Football penalty kicks are having increasing influence in today’s professional game. Despite this, little scientific evidence currently exists to ascertain the mechanisms behind performance failure in this task and/or the efficacy of training designed to improve penalty shooting. In a football penalty kick it has been reported that the majority of kickers do not look to the area they wish to place the ball; preferring to focus on the ‘keeper and predict anticipatory movements before shooting. Such a strategy seems counterproductive and contradictory to current research findings regarding visually guided aiming. Coordination of eye and limb movements has been shown to be essential for the production of accurate motor responses. A disruption to this coordination not only seems to negatively affect performance, but subsequent motor responses seem to follow direction of gaze. Thus, where the eyes lead actions tend to follow. In study 1, ten participants were asked to kick a standard sized football to alternate corners of a goal, whilst looking centrally and whilst looking where they intended to hit. This disruption of eye-limb coordination brought about a 15% reduction in kicking accuracy. When participants were asked to fixate centrally, their shots hit more centrally (17cm) than when they were allowed to look where they intended to hit. These results were in spite of no significant differences between the number of missed shots, preparation time and ball speed data across conditions. We concluded that centrally focused fixations dragged resultant motor actions inwards towards more central target locations. Put simply, where the eyes looked shots tended to follow. The second study sought to test the predictions of attentional control theory (ACT) in a sporting environment in order to establish how anxiety affects performance in penalty kicks. Fourteen experienced footballers took penalty kicks under low- and high-threat counterbalanced conditions while wearing a gaze registration system. Fixations to target locations (goalkeeper and goal area) were determined using frame-by-frame analysis. When anxious, footballers made faster first fixations and fixated for significantly longer toward the goalkeeper. This disruption in gaze behaviour brought about significant reductions in shooting accuracy, with shots becoming significantly centralized and within the goalkeeper’s reach. These findings support the predictions of ACT, as anxious participants were more likely to focus on the “threatening” goalkeeper, owing to an increased influence of the stimulus-driven attentional control system. A further prediction of ACT is that when anxious, performers are more likely to be distracted, particularly if the distracter is threat related. When facing penalty kicks in football (soccer), goalkeepers frequently incorporate strategies that are designed to distract the kicker. However, no direct empirical evidence exists to ascertain what effect such visual distractions have on the attentional control, and performance, of footballers. In the third study, eighteen experienced footballers took five penalty kicks under counterbalanced conditions of threat (low vs. high) and goalkeeper movement (stationary vs. waving arms) while wearing eye-tracking equipment. Results suggested that participants were more distracted by a moving goalkeeper than a stationary one and struggled to disengage from a moving goalkeeper under situations of high threat. Significantly more penalties were saved on trials when the goalkeeper was moving and shots were also generally hit closer to the goalkeeper (centrally) on these trials. The results provide partial support for the predictions of attentional control theory and implications for kickers and goalkeepers are discussed. The previous studies showed that anxiety can disrupt visual attention, visuomotor control and subsequent shot location in penalty kicks. However, optimal visual attention has been trained in other far aiming skills, improving performance and resistance to pressure. In study 4, we therefore asked a team of ten university soccer players to follow a quiet eye (QE; Vickers, 1996) training program, designed to align gaze with aiming intention to optimal scoring zones, over a seven week period. Performance and gaze parameters were compared to a placebo group (ten players) who received no instruction, but practiced the same number of penalty kicks over the same time frame. Results from a retention test indicated that the QE trained group had more effective visual attentional control; were significantly more accurate; and had 50% fewer shots saved by the goalkeeper than the placebo group. Both groups then competed in a penalty shootout to explore the influence of anxiety on attentional control and shooting accuracy. Under the pressure of the shootout the QE trained group failed