Different Faces of Variability in the Adaptive Process of Motor Skill Learning.

This study investigated the variability by considering an action programme as hierarchically organized, which reconciles invariant and variant features of motor skills at the macro- and microstructural level of analysis. It was assumed that invariant aspects of skilled actions express the macrostructure and therefore measures of sequencing, relative size, relative timing, relative force and relative pause time. The microstructure was related to the variant aspects so that total size, total movement time, total force, and total pause time were selected as its measures. These propositions were tested in an experimental design comprised by three learning phases: a stabilisation phase that entailed a given number of trials to achieve the functional stabilization on a graphic task, followed by transfer and retention phases. In the transfer phase, the graphic task was modified to yield different demands upon skill reorganization. Two such modifications demanded parametric changes (i.e. microstructure changes), in which graphic size and drawing speed were altered. Another modification demanded structural alterations (i.e. macrostructure change), in which drawing was changed. Overall, results supported the main predictions by showing that parametric changes in the task affected the microstructure, but did not affect the macrostructure consistently. Furthermore, a structural change affected both macro- and microstructure.

Integrating fundamental movement skills in late childhood.

The study examined how children of different ages integrate fundamental movement skills, such as running and throwing, and whether their developmental status was related to the combination of these skills. Thirty children were divided into three groups (G1 = 6-year-olds, G2 = 9-year-olds, and G3 = 12-year-olds) and filmed performing three tasks: running, overarm throwing, and the combined task. Patterns were identified and described, and the efficiency of integration was calculated (distance differences of the ball thrown in two tasks, overarm throwing and combined task). Differences in integration were related to age: the 6-year-olds were less efficient in combining the two skills than the 9- and 12-year-olds. These differences may be indicative of a phase of integrating fundamental movement skills in the developmental sequence. This developmental status, particularly throwing, seems to be related to the competence to integrate skills, which suggests that fundamental movement skills may be developmental modules.

Modularity and hierarchical organization of action programs in children's acquisition of graphic skills.

The organization of actions is based on modules in memory as a result of practice, easing the demand of performing more complex actions. If this modularization occurs, the elements of the module must remain invariant in new tasks. To test this hypothesis, 35 children, age 10 yr., practiced a graphic criterion task on a digital tablet and completed a complex graphic task enclosing the previous one. Total movement and pause times to draw the figure indicated skill acquisition. A module was identified by the variability of relative timing, pause time, and sequencing. Total movement to perform the criterion task did not increase significantly when it was embedded in the more complex task. Modularity was evidenced by the stability of relative timing and pause time and sequencing. The spatial position of new elements did not perturb the module, so the grammar of action may still have been forming.

Leg preference and interlateral asymmetry of balance stability in soccer players.

To examine the effect of long lasting practice on pedal behavior in sport, we compared experienced adult soccer players and nonsoccer players on leg preference in motor tasks requiring general mobilization, soccer related mobilization, and body balance stabilization. We also evaluated performance asymmetry between the right and left legs in static and dynamic unipedal body balance, based on center of pressure displacement, and correlated that with leg preference in balance stabilization tasks. Results revealed (a) a distinct leg preference between mobilization and stabilization tasks, which were significantly different between players and nonplayers, (b) similar balance stability between the right and left legs, (c) greater stability of experienced players compared with nonplayers in static and dynamic balance, and (d) absence of a significant leg preference correlation with interlateral balance asymmetry. These results suggest an effect of extensive soccer skill practice on establishing leg preference for specific mobilization tasks and overall balance control.

Relative frequency of knowledge of results and task complexity in the motor skill acquisition.

The aim of this study was to investigate the effects of knowledge of results (KR) frequency and task complexity on motor skill acquisition. The task consisted of throwing a bocha ball to place it as close as possible to the target ball. 120 students ages 11 to 13 years were assigned to one of eight experimental groups according to knowledge of results frequency (25, 50, 75, and 100%) and task complexity (simple and complex). Subjects performed 90 trials in the acquisition phase and 10 trials in the transfer test. The results showed that knowledge of results given at a frequency of 25% resulted in an inferior absolute error than 50% and inferior variable error than 50, 75, and 100% frequencies, but no effect of task complexity was found.