1,721,214 research outputs found
Implicit motor learning promotes neural efficiency during laparoscopy.
Get PDFAn understanding of differences in expert and novice neural behavior can inform surgical skills training. Outside the surgical domain, electroencephalographic (EEG) coherence analyses have shown that during motor performance, experts display less coactivation between the verbal-analytic and motor planning regions than their less skilled counterparts. Reduced involvement of verbal-analytic processes suggests greater neural efficiency. The authors tested the utility of an implicit motor learning intervention specifically devised to promote neural efficiency by reducing verbal-analytic involvement in laparoscopic performance
Conscious monitoring and control (reinvestment) in surgical performance under pressure.
Get PDFResearch on intraoperative stressors has focused on external factors without considering individual differences in the ability to cope with stress. One individual difference that is implicated in adverse effects of stress on performance is "reinvestment," the propensity for conscious monitoring and control of movements. The aim of this study was to examine the impact of reinvestment on laparoscopic performance under time pressure
Information over function: a reappraisal of the perception-action model
No full textIn the influential perception-action model, the ventral visual system of the primate brain serves to obtain knowledge of objects in the environment, while the dorsal system serves to control actions in interaction with those objects. In recent years, criticism of the model has gained momentum following reports of evidence that involvement of the two systems may not principally depend on whether observers are engaged in action or perception tasks. This thesis appraises the perception-action model over the course of five experiments that test a number of the model’s central assertions. Evidence for an alternative functional characterization of the dorsal and ventral systems is obtained. Specifically, the evidence suggests that the dorsal system can be involved in both action and perception on the basis of fast egocentric information pickup, while the ventral system can be involved in both perception and action on the basis of slower allocentric information pickup. This raises the possibility that a more fundamental distinction pertains to the characteristics of information pickup by the two systems rather than to the behavioral functions subserved.
The thesis develops a stance in which involvement of the two systems in the visual guidance of behavior is dependent on their operational characteristics in combination with the constraints of the task. The proposed relevant task constraints are: (i) whether tasks allow for egocentric and/or allocentric information pickup, (ii) the amount of time that is available for information pickup in a task and, possibly, (iii) whether stimuli are located within or outside functional space (the space that affords action for an observer). Whether a task requires an immediate or a delayed response is of less importance. It is argued that while the typical requirements of perception and action tasks bring about a tight coupling between perception and the ventral system and action and the dorsal system, this coupling is not invariant; perception can involve fast egocentric information pickup and action can involve slower allocentric information pickup. The findings are discussed in the context of higher-level theories of visual perception. It is proposed that the view of the dorsal and ventral visual systems that is suggested by the findings presented in this thesis corresponds better with ecological than with constructivist approaches to visual perception.published_or_final_versionHuman PerformanceDoctoralDoctor of Philosoph
Thinking the unthinkable: physical activity behavioral change and propensity for rehearsal in Chinese children
No full textThe continued surge in childhood obesity rates globally has created much impetus for
researchers to develop intervention strategies effective in changing physical activity behavior
during childhood. Despite such interest there has been limited success, and very rarely have
cross-cultural applicability of these initiatives been considered. This thesis begins with an
examination of the applicability of a Western-modeled school-based intervention, America
on the Move, using pedometers and point-of-choice prompts in an attempt to change the
walking behavior of Chinese Hong Kong children (Chapter 2). To achieve this, the
intervention mapping protocol was followed. The process comprised three studies. First, health messages prompting walking behaviors were developed and tested for motivational
properties. Second, two piezoelectric pedometers were validated for our target population,
and finally, a 7-week pilot of the intervention using the validated health messages and
pedometers was implemented and evaluated among 8-12 year old Chinese Hong Kong
children.
The second part of the thesis took the unexpected results of the pilot intervention and
explored how a goal-related psychological construct, emotional rehearsal, which has been
associated with dysregulated health behaviors, may contribute to these. This part commences
with an overview of the conceptualization of rehearsal and presentation of a conceptual
model between stress and dysregulated health behavior mediated by the propensity for
rehearsal (Chapter 3). Three studies were then undertaken to examine the relationship
between rehearsal and dysregulated physical activity behavior. First, a Chinese version of the
Rehearsal Scale for children (RSC-C) measuring propensity of rehearsal in children was
adapted and validated for use in the subsequent two studies (Chapter 4). The second study
investigated the existence of pedometer reactivity and how this might interact with propensity
for rehearsal (Chapter 5). Lastly, the relationship between rehearsal and child health was
examined through an assessment of the propensity for rehearsal and central adiposity status.
Taken together, results of these empirical studies show promise in supporting the
proposition that the effectiveness of intervention strategies may be culturally bound via the
propensity for rehearsal and its link with cardiovascular health. Limitations of this thesis and
future research directions are explored in the final chapter.published_or_final_versionHuman PerformanceDoctoralDoctor of Philosoph
The attentional demands of implicit motor learning
No full textpublished_or_final_versionHuman PerformanceDoctoralDoctor of Philosoph
Application of implicit learning paradigm in voice motor learning
No full textThe production of sufficient speech intensity is a prerequisite for living a normal life. Mixed findings regarding the efficacy of different speech intensity interventions have been reported. Therefore, identification of optimal intervention paradigms for patients with low speech intensity is needed. One approach to this issue involves the application of principles of limb motor learning to the speech motor domain. Thus far, only a handful of studies utilising these principles of motor learning in the speech domain have been published, generally demonstrating promising results.
