Doctor of Philosophy in Kinesiology (PhD)
Motor system involvement in action observation
Sport development pathways, women's and men's soccer, action observation and prediction, observational learning of perceptual motor skills, optimizing practice conditions through practice manipulations and instructions, motor skill expertise and associated processes
Interest and experience in experimental psychology/working in labs where experimental research is conducted, particularly with a behavioural focus.
Strong grades and experience in statistics and research methods
Excellent grades in motor behaviour courses (motor control, motor learning, motor development...) and /or attention and memory, neuroscience courses related to motor control and learning, vision and perception.
Experience with programming software (such as Labview/Matlab/eprime or online experimental platforms)
Experience with motion analysis, data processing
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Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
The goal of this dissertation was to study the impact of a co-learner on individuals’ motor performance, learning, and perceptions of the practice experience. In Experiment 1, we introduced “concurrent” practice, where partners practiced and observed one another simultaneously. Concurrent practice promoted movement coupling within pairs and was perceived as more interfering than individual and turn-taking practice of a balance-related task. However, these differences did not impact error during practice or testing. In Experiment 2, we studied whether matching or mismatching a partner is better for multi-skill learning. Partners practiced the same or different golf-putting skills in alternation. Although contextual interference would be higher for the mismatched group, mismatching did not modulate performance in practice or retention compared to matching or pure physical practice. In Experiments 3–5, we studied multi-skill learning when learners have control over how to practice. Experiment 3 tested self- versus peer-directed practice, when one partner practiced and the other passively observed or made task-switching decisions for the performer. Both self- and peer-schedulers made performance-dependent decisions, choosing to switch tasks based on timing error. Although peer-schedulers chose to switch more frequently, the groups did not differ in retention. In Experiments 4 and 5, we assessed the impact of a partner on self-directed practice choices, when partners switched turns after 9-trial blocks or after every trial. Self-directed learners showed partner-dependent practice, with the partner’s practice impacting sequence selection and switching frequency. Importantly, self-directed learners did not sacrifice the performance-dependent nature of their task-switching, suggesting that some practice behaviours are resistant to a partner’s practice while others are susceptible to modulation. Overall, this dissertation provides evidence that practice in pairs influences the practice decisions/behaviours of learners and provides efficiency benefits, as two people can be trained in the time otherwise devoted to one learner. However, practice in pairs did not improve learning compared to practice alone. Merely practicing with a partner, even if they exert some influence on decisions, was not enough to yield motor learning benefits for the individual. There is a need for well-powered studies to explore the conditions which might promote such benefits.
A multivariable measurement approach was used to determine relationships between talent development pathways in soccer and outcomes related to future elite success, soccer skill ratings and motivation. In Study 1, elite “Academy” youth soccer players in the UK were followed over 5-years to ascertain the developmental activities that distinguished players which progressed to youth and adult professional levels. Professional players followed an early majority engagement pathway characterized by predominant involvement in high volumes of soccer practice and play (i.e., self-led activities) from an early age. They participated in other sports but the majority time was in soccer. Adult professional players accumulated more hours in soccer play compared to youth professionals, but not practice. In Study 2, coach ratings of soccer skills were related to attainment of youth and adult professional status. Coach ratings of technical, tactical and creative skill were higher in players that achieved professional youth status, versus de-selected academy players. Only tactical skill, and somewhat, technical skill, differentiated adult from youth professionals. Technical and tactical skill ratings were primarily related to hours in soccer practice, but there were no relations to hours in play. In Study 3, practice amounts were related to markers of self-determined motivation (SDM) but soccer play hours were not related to SDM. Through comparisons with recreational, age-matched soccer players, SDM was shown to become less self-determined from 15 -17 yr, but only among elite players. In Study 4, the developmental pathways engaged in by elite (National-team) and sub-elite (Varsity) adult women soccer players were assessed. National players followed an early majority engagement pathway, engaging in more soccer play than sub-elites, which was also rated as more challenging. In summary, success in elite soccer is characterized by an early, majority engagement pathway consisting of early childhood involvement in soccer, relatively high volumes of practice and play, and majority time in soccer, in comparison to other sports.
