Generalized motor program and parameter learning: Effects of knowledge of results and practice variabilit

Six experiments examined the effects of knowledge of results (KR) on motor learning. Experiments 1 and 2 utilized a similar experimental paradigm as that of Winstein and Schmidt (1990) to investigate KR frequency effect in constant practice. The results of both experiments indicated reduced KR frequency in constant practice did not enhance learning relative to 100% KR, and thus did not support the guidance hypothesis and the conclusion of Winstein and Schmidt (1990). Experiments 3, 4, 5, and 6 utilized the same sequence-key-press task. Specifically, Experiment 3 investigated the effect of reduced KR frequency on generalized motor program (GMP) learning in constant and variable practice. It replicated those of Wulf, Lee, and Schmidt (1994) on GMP learning in variable practice and extended the investigation to constant practice. The analysis indicated reduced KR frequency enhanced GMP learning for variable practice but not for constant practice. Response stability in acquisition appeared to contribute this differential effect. Specifically, reduced KR frequency in variable practice promoted GMP response stability in acquisition and resulted in better learning in retention and transfer. Constant practice produced a powerful effect on increasing response stability, and thus reduced KR frequency did not have an additional effect on constant practice. In addition, compared to constant practice, variable practice enhanced parameter learning in a transfer test that was consistent with the practice variability hypothesis, but degraded GMP learning. The differential effects on GMP and parameter by practice variability further suggested the separation of the two learning levels. Experiment 4 revealed that bandwidth KR had a similar effect as reduced KR frequency and suggested GMP was relatively unaffected after the consolidation of relative timing structure in early acquisition. Experiments 5 and 6 investigated methods to optimize GMP and parameter learning. The differential effect on GMP and parameter learning required the combination of practice conditions in order to maximize GMP and parameter learning. The results indicated that constant-variable practice, with constant practice in the first half of acquisition (developing relative timing structure) and variable practice in the second half (increasing parameter association), optimized both GMP and parameter learning.