to maintain their accuracy advantage, despite maintaining more distal aiming fixations of longer duration. The results therefore provide only partial support for the effectiveness of brief QE training interventions for experienced performers. This series of studies are the first to explore the gaze behaviour of football penalty takers in a quest to uncover and understand anxiety’s negative influence on attentional control and performance. They are also the first to explore the efficacy of goalkeeper distractions and training in improving performance from both the goalkeeper’s and kicker’s perspective. The results of these studies conclude that when anxious, penalty takers show an attentional bias toward the ‘threatening’ goalkeeper that can be increased and utilised by a goalkeeper employing distraction techniques and that penalty takers do benefit, to some extent, from a gaze-based pre-shot routine

Human movements are remarkably adaptive, such that we are capable of completing movements in a novel environment with similar accuracy to those performed in a typical environment. Our ability to perform in these environments involves accurate processing of sensory feedback for online and offline control. These processes of control have been widely studied for well learned actions, but not for actions in a novel visuomotor environment. In two experiments, we examined control processes underlying reaches when participants were first introduced to a visuomotor rotation (Experiment 1) and then following visuomotor adaptation (Experiment 2). All participants completed 150 reach training trials when (1) a cursor accurately represented their hand motion (i.e., aligned cursor) and (2) a cursor was rotated 45 degrees clockwise relative to their hand motion (i.e., rotated cursor). In Experiment 1, we sought to determine if the control processes underlying movements in typical and novel visuomotor conditions were comparable. Participants (n = 16) received either continuous visual feedback or terminal visual feedback regarding movement endpoint during reach training. Analyses revealed that participants were able to demonstrate similar outcomes (i.e., movement time and endpoint errors) regardless of visual or cursor feedback, but also demonstrated more offline control (i.e., took more time planning and were less consistent in initiating their movements) when reaching with a rotated cursor compared to an aligned cursor, even at the end of training. Together, the results suggest a greater contribution of offline control processes and less effective online corrective processes when reaching in a novel environment compared to when reaching in a typical environment. In attempt to promote online corrective processes, participants (n = 16) in Experiment 2 first completed the training trials with continuous visual feedback and then completed an additional 45 reaches under (1) slow movement time (i.e., Slow MT: 800-1000 ms) and (2) fast movement time (i.e., Fast MT: 400-500ms) constraints. Results showed a shift to online control (i.e., greater endpoint accuracy) when reaching with an aligned and rotated cursor, when sufficiently more time was provided (i.e., Slow MT). Specifically, participants were able to more effectively utilize visual feedback for online control under the Slow MT constraint compared to when reaching quickly (i.e., Fast MT). Together, these experiments demonstrate a flexibility in control processes underlying reaches with rotated visual feedback of the hand. In that reaches first engage in offline control processes during adaptation to a visuomotor rotation, and then shift to online corrective processes following visuomotor adaptation.

Flow is a mental state characterised by a feeling of energised focus, complete involvement and success when fully immersed in an activity. The dimensions of and the conditions required for flow to occur have been explored in a broad spectrum of situational contexts. The close relationship between flow and peak performance sparked an interest in ways to induce flow. However, any process of flow induction requires a measure to trace the degree to which flow is in fact occurring. Self-reports of the flow experience are subjective and provide ad hoc information. Psycho-physiological measures, such as EEG, can provide objective and continuous indications of the degree to which flow is occurring. Unfortunately few studies have explored the relationships between psycho-physiological measures and flow. The present study was an attempt to determine the EEG correlates of flow under conditions of peak performance. Twenty participants were asked to perform a continuous visuomotor task 10 times. Time taken per task was used as an indicator of task performance. EEG recordings were done concurrently. Participants completed an Abbreviated Flow Questionnaire (AFQ) after each