This thesis investigates the effects of two motor learning paradigms, error-reduced learning and subliminal feedback learning, in the area of voice motor learning. Additionally, we investigate whether long-term retention of voice motor learning is present after use of these paradigms. Chapter 2 identified the Just Noticeable Differences (JNDs) for discriminating subtle differences in a visual task associated with speech intensity. The JNDs were then used to investigate the effects of subliminal feedback learning in a speech intensity task in Chapter 3. Results indicated that it is possible to trigger adaptations of an individual’s motor behaviour (i.e., speech intensity) by subtle manipulations of the visual stimuli. Chapter 4, 5 and 6 investigated the effects of an error-reduced learning paradigm on voice motor learning. The experiments tested the efficacy of error-reduced training protocols for speech intensity control. The final chapter compared a combined JND error-reduced learning paradigm with a learning condition similar to a conventional voice treatment for enhancing speech intensity level.
In general, results demonstrated a significant increase in speech intensity. Unfortunately, significant long-term effects were not found and speech intensity returned back to baseline levels after 3 days. This thesis yields insights into the potentials of two implicit motor learning paradigms in the domain of voice motor learning. Directions for further research are indicated to enhance the retention of the learnt task.published_or_final_versionSpeech and Hearing SciencesDoctoralDoctor of Philosoph
Using EEG methodology to examine the effect of exercise induced fatigue on the direction of attention during motor skill performance
No full textExercise induced fatigue can have a negative impact on motor skill performance. While part of the decline is attributable to physiological factors that directly influence the coordination of movement, psychological factors may also contribute. Typically, motor learning environments encourage the accumulation of task-relevant declarative knowledge, which can be depended on to consciously support performance. The literature suggests that skills learnt in this way are vulnerable to demanding performance environments, including those in which the performer is fatigued. Recent empirical work has demonstrated that ‘implicit’ motor learning environments, devised to limit declarative knowledge buildup and/or dependence on working memory, promote resilient skill performance even after exhaustive fatigue protocols. Such findings imply that dependence on declarative knowledge to support motor skill execution may be a limiting factor under physiologically fatigue. However, it remains unclear the effect fatigue has on attentional resources, such as working memory.
Using established experimental paradigms and EEG methodology, a research project was designed to investigate. Two explanations were considered: (1) fatigue distracts attention away from the control of movement or (2) fatigue directs attention to the skill, which interferes with automated control of the movement. In this study novice participants were allowed to freely accumulate declarative knowledge before completing a targeted muscle-fatigue protocol. A probe response paradigm assessed participants’ ability to recall the position of movement at the time a tone sounded, under the assumption that better recall reflects skill-focused attention. Neural activity was monitored by wireless EEG technology. Neural co-activation (or coherence) between brain regions associated with motor planning (Fz or F3) and with verbal-analytical processing (T3) has been suggested to reflect conscious control of motor skills. Therefore, a fatigue induced increase in T3-F3 coherence can be interpreted as increased conscious involvement in movement control, whereas, a decrease suggests a shift of attention away from movement control. The data collected suggests that to some extent fatigue raises visual-spatial and verbal-analytical contributions to motor control, but highlights methodological issues and limitations of the work.published_or_final_versionHuman PerformanceMasterMaster of Philosoph
Examining the influence of marginally modified constraints on motor behaviour
No full textThe thesis examines the influence of visual misperceptions of the primary environmental constraints related to motor behaviour, and explores whether motor adaptation can be caused implicitly by introducing systematic, undetectable changes in key constraints in the performance environment. The first two experiments (Chapter 2) were conducted to determine if a simple manipulation of the height of the uprights can cause participants to perceive the dimensions of the rugby goalposts differently. The findings support the existence of a rugby goalpost illusion. Misperceptions of the dimensions of the goalposts may influence decisions about where to place the ball when converting a try. In Chapter 3, a series of experiments tested this hypothesis both in a laboratory setting and in real life games. Experiment 3 showed that narrow goalposts caused kickers to place the ball further from the try-line than wide goalposts. Furthermore, misperceptions of the uprights width induced by the rugby posts illusion caused kickers to place the ball differently when making kicks (Experiment 4). By introducing pitch-markings in Experiment 5, we tested whether the effect of the illusion is moderated by use of familiar cues in the environment. An observational study (Experiment 6) suggested that the influence of the rugby posts illusion, intimated in our experimental work, is not evident in real life. Both Chapters 4 and 5 were designed to examine whether very subtle changes in constraints in the environment can be used specifically to induce implicit motor learning. In Chapter 4, the smallest detectable difference between two levels of sensory stimulus was determined for simple line drawings representative of rugby goalpost uprights (Experiment 7) or crossbars (Experiment 8). The findings from Chapter 5 suggested that (implicit) motor adaptations might be caused by gradual incremental changes in environmental constraints.published_or_final_versionHuman PerformanceDoctoralDoctor of Philosoph
The role of movement specific reinvestment, fall efficacy and perception in walking and falling in community-dwelling older adultsin Hong Kong
No full textIn six experiments, the relationships between history of falls, reinvestment, fear of falling, perception, balance ability and walking ability of community-dwelling older adults was investigated. In addition, the Movement Specific Reinvestment Scale (MSRS) (Masters, Polman, & Hammond, 1993; Masters, Eves, & Maxwell, 2005) was further validated, using a Chinese version (MSRS-C). In the first experiment (Chapter 2), it was shown that elder fallers scored significantly higher than non-fallers on both the movement self-consciousness and the conscious motor processing components of the MSRS-C. The conscious motor processing component of the MSRS-C was found to discriminate previous faller from non-faller status. In the second experiment (Chapter 3), findings demonstrated that internal focus of attention was greater in elder repeat fallers and increased as task demands increased.