Though acknowledged to play a role in motor learning, motivation was thought to mainly exert temporary energizing effects on performance. More recently, motivational-related factors have been shown to impact motor learning more directly. Perceptions of success, somewhat independent of actual success and errors in practice, have impacted what learners retain over time. The aim of my thesis was to study how motor learning is affected by the subjective perceptions of errors and success over the course of learning and to test between competing theories and mechanisms which might underlie such advantages. In Studies 1-3, I manipulated dart-throwing practice difficulty by varying distance progressions (near-to-far/easy-to-difficult or far-to-near) and target size (large or small). These manipulations had no impact on performance or learning in all three studies, despite the fact that in Studies 2 and 3, perceptions of success had changed (i.e., perceived self-efficacy and competency). Due to the saliency of veridical error feedback (i.e., actual landing position), which could have moderated the effects of target size manipulations and the variability inherent in dart throwing accuracy, in Studies 4 and 5 I switched to study learning on a balance task. I manipulated the criteria used for feedback about success (accuracy) and compared groups that differed on the stringency of this criteria (fixed across practice or increasing/decreasing). Neither absolute changes to feedback, nor changes in the stringency affected behavioural measures of learning. Study 5 was a replication and extension of a well-cited study claiming benefits for comparative (better or worse than average), success-related feedback. Despite our ability to successfully change competency perceptions and intrinsic motivation, I did not replicate the behavioural results in terms of improved learning. Overall, these studies do not support predictions emanating from current theories about errors, success and learning (i.e., OPTIMAL theory and reinvestment theory). For success manipulations to impact learning behaviours, it is likely that tasks or groups are required where motivation to do well is low to start and/or no other performance indicators are present. Given these current data, I would recommend that efforts be directed to learning improvements through changes to actual behaviours, rather than perceptions.
The overarching aim of this thesis was to further understand the processes and internal representations involved in predicting action outcomes, by manipulating information sources during learning and prediction. Growing evidence suggests that the human motor system is activated during action observation, such that motor representations are invoked, through simulative processes that help facilitate an understanding of the unfolding action. In this work, we employed a design that manipulated visual and motor influences during learning and prediction, to try to understand; a) the types of internal representations acquired during practice, and b) how, and under what conditions, these representations are activated during prediction, and, more specifically, the conditions under which action prediction can come about through either visual- or motor-based mechanisms. In Experiment 1 we found that a group that learned to throw darts without vision of the action performed as well, on a post-practice prediction task, as a group that practiced with full vision. These results suggested that motor practice was key to learning the skill, and vision appeared not to be important. However, it was unclear whether motor representations were formed during practice, and then simulated during action prediction, or that visual representations were formed during practice and later compared to the visual input through a perceptual matching process. In Experiment 2 we found that an incongruent secondary motor task interfered with the prediction process, reducing prediction accuracy of experts to the level of a novice with no motor experience with the task. These results implied that motor system activation was responsible for prediction accuracy, by simulating established motor representations within the observer. In Experiment 3, results showed that a group that trained physically, significantly improved their prediction accuracy, but performed at a pre-training level while engaging in an effector-specific, incongruent secondary motor task during prediction. In contrast, a perceptually trained group also significantly improved their prediction accuracy after practice, but did not exhibit any modulation of prediction accuracy while engaged in the secondary motor task. These results suggest that action prediction can be mediated by different processes, one motor-based and one visually-based, depending on type of training.
No abstract available.