task and a Game Flow Inventory (GFI) after having finished all 10 tasks. On completion, performance times and associated flow scores were standardised where after the sample was segmented into a high flow - peak performance and a low flow - low performance level. Multi-variate analysis of variance (MANOVA) was conducted on the performance, flow and EEG data to establish that a significant difference existed between the two levels. In addition, a one-way analysis of variance between high and low flow data was conducted for all variables and main effects were established. Inter-correlations of all EEG data at both levels were then conducted across four brain sites (F3, C3, P3, O1). In high flow only, results indicated increased lobeta power in the sensorimotor cortex together with a unique EEG pattern showing beta band synchronisation between the prefrontal and sensori-motor areas and de-synchronisation between all other areas, while all other frequencies (delta, theta, alpha, lobeta, hibeta, and gamma) remained synchronised across all scalp locations. These findings supported a theoretical neuropsychological model of flow. / Psychology / D. Com. (Consulting Psychology)

Lorsque le système nerveux central est exposé à une nouvelle association visuoproprioceptive, l’adaptation de la carte visuomotrice est nécessaire afin d’exécuter des mouvements précis. L’efficacité de ces processus adaptatifs correspond aussi à la capacité à les transférer dans des contextes différents de l’apprentissage de cette nouvelle association, par exemple dans de nouvelles régions de l’espace extrapersonnel (généralisation spatiale). Comme le contexte exerce une influence considérable sur les processus adaptatifs, les composantes multidimensionnelles de la tâche et de la perturbation pourraient constituer des éléments affectant considérablement l’adaptation et la généralisation spatiale. Ce mémoire présente une étude exploratoire de l’adaptation à une perturbation triaxiale, introduite graduellement, réalisée dans un environnement virtuel tridimensionnel et sa généralisation spatiale. Nos résultats suggèrent que les trois axes de l’espace présentent des différences importantes quant aux processus adaptatifs qui les sous-tendent. L’axe vertical présente à la fois une plus grande variabilité et de plus grandes erreurs spatiales au cours de l’adaptation comparativement à l’axe sagittal et à l’axe horizontal, tandis que l’axe sagittal présente une plus grande variabilité que l’axe horizontal. Ces différences persistent lors de l’effet consécutif, l’axe vertical affichant une désadaptation importante. Le test de généralisation spatiale montre une généralisation à l’ensemble des cibles, cependant, la généralisation semble plus faible le long de l’axe vertical. Ces résultats suggèrent que l’adaptation à une translation tridimensionnelle se généralise à travers l’espace le long des trois axes de l’espace et renforcent l’idée que le système nerveux central utilise une stratégie de décomposition modulaire des composantes de l’espace tridimensionnel. / We explored visuomotor adaptation and spatial generalization in the context of three-dimensional reaching movements performed in a virtual reality environment using a learning paradigm composed of four phases: pre-exposure, baseline, learning, and post-exposure (aftereffect and generalization). Subjects started by performing five reaching movements to six 3D memorized target locations without visual feedback (pre-exposure). Next, subjects performed twelve reaching movements to the learning target with veridical visual feedback (baseline). Immediately after, the 3D visuomotor dissociation (horizontal, vertical and sagittal translations) between actual hand motions and visual feedback of hand motions in the 3D virtual environment was gradually introduced (learning phase). Finally, subjects aimed at the pre-exposure and baseline targets without visual feedback (post-exposure). Although subjects were unaware of the visuomotor perturbation, they showed movement adaptation for each component of the triaxial perturbation, but they displayed reduced adaptation rate along the vertical axis. Subjects persisted in applying the new visuomotor association when the perturbation was removed, but the magnitude of this post-exposure shift was lower along the vertical axis. Similar trends were observed for movement aimed at pre-exposure targets. Furthermore, these post-exposure shifts were, on average, greater along the horizontal and sagittal axes relative to the vertical axis. These results suggest that the visuomotor map may be more adaptable to shifts in the horizontal and sagittal directions, than to shifts in the vertical direction. This finding supports the idea that the brain may employ a modular decomposition strategy during learning to simplify complex multidimensional visuomotor tasks.