However, external focus of attention increased in both elder repeat fallers and elder non-fallers as task demands increased. Elder repeat fallers scored significantly higher than elder non-fallers on the MSRS-C. In the third and fourth experiments (Chapter 4), it was revealed that elder fallers demonstrated greater fear of falling and a higher propensity for movement specific reinvestment than non-fallers. Elderly people perceived stairs as steeper than they were and judged stairs as steeper when making visual-matching and verbal-report estimates that required conscious involvement compared to haptic estimates that are thought to require little conscious involvement. Overestimations when making explicit, conscious judgments were reduced by carrying out a concurrent secondary task during estimation, but there was little effect of the secondary task on implicit, non-conscious judgments of steepness. In Chapter 5, focus group work was conducted to investigate whether (1) elderly people respond differently when asked to complete the MSRS-C in respect of contexts that are not directly related to balance or locomotion and (2) elderly people are better able to differentiate a 4-point Likert response format when completing the MSRS-C than the original 6-point format. Experiment five (Chapter 6) further validated the MSRS-C based on the findings from Chapter 5. Results revealed that both the MSRS-C (general) and MSRS-C (walking) can be used with a six-point or a four-point response format to differentiate elderly Chinese fallers from non-fallers. The overall findings were discussed in the context of theories of motor learning and reinvestment. Implications for rehabilitation training were elucidated.published_or_final_versionHuman PerformanceDoctoralDoctor of Philosoph
Investigating the relationship among errorless motor training, motor performance, and visuomotor behaviors
No full textIn these seven studies, the relationships among errorless motor training, motor performance, and visuomotor behaviors were investigated. The first two studies in Chapter 2 recruited the healthy young (study 1) and older (study 2) adults to participate in the computer-based reaching task to explore the effect of errorless motor training on motor performance and gaze behaviors. Results revealed errorless motor training could increase fixation duration on target among both young and older adults, which implied that errorless motor training might successfully modify the visual selective attentional process to concentrate on the relevant information and neglect irrelevant visual distraction, differently from errorful and normal motor training. In Chapter 3, two studies aimed to investigate the errorless motor training effect on motor performance and gaze behaviors in the same computer-based reaching motor task as Chapter 2 under the simulated visual deficit by blocking parts of online visual feedback of hand-controlled mouse cursor among healthy young (study 3) and older (study 4) adults. It was found that errorless motor training decreased fixation duration among both young and older adults, indicating that errorless motor training might modify perceptual and attentional processes under a simulated visual deficit in this reaching motor task, differently from errorful and normal training. Chapter 4 assessed the influence on motor performance and gaze behaviors after taking errorless motor training in a daily-life reaching motor task among healthy young and older adults. It was revealed that errorless motor training improved motor performance by increasing movement accuracy and reducing movement variability, among both young and older adults in normal vision. In addition, errorless trainees conducted higher movement accuracy and less movement variability under the simulated visual deficit than errorful and normal trainees in the two age groups. Furthermore, errorless motor training decreased fixation duration among young and older adults. The errorless motor training may induce a multisensory reweighting by up-weighting on proprioception and down-weighting on vision to facilitate movement execution in the daily-life reaching motor task. Chapter 5 employed the errorless motor training in the Y balance reaching task (study 7), which focused on improving dynamic balance ability. Findings demonstrated that errorless motor training improved dynamic balance ability and proprioceptive ability significantly when compared with errorful and normal motor training. Also, fixation duration and eye activity on target decreased, which suggested the decreasing demand for visual information. The decreasing demand for visual information implied the down-weighting on vision for movement execution and further this down-weighting on vision was successfully compensated by up-weighting on proprioception. This multisensory reweighting by the down-weighting on vision and up-weighting on proprioception might contribute to improving dynamic balance ability in this Y balance reaching task. The overall findings imply that errorless motor training could contribute to the improvement of motor performance by successful modification of gaze behaviors, suggesting that errorless motor training may modify the perceptual and attentional processes to facilitate movement execution in different reaching motor tasks.published_or_final_versionPublic HealthDoctoralDoctor of Philosoph
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