Motor overflow and children's tracking performance: is there a link?

The aim of this study was to investigate the interaction of skill performance, motor overflow, and hand linkage in the form of mirror movements in a visual-manual tracking paradigm across practice trials. We hypothesized that both the amount of motor overflow and the degree of hand linkage would be linked in an inverse way to the quality of task performance. Furthermore, we expected a short-term decrease in both of these factors as children practiced and improved their task performance. Sixteen right-handed, 6-year-old children tracked a visual target with their right hand by pinching two parallel steel bars instrumented with strain gauges. The left hand was also positioned by similar instrumented steel bars to measure overflow/mirroring. At both the beginning and end of practice trials, a cluster analysis was used to determine relationships among performance, overflow, and hand linkage variables. In general, the results support the main hypothesis that the amount of motor overflow and the degree of hand linkage are linked to the quality of task performance, but the relationships between these variables across short-term learning are nonlinear. Copyright 1999 John Wiley & Sons, Inc.