Generalized motor program (GMP) learning: Effects of reduced frequency of knowledge of results and practice variability

The effects of reduced frequency of presentation of relative-timing knowledge of results (KR) on constant and serial practice and whether response stability is associated with increased generalized motor program (GMP) learning were examined. Participants (N = 40) were asked to sequentially depress 4 keys (2, 4, 8, and 6) on the numeric pad portion of the computer keyboard by using the index fingers of their right hands. The frequency (50% and 100%) with which relative-timing KR was presented was manipulated in constant and in serial practice conditions. The tasks used in both the constant and the serial conditions had the same relative-timing structure, but serial practice had 3 different absolute-timing requirements. The results, which indicated that reduced KR frequency enhances GMP learning in the serial practice condition, replicate the findings of Wulf, Lee, and Schmidt (1994). The reduced frequency of KR effect was not evident for the constant practice groups, however. More interesting was the finding that constant practice was significantly better than serial practice for the development and learning of the GMP. The data also showed that after either constant practice or reduced frequency of KR, response stability was enhanced in comparison with the stability of responses following serial practice and frequent KR. Those findings suggest that when response stability is improved either by reducing the frequency with which KR is presented or by reducing the number of task variations practiced, the development of the GMP is enhanced but parameter specification in transfer tasks tends to be degraded.