scheme needs to be able to take a test-task as input, and facilitate rating of the test task on a number of dimensions. / Initially, the scheme proposed by Norris Brown, Hudson, and Yoshioka (1998) was explored for validity and practicality in the Chinese context. Since this scheme did not work very effectively, a new analytic scheme for curriculum-based test-tasks was developed through a series of developmental cycles. At the end of this process, an Input-Processing-Output (IPO) task difficulty matrix was established which provided reliable estimates of rated test-task difficulty at both global and analytic levels. The IPO task difficulty matrix designed and used in the series of studies appears to have adequately distinguished between three levels of difficulty of a CNEC theme. / The research establishes (1) that the difficulty of the tasks can be used to sequence effectively both for testing and for teaching; (2) the methods by which the principles of task selection and task difficulty can be used with a wider range of test generators and test users, and (3) that rated task difficulty connects with objective measures of performance as well as conventional ratings of performance. / The scheme provides a practical tool, but also a theoretical perspective on how tasks themselves can be analyzed effectively. The main developmental cycles required experienced and trained ELT professionals to use the analytic rating scheme. A later phase employed less experienced and trained teachers and explored how they could be trained to use the rating scheme. This phase established that the scheme can be used in "non-expert" English language teaching (ELT) situations, provided that there is adequate training. Validity was explored through the use of a range of discourse analysis measures of the writing performance of a number of school-based EFL learners in China. / Luo, Shaoqian. / "October 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: A, page: 3132. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 339-367). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

It has been proposed that backward inhibition (BI) is a mechanism which facilitates task-switching by suppressing the previous task. One view is that BI is generated in response to conflict between tasks being experienced during task-performance. Across twelve experiments, this thesis investigated this proposition by addressing two questions: What affects the size/presence of BI? and When is BI triggered?: What affects the size/presence of BI? and When is BI triggered? The findings from Chapter 2 suggest that BI is increased when conflict stemming from shared target features is present, and that the expectation, as well as experience, of conflict might increase BI. Chapter 3 suggests that BI is increased when target features are shared (and that no BI is present otherwise), but contrary to previous findings, BI is not increased when response features are shared. Chapter 4 provided indirect support for the view that BI can be present without between-task conflict (i.e., neither shared targets nor responses), and indicated that in such a context BI (at least at item-level) requires trial-by-trial cuing. Chapter 5 indicates that BI is triggered prior to response execution and after the preparation stage of task processing, therefore indicating that either the target processing stage or the response selection stage of task processing are responsible for triggering BI. Together, the results of the experiments in this thesis indicate that BI can be driven by conflict stemming from target sharing. However, there was no evidence that conflict stemming from response sharing drives BI. In addition, the data suggested that BI might be generated by the expectation of conflict and by task preparation. Therefore, BI might be applied in response to conflict at any stage of task processing and the decision to apply BI might be decided in advance of such conflict.

No description available.

A multi-agent system consists of a number of agents, which may include software agents, robots, or even humans, in some application environment. Multi-robot systems are increasingly being employed to complete jobs and missions in various fields including search and rescue, space and underwater exploration, support in healthcare facilities, surveillance and target tracking, product manufacturing, pick-up and delivery, and logistics. Multi-agent task allocation is a complex problem compounded by various constraints such as deadlines, agent capabilities, and communication delays. In high-stake real-time environments, such as rescue missions, it is difficult to predict in advance what the requirements of the mission will be, what resources will be available, and how to optimally employ such resources. Yet, a fast response and speedy execution are critical to the outcome. This thesis proposes distributed optimisation techniques to tackle the following questions: how to maximise the number of assigned tasks in time restricted environments with limited resources; how to reach consensus on an execution plan across many agents, within a reasonable time-frame; and how to maintain robustness and optimality when factors change, e.g. the number of agents changes. Three novel approaches are proposed to address each of these questions. A novel algorithm is proposed to reassign tasks and free resources that allow the completion of more tasks. The introduction of a rank-based system for conflict resolution is shown to reduce the time for the agents to reach consensus while maintaining equal number of allocations. Finally, this thesis proposes an adaptive data-driven algorithm to learn optimal strategies from experience in different scenarios, and to enable individual agents to adapt their strategy during execution. A simulated rescue scenario is used to demonstrate the performance of the proposed methods compared with existing baseline methods.

Delay discounting (the devaluation of rewards delayed in time) has been studied extensively using animal models with psychophysical adjustment procedures. Similar procedures were soon developed to assess delay discounting in humans. Although across species the same mathematical function relates discounted value to imposed delay, several methodological concerns have been implicated in human delay discounting procedures. A procedure recently developed to address these concerns is the Experiential Discounting Task (EDT). This task arranges experienced delays and rewards that humans make decisions regarding—experiencing the outcomes of their choices within session before making additional choices. The popularity of this procedure has been fueled by reports of its sensitivity to acute experimental manipulation, and that it has been predictive of treatment success. Similar sensitivity results have not been found when a traditional delay discounting task (DDT) has been used. Though the EDT appears useful for a variety of reasons, it has not been subjected to the same rigorous internal validity and reliability tests that traditional DDTs have. In two experiments we examined the test-retest reliability of the EDT (Experiment 1) and the way in which choice trials are regulated (Experiment 2). Results demonstrate that the EDT is reliable across time and choice is insensitive to trial regulation differences. We conclude with a critique of the EDT as a procedure for assessing delay discounting and hypothesize other processes it may be measuring.

Recently, task-based research motivated by a Vygotskian theoretical perspective has led to studies that demonstrate how the task-as-workplan is interpreted and reshaped by learners in actual performance (Coughlan and Duff, 1994). The ability of learners to set their own ‘tasks’ suggests that researchers need to investigate how individual students react to the tasks they have been asked to perform (Ellis, 2003). To date, there have been very few systematic studies on learner and teacher perceptions in this particular field. Four studies conducted by Kumaravadivelu (1989, 1991), Slimani (1989, 1992), Block (1994, 1996), and Barkhuizhen (1998) have shed light on the learner and teacher perception of classroom events. This study has continued the investigation into how individual students react to the tasks they have been asked to perform. In particular, it has focussed on four potential mismatches between teacher intention and learners’ interpretation of task, previously identified in a study by Kumaravadivelu (2003): instructional, pedagogic, procedural and strategic. The study aimed to look at teacher and learners’ perceptions and therefore a qualitative approach was used to gather information. The study was triangulated on two levels, using a variety of data (data triangulation) and different methods (questionnaires and interviews) to collect the data (methodological triangulation). Sixteen students studying for a Certificate in English at the School of Languages and Social Sciences at Auckland University of Technology were asked to perform a task and then complete a questionnaire which was designed to elicit information regarding the four potential mismatches, between teacher intention and learner interpretation, referred to above. Four pairs of students participated in each of the two tasks. Four students, one from each pair was then interviewed in order to elicit more in-depth information regarding the four mismatches referred to above. The teacher was also interviewed after the task had been completed. The student answers from the questionnaires were compared with the data gathered from the student and teacher interviews. The findings seem to show that two mismatches between teacher intention and learners’ interpretation were evident, namely instructional and pedagogic. There was no clear evidence of a strategic or procedural mismatch. Despite the small sample size, the study seems to show that mismatches are identifiable. Given the importance of perceptual mismatches and the fact that they are part of the practice of everyday teaching, it is important that we try to identify as many mismatches as possible in future research. It is reasonable to assume that the narrower the gap between teacher intention and learner interpretation, the greater the chances of achieving learning and teaching objectives (Kumaravadivelu, 2003).