La pratique physique a longtemps été perçue comme le déterminant premier de l’apprentissage du mouvement. Souvent exprimée par l’expression « Vingt fois sur le métier remettez votre ouvrage», cette idée se base sur l’observation qu’une grande quantité de pratique est nécessaire pour maîtriser un geste technique complexe. Bien que l’importance de la pratique physique pour l’apprentissage du mouvement demeure indéniable, il a récemment été démontré que les changements neurobiologiques qui constituent les bases de la mémoire prennent place après la pratique. Ces changements, regroupés sous le terme « consolidation », sont essentiels à la mise en mémoire des habiletés motrices. L’objectif de cette thèse est de définir les processus de consolidation en identifiant certains facteurs qui influencent la consolidation d’une habileté motrice. À l’aide d’une tâche d’adaptation visuomotrice comportant deux niveaux de difficulté, nous avons démontré qu’une bonne performance doit être atteinte au cours de la séance de pratique pour enclencher certains processus de consolidation. De plus, nos résultats indiquent que l’évaluation subjective que l’apprenant fait de sa propre performance peut moduler la consolidation. Finalement, nous avons démontré que l’apprentissage par observation peut enclencher certains processus de consolidation, indiquant que la consolidation n’est pas exclusive à la pratique physique. Dans l’ensemble, les résultats des études expérimentales présentées dans cette thèse montrent que la consolidation regroupe plusieurs processus distincts jouant chacun un rôle important pour l’apprentissage du mouvement. Les éducateurs physiques, les entraineurs sportifs et les spécialistes de la réadaptation physique devraient donc planifier des entrainements favorisant non seulement l’acquisition de gestes moteurs mais également leur consolidation. / Physical practice has long been regarded as the single most determinant factor of motor skill acquisition. Often expressed by the old adage “practice makes perfect,” this idea easily relates to the common observation that extensive practice is necessary to master complex motor skills. Although the importance of physical practice for motor skill learning is undeniable, recent evidence demonstrates that the neurobiological changes that constitute the foundation of memory occur after physical practice. Regrouped under the term “consolidation”, these changes are essential for the memory storage of motor skills. The objective of this thesis was to identify factors that influence motor skill consolidation. Using a visuomotor adaptation task with two levels of difficulty, we showed that a good performance must be attained during practice to trigger certain consolidation processes. In addition, our results indicate that the learner’s subjective evaluation of his/her own performance can also modulate consolidation. Finally, we showed that observation triggers consolidation processes, indicating that consolidation is not exclusive to physical practice. Together, the results presented in this thesis demonstrate that consolidation regroups several distinct processes that each plays an important role for motor skill learning. Physical education teachers, athletic coaches and rehabilitation specialists should therefore plan training schedules favoring not only motor skill acquisition but also motor skill consolidation.

De nombreuses situations modifient les coordinations sensorimotrices (e.g., croissance, pathologie, interfaces optiques ou mécaniques). Le système nerveux doit alors s’adapter afin de préserver la précision de ses interactions avec l’environnement. Si l’adaptation visuomotrice à une altération de la direction visuelle par prismes latéraux a été largement étudiée, les mécanismes de l’adaptation visuomotrice à une altération des distances apparentes sont en revanche peu connus. Ce travail regroupe une série d’études de psychophysique explorant les mécanismes de l’adaptation visuomotrice à une altération des distances apparentes, lors d’une exposition à court terme dans l’espace de préhension. L’altération des distances apparentes a été réalisée par modification de la vergence à l’aide de prismes à bases externes. La manipulation des retours visuels a permis de mettre en évidence trois niveaux d’adaptation. Le premier niveau concerne la modification des distances perçues liée à l’augmentation de la vergence tonique. Cette modification résulte de la potentiation musculaire extra-oculaire (EMP) induite par une convergence soutenue. Le second niveau implique la recalibration du signal altéré de distance dérivé de la vergence par les signaux proprioceptivo-moteurs du membre supérieur exposé. Le troisième niveau résulte d’une réorganisation des commandes motrices du membre exposé. Aucune adaptation proprioceptive du membre exposé n’a été retrouvée. La nature des composantes adaptatives à une altération des distances apparentes diffère de celle classiquement décrite pour l’altération de la direction visuelle impliquant essentiellement des composantes proprioceptive et motrice. La contribution des composantes adaptatives sensorielles est déterminée par la précision respective de la localisation spatiale fondée sur la vision et sur la proprioception, qui diffère en latéral et en profondeur. D’autre part, les aspects géométriques de la perception des distances fondée sur la vergence ont été explorés par comparaison de l’adaptation