Manipulating generalized motor program difficulty during blocked and random practice does not affect parameter learning

Blocked practice engenders more trial-to-trial response stability, which is thought to be crucial for developing the generalized motor program (GMP) but not parameter learning (Lai, Shea, Wulf & Wright, 2000). It was hypothesized that reducing the difficulty of the the GMP might permit additional cognitive resources to be allocated to learning the parameter requirements. However, GMP theory maintains the independence of the memories governing the GMP and parameters. This notion suggests that manipulating the difficulty of the GMP should have no effect on the blocked practice participant's ability to successfully specify the appropriate parameters. Participants learned a simple or complex relative timing pattern under either blocked or random practice conditions. Smaller GMP errors were exhibited for the simple relative timing patterns, but this was not associated with improvements in parameter specification following blocked practice. A clear advantage for parameter specification was evident in transfer following random practice. Taken together, these data support the theoretical separation of the GMP and parameter processes.