Self-organization aspects in the temporal formation of movement gestalts

From visuo-motor interactions to imitation learning: Behavioural and brain imaging studies

We review three areas of research and theory relating to the involvement of motor processing in action observation: behavioural studies on imitation learning, behavioural work on short-term visuomotor interactions, and related neurophysiological and neuroimaging work. A large number of behavioural studies now indicate bi-directional links between perception and action: visual processing can automatically induce related motor processes, and motor actions can direct future visual processing. The related concept of direct matching (Rizzolatti et al., 2001) does not, however, imply that observed actions are transduced into a corresponding motor representation that would guarantee an instant and accurate imitation. Rather, studies on the mirror neuron system indicate that action observation engages the observer's own motor prototype of the observed action. This allows for enhanced action recognition, imitation recognition, and, predominantly in humans, imitation and observational learning. Despite the clear impact of action observation on motor representations, recent neuroimaging work also indicates the overlap of imitation learning with processes of non-imitative skill acquisition.

Learning to detect error in movement timing using physical and observational practice

Three experiments assessed the possibility that a physical practice participant's ability to render appropriate movement timing estimates may be hindered compared to those who merely observed. Results from these experiments revealed that observers and physical practice participants executed and estimated the overall durations of movement sequences similarly and more accurately than those who were not privy to any previous practice. This was true for a case in which (a) the execution demands for the physical practice participant were relatively high when multiple movement sequences were practiced with a consistent relative time structure but different overall durations (Experiment 1) and (b) the execution demands were relatively modest when only a single sequential motor task was learned (Experiment 2). Moreover, this general set of findings remained true for individuals who had previous experience with physical or observational practice, even when timing estimations were made during tests with no execution demands (Experiment 3). Thus, executing a movement sequence does not appear to interfere with the development of a learner's subjective evaluation of overall timing performance. Specifically, these data provided evidence that recognizing error in movement timing can be accomplished via observation, and, more generally, they add to the growing evidence supporting the claim that observational practice is a legitimate method facilitating the acquisition of sequential movement behaviors.

The natural physical alternative to cognitive theories of motor behaviour: an invitation for interdisciplinary research in sports science?

This review examines the viability of the natural physical alternative to traditional cognitive modelling of the sport performer. It is concluded that the natural physical perspective offers an attractive framework for the study of movement control and co-ordination in sport, but, at present, does not seem capable of superseding cognitive explanations. As a consequence of the nature of the questions they are asking, natural physical theorists offer a significant avenue for interdisciplinary research in sports science. Significant differences in the philosophy underpinning both theoretical views are acknowledged, but growing support for an integrated approach to motor control is highlighted. A major task for sports scientists may be to verify empirically the nature of an integrated model of the sport performer.

A dynamical systems approach to skill acquisition

This paper argues that the answer to the question, what has to be learned, needs to be established before the question, how is it learned, can be meaningfully addressed. Based on this conviction, some of the limitations of current and past research on skill acquisition are discussed. Motivated by the dynamical systems approach, the question of "what has to be learned" was tackled by setting up a non-linear mathematical model of the task (i.e. learning to make sideways movements on a ski apparatus). On the basis of this model, the phase lag between movements of the platform of the apparatus and the actions of the subject was isolated as an ensemble variable reflecting the timing of the subject in relation to the dynamics of the apparatus. This variable was subsequently used to study "how" the task was learned in a discovery learning experiment, in which predictions stemming from the model were tested and confirmed. Overall, these findings provided support for the hypothesis, formulated by Bernstein (1967), that one of the important effects of practice is learning to make use of reactive forces, thereby reducing the need for active muscular forces. In addition, the data from a previous learning experiment on the ski apparatus--the results of which had been equivocal--were reconsidered. The use of phase lag as a dependent variable provided a resolution of those findings. On the basis of the confirmatory testing of predictions stemming from the model and the clarification of findings from a previous experiment, it is argued that the dynamical systems approach put forward here provides a powerful method for pursuing issues in skill acquisition. Suggestions are made as to how this approach can be used to systematically pursue the questions that arise as a natural outcome of the experimental evidence presented here.