visuelle aux prismes à bases externes (augmentant la demande en vergence d’un angle constant pour toutes les distances de fixation) et au téléstéréoscope (multipliant la demande en vergence pour toutes les distances de fixation). Quel que soit le dispositif optique utilisé, l’adaptation visuelle a consisté en un effet consécutif ne dépendant pas de la distance d’observation, contrairement aux résultats prédits sur la base du signal de vergence. / There are numerous situations in which sensorimotor coordination is altered (e.g., growth, pathology, optical or mechanical interfaces). In such situations, the nervous system must adapt so that the organism continues to interact successfully with the environment. While visuomotor adaptation to visual direction alteration by lateral prisms has been widely studied, the mechanisms underlying visuomotor adaptation to alteration of apparent distance remain poorly known. We performed a series of psychophysical studies to explore the various components of adaptation to alteration of apparent distance. Base-out prisms were used to alter apparent distance by modifying vergence demand. By manipulating visual feedback, we were able to demonstrate three adaptation levels. The first level corresponds to changes in perceived distance related to tonic vergence. These changes result from eye muscle potentiation (EMP) induced by sustained vergence. The second level involves a recalibration of the altered distance signal derived from vergence by limb proprioceptive-motor signals. The third level results from a reorganization of motor commands of the upper limb used. No limb proprioceptive component was identified. The nature of adaptive components to apparent distance alteration differs from that described for visual direction alteration, which involves essentially proprioceptive and motor components. This difference can be attributed to differences in accuracy between proprioception and vision for localization in depth or in lateral directions. The geometrical aspects of distance perception based on vergence were also explored by comparing visual adaptation to base-out prisms (introducing an offset in vergence demand) and to a telestereoscope (multiplying vergence demand for all fixation distances). Regardless of which optic device was used, the recalibration of the relationship between the vergence signal and perceived distance consisted in a constant bias over distances.

La capacité de coordonner efficacement nos yeux avec nos mains est déterminante pour le succès de nos actions quotidiennes. En outre la capacité de prédire les conséquences sensorielles de nos propres actions est cruciale pour nos habilités motrices. Dans ce travail, à l’aide d’une tâche dans laquelle les participants doivent suivre avec leurs yeux une cible visuelle bougée par leur main, nous nous intéressons aux mécanismes prédictifs sous-tendant la coordination œil-main. Dans une première étude utilisant un protocole d’adaptation à une rotation visuomotrice, nous montrons que ces mécanismes prédictifs peuvent être mis à jour indépendamment de notre capacité à effectuer des mouvements précis de la main. Dans l’étude suivante nous cherchons à déterminer l’effet de la préférence manuelle, et montrons que malgré des différences évidentes en termes de précision concernant le contrôle manuel, la capacité d’anticiper les conséquences visuelles de nos actions reste identique que la cible soit bougée par la main droite ou gauche. Enfin, grâce à la stimulation magnétique transcranienne, nous testons l'hypothèse selon laquelle ces mécanismes prédictifs utilisent des signaux efférents de la main issus du cortex moteur primaire (M1). Nos résultats montrent que si cette contribution existe, elle doit se faire nécessairement en amont de M1. Au bout du compte nous proposons que la coordination œil-main soit sous-tendue par des mécanismes prédictifs similaires pour nos deux mains, situés vraisemblablement en amont de M1, et pouvant être mis à jour indépendamment du contrôle de la main. / The ability to coordinate efficiently eye and hand actions is central for humans in everyday activities. Furthermore it is argued that the ability to predict the sensory consequences of self-initiated movements is crucial for skilled motor behavior. Here by means of a task in which participants were asked to track with the eyes a visual target that was moved by their hand, we investigated the predictive mechanisms underlying eye-hand coordination. In a first study, using a protocol in which participants had to adapt to rotated hand visual feedback, we show that these predictive mechanisms can be updated independently of the ability to perform accurate hand movements. In a follow up study we tested the effect of hand dominance, and showed that, despite obvious differences in the accuracy of hand movement control, the ability to predict visual consequences of right and left hand actions was similar. Finally, by means of transcranial magnetic stimulation, we tested the hypothesis that those predictive mechanisms rely on hand efferent signals from the primary motor cortex (M1). However our results failed to support this view, and instead suggest that if such a contribution exists, it must be upstream of M1. Overall, we propose that eye-hand coordination relies on similar predictive mechanisms for both hands, possibly located upstream of M1, which can be updated independently of hand movement control.

