Type of KR and KR frequency effects on motor learning

The effects of type of KR and KR frequency on the learning of a sequential timing task were examined. Subjects practiced three task versions that all had the same relative timing among movement segments, but differed with regard to the overall movement time (MT). KR was either presented in terms of the relative segment MTs or in terms of the absolute segment MTs, in addition to the overall duration. The type of KR was crossed with KR frequency in a 2 x 2 design. That is, subjects under both relative-timing KR and absolute-timing KR conditions were given KR either after every practice trial (100% KR) or after every other trial (50% KR). In a delayed retention test on the practiced task versions, type of KR and KR frequency produced additive effects, with relative-timing KR and a reduced KR frequency leading to more effective learning of the relative-timing structure than absolute-timing KR and KR after every trial. Transfer to task versions with the same relative timing but novel overall durations was facilitated by relative-timing KR, compared to absolute-timing KR, whereas the effect of the reduced KR frequency did not reach significance. When transfer to tasks with a new relative timing was required, however, the reduced KR frequency generally produced better relative timing performance than frequent KR. Overall, the results suggest that both reducing the relative frequency of KR and providing subjects with KR about relative timing can enhance the learning of the relative timing structure, or GMP learning. In addition, the present results demonstrate that a reduced KR frequency not only enhances learning of the practiced relative timing structure but also transfer to a new relative timing, compared to frequent KR.