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
Previous studies have provided evidence consistent with the proposal that people “simulate” observed actions, based on their own motor experiences, to help predict the outcome of others’ actions. This simulation is believed to be based on low-level activation of the observer’s motor system at the time of the decision. In this experiment, we tested how closely people’s motor experiences influence their ability to predict action outcomes and whether these experiences generalize to predicting outcomes of novel stimuli. To do this, we manipulated the experiences (and therefore, the type of internal model formed during physical practice), by asking people to practice throwing darts with or without a wrist weight. Participants were asked to predict outcomes of people throwing under opposite or the same conditions as those experienced during practice. Although we showed evidence that prediction ability is specific to one’s practice experience, this was only seen in people who physically practiced without a weight and not for people who physically practiced with a wrist weight. The contribution of the motor system to these predictive decisions was also assessed by secondary-motor tasks designed to probe motor system involvement during prediction. Although we showed that predicting dart outcomes while wearing a wrist weight aided prediction accuracy, this was only observed in people who physically practiced without a weight. Contrary to previous studies, we were unable to show interference from a secondary, incongruent movement task (light press on a force gauge) after physical practice. Both physical and perceptual practice resulted in improvement in prediction accuracy post-practice, although this was strongest for the no-weight physical practice group. Overall, these data provide evidence that physical practice transfers to improvement in perceptually-driven predictive decisions. However, although the secondary tasks gave some evidence that prediction was dependent on the motor system (when holding a weight), and that the type of motor experience (weight or no-weight) impacts predictive decisions, evidence for motor simulation was not shown. Limits of the current methods are discussed.
In this thesis I investigate how people adapt manual aiming in novel visual-motor environments and how different adaptation processes (implicit/explicit) depend on feedback type, and existing internal models (action experience). How implicit and explicit processes interact to facilitate accurate performance in adaptation paradigms is debated. One key study concluded that implicit adaptation, driven by error in expected sensory consequences, guided adaptation independent of ‘correct’ strategic/explicit processes (Mazzoni & Krakauer, 2006). We hypothesized that if these processes are independent, later explicit re-adaptation should not influence a previously acquired implicit adaptation (evidenced by unchanged after-effects). In Experiment 1, numeric post-trial knowledge of results (KR) was used to promote explicitly-guided, re-adaptation of an implicit adaptation. Thirty participants gradually adapted aiming movements to a 30° CW visual rotation to achieve implicit adaptation (evidenced by strong after-effects). Participants practiced again with correct or incorrect (+/-15°) KR about cursor endpoint accuracy while still receiving correct cursor feedback. The incorrect KR groups showed the highest variable error, indicative of error-reducing strategic adjustments. Only the +15° error group re-adapted to KR. This resulted in larger after-effects than before KR exposure. If KR engaged only explicit processes, these results would suggest that these processes are interdependent, whereby an (implicit) internal model for aiming was updated by explicit processes, resulting in augmented after-effects. Despite existing evidence suggesting that post-trial KR facilitates only explicit adaptation, we had to test this result in our research design before concluding that the effects of KR were unique to re-adaptation. Therefore, we conducted Experiment 2 to determine whether post-trial KR could be used to update internal models for aiming without previous visual-motor experience. Thirty participants gradually adapted to a 30° CW visual rotation receiving either concurrent or post-trial cursor feedback, or post-trial numeric KR. Although all groups showed after-effects following practice, suggesting implicit adaptation in all feedback conditions, the magnitude of after-effects was smaller for the numeric KR group. From these data we conclude that numeric KR results in both implicit and explicit adaptation and that the relative contributions of these processes to adaptation likely depends on self-attribution of errors and timing of visual feedback.