La pratique physique a longtemps été perçue comme le déterminant premier de l’apprentissage du mouvement. Souvent exprimée par l’expression « Vingt fois sur le métier remettez votre ouvrage», cette idée se base sur l’observation qu’une grande quantité de pratique est nécessaire pour maîtriser un geste technique complexe. Bien que l’importance de la pratique physique pour l’apprentissage du mouvement demeure indéniable, il a récemment été démontré que les changements neurobiologiques qui constituent les bases de la mémoire prennent place après la pratique. Ces changements, regroupés sous le terme « consolidation », sont essentiels à la mise en mémoire des habiletés motrices. L’objectif de cette thèse est de définir les processus de consolidation en identifiant certains facteurs qui influencent la consolidation d’une habileté motrice. À l’aide d’une tâche d’adaptation visuomotrice comportant deux niveaux de difficulté, nous avons démontré qu’une bonne performance doit être atteinte au cours de la séance de pratique pour enclencher certains processus de consolidation. De plus, nos résultats indiquent que l’évaluation subjective que l’apprenant fait de sa propre performance peut moduler la consolidation. Finalement, nous avons démontré que l’apprentissage par observation peut enclencher certains processus de consolidation, indiquant que la consolidation n’est pas exclusive à la pratique physique. Dans l’ensemble, les résultats des études expérimentales présentées dans cette thèse montrent que la consolidation regroupe plusieurs processus distincts jouant chacun un rôle important pour l’apprentissage du mouvement. Les éducateurs physiques, les entraineurs sportifs et les spécialistes de la réadaptation physique devraient donc planifier des entrainements favorisant non seulement l’acquisition de gestes moteurs mais également leur consolidation. / Physical practice has long been regarded as the single most determinant factor of motor skill acquisition. Often expressed by the old adage “practice makes perfect,” this idea easily relates to the common observation that extensive practice is necessary to master complex motor skills. Although the importance of physical practice for motor skill learning is undeniable, recent evidence demonstrates that the neurobiological changes that constitute the foundation of memory occur after physical practice. Regrouped under the term “consolidation”, these changes are essential for the memory storage of motor skills. The objective of this thesis was to identify factors that influence motor skill consolidation. Using a visuomotor adaptation task with two levels of difficulty, we showed that a good performance must be attained during practice to trigger certain consolidation processes. In addition, our results indicate that the learner’s subjective evaluation of his/her own performance can also modulate consolidation. Finally, we showed that observation triggers consolidation processes, indicating that consolidation is not exclusive to physical practice. Together, the results presented in this thesis demonstrate that consolidation regroups several distinct processes that each plays an important role for motor skill learning. Physical education teachers, athletic coaches and rehabilitation specialists should therefore plan training schedules favoring not only motor skill acquisition but also motor skill consolidation.

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.

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.