The aim of the research described in this thesis is to improve our understanding of how the central nervous system (CNS) integrates feedback information from different sensory modalities to permit skill acquisition, and the subsequent consolidation of that skill, when exposed to a novel visuomotor environment. Indeed, such adaptation must be consolidated and recalled when appropriate such that we do not have to continually relearn skills we once possessed. By manipulating the sensory feedback available from the visual and proprioceptive systems during learning, it is possible to determine those facets of the sensory feedback that are essential for adaptation to occur. The thesis consists of seven chapters. The first and last provide a conceptual basis for, and an overall discussion of, the research. Chapter 2 reviews current visuomotor adaptation research, with particular focus on the manner in which information about novel tasks is stored within the CNS as we adapt, and the sensory information that is necessary to allow this adaptation to occur. Furthermore, this chapter serves to introduce many of the experimental techniques that are used to investigate motor learning in humans. Chapter 3 is a report of an investigation of the issues of interference and consolidation in an isometric target acquisition task. Exposure to a 30° counter-clockwise (CCW) rotation was followed by a period of rest, trials with no rotation, or trials with a 60° clockwise (CW) rotation. Retention of the initial adaptation was assessed 5 hours later. Full interference was manifested in circumstances in which either counter-rotated or non-rotated trials were encountered following the initial learning period. These results are consistent with the view that the observed interference is anterograde in nature, and highlight differences in the mechanisms employed by the CNS when compensating for novel kinematics (e.g. visuomotor rotations) compared with adapting to novel dynamics (e.g. external forces). Chapter 4 is a report of an investigation of the role of visual feedback in adapting to novel visuomotor environments in an isometric target acquisition task. Following trials with no rotation, participants adapted to a 60° CCW visuomotor rotation before returning to the non-rotated condition. Separate groups received either continuous visual feedback (CF) of cursor position during task execution or post-trial visual feedback (PF), both indicating task performance. One CF group were instructed to make any (feedback) modifications necessary during the task to reduce errors and acquire the target, while another CF group were instructed to make uncorrected, ballistic movements. Colour cues permitted the identification of the task environment (nonrotated/ rotated) on every trial. The results indicate that an automatic recalibration of the visuomotor mapping occurs when CF is provided, and suggest that performance improvements with PF may occur via the adoption of a cognitively mediated strategy. Furthermore, execution of feedback motor commands to correct errors did not enhance the adaptation that occurred when CF was provided, indicating that the perception of sensory errors (and not feedback commands that may be applied to reduce those errors) drives feedforward visuomotor adaptation. To investigate whether additional proprioceptive feedback associated with movement altered the adaptation patterns observed in chapter 4, a study similar to that reported in chapter 4 was undertaken, and is reported in chapter 5. In this instance a discrete, goaldirected, movement task replaced the isometric task. Subjects were deprived of vision of their arm, but were provided with PF or CF indicating task performance. The patterns of adaptation noted in the isometric task were also exhibited in this dynamic task, indicating that the timing of the visual feedback of task performance has a profound effect on how performance improvements in a novel visuomotor rotation occur. The experiment reported in Chapter 6 assessed the ability to adapt to two conflicting visuomotor rotations interleaved within the same training period, when each task variant (rotation) could be identified by contextual (colour) cues. While full dual adaptation was not observed, the results suggest that the colour cues may have been utilised to explicitly select distinct motor commands for each task rotation.

Stroke is a rapidly increasing disease worldwide, and speech and language impairments are common in stroke patients. A patient’s ability to speak, listen, read and write is reduced after stroke which affects the patient's independently living and quality of life. After an initial evaluation at the hospital, the stroke survivors are referred to the stroke rehabilitation centre where the speech therapists assist them in their challenging and long journey towards speech and language relearning. To enhance the patient's quality of life and to facilitate the speech therapists, technology-enhanced systems can play an important role. However, the currently used software applications such as online speech and language relearning applications are not specifically designed after the user’s need, and the user’s participation and empowerment are compromised. Medical caregivers and stroke patients are the main stakeholders and potential users of these software applications. Therefore, this study is aimed to understand the medical caregivers and the stroke patients’ needs for technology-enhanced speech and language relearning from medical caregivers’ viewpoint.  Design science research strategy was adopted to create, implement and evaluate the artefact. Some important stakeholders such as speech therapists, a stroke specialist doctor, information and technology professionals and one stroke survivor participated in this study. Following the speech therapist’s expert opinion, an application for speech and language assessment was developed as an artefact. The application was then evaluated for technology acceptance with the speech therapists. The Unified Theory of Acceptance and Use of Technology (UTAUT) was used as the theoretical foundation for making the interview questions and data analysis.  The user's requirements for software application differ from one patient to another depending upon the patient's overall health after stroke, their age, social life, the level of speech and language loss, and previous experience with technology use. Stroke is common in adults and adults like to participate in designing their relearning process; therefore, adults should be involved in deciding the learning objectives, and adult learning principles are helpful to understate their needs for speech and language relearning. Due to impaired physical and cognitive conditions, the patients need a bigger interface with larger fonts and pictures and more constructive colours than usual. Tablets with touch pens are preferred hardware. The speech therapist should have the possibility to change the exercises runtime according to the patient's abilities and stamina to do the exercises.  The technology acceptance evaluation showed that the developed application was easy to use and efficient for speech therapists. The study participants also highlighted some critical issues for better usability and technology acceptance. The application should be synchronized with speech therapists’ existing workflow and routines, and it should directly be connected to the hospital records system so that the patients’ data can easily be transferred to their journals.  The role of facilitating conditions such as proper education and training about the system, and personalised support is also important in technology acceptance. The user’s trust in the system’s security and privacy and their personal integrity were also highlighted as main determinants for technology adoption and use. To achieve better coherence between the users and technology, all the tasks/exercises and sub-tasks in the application should be designed in close collaboration with speech therapists and stroke patients. Due to the Covid-19 pandemic, only one stroke survivor was interviewed in this study. However, the patients’ perspective is of utmost importance, and in future research, they will be involved in the design and development of such technology-enhanced systems.