Based upon postulates derived from the Developmental Model of Sports Participation (Côté et al., 2012) we tested the effects of domain specific activities (play and practice), as well as sporting diversity during the sampling years, on the development of motivation, passion and skill ratings. The first component of our study required testing predictions that play and diversity during the sampling years (age 5-12 yr) were positively correlated with intrinsic motivation and passion. We questioned elite youth level soccer players (N= 148), across 3 age groups, who were on the pathway towards achieving professional status at the adult level. Overall, we found no significant correlations between play and early sporting diversity during the sampling years with scores of motivation or passion. A small, yet significant positive correlation was observed between accumulated hours in soccer practice and integrated regulation. However, independent analysis of age groups yielded significant negative correlations between hours accumulated in soccer practice and measures of intrinsic motivation (Under 15 yr) and harmonious passion (Under 17 yr). The second study component investigated associations between time spent in soccer activities during the sampling years and across participants’ full careers as well as sporting diversity with coach ratings of skill. For the U17 group, hours accumulated in organized practice were related to creative and overall skill, while accumulated hours in soccer practice were related to technical skill for the U15 group. Moreover, for the U17 group, % accumulated hours in play negatively correlated with technical and overall skill ratings. The youngest group (U13) showed a different pattern of results to the older players, with more hours in play (% and total) related to creative skill. Due to these overall relationships, we conclude that recommendations towards early sporting diversity and more time in deliberate play activities (i.e., individually-led practice or play) should be treated with caution, because they do not inoculate against any hypothesized negative effects of early specialization in sport and are negatively related to predictors of skill (at least for the older players). Follow-up longitudinal analysis is recommended to determine how these practice and motivation variables are related to future success.
In two experiments, we tested whether non-task related variability, in the form of randomly administered mechanical perturbations during practice, would facilitate the acquisition of a novel two-handed coordination movement. There is considerable evidence in the motor learning literature showing that task-related variability, in the form of practice of variations of a skill or practicing skills in a more variable order, can benefit learning and transfer. Moreover, there is recent evidence that non-task related variability added to the learning process, termed differential learning, is beneficial to learning by simply providing a greater exploration of the dynamic environment. In both experiments, we failed to find evidence to support these predictions about the beneficial effects of non-task related variability. In Experiment 1, when variability was administered after a period of stabilization, and in the presence of performance enhancing feedback (i.e., a Lissajous display), no differences between a control group and a variability (perturbation) group were found in retention. This was despite significant improvements for both groups and evidence that the perturbations worked to increase variability later in practice for the perturbation group. In a second Experiment, we increased the amount of practice, changed the feedback display, and provided variability throughout practice. Despite these changes, externally added, mechanical perturbations added to the movement still failed to aid acquisition, retention or transfer. We conclude that this method of practice, when the variability is externally administered and not dependent on performance, fails to aid acquisition or facilitate long term retention or transfer of new motor skills. Therefore, variability, in and of itself, is not a sufficient variable to bring positive changes in performance and learning, considerations need to be made in regards to the difficulty of the task, the competence of the performer and the specific types of variability, in order to be beneficial.
It has been suggested that observational practice engages neural mechanisms for movement planning and execution similar to those engaged in physical practice. In three experiments we investigated observational practice during adaptation to a novel visuomotor environment. Participants were tested in the normal visuomotor environment before and after observation, and in the novel environment after observation. In the latter, learning would be seen by immediate performance benefits from watching. In the former, negative after-effects in the normal environment would suggest an updating of internal models based on the visuomotor discordance, arguably a more robust index of learning. In Experiment 1, observers showed benefits in the novel environment, but no after-effects. Because after-effects are believed to be a result of perceived discrepancies between sensory input and predicted sensory consequences, we hypothesised that observational practice might not engage covert simulation involving motor processes to the same degree as initially implied. To more thoroughly test this idea, in Experiment 2 we encouraged more active observation (or simulation) through conditions requiring imagery and error estimation. Despite these manipulations, only actors showed after-effects. In Experiment 3, a group of observers was also passively moved during observation, to determine whether the absence of after-effects was more linked to afferent feedback instead. However, this condition still failed to yield after-effects. A second observer group actively imitated the movements of the actor during observation but this group’s performance was not different from that of passive observers. Because the primary difference between actors and active-observers was the lack of self-generated visual reafference, these results strongly suggest that to update internal models, experiencing visual reafference of one’s own movement is critical. We speculate that learning might have been realized in observers via a more cognitive-strategic route, as compared to actors, based on data across the three experiments showing that observers acquired more accurate explicit knowledge about the direction and size of the visuomotor perturbation, compared to actors. In conclusion, it appears that doing and seeing engage different processes which in the case of visuomotor adaptation, result in different types of learning and learning outcomes for observers and actors.