CHANGING COORDINATIVE STRUCTURES IN COMPLEX SKILL ACQUISITION

The present paper puts forward the concept of coordinative structures as a way to move from the dynamics of the behavioral outcome towards a characterization of what the subject is actually doing to achieve tha t outcome. In a discovery learning experiment, five subjects learned t o perform slalom-like movements on a ski apparatus over a 7-day period . Kinematics of body segments and apparatus were recorded in three dim ensions using an opto-electronic Selspot camera system. A stepwise ana lysis of the learning process was performed in terms of the platform d ynamics, the apparatus-subject interaction (i.e., dynamics of the rela tive phase between platform and centre of mass movements), end the sub ject (i.e., body configuration and the dynamics of the position of cen tre of mass). Results showed that stability, as indicated by phase pla ne measures, was established early in practice in movements of the pla tform, relative phase, and centre of mass. Later in practice, addition al changes were observed in the height and coefficient of variation of height of the centre of mass. These differences in the timing of chan ges suggest that learning can be interpreted as proceeding globally in three different 'stages'. The coordinative structure in each of the s tages is interpreted as a different instance of pendulum systems. At t he end of the paper, we contemplate the potential of low-dimensional, subject-related descriptions of complex movement behavior to advance n eurological models of movement control. (C) 1997 Elsevier